JPH10209111A - Method and apparatus for manufacturing semiconductor device - Google Patents

Abstract

(57) [Problem] To provide a method of manufacturing a semiconductor device for removing adsorbed substances and the like on a silicon substrate surface after isopropyl alcohol vapor drying. SOLUTION: A silicon substrate that has been subjected to isopropyl alcohol vapor drying after hydrofluoric acid cleaning (hydrogen termination treatment) is subjected to desorption of terminal hydrogen at a temperature not lower than the peak intensity of isopropyl alcohol desorption intensity in a clean atmosphere. Heating is performed at a temperature lower than the temperature at the time of the intensity peak for a certain period of time to remove residual isopropyl alcohol and the like, and thereafter, an oxide film forming process and the like are performed. [Effect] Contaminants adsorbed on the substrate surface can be effectively removed without affecting the terminal hydrogen that stabilizes the silicon substrate surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a semiconductor device, and more particularly to a technique effective when applied to a surface treatment of a semiconductor substrate after vapor drying using isopropyl alcohol.

[0002]

2. Description of the Related Art In manufacturing a semiconductor device, a semiconductor substrate (wafer) is repeatedly washed and dried. As one method of drying a semiconductor substrate, for example, Japanese Patent Application Laid-Open No. 61-23 / 1986
As described in JP 7429, a vapor drying method using isopropyl alcohol (IPA) is known.

[0003] In this document, a semiconductor substrate is vertically arranged in the vapor of isopropyl alcohol, and alcohol is substituted for the cleaning liquid remaining on the surface of the semiconductor substrate to form organic droplets. A technique (vapor drying method) for drying the surface of a semiconductor substrate by utilizing the fact that a drop travels along a wafer surface and drops or evaporates is disclosed.

On the other hand, IEICE Technical Report, published by the Institute of Electronics, Information and Communication Engineers, ED96-13 (1996-0)
4), P91 to P96, describe "adsorption of IPA on solution-treated Si surface".

[0005] This document includes an H-terminated Si (100).
The surface is easier to adsorb organic substances than the solution oxidation surface (the surface treated by HNO ₃ -hot treatment and running water rinsing);
In the H-terminated Si (100) plane, SiH and SiH
₂ H reacts with IPA to form C ₃ H ₇ O—Si; H ₂ desorption intensity has peaks at 430 ° C. and 520 ° C .; desorption temperature of IPA (desorption intensity peak Temperature, that is, the desorption temperature of C ₃ H ₈ (temperature at the peak of desorption intensity) is very close to the desorption temperature of H ₂ from SiH ₂ (temperature at the peak of desorption intensity). Etc. are described.

Further, this document describes that organic contamination adsorbed on the wafer surface lowers the breakdown voltage of the gate oxide film in the semiconductor device and inhibits Si epitaxial growth.

On the other hand, the desorption temperature of hydrogen varies slightly depending on the reporter. Regarding the desorption temperature of hydrogen, for example,
(1) J.Vac.Sci.Technol.A 13 (6), Nov / Dec 1995 P2709
~ P2714, (2) Appl. Phys. Lett. 56 (5), 29 January 199
0 P451-P453, (3) JAPANESE JOURNAL OF APPLIED PHY
SICS Vol.30, No.3B, MARCH, 1991, PP.L419-L422.

According to these documents, the temperature at the peak of the desorption intensity on the low-temperature side of the desorption temperature of hydrogen is 400 ° C., 430
C., 440.degree. C., and 470.degree. C., and the temperatures at the peak of the desorption strength on the high temperature side are about 500.degree. C., 520.degree. C., and 570.degree.

Further, as a furnace used for forming an oxide film, for example, "VLSI Process Equipment Handbook" published by the Industrial Research Council, published on June 10, 1990, P230
To P247, a batch type horizontal furnace, a vertical furnace, and a single-wafer type lamp heating furnace are known.

[0010]

SUMMARY OF THE INVENTION Silicon (Si) using isopropyl alcohol in the manufacture of semiconductor devices
During vapor drying of a substrate (wafer), adsorbed isopropyl alcohol remains on the surface of the semiconductor substrate. There is a problem that this residue becomes organic pollution and affects the subsequent steps.
The organic contamination inhibits Si epitaxial growth in the manufacture of semiconductor devices,
(Metal Oxide Semiconductor Field Effect Transisto
It must be avoided from lowering the withstand voltage of the gate oxide film in r).

Particularly, in a gigabit-class memory device with a high degree of integration or a device requiring ultra-high speed,
The thickness of the gate oxide film tends to be extremely thin, and
When the thickness is less than nm, the influence of the organic contamination appears and the withstand voltage characteristic is significantly deteriorated, and the element is destroyed by applying a voltage.

On the other hand, for the surface stabilization treatment by hydrofluoric acid (HF) cleaning or other method for suppressing natural oxidation and avoiding surface contamination, that is, for drying after the hydrogen termination treatment step, the above-mentioned vapor drying technique using isopropyl alcohol is used. When used, the residual isopropyl alcohol together with the surface-bound hydrogen plays a part in suppressing the surface oxidation.

Therefore, in order to suppress the natural oxidation of the silicon substrate surface, it is effective to leave the terminal hydrogen and isopropyl alcohol on the substrate surface until the next step.

On the other hand, a study by the present inventors has revealed that the temperature at the peak of the desorption intensity of isopropyl alcohol in a normal pressure (atmospheric pressure) atmosphere is lower than the temperature at the peak of the desorption intensity of hydrogen. That is, when the crystal plane of the surface of the silicon substrate is (100), two peaks of the desorption intensity of hydrogen appear, but the difference between the temperature at the peak at the lower temperature and the temperature at the peak of the desorption intensity of isopropyl alcohol. Is 10
℃.

The crystal plane of the surface of the silicon substrate is (1).
In the case of 11), the peak of the desorption intensity of hydrogen is one, but the temperature at the peak of the desorption intensity is almost the same as the temperature at the peak of the desorption intensity on the (100) plane on the high temperature side, There is a great difference between the temperature at the peak of the desorption intensity of isopropyl alcohol.

The inventor of the present invention has proposed a method of selectively desorbing isopropyl alcohol at a temperature between the temperature at the peak of the desorption intensity of isopropyl alcohol and the temperature at the peak of the desorption intensity of hydrogen (selective desorption of isopropyl alcohol). Thus, the present invention has been realized in that the residual isopropyl alcohol, which is a polluting source, can be eliminated while suppressing the elimination of hydrogen.

An object of the present invention is to provide a semiconductor device manufacturing method and a semiconductor manufacturing apparatus for removing an adsorbed substance adsorbed on a semiconductor substrate during steam drying or the like.

Another object of the present invention is to provide a method for removing adsorbed substances adsorbed on the surface of a silicon substrate during steam drying or the like without impairing the stability of the substrate surface.

Another object of the present invention is to provide a semiconductor device in which the effect of the adsorbed substance on the thermal oxide film formed in the next step is avoided while effectively utilizing the surface oxidation suppressing effect of the residual isopropyl alcohol as the adsorbed substance. Is provided.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0021]

The following is a brief description of an outline of typical inventions disclosed in the present application.

(1) A step of cleaning the semiconductor substrate, a step of drying the semiconductor substrate with isopropyl alcohol vapor (steam drying), and a predetermined processing (for example, formation of a gate oxide film) on the surface of the semiconductor substrate. And forming a film such as a dielectric film forming a capacitor), the residue on the surface of the semiconductor substrate (isopropyl alcohol) after the steam drying.
Is performed in a clean atmosphere for a predetermined period of time, and then the above processing is performed. The selective desorption is performed immediately before the processing.

The semiconductor substrate has a crystal face of (10
0), which is subjected to a hydrogen terminating treatment, and then dried by steam drying with isopropyl alcohol.

The selective desorption is carried out at a temperature lower than the temperature at the peak of the desorption intensity of hydrogen and at a temperature higher than the temperature at the peak of the desorption intensity of isopropyl alcohol. For example,
The selective desorption is performed at a temperature lower than the temperature at the peak of the desorption strength of hydrogen on the high-temperature side and higher than the temperature at the peak of the desorption strength of hydrogen on the low-temperature side.

The above-mentioned selective desorption is carried out in a normal pressure atmosphere using any of an inert gas, a nitrogen gas and a hydrogen gas or a mixed gas thereof. For example, it is performed in an argon gas atmosphere.

The selective desorption is performed immediately before the process of forming the gate oxide film of the DRAM and the process of forming the dielectric film constituting the capacitor.

(2) In the structure of the means (1), the selective desorption is performed at a temperature lower than the temperature at the peak of the desorption strength of hydrogen and higher than the temperature at the peak of the desorption intensity of isopropyl alcohol. I do.

(3) In the structure of the means (1) or (2), the semiconductor substrate is irradiated with energy rays to perform selective desorption.

(4) In the structure of the means (1) to (3), the selective desorption is performed in a reduced pressure atmosphere.

(5) In the structure of the means (1) to (4), the selective desorption is performed during the processing. For example,
This is performed at the time of forming a gate oxide film at the time of forming a DRAM or at the time of forming a dielectric film. Specifically, in a heating furnace during a gate oxide film forming process or a dielectric film forming process, a semiconductor substrate temperature in the furnace is heated at a first heating rate and a preset first temperature is detected. At this time, in order to perform the selective desorption, the temperature in the furnace is maintained at the first temperature for a predetermined time, or a second heating rate (a predetermined time or until a predetermined temperature is reached). Then, the semiconductor substrate is heated at the first temperature rising rate again to form a predetermined oxide film (dielectric film) on the surface of the semiconductor substrate.

(6) A closed-type furnace for accommodating a semiconductor substrate, a substrate support disposed in the furnace for supporting the semiconductor substrate, and a loader for loading / unloading the semiconductor substrate with respect to the substrate support. A heating unit that heats a semiconductor substrate in the furnace, a temperature detection unit that detects a temperature of the semiconductor substrate, a gas supply unit that supplies a predetermined gas into the furnace, and a predetermined pressure in the furnace. A semiconductor manufacturing apparatus having a pressure control unit for controlling an atmosphere and a control unit for controlling each unit, wherein a forced exhaust device controlled by the control unit is connected to the furnace. The forced evacuation device operates in synchronization with a selective desorption process performed before performing predetermined processing on the semiconductor substrate housed in the furnace, and removes desorbed substances desorbed from the surface of the semiconductor substrate into the furnace. It is configured to forcibly exhaust air to the outside.

According to the means (1), the selective desorption is performed at a temperature higher than the temperature at the peak of the desorption intensity of isopropyl alcohol immediately before the gate oxide film forming process and the dielectric film forming process at the time of forming the DRAM. As a result, the residual isopropyl alcohol adsorbed on the surface of the silicon substrate subjected to the hydrogen termination treatment is completely eliminated from the substrate surface. Therefore, in the formation of the gate oxide film or the dielectric film immediately after the selective desorption, a high-quality gate oxide film or a dielectric film containing no carbon can be formed. In addition, since isopropyl alcohol remaining on the surface of the silicon substrate is removed by heating in an argon gas, cleanliness of the substrate surface is not impaired.

Further, since the selective desorption is performed immediately before the gate oxide film forming process and the dielectric film forming process, the surface of the substrate is suppressed by surface-bonded hydrogen and residual isopropyl alcohol until the selective desorption. And natural oxidation of the silicon substrate surface is suppressed. Therefore, formation of a gate oxide film or a dielectric film having good quality and a constant film thickness can be achieved.

Further, the selective desorption is performed at a temperature lower than the temperature at the peak of the desorption strength of hydrogen on the high-temperature side and higher than the temperature at the peak of the desorption strength of hydrogen on the low-temperature side. One of the two bonds of an atom may become an unbonded bond (dangling bond) due to the elimination of hydrogen or isopropyl alcohol, while the other is terminated with hydrogen and the substrate is selectively desorbed. Since the gate oxide film forming process and the dielectric film forming process are performed immediately after the separation, the chance of adsorbing foreign matter on the substrate surface is reduced, and a high quality gate oxide film and dielectric film can be formed.

According to the means (2), the following effect is obtained in addition to the effect obtained by the means (1). In other words, since selective desorption is performed at a temperature lower than the temperature at the peak of the desorption strength of hydrogen and at a temperature equal to or higher than the temperature at the peak of the desorption intensity of isopropyl alcohol, the bond of silicon atoms on the surface of the substrate is Even when the bound isopropyl alcohol is desorbed, the desorption of hydrogen bonded to the bond of the silicon atom on the surface of the substrate is small. Residual isopropyl alcohol due to steam drying has a ratio of about 0.1% to several percent of the number of silicon atoms on the surface of the substrate and is small in area, and the gate oxide film forming process and the dielectric film forming immediately after selective desorption. Since the treatment is performed, contamination of the substrate at the time of film formation hardly occurs, and a high-quality gate oxide film or dielectric film having a constant film thickness can be formed.

According to the means (3), since the semiconductor substrate is subjected to selective desorption by irradiating the semiconductor substrate with energy rays, the residual isopropyl alcohol not only receives the thermal desorption energy but also reacts with isopropyl alcohol and hydrogen. In order to receive the energy for breaking the atomic junction, selective desorption can be reliably performed, and then a high-quality oxide film can be formed.

According to the means (4), even if the selective desorption is performed in a reduced pressure atmosphere, the residual isopropyl alcohol can be reliably removed from the silicon substrate surface, and thereafter, a high-quality oxide film is formed. be able to.

According to the means (5), the following effects are obtained in addition to the effects obtained by the means (1) to (4). That is, since the selective desorption is performed simultaneously during the gate oxide film formation processing and the dielectric film formation, if isopropyl alcohol is desorbed from the bond of silicon atoms on the surface of the substrate, oxygen is replaced without a long time. And the like, there is no opportunity for foreign matter to enter the interface between the silicon substrate surface and the formed gate oxide film or dielectric film, and a high-quality and uniform-thickness gate oxide film or dielectric film is formed. Can be.

According to the above-mentioned means (6), the heating furnace is provided with a forced exhaust device, and this forced exhaust device is performed before performing predetermined processing on the semiconductor substrate housed in the furnace. It operates in synchronization with the selective desorption process, and is configured to forcibly exhaust the desorbed substances desorbed from the surface of the semiconductor substrate to the outside of the furnace. Processing is ensured, and high-yield processing can be achieved. The formation of a high-quality oxide film on the surface of the silicon substrate is also realized by the desorption.

[0040]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for describing the embodiments of the present invention, components having the same functions are denoted by the same reference numerals, and their repeated description will be omitted.

FIGS. 1 to 14 are views related to a method of manufacturing a semiconductor device (DRAM) according to the first embodiment of the present invention.

In the manufacture of a semiconductor device using a silicon substrate, thermal oxidation, etching, epitaxial growth,
There are various kinds of processing such as impurity diffusion, ion implantation, and film formation by CVD (vapor phase chemical growth). Then, hydrofluoric acid cleaning and subsequent steam drying and the like are performed as pre-processing of these processing.

The present invention is a technique for removing the residue of the substance used in the steam drying by selective desorption, and is performed as a pre-treatment for the various kinds of processing such as the thermal oxidation, etching, epitaxial growth, and impurity diffusion.

Here, the present invention is applied to a DRAM (Dynamic Rand).
Before describing an example applied to the manufacture of an om Access Memory, an example in which a hydrogen termination process is performed and applied as a pre-process to a thermal oxidation process (gate oxide film formation) of a silicon substrate vapor-dried with isopropyl alcohol. Will be described.

FIG. 1 is a flowchart of a method for manufacturing a semiconductor device according to the first embodiment, FIG. 2 is a cross-sectional view showing a semiconductor substrate processing step in the method for manufacturing a semiconductor device according to the first embodiment, and FIGS. Fig. 3 is a graph obtained by analysis by the inventor, Fig. 3 is a graph showing the correlation between the amount of H desorption and IPA desorption and temperature, Fig. 4 is a graph showing the correlation between the desorption amount of IPA and temperature, 5 is a graph showing the correlation between the amount of H desorption and the temperature, FIG. 6 is a graph showing the distribution of desorption intensity of IPA, and FIG. 7 is a graph showing the correlation between the residual IPA and the amount of SiC generated in the thermal oxide film. .

First, as shown in FIG. 2A, a semiconductor substrate 1 is prepared. The semiconductor substrate 1 is made of silicon and has a state in which the field insulating film 3 has been selectively formed on the surface of the semiconductor substrate 1. The silicon region which is not covered with the field insulating film 3 is a region where a device such as a MOSFET is formed (device forming region 30).

In the first embodiment, the surface of the semiconductor substrate 1 (wafer) on which elements and the like are formed, that is, the main crystal plane is the (100) plane. Further, the semiconductor substrate 1
Has a thickness of, for example, 400 to 600 μm and a diameter of several to several tens of inches.

The semiconductor substrate 1 is pre-oxidized (thermally oxidized) as shown in the flowchart of FIG. 1 (step 101). Due to this pre-oxidation, a thermal oxide film 31 having a slight thickness is formed on the surface of the semiconductor substrate 1 as shown in FIG.

Next, the semiconductor substrate 1 is immersed in a hydrofluoric acid solution to perform hydrofluoric acid cleaning, as shown in FIG.
The thermal oxide film 31 covering the element formation region 30 on the surface of the semiconductor substrate 1 is removed (Step 102: see FIG. 1). At this time, contaminants such as metal and dust adhering to the surface of the semiconductor substrate 1 together with the thermal oxide film 31 are also removed.

Next, the semiconductor substrate 1 is washed with water to remove the hydrofluoric acid solution remaining on the surface of the semiconductor substrate 1 (step 103: see FIG. 1).

Next, the semiconductor substrate 1 is dried by vapor drying using isopropyl alcohol (step 104: see FIG. 1).

The surface state of the semiconductor substrate 1 after the vapor drying is such that most of the dangling bonds of the surface silicon atoms are terminated with hydrogen, and varies depending on the processing conditions (temperature and time) of the vapor drying. However, isopropyl alcohol remains in a ratio of about 0.1% to several% of the number of silicon atoms on the surface.

In the thermal oxidation step (gate oxide film forming step) described later, if the residual isopropyl alcohol is changed into SiC and taken into the gate oxide film, a breakdown voltage failure is caused. Then, in order to remove the residual isopropyl alcohol, the semiconductor substrate 1 is selectively desorbed (Step 105: see FIG. 1).

In this selective desorption step, the temperature of the semiconductor substrate 1 is raised to the desorption temperature of isopropyl alcohol (about 250 to about 4).
00 ° C .: see FIG. 6) and the desorption temperature of hydrogen (the temperature of the region where the desorption intensity high-temperature side peak is formed: about 450 to about 500)
(° C .: refer to FIG. 3).
By this heat treatment, isopropyl alcohol is thermally desorbed by utilizing the difference between the desorption temperatures of isopropyl alcohol and hydrogen.

Therefore, as the holding time, a sufficient time is required for desorbing isopropyl alcohol.

In this embodiment, the semiconductor substrate 1 is heated at 400 ° C. for 30 seconds in an argon gas atmosphere at normal pressure.

In the selective desorption, the semiconductor substrate 1
When isopropyl alcohol is desorbed from the surface of the substrate, dangling bonds of reactive silicon are formed on the surface, and the surface is easily affected by contamination. Therefore, this selective desorption needs to be performed in a clean atmosphere.

Then, the semiconductor substrate 1 is thermally oxidized to
As shown in (d), a gate oxide film (gate insulating film) 4 is formed (Step 106: see FIG. 1).

FIG. 7 is a graph showing the effect of the first embodiment. The remaining amount of organic matter in the drying step and the amount of sulfur after thermal oxidation are shown.
It is a graph which shows the correlation with iC production amount.

As shown in FIG. 7, in the conventional method, as the amount of organic matter remaining in the drying step increases, the amount of sulfur in the thermal oxide film increases.
Although the iC amount also increases, in the present invention, the SiC amount hardly increases even if the organic matter amount increases. Therefore, the characteristic deterioration of the thermal oxide film 31 can be effectively prevented.

Here, the processing mode of the present invention will be described.

The selective desorption of the residual isopropyl alcohol between the vapor drying and the processing is performed between the vapor drying step and the processing step, for example, the gate oxide film forming step, and during the processing step. There are cases.

When the process is performed between the vapor drying step and the processing step, the processing may be performed immediately before the processing step.

As a structure to be performed between the vapor drying step and the processing step, as shown in FIG. 15, a vapor drying section 110, a selective desorption processing section 111, and a processing section 1
In some cases, the semiconductor substrates 1 are connected to each other by the transfer unit 113 formed of a cavity, and the semiconductor substrate 1 is transferred into the cavity.

At this time, since the substrate after the selective desorption is processed without being exposed to the outside air, the surface of the substrate is not contaminated again. Therefore, the contaminants are prevented from being taken into the oxide film during the processing step, for example, when the gate oxide film is formed, and a gate oxide film having a high withstand voltage is formed.

When the selective desorption is performed during the processing step, the temperature range in the course of the temperature rise of the processing chamber in the processing is used as the selective desorption. in this case,
For example, if the processing step is a gate oxide film forming step,
In the course of heating the substrate to a target temperature for forming an oxide film, selective desorption corresponding to an IPA desorption step, ie, IP
Heating is performed for a fixed time at a temperature equal to or higher than the A desorption temperature and equal to or lower than the terminal hydrogen desorption temperature.

The selective desorption system includes a batch system and a single wafer system. The single-wafer processing method for in-line substrates has high productivity and can prevent contamination from being contaminated, thereby increasing the yield of selective desorption. Further, the single-wafer lamp heating furnace is superior in temperature control performance as compared with a batch-type furnace.

The selective desorption temperature may be (a) fixed at a predetermined temperature for a predetermined time, or (b) selective desorption while slowly increasing the temperature over a predetermined temperature range.

In the case of the above (b), for example, in a heating furnace, the temperature of the semiconductor substrate in the furnace is heated at a first heating rate, and the selective desorption is performed at the time when a preset first temperature is detected. To perform, heating at a second heating rate up to a preset time or a preset temperature,
Thereafter, the semiconductor substrate is heated again at the first temperature raising rate to perform a predetermined processing on the surface of the semiconductor substrate.

FIG. 6 is a graph showing the desorption intensity distribution of IPA obtained by analysis by the present inventors. Curve A shows the desorption strength (desorption amount) of isopropyl alcohol remaining on the surface of the silicon substrate during vapor drying. The temperature at the peak desorption intensity of IPA is about 360 ° C. Is about 250 to about 400 ° C.

On the other hand, when the silicon substrate is immersed in isopropyl alcohol and then naturally dried,
As shown in the curve B, the temperature at the desorption intensity peak and the desorption occurrence temperature range are substantially the same, but the desorption intensity peak becomes larger than in the case of vapor drying according to the immersion time.

Curve C is obtained by immersing the silicon substrate in isopropyl alcohol and then naturally drying the same as in the case of Curve B, but for the SiO ₂ film. In this case, the peak of the desorption intensity is larger than that in the case of vapor drying, and the temperature at the peak of the desorption intensity is about 30 ° C. as compared with about 360 ° C. in the case of vapor drying.
It was found that the temperature was lowered by about 60 ° C. to about 0 ° C.

The measurement of the desorption strength (desorption amount) was performed by using TDS-APIM in an atmosphere of normal pressure and an atmosphere of argon gas.
S (Thermal desorption spectroscopy-Atmospheric Pr
essure Ionization Mass spectrometer).

FIG. 5 is a graph showing the correlation between the amount of desorbed H and the temperature obtained by the analysis by the present inventors.
Also in this case, the TDS-APIMS method is performed in a normal pressure atmosphere and an argon gas atmosphere. Since the crystal plane of the surface of the silicon substrate is a (100) plane, two peaks appear at the peak of the desorption intensity of hydrogen, and the desorption temperature range is 25.
It will be about 0-600 ° C. The temperature at the peak of the desorption strength on the high temperature side is about 500 ° C., and the temperature at the peak of the desorption strength on the low temperature side is about 370 ° C.

FIG. 4 shows the correlation between the desorption amount and the temperature of the graph IPA obtained by analysis by the present inventors under the same conditions as in FIG. FIG.
It is a graph which shows the correlation between the amount of desorption, the amount of IPA desorption, and temperature. The H desorption amount graph and the IPA desorption amount graph are separately shown in FIGS. 4 and 5 in detail.

Therefore, when the selective desorption is performed for a predetermined time while fixing at a predetermined temperature as in the above (a), the following is performed.

(A1) The temperature at the time of selective desorption is selected to be higher than the temperature T1 at the peak of the desorption intensity of IPA and lower than the temperature T3 at the peak of the desorption intensity of hydrogen at the high temperature side.
In this case, for example, 400 ° C. is selected as the selective desorption temperature.

(A2) The temperature at the time of selective desorption is selected to be higher than the temperature T1 at the peak of the desorption intensity of IPA and lower than the temperature T2 at the peak of the lower desorption intensity of hydrogen.
In this case, for example, 365 ° C. is selected as the selective desorption temperature.

According to this method, the selective desorption is performed at a temperature lower than the temperature at the peak of the desorption intensity of hydrogen and at a temperature equal to or higher than the temperature at the peak of the desorption intensity of isopropyl alcohol. Even if isopropyl alcohol bonded to a bond of a surface silicon atom is desorbed, little hydrogen is bonded to a bond of a surface silicon atom of the substrate. Residual isopropyl alcohol due to steam drying has a ratio of about 0.1% to several percent of the number of silicon atoms on the surface of the substrate and is small in area, and the gate oxide film forming process and the dielectric film forming immediately after selective desorption. Since the treatment is performed, contamination of the substrate at the time of film formation hardly occurs, and a high-quality gate oxide film or dielectric film having a constant film thickness can be formed.

In the case where the selective desorption is performed while the temperature is slowly increased over a predetermined temperature range as in the above (b), the following is performed.

(B1) The temperature at the time of selective desorption is selected to be higher than the temperature T1 at the peak of the desorption intensity of IPA and lower than the temperature T3 at the peak of the desorption intensity of hydrogen at the high temperature side.
In this case, the selective desorption temperature is slowly changed, for example, from about 300 ° C. to about 500 ° C.

(B2) The temperature at the time of selective desorption is selected to be higher than the temperature T1 at the peak of the desorption intensity of IPA and lower than the temperature T2 at the peak of the desorption intensity of hydrogen at the lower temperature side.
In this case, the selective desorption temperature is, for example, 300 to 370 ° C.
And the temperature rises slowly.

Next, an example in which the present invention is applied to the manufacture of a DRAM will be described. In the first embodiment, selective desorption is performed before forming a gate oxide film and a dielectric film forming a capacitor.

FIGS. 8 to 14 are diagrams relating to a DRAM manufactured by the method of manufacturing a semiconductor device according to the first embodiment. FIG. 8 is an equivalent circuit diagram of a memory cell of the DRAM, and FIG. It is sectional drawing. 10 to 14 are views related to a method of manufacturing a DRAM, FIG. 10 is a cross-sectional view showing a part of a silicon substrate before a gate oxide film is formed, and FIG. 11 is a part of a silicon substrate after a gate oxide film is formed. 12, FIG. 12 is a cross-sectional view showing a part of a silicon substrate on which a polysilicon film for forming an electrode is formed, and FIG. 13 is a cross-sectional view showing a part of the silicon substrate before a capacitor dielectric film is formed. FIG. 14 is a sectional view showing a part of the silicon substrate after the formation of the capacitor dielectric film.

In a DRAM which is a semiconductor device, 1
The memory cell (M) that stores the information of [bit]
It is composed of a series circuit of an SFET (Q) and a capacitive element (C).

The MOSFET is mainly composed of a semiconductor region which is a channel forming region, a gate insulating film, a gate electrode, and a pair of semiconductor regions which are a source region and a drain region. This MOSFET is formed on the surface of an active region (element formation region 30) of a semiconductor substrate. Capacitive element includes a lower electrode, a dielectric film, and a sequentially laminated STC (St acked C apacitor) structure of each of the upper electrode. This capacitive element is formed above the MOSFET in order to reduce the planar size of the memory cell.

FIG. 8 shows a DRA according to an embodiment of the present invention.
FIG. 9 is an equivalent circuit diagram of a memory cell mounted on M, and FIG. 9 is a cross-sectional view of a main part of a DRAM. Note that, in FIG. 9, an upper portion of a capacitive element, which will be described later, is not illustrated for easy viewing.

As shown in FIG. 8, a memory cell M mounted on a DRAM is constituted by a series circuit of a MOSFET Q and a capacitor C. The memory cell M is arranged at an intersection of a word line WL extending in a row direction (Y direction) and a data line DL extending in a column direction (X direction), and is 1 [bit].
Is stored.

One semiconductor region of the MOSFET Q is electrically connected to the data line DL, the other semiconductor region is electrically connected to one electrode of the capacitive element C, and the gate electrode is electrically connected to the word line WL. Connected.

When the memory cell M is selected, the word line WL is fixed at a potential of, for example, 5 [V]. When the memory cell M is not selected, the word line WL is fixed at a potential of, for example, 0 [V]. The data line DL is fixed at a potential of, for example, 3.3 [V] when charges are stored in the capacitor C, and is 0 [V] when charges are not stored in the capacitor C, for example.
The potential is fixed to the potential.

A plurality of the memory cells M are arranged in the row direction in which the word lines WL extend and in the column direction in which the data lines DL extend, and constitute a memory cell array. The memory cell array is formed in a memory cell array formation region surrounded by a peripheral circuit formation region in which peripheral circuits such as a word driver circuit, an X decoder circuit, and a Y decoder circuit are arranged.

Next, a specific structure of the memory cell M mounted on the DRAM will be described with reference to FIG.

As shown in FIG. 9, the DRAM mainly includes a semiconductor substrate (semiconductor substrate) 1. This semiconductor substrate 1 is formed of, for example, a p-type semiconductor substrate made of single crystal silicon (silicon).

On the surface of the memory cell array forming region of the semiconductor substrate 1, a p-type well region 2 is formed.

The MOSFET Q of the memory cell M is p
It is formed on the surface of the active region of the mold well region 2. p
The periphery of the surface of the active region of the mold well region 2 is defined by a field insulating film 3 formed on the surface of the non-active region. That is, the MOSFET Q is formed on the surface of the p-type well region 2 whose periphery is defined by the field insulating film 2.

On the surface of the p-type well region 2 whose periphery is defined by the field insulating film 3, MOSFETs Q of two memory cells M are formed.

The MOSFET Q mainly includes a p-type well region 2 serving as a channel forming region, a gate insulating film 4, a gate electrode 5, a pair of n-type semiconductor regions 7 serving as a source region and a drain region, and a pair of n + -type It is composed of a semiconductor region 9.

The gate insulating film 4 is formed on the surface of the active region of the p-type well region 2. This gate oxide film 4 is formed of, for example, a thermal oxide film. The gate electrode 5 is formed on the gate oxide film 4. Gate electrode 5 is formed of, for example, a polysilicon film (polycrystalline silicon film) into which an impurity (for example, phosphorus (P)) for reducing a resistance value is introduced.

Each of the pair of n-type semiconductor regions 7 serving as the source region and the drain region is formed on the surface of the active region of the p-type well region 2. Each of the pair of n-type semiconductor regions 7 is formed in self-alignment with the gate electrode 5. Each of the pair of n + -type semiconductor regions 9 serving as the source region and the drain region has p
It is formed on the surface of the active region of the mold well region 2. Each of the pair of n + -type semiconductor regions 9 is formed in a self-alignment manner with a side wall spacer 8 covering the side wall surface of the gate electrode 5 in the gate length direction.

Each of the pair of n-type semiconductor regions 7 serving as the source region and the drain region has a lower impurity concentration than those of the pair of n + -type semiconductor regions 9 serving as the source region and the drain region. I have. That is, the MOSFET Q of the memory cell M is LDD (Lightly
Doped Drain) structure.

The gate electrode 5 of the MOSFET Q extends on the gate oxide film 4 in the same direction as the extending direction of the word line WL extending on the field insulating film 3.
L. That is, the gate electrode 5 is electrically connected to the gate electrode 5 of the MOSFET of another memory cell M arranged in the extending direction (Y direction) of the word line WL.

The respective upper surfaces of the gate electrode 5 and the word line WL are covered with an insulating film 6. The side wall surfaces of the gate electrode 5 and the word line WL are covered with side wall spacers 8. The insulating film 6 is formed of, for example, a SiO ₂ film. The sidewall spacers 8 are formed by forming, for example, a SiO ₂ film on the gate oxide film 4 including the insulating film 6 and then performing anisotropic etching on the SiO ₂ film.

The data line DL is electrically connected to one n + -type semiconductor region 9 of the MOSFET Q of the memory cell M. Data line DL is formed of, for example, polysilicon film 10A into which an impurity for reducing the resistance value has been introduced and tungsten film 10B formed on the surface of polysilicon film 10A.

The capacitance element C of the memory cell M is formed on the surface of the interlayer insulating film 11. This capacitive element C
It has an STC structure in which a lower electrode 15, a dielectric film 17, and an upper electrode 18 are sequentially laminated.

The lower electrode 15 is made of, for example, a polysilicon film into which an impurity (for example, phosphorus (P)) for reducing a resistance value is introduced, and has a predetermined pattern. The dielectric film 17 is formed of, for example, a tantalum pentoxide (Ta ₂ O ₅ ) film which is a high dielectric constant film having a higher dielectric constant than the SiO ₂ film and the silicon nitride film. The upper electrode 18
Is formed of, for example, a tungsten film.

The lower electrode 15 of the capacitive element C is connected to the MOSFE through the connection hole 12 formed in the interlayer insulating film 11.
It is electrically connected to the other n + -type semiconductor region 9 of TQ.

Although not shown, the upper electrode 18 of the capacitor C is covered with an interlayer insulating film. A wiring layer is formed on the surface of the interlayer insulating film, and the wiring layer is covered with a final protective film.

Next, a method of manufacturing a DRAM will be described with reference to FIGS. 10 to 14 and FIG.

First, as shown in FIG. 10, a p-type silicon substrate (semiconductor substrate) 1 is prepared.

Next, as shown in FIG. 10, a p-type well region 2 is formed on the surface of the memory cell array forming region of the semiconductor substrate 1.

Next, a field insulating film 3 is formed on the surface of the non-active region of the p-type well region 2. Field insulating film 3 is formed of, for example, a SiO ₂ film formed by a known selective oxidation method.

Next, the silicon substrate is subjected to hydrogen termination. In the hydrogen termination treatment, the silicon substrate is etched with hydrofluoric acid and washed with pure water. Drying is performed by vapor drying using isopropyl alcohol. Drying may be steam drying with another organic substance.

Next, just before the step of forming the gate oxide film 4, selective desorption is performed. The selective desorption is performed, for example, at a temperature lower than the temperature at the peak of the desorption strength of hydrogen on the high temperature side and at a temperature higher than the temperature at the peak of the desorption strength of IPA. The selective desorption may be performed at a temperature higher than the temperature at the peak of the desorption intensity of IPA and lower than the temperature at the peak of the desorption intensity of hydrogen on the lower temperature side.

In this embodiment, the selective desorption is performed in a normal pressure atmosphere and a clean argon gas atmosphere. The selective desorption is performed, for example, at 400 ° C. (first temperature) for 30 seconds.

Thus, the adsorbed substance (residual isopropyl alcohol) adhering to the surface of the semiconductor substrate 1 can be removed.

Even when the selective desorption is performed in a reduced pressure atmosphere, the selective desorption of isopropyl alcohol can be surely performed.

Even when the selective desorption is performed in a gas atmosphere using any of an inert gas, a nitrogen gas, a hydrogen gas or a mixed gas thereof, the selective desorption of the isopropyl alcohol can be surely performed.

Thus, no isopropyl alcohol remains on the surface of the silicon substrate.

Next, as shown in FIG. 11, a gate insulating film (gate oxide film) 4 is formed on the surface of the active region (element forming region 30) of the p-type well region 2.

The gate oxidation, that is, the oxide film forming process,
Since selective desorption is performed as a pretreatment, isopropyl alcohol does not remain on the surface of the silicon substrate. Therefore, SiC is not generated in the formed gate oxide film 4 and the withstand voltage of the gate oxide film 4 is not reduced.

It is desirable that the selective desorption be performed immediately before the next processing (forming a gate oxide film) in order to prevent re-contamination of the surface of the semiconductor substrate 1.

It is preferable that the semiconductor substrate 1 be kept in an atmosphere free from contamination from the time of the selective desorption until the time of the gate oxide film forming process.

In order to prevent contamination of the semiconductor substrate 1, for example, as shown in FIG. 15, a space in an inert gas atmosphere is provided between each of the vapor drying unit 110, the selective desorption processing unit 111, and the processing unit 112. The semiconductor substrate 1 is connected by the transfer unit 113 and transferred into the cavity. At this time, since the semiconductor substrate 1 after the selective desorption is processed without being exposed to the outside air, the surface of the substrate is not contaminated again. Therefore, when a gate oxide film is formed in the processing portion 112, contaminants are prevented from being taken into the oxide film, and a gate oxide film having a high withstand voltage is formed.

Next, as shown in FIG. 12, a polysilicon film and an insulating film are sequentially formed on the entire surface of the semiconductor substrate 1 including the gate oxide film 4 and the field insulating film 3. During or after the deposition of the polysilicon film, an impurity for reducing the resistance value is introduced.

Next, the insulating film and the polysilicon film are sequentially patterned to form a gate electrode 5 whose upper surface is covered with the insulating film 6 and a word line WL whose upper surface is covered with the insulating film 6. .

Next, an n-type impurity is introduced into the surface of the active region of the p-type well region 2 in a self-aligned manner with respect to the gate electrode 5, and a pair of n-type impurities serving as a source region and a drain region are formed.
A type semiconductor region 7 is formed.

Next, the gate electrode 5, the word line WL
Are formed on the respective side wall surfaces. The sidewall spacers 8 are formed by forming, for example, a SiO ₂ film on the gate insulating film 4 including the insulating film 6, and then performing anisotropic etching on the SiO ₂ film.

Next, an n-type impurity is introduced into the surface of the active region of the p-type well region 2 in a self-aligned manner with respect to the side wall spacers 8 to form a pair of n + -type semiconductor regions 9 serving as a source region and a drain region. To form In this step, the MOSFET Q of the memory cell M is formed.

Next, one n + of the MOSFET Q
A data line DL electrically connected to the mold semiconductor region 9 is formed. The data line DL is formed by a polysilicon film 10A and a tungsten film 10B formed thereon.

Next, an interlayer insulating film 11 is formed on the entire surface of the semiconductor substrate 1 including on the data lines DL. Interlayer insulating film 11 is formed of, for example, a SiO ₂ film.

Next, a MOSF is formed on the interlayer insulating film 11.
A connection hole 12 exposing the surface of the other n + -type semiconductor region 9 of the ETQ is formed.

Next, a polysilicon film 13A is formed on the entire surface of the semiconductor substrate 1 including the inside of the connection hole 12. An impurity (for example, phosphorus (P)) that reduces the resistance value during or after the deposition of the polysilicon film 13A is introduced.

Next, the polysilicon film 13A is selectively removed by a conventional photolithography technique and etching technique, and a lower electrode 15 having a predetermined pattern is formed as shown in FIG.

Next, the silicon substrate is subjected to a hydrogen termination treatment to remove the natural silicon oxide film formed on the surface of the lower electrode 15. Drying is performed by steam drying using isopropyl alcohol. In this case as well, similar to the case of forming the gate oxide film, selective desorption is performed immediately before the step of forming the dielectric film 17 constituting the capacitor to remove the residual isopropyl alcohol.

The selective desorption is performed, for example, at a temperature lower than the temperature at the peak of the desorption strength of hydrogen and higher than the temperature at the peak of the desorption intensity of IPA. In the present embodiment, heating is performed in a normal pressure atmosphere and a clean argon gas atmosphere. The selective desorption is performed, for example, at 400 ° C. for 30 seconds.

As a result, isopropyl alcohol does not remain on the surface of the silicon substrate.

Next, as shown in FIG. 14, a dielectric film 17 is formed over the entire surface of the silicon substrate. The dielectric film 17 is made of, for example, a tantalum pentoxide (Ta ₂ O ₅ ) film. The formation of the Ta ₂ O ₅ film is performed, for example, under conditions where Ta (OC ₂ H ₅ ) is flowed as a process gas into an atmosphere at a temperature of about 400 ° C.

Next, the silicon substrate is, for example, 700
An oxygen annealing treatment is performed in a temperature atmosphere of about 1000 ° C.

As a result of the selective desorption, since no isopropyl alcohol remains on the surface of the lower electrode 15 made of a polysilicon film, the dielectric film 17 is stable as a dielectric film constituting a capacitor. can get.

Next, an upper electrode 18 having a predetermined pattern is formed on the surface of the silicon substrate. Upper electrode 18
Is formed of, for example, a tungsten film.

In this step, as shown in FIG. 9, a capacitive element C in which the lower electrode 15, the dielectric film 17, and the upper electrode 18 are sequentially laminated is formed.

Next, an interlayer insulating film covering the upper electrode 18 of the capacitor C is formed, a wiring layer is formed on the interlayer insulating film, and a final protective film is formed on the wiring layer. The DRAM of this embodiment is almost completed.

After that, the silicon substrate is divided vertically and horizontally to manufacture a semiconductor chip constituting a DRAM. Each semiconductor chip is sealed in a predetermined package to form a semiconductor device.

The following effects are obtained in the method of manufacturing the semiconductor device of the first embodiment, that is, in the manufacture of the DRAM.

According to the means (1), immediately before the process of forming the gate oxide film 4 of the DRAM and the process of forming the dielectric film 17 constituting the capacitor, the temperature equal to or higher than the temperature at the peak of the desorption intensity of isopropyl alcohol. , The residual isopropyl alcohol adsorbed on the surface of the hydrogen-terminated silicon substrate is completely desorbed from the substrate surface. Therefore, in the formation of the gate oxide film or the dielectric film immediately after the selective desorption, a high-quality gate oxide film or a dielectric film containing no carbon can be formed. Further, since isopropyl alcohol remaining on the surface of the silicon substrate is removed by heating in an argon gas, the stability of the substrate surface is not impaired.

(2) Since the selective desorption is performed immediately before the gate oxide film forming process and the dielectric film forming process, the surface of the silicon substrate is surfaced with surface-bonded hydrogen and residual isopropyl alcohol until the selective desorption. Oxidation is suppressed,
Spontaneous oxidation of the silicon substrate surface is suppressed. Therefore, formation of a gate oxide film or a dielectric film having good quality and a constant film thickness can be achieved.

(3) If the semiconductor substrate is placed in an atmosphere free from contamination after the selective desorption until the next processing (formation of a gate oxide film or formation of a dielectric film), the semiconductor substrate after the selective desorption becomes Since the gate oxide film and the dielectric film are formed without being exposed to the outside air, the gate oxide film 4 and the dielectric film 17 having a high withstand voltage are formed.

(4) Since the selective desorption is performed at a temperature lower than the temperature at the peak of the desorption strength of hydrogen on the high-temperature side and higher than the temperature at the peak of the desorption strength of hydrogen on the low-temperature side, the surface of the silicon substrate is One of the two bonds of the silicon atom may become an unbonded bond due to elimination of hydrogen or isopropyl alcohol, but the other is terminated with hydrogen and immediately after the selective desorption of the silicon substrate. Since the gate oxide film forming process and the dielectric film forming process are performed first, the chance of adsorbing foreign matter on the surface of the silicon substrate is reduced, and the formation of the gate oxide film 4 and the dielectric film 17 of good quality can be achieved.

(5) Since the thicknesses of the gate oxide film 4 and the dielectric film 17 forming the capacitor have become thinner, that is, 10 nm or less, stabilization of the gate oxide film 4 and the dielectric film 17 requires a DRAM. The characteristics of the semiconductor device having various structures, such as the first and second structures, are greatly affected, and the manufacture of a high-performance semiconductor device can be achieved by applying the first embodiment.

(6) According to the first embodiment, the yield of forming an oxide film or the like can be improved, and the manufacturing cost of a semiconductor device can be reduced.

In the first embodiment, isopropyl alcohol remaining after vapor drying is described. However, other contaminants can be removed by the same selective desorption. In this case, the heat treatment temperature becomes higher than the temperature at the peak of the desorption intensity of the substance in place of the temperature at the peak of the desorption intensity of the remaining isopropyl alcohol.

In the first embodiment, the thermal desorption is described. However, the semiconductor substrate may be irradiated with energy rays to perform the selective desorption. In this case, the first embodiment
In the same manner as in the selective desorption method according to the above, the irradiation amount of the energy beam is set to be equal to or more than the energy amount for desorbing the surface residual IPA and equal to or less than the surface termination hydrogen desorption energy amount, thereby obtaining the same effect as in the first embodiment. Can be.

Residual isopropyl alcohol adhering to the surface of the semiconductor substrate not only receives thermal desorption energy but also receives energy for breaking the atomic junction between isopropyl alcohol and hydrogen, so that selective desorption can be reliably performed.

Since the bond strength of SiO forming the bond structure of isopropyl alcohol is about 2 to 5 eV, this is not particularly limited as an energy ray, but, for example, an ultraviolet ray or a visible ray is suitable. .

Further, in the first embodiment, the selective desorption processing based on the hydrogen termination processing and the vapor drying has been described. However, the selective desorption processing may be performed without performing the hydrogen termination processing and the vapor drying. good. That is, a substance released from a member such as a cartridge accommodating the semiconductor substrate or a substance floating in the air is adsorbed on the surface of the semiconductor substrate. Therefore, selective desorption is performed before the processing to selectively desorb the adsorbed substance attached to the surface of the semiconductor substrate, and then the processing is performed. As a result, the processing can be performed in a state where there is no adsorbed substance adhering to the surface of the semiconductor substrate, so that a high-quality processing can be performed.

[0156] Isopropyl alcohol has a high temperature at the peak of desorption intensity, but substances (such as organic substances) released from jigs such as cartridges and building materials have lower thermal desorption temperatures than the isopropyl alcohol. Therefore, the desorption temperature may be as high as in the case of isopropyl alcohol, but if it is considered that there is no residual isopropyl alcohol in the process, the desorption temperature may be reduced with respect to the adsorbed substance which can be assumed to be attached to the surface of the semiconductor substrate. The temperature can be selected and set, and a low temperature can be selected.

(Embodiment 2) FIG. 16 is a graph showing a temperature profile at the time of selective desorption and oxide film formation processing in a method of manufacturing a semiconductor device according to Embodiment 2 of the present invention.

In the second embodiment, the selective desorption is performed during the processing. The selective desorption is performed during the formation of the oxide film. Specifically, selective desorption is performed in a processing chamber (processing furnace) for forming a gate oxide film or a processing chamber (processing furnace) for forming a dielectric film. When the temperature rises during the forming process, the temperature is kept constant for a predetermined time to perform selective desorption.

As shown in FIG. 16, the temperature profile of the conventional processing chamber for forming a gate oxide film is as follows: after the substrate is carried into the processing chamber, the temperature of the silicon substrate is changed from room temperature to a temperature close to the thermal oxidation temperature (for example, 900 ° C. to 900 ° C.). (About 1000 ° C.) at a stretch at the first heating rate. For example, the heating rate is about 10 ° C./sec to 50 ° C./sec.

However, in the second embodiment, the temperature between the IPA desorption temperature (the temperature at the peak of the IPA desorption intensity) and the H desorption temperature (the temperature at the peak of the H desorption intensity), for example, 40 ° C.
After heating at 0 ° C. for a predetermined time (first temperature, for example, 30 seconds) to remove isopropyl alcohol remaining on the surface of the silicon substrate, the temperature of the processing chamber is raised to a temperature at which gate oxide film 4 is formed ( (Increase at a second heating rate).

The dielectric film 17 is made of tantalum pentoxide (Ta)
_In the case of a ₂ O ₅ ) film, for example, the processing chamber temperature is about 400 ° C.
Is the same, but the SiO ₂ film or the two-layer Si
Multilayer dielectric film 17 with another insulating film interposed between O ₂ films
In the case of, the processing temperature is high. Note that there is no particular problem even if the processing temperature and the selective desorption temperature are almost the same.

According to the second embodiment, since the selective desorption is performed simultaneously during the gate oxide film formation processing and the dielectric film formation, when isopropyl alcohol is desorbed from the bond of the silicon atom on the surface of the substrate, Oxygen and the like are bonded instead of a long time, eliminating the opportunity for foreign substances to enter the interface between the silicon substrate surface and the formed gate oxide film or dielectric film. A film or a dielectric film can be formed.

In Embodiment 2, selective desorption is performed in a single-wafer heating furnace. In the single-wafer heating furnace, since the setting and management of the temperature profile can be easily performed with high accuracy, the yield of selective desorption can be improved, and the cost of the semiconductor device can be reduced.

(Embodiment 3) FIG. 17 is a graph showing a temperature profile at the time of selective desorption and oxide film formation processing in a method of manufacturing a semiconductor device according to Embodiment 3 of the present invention.

The present embodiment 3 is intended to perform the selective desorption at the time when the temperature of the semiconductor substrate in the furnace is heated at the first heating rate and the preset first temperature is detected in the heating furnace. Then, heating is performed at a second heating rate until a predetermined time or a preset temperature is reached, and then heating is again performed at the first heating rate to form a predetermined film (oxide film) on the surface of the semiconductor substrate. ).

As an example, as shown in the graph of FIG. 17, instead of maintaining the temperature as in the second embodiment,
At a temperature of about 400 ° C., the heating rate is reduced, for example,
5 ° C./sec in the range of 300 ° C. to 500 ° C. Then, after the temperature reaches a preset temperature, it is heated again at the first temperature increasing rate to increase the temperature to the oxidation temperature, and thermal oxidation is performed to form a gate oxide film and a dielectric film.

In the case of the third embodiment, the controllability of the temperature control is excellent because the temperature is kept rising even if it is slow without stopping the temperature. Further, the temperature range in which the temperature rises slowly is not limited to the above numerical value.

In the second and third embodiments, the generation of SiC can be effectively suppressed by a very simple method of changing the temperature raising method in the oxidation step.

In the second and third embodiments, the selective desorption is performed in the single-wafer heating furnace, but a horizontal heating furnace or a vertical heating furnace may be used. In this case, the inside of the heating furnace is set so as to have a temperature gradient according to the temperature profiles shown in FIGS. 16 and 17, and the semiconductor substrate is moved in the heating furnace in a single wafer type or a batch type. . At this time, by adjusting the moving speed of the semiconductor substrate to an appropriate value, the temperature of the semiconductor substrate can be set so as to follow the temperature profile shown in FIGS.

(Embodiment 4) FIG. 18 is a configuration diagram showing a semiconductor manufacturing apparatus according to Embodiment 4 of the present invention.

The semiconductor manufacturing apparatus has a closed furnace 121 for accommodating the semiconductor substrate 1. This furnace (heating furnace) 1
Reference numeral 21 is formed of, for example, a quartz tube.

In the furnace 121, there is provided a substrate support portion 122 composed of a plurality of protrusions. The semiconductor substrate 1 is placed horizontally on the substrate support section 122.

At the left end of the furnace 121, a loader 124 for loading and unloading the semiconductor substrate 1 with respect to the substrate support 122 is provided. A slide door 123 is provided between the loader 124 and the loader 124.
It is opened when loading and unloading the semiconductor substrate 1.

A heating section 125 for heating the semiconductor substrate 1 in the furnace 121 is provided on the outer periphery of the furnace 121. The heating unit 125 has, for example, a lamp heating configuration.

An optical temperature detector 12 for detecting the temperature of the semiconductor substrate 1 in the furnace 121 is provided on the outer periphery of the furnace 121.
6 are provided.

A gas supply unit 130 for supplying a predetermined gas into the furnace 121 is provided at the right end of the furnace 121.
A pressure controller 131 for controlling the inside of the furnace 121 to a predetermined pressure atmosphere is provided.

This is one of the features of the present invention. A forced exhaust device 132 is connected to the furnace 121. The forced evacuation device 132 operates in synchronization with a selective desorption process performed before performing predetermined processing on the semiconductor substrate 1 housed in the furnace 121, and desorbs from the surface of the semiconductor substrate 1. The material is forcibly exhausted out of the furnace. This forced exhaust device 132 is provided with a suction pipe 133.
Forcibly exhausts the inside of the furnace 121.

Further, the semiconductor manufacturing apparatus has a control section 135 for controlling the above-mentioned sections.

When a gate oxide film of a DRAM or a flash memory is formed in such a semiconductor manufacturing apparatus, selective desorption is performed in the same furnace before forming the oxide film.

Next, the selective desorption and oxide film formation processing performed using the semiconductor manufacturing apparatus will be described.

First, the furnace 121 of the semiconductor manufacturing apparatus is set to an oxidizing atmosphere by the gas supply unit 130, and is set to normal pressure or reduced pressure by the pressure control unit 131.

Next, after the semiconductor substrate 1 is supplied onto the substrate supporting portion 122 by the loader 124, the semiconductor substrate 1 is heated by the heating portion 125. The temperature of the semiconductor substrate 1 is detected by the temperature detector 126. That is, the temperature detecting unit 126 optically detects the back surface temperature of the semiconductor substrate 1 through the furnace wall of the furnace 121 made of a transparent quartz tube. The control unit 135 controls the heating unit 125 based on information detected by the temperature detection unit 126.

In the heating furnace 121, in order to heat the semiconductor substrate temperature in the furnace 121 at a first heating rate and to perform the selective desorption at the time when a preset first temperature is detected, Is maintained at the first temperature for a predetermined time, or heated at a second temperature rising rate until reaching a preset time or a preset temperature, and then again at the first temperature rising rate. By heating, a predetermined oxide film is formed on the surface of the semiconductor substrate 1.

As described above, the selective desorption is performed by (1) maintaining the first temperature for a predetermined time after the detection of the first temperature, and (2) detecting the first temperature after the detection of the first temperature. The heating can be performed for a preset time during the heating at the second heating rate, or (3) during the heating at the second heating rate until the preset temperature is reached after detecting the first temperature. .

In the case of the second embodiment shown in FIG. 16, an example in which the first temperature is detected and then the first temperature is maintained at the first temperature for a predetermined time to perform selective desorption is described in (1).

Further, in the example shown in FIG. 17, in which the above-mentioned (3) selective desorption is performed by detecting the first temperature and then heating at a second temperature increasing rate until reaching a preset temperature. Form 3
Is the case.

In such selective desorption, the forced exhaust device 132 operates in synchronization with the selective desorption processing. That is, during the selective desorption, a desorbed substance desorbed from the surface of the semiconductor substrate 1 is generated in the furnace, and this desorbed substance is forcibly sucked into the suction pipe 133 at the same time as the desorption and floating, and is discharged outside the furnace. Exhausted. As a result, when the oxide film is formed following the selective desorption, the desorbing substance does not enter the oxide film, the formation of the oxide film containing carbon or the like can be prevented, and the oxide film having excellent withstand voltage (gate insulating film) can be prevented. A dielectric film for forming a film or a capacitor) can be formed.

Although the invention made by the inventor has been specifically described based on the embodiment, the invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention. Needless to say.

[0189]

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

(1) Since the silicon substrate subjected to the hydrogen termination treatment is dried by vapor drying using isopropyl alcohol or the like, it is subjected to selective desorption immediately before processing such as formation of a gate oxide film. Isopropyl alcohol and the like remaining on the surface are eliminated. As a result, it is possible to form a gate oxide film or the like having a uniform thickness and high precision with little contamination.

(2) Since the selective desorption is performed immediately before the processing, the surface of the silicon substrate is protected by terminal hydrogen, residual isopropyl alcohol and the like until the selective desorption. Furthermore, since isopropyl alcohol and the like can be thermally desorbed while leaving the terminal hydrogen of the substrate silicon stabilizing the surface, contamination due to residual isopropyl alcohol and the like can be removed without impairing the stability of the surface. .

(3) When the selective desorption is performed simultaneously with the processing such as thermal oxidation, the oxidation can be performed simultaneously with the desorption of isopropyl alcohol or the like. Surface contamination and spontaneous oxidation of the substrate surface can be minimized.

(4) In the manufacture of a semiconductor device, since the processing accuracy in the processing before the vapor drying such as the formation of an oxide film is improved, a semiconductor device having excellent quality can be manufactured at a high yield. Therefore, a reduction in the manufacturing cost of the semiconductor device can be achieved.

[Brief description of the drawings]

FIG. 1 is a flowchart of a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a substrate processing stage in the method for manufacturing a semiconductor device according to the first embodiment.

FIG. 3 is a graph showing the correlation between the amount of H desorption and the amount of IPA desorption obtained by analysis by the present inventors and temperature.

FIG. 4 is a graph showing the correlation between the desorption amount of IPA and the temperature obtained by analysis by the present inventors.

FIG. 5 is a graph showing the correlation between the amount of desorbed H and the temperature obtained by analysis by the present inventors.

FIG. 6 is a graph showing a desorption intensity distribution of IPA obtained by analysis by the present inventors.

FIG. 7: Residual IP obtained by analysis by the present inventors
6 is a graph showing a correlation between A and the amount of SiC generated in a thermal oxide film.

FIG. 8 is an equivalent circuit diagram of a memory cell mounted on a DRAM manufactured by the method for manufacturing a semiconductor device according to the first embodiment.

FIG. 9 is a sectional view of a main part of the DRAM.

FIG. 10 is a cross-sectional view showing a part of the silicon substrate before a gate oxide film is formed in the DRAM manufacturing method.

FIG. 11 is a cross-sectional view showing a part of the silicon substrate after a gate oxide film is formed in the DRAM manufacturing method.

FIG. 12 is a cross-sectional view showing a part of a silicon substrate on which a polysilicon film for forming an electrode is formed in the DRAM manufacturing method.

FIG. 13 is a cross-sectional view showing a part of the silicon substrate before a capacitor dielectric film is formed in the DRAM manufacturing method.

FIG. 14 is a cross-sectional view showing a part of the silicon substrate after a capacitor dielectric film is formed in the DRAM manufacturing method.

FIG. 15 is an apparatus configuration diagram for explaining a vapor drying step, a selective desorption processing step, and a processing step of the present invention.

FIG. 16 is a graph showing a temperature profile at the time of selective desorption and oxide film formation processing in the method for manufacturing a semiconductor device according to the second embodiment of the present invention.

FIG. 17 is a graph showing a temperature profile at the time of selective desorption and oxide film formation processing in the method for manufacturing a semiconductor device according to the third embodiment of the present invention.

FIG. 18 is a configuration diagram illustrating a semiconductor manufacturing apparatus according to a fourth embodiment of the present invention.

[Explanation of symbols]

1 ... semiconductor substrate (semiconductor substrate), 2 ... p-type well region,
3 ... field insulating film, 4 ... gate oxide film (gate insulating film), 5 ... gate electrode, 6 ... insulating film, 7 ... n-type semiconductor region, 8 ... sidewall spacer, 9 ... n + type semiconductor region, 10A ... Polysilicon film, 10B tungsten film, 11 interlayer insulating film, 12 connection hole, 13A polysilicon film, 15 lower electrode, 17 dielectric film, 18 upper electrode, 30 element formation region, 31 Thermal oxide film, 110
... vapor drying section, 111 ... selective desorption processing section, 112 ... processing section, 113 ... transport section, 121 ... furnace (heating furnace), 1
22: substrate support section, 123: door, 124: loader, 12
5: heating unit, 126: temperature detection unit, 130: gas supply unit, 131: pressure control unit, 132: forced exhaust device, 13
3: suction tube, 135: control unit, C: capacitance element, Q: MO
SFET, M: memory cell, WL: word line, DL: data line.

Claims (19)

[Claims] 1. A semiconductor comprising: a step of cleaning a semiconductor substrate; a step of drying the semiconductor substrate; and a step of selectively desorbing an adsorbed substance attached to a surface of the semiconductor substrate after the drying. Device manufacturing method. 2. The method according to claim 1, further comprising a step of cleaning the semiconductor substrate, a step of drying the semiconductor substrate, and a step of performing a predetermined processing on the semiconductor substrate. A method of manufacturing a semiconductor device, comprising: performing selective desorption for desorbing adsorbed substances to be attached, and placing the semiconductor substrate in an atmosphere free from contamination after the selective desorption until the processing. 3. A step of cleaning the semiconductor substrate, a step of drying the semiconductor substrate, and a step of performing a predetermined processing on the semiconductor substrate, wherein the semiconductor substrate adheres to the surface of the semiconductor substrate during the processing. A method for manufacturing a semiconductor device, comprising performing selective desorption for desorbing adsorbing substances to be desorbed. 4. A method for manufacturing a semiconductor device, comprising a step of performing a predetermined processing on a semiconductor substrate, wherein a selective desorption for desorbing an adsorbed substance attached to a surface of the semiconductor substrate is performed before the processing. A method of manufacturing a semiconductor device. 5. The semiconductor according to claim 1, wherein the selective desorption is performed at a temperature equal to or higher than the temperature at the peak of the desorption intensity of the substance used for the drying treatment. Device manufacturing method. 6. The method according to claim 1, wherein the semiconductor substrate made of silicon is subjected to a hydrogen termination treatment, and then the selective desorption is performed at a temperature lower than the temperature at the peak of the desorption intensity of hydrogen.
A method for manufacturing a semiconductor device according to claim 5. 7. A step of cleaning a silicon substrate, a step of drying the silicon substrate, a step of selectively desorbing an adsorbing substance adhering to a surface of the silicon substrate after the drying, and Performing a processing step, wherein the crystal plane of the surface of the silicon substrate is (100).
Wherein the selective desorption is performed at a temperature lower than the temperature at the peak of the desorption strength of hydrogen on the high-temperature side and higher than the temperature at the peak of the desorption strength of hydrogen on the low-temperature side. Method. 8. A step of cleaning the silicon substrate, a step of drying the silicon substrate, a step of selectively desorbing an adsorbing substance adhering to the surface of the silicon substrate after the drying, and Performing a processing step, wherein the crystal plane of the surface of the silicon substrate is (100).
Wherein the selective desorption is performed at a temperature lower than the temperature at the peak of the desorption strength of hydrogen on the low temperature side. 9. A step of cleaning a silicon substrate, a step of drying the silicon substrate, a step of selectively desorbing an adsorbing substance adhering to the surface of the silicon substrate after the drying, and Performing a processing step, wherein the selective desorption is performed in a reduced pressure atmosphere. 10. A step of cleaning a silicon substrate, a step of drying the silicon substrate, a step of selectively desorbing an adsorbing substance adhering to the surface of the silicon substrate after the drying, and Performing a processing step, wherein the selective desorption is performed in a gas atmosphere using any of an inert gas, a nitrogen gas, a hydrogen gas, or a mixed gas thereof. 11. A step of cleaning a silicon substrate, a step of drying the silicon substrate, a step of selectively desorbing an adsorbed substance adhering to the surface of the silicon substrate after the drying, and Performing a processing step, wherein the selective desorption is performed while forming an oxide film. 12. A step of cleaning a silicon substrate, a step of drying the silicon substrate, a step of selectively desorbing an adsorbing substance adhering to the surface of the silicon substrate after the drying, and In the heating furnace, heating the semiconductor substrate temperature in the furnace at a first heating rate, and performing the selective desorption at the time of detecting a preset first temperature. For this purpose, the temperature in the furnace is maintained at the first temperature for a predetermined time, or the furnace is heated at a second heating rate until a predetermined time or a predetermined temperature is reached, and then the first temperature is returned again. A method for manufacturing a semiconductor device, wherein a predetermined film is formed on a surface of a semiconductor substrate by heating at a temperature increasing rate. 13. The method for manufacturing a semiconductor device according to claim 1, wherein the semiconductor substrate is irradiated with energy rays to perform selective desorption. 14. The method of manufacturing a semiconductor device according to claim 1, wherein the drying is performed by vaporizing an organic substance. 15. The method according to claim 14, wherein the organic material is isopropyl alcohol. 16. The method according to claim 1, wherein the selective desorption is performed before forming a gate oxide film on a surface of a semiconductor substrate made of silicon, and thereafter, the gate oxide film is formed. 9. The method for manufacturing a semiconductor device according to claim 1. 17. A MOSFE using the gate oxide film.
The method of manufacturing a semiconductor device according to claim 16, wherein T is formed. 18. A closed furnace for containing a semiconductor substrate,
A substrate supporter disposed in the furnace for supporting the semiconductor substrate, a loader for loading / unloading the semiconductor substrate with respect to the substrate supporter, a heating unit for heating the semiconductor substrate in the furnace, A temperature detection unit that detects a temperature of the substrate, a gas supply unit that supplies a predetermined gas into the furnace, a pressure control unit that controls the inside of the furnace to a predetermined pressure atmosphere, and a control unit that controls each unit. A forcible exhaust device controlled by the control unit is connected to the furnace. 19. The forced evacuation device operates in synchronization with a selective desorption process performed before performing a predetermined processing on a semiconductor substrate housed in the furnace, and desorbs from the surface of the semiconductor substrate. 19. The semiconductor manufacturing apparatus according to claim 18, wherein the desorbed material is forcibly exhausted out of the furnace.