JPH01312840A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable control of oxygen deposit at a process which requires thermal treatment of 950 deg.C or higher at a manufacturing process by applying thermal treatment to a substrate under specific conditions. CONSTITUTION:At an initial stage of a manufacturing process of a semiconductor device, heat treatment is applied to a silicon semiconductor substrate 11 at 950 deg.C or higher for at least 10 minutes to diffuse oxygen 12 of a surface region of the substrate 11 outward and to form a denuded layer 13 having an extremely low density of oxygen. Furthermore, at a process which requires thermal treatment of 950 deg.C or higher in a later manufacturing process, for example, at a manufacturing process of a gate oxide film, a temperature-up speed C from a low temperature range of 500 deg.C-900 deg.C to a high temperature range of 950 deg.C-1300 deg.C at the heat treatment is made not exceeding 14 deg.C/min. According to this constitution, oxygen deposit can be controlled, thus growing more defect cores 14 or defects inside the substrate 11 while maintaining a denuded layer 13 and enabling formation of a gate oxide film on the denuded layer 13.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for manufacturing a semiconductor device, particularly a method for heat treatment in the manufacturing process of a semiconductor device, the present invention relates to a method for manufacturing a semiconductor device, in particular, a method for heat treatment in the manufacturing process of a semiconductor device. This is also a heat treatment method for the manufacturing process of a semiconductor device using a silicon semiconductor substrate, the purpose of which is to control oxygen precipitation.
℃ or more for 10 minutes or more, and in the subsequent manufacturing process that requires heat treatment at 950 ℃ or more, from a low temperature range of 500 ℃ to 900'' C.
The temperature increase rate to the high temperature range of 50℃ to 1300℃ is 14”C.
/win or less, a heat treatment method for a manufacturing process of a semiconductor device using a silicon semiconductor substrate having an epitaxial silicon layer, the method comprising: heat treating the substrate at a temperature of 950° C. or higher;
'C to 900℃ low temperature range to 950"C to 1300℃
“The temperature increase rate to the high temperature range of C is 14° (/l1in) or less, and the substrate is heat-treated.

[Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device,
More specifically, the present invention relates to a heat treatment method in the manufacturing process of a semiconductor device.

In recent years, semiconductor devices have become highly integrated, miniaturized, and silicon wafers have a larger diameter.The manufacturing of semiconductor devices requires careful consideration of the characteristics of the wafer that serves as the substrate, such as oxygen precipitation, etc.
There is a need for something that can be controlled with better reproducibility.

This is because silicon wafers are generally processed using the CZ method (Czochr method).
This is because the crystal is produced using a silicon single crystal pulled by the Alski method, so oxygen is present which melts from the crucible during crystal pulling.

This oxygen can be beneficial or harmful depending on how it is used. So you need to control it so that this oxygen works efficiently.

Furthermore, silicon wafers tend to have larger diameters, and crystal defects such as slip lines are more likely to occur due to heat treatment of the wafers to control oxygen. Therefore, such heat treatment needs to be controlled under conditions that prevent the occurrence of these crystal defects.

[Prior Art] FIG. 5 is a diagram illustrating a method of manufacturing a semiconductor device according to a conventional example, and shows a heat treatment process diagram of a silicon wafer.

As shown in FIG. 5A, first, a silicon wafer I is heat-treated at 1100° C. for about 20 hours in an N2 atmosphere.

In a silicon wafer 1 produced by the normal CZ method, 0.5 to 2. OXIO"C11-' (ASTM standard,
Oxygen 2 is contained in the crystal at a density of about 100% (hereinafter the same shall apply), and although the mechanism itself is not yet public, it is known that this oxygen concentration is an important factor in the formation of crystal defects. .

Here, by performing heat treatment at 1000° C. or higher, oxygen 2 near the surface is out-diffused to the outside as schematically shown by arrows.

At the same time, inside the wafer l, the wafer formation state (as-
The defective nuclei that existed in the grown state) disappear or dissolve into solid solution. In addition, in the normal IG method described below, the wafer surface is coated with a protective film such as Sin in advance in order to prevent the wafer surface from becoming rough due to long-term high-temperature processing.

Next, as shown in FIG. 4B, a heat treatment is performed at a temperature of 700 to 800° C. for about 40 hours in the same N2 atmosphere, which is a process of forming high-density defect nuclei 4 by so-called low-temperature annealing.

In the process shown in FIG. 2A, oxygen 2 near the surface of the wafer 1 is out-diffused to the outside, but the oxygen concentration inside the wafer 1 is still high. By applying heat treatment at 700 to 800"C, the oxygen 2 is concentrated to form defect nuclei 4.

That is, in this process, high-density defect nuclei 4 are increased to some extent inside the wafer l. However, near the surface of the wafer 1, the high-temperature annealing shown in FIG. 4(a) sufficiently lowers the oxygen level by 4 degrees Celsius, and the defect nuclei 4 are eliminated or dissolved into solid solution, so the formation of a high density of defect nuclei 4 is prevented. do not have.

After that, as shown in the same figure (c), 105
The defect-free line area (DZ) is
) form 3.

Note that some semiconductor device manufacturing processes require heat treatment at a high temperature of 950° C. or higher. For example, selective oxidation, impurity diffusion, etc.

These heat treatments have an adverse effect on, for example, the silicon wafer 1, which is a substrate for forming ordinary semiconductor devices.

First, long-term high-temperature heating causes warping or distortion of the substrate, making it difficult to accurately align masks, which is essential for microfabrication.

Second, oxygen 2 contained in silicon wafers currently produced by the CZ method is used to form crystal defects 4 inside the silicon wafers, and the defects 4 are present in regions related to device operation. Indoline mink that gets rid of impurities
One gettering method (hereinafter referred to as IC method) has been proposed. In the [G method, as a pre-processing step for manufacturing semiconductor devices, crystal defects are formed only inside the silicon wafer l to prevent device operation. This area is called Denuded Zone.
e (hereinafter referred to as DZ) 3, which eliminates defective nuclei 4 and causes oxygen 2 to out-diffusion. Furthermore, as long as no defects appear in the element operation region, the thinner the width of the DZ, the better the IC effect can be obtained. However, in a normal semiconductor device manufacturing process, a number of high-temperature treatments must be performed even after the pretreatment step for forming crystal defects. In this series of heat treatment steps, crystal defects in f) ennuded Zone 3 and internal crystal defects of the initially formed silicon wafer 1 are greatly affected. That is, the defects and defect nuclei 4 formed inside the substrate disappear or dissolve into solid solution during the high-temperature treatment for manufacturing the semiconductor device, thereby weakening the gettering effect from the DZ 3. Alternatively, the solid-dissolved oxygen 2 may dissolve into the DZ 3 and adversely affect the operation of the element. Due to the disappearance of defects due to such heat treatment, the crystal defects and DZ3 formed for cleaning the device operating region lose their meaning.

For this reason, in semiconductor manufacturing processes that require heat treatment at temperatures of 950°C or higher, heat treatment of 500°C to 90°C is required to prevent slip lines from forming and warping of silicon wafers.
Temperature increase rate 1 from a low temperature range of 00 °C to a temperature of 950 °C or higher
It is necessary to raise the temperature at 4° C./sign or less.

Ru.

Furthermore, unless the temperature increase rate is controlled according to the oxygen concentration,
A phenomenon occurs that is harmful to the semiconductor device.

For example, if a silicon wafer is heat-treated at a temperature increase rate of 14°C/+sin or higher, a solid solution of precipitated oxygen 2, that is, a phenomenon in which oxygen 2 dissolves between silicon crystal lattices, occurs, and the internal gettering effect is reduced. Become thin. Furthermore, if the temperature increase rate is set to 14° C./win or less, oxygen 2 will precipitate near the surface, which will be harmful unless the M element concentration is specified.

Therefore, in order to increase the precipitation of oxygen inside the crystal and prevent the precipitated oxygen from forming a solid solution, the temperature increase rate should be set to 14"C/win or less, especially 5"C/sin or less, and the temperature increase should be slowed down. However, there is a problem in that the oxygen concentration must be regulated.

(Problems to be Solved by the Invention) According to the conventional method for manufacturing a semiconductor device, heat treatment is performed under the conditions as described in Patent Application Publication No. 11782 of 1988. That is, 95 of semiconductor devices
In a process that requires heat treatment at 0°C or higher, soo'c
When performing heat treatment that includes heating from a low temperature of 900°C to a high temperature of 950°C to 1300°C and cooling from a high temperature to a low temperature, silicon wafers with an oxygen concentration of 1.5 x to "cym-' or more , temperature increase and decrease rate of 5℃/sin
14° or more (:/sin or less, and the oxygen concentration is 1.5
For a silicon wafer l smaller than XIO"ell-3, the temperature increase and decrease rates are set to 14 degrees (/win or less).

Therefore, the following problems arise.

■Oxygen concentration must be measured for each silicon wafer.

■Due to the requirements of semiconductor devices, DZ3 requires oxygen precipitation,
That is, in order to eliminate the defect nuclei 4 and improve the gettering effect, it is necessary to form a large number of defect nuclei 4 in the silicon wafer l.

■Since it is necessary to separate silicon wafers according to oxygen concentration, heat treatment such as selective oxidation and impurity diffusion of semiconductor devices must be performed to control oxygen precipitation for each semiconductor device having the same oxygen concentration.

The present invention was created in view of the problems of the conventional example, and it is possible to control oxygen precipitation under the same heat treatment conditions, regardless of the oxygen concentration of the silicon wafer, and also as a heat treatment in the semiconductor device manufacturing process. The purpose is to provide a method for manufacturing semiconductor devices that makes it possible to manufacture semiconductor devices.

[Means to solve the problem]

The method for manufacturing a semiconductor device of the present invention is described in the first embodiment to
As shown in FIG. 4, the first manufacturing method is a heat treatment method in the manufacturing process of a semiconductor device using a silicon semiconductor substrate, and in the initial stage of the manufacturing process of the semiconductor device, 950
℃ or more for 10 minutes or more, and in the subsequent manufacturing process that requires heat treatment at 950℃ or more, from a low temperature range of 500℃ to 900℃ to 95℃.
The temperature increase rate to the high temperature range from 0℃ to 1300℃ is 14℃/w.
The method is characterized in that the substrate is heat-treated at a temperature of less than or equal to in.
The second manufacturing method is a heat treatment method for the manufacturing process of a semiconductor device using a silicon semiconductor substrate having a silicon kidney, and in the process requiring heat treatment at 950°C or higher, 500°C
The third manufacturing method is characterized in that the substrate is heat-treated at a rate of temperature increase from a low temperature range of 950°C to 1300°C to a high temperature range of 14″C/sin or less; From the low temperature range of ℃9
For high temperature ranges from 50℃ to 1300℃! W temperature rate is 5℃/
sin or less, and achieves the above objectives.

do.

[Effect]

According to the first manufacturing method of the present invention, the silicon semiconductor substrate is heated to 950° C. in the initial stage of the semiconductor device manufacturing process.
As described above, by performing the heat treatment for 10 minutes or more, oxygen in the surface region of the silicon semiconductor substrate can be diffused outward to form a defect-free layer with an extremely low oxygen concentration. ! In manufacturing processes that require heat treatment of 950"C or higher, for example, in the gate oxide film manufacturing process, the heat treatment is carried out from a low temperature range of 500°C to 900°C to 950°C.
The temperature increase rate to the high temperature range of 1300℃ to 14℃/*ir
By controlling the oxygen precipitation to less than l, it is possible to control oxygen precipitation, grow many defect nuclei or defects inside the substrate while maintaining a defect-free layer, and form a gate oxide film on the defect-free layer. becomes.

Further, according to the second manufacturing method of the present invention, an epitaxy silicon layer serving as an element formation region is provided on the silicon semiconductor substrate.

Therefore, compared to the first manufacturing method, 950
℃ or more for 10 minutes or more can be omitted, and by performing the heat treatment for forming defect nuclei in the semiconductor substrate in the same manner as in the first manufacturing method, it can also be used, for example, as the gate oxide film manufacturing process. It becomes possible to do so.

Further, according to the third manufacturing method of the present invention, the temperature can be reduced from the low temperature range of 500°C to 900°C according to the manufacturing method 1.2.
The temperature increase rate from 0°C to 1300°C is set to 5°C/win or less.

Therefore, the width of the defect-free layer can be narrowed, and many defects can be grown inside the substrate, so even if contaminants, heavy metals, etc. are mixed into the substrate in the subsequent resist film stripping process, defects will occur. It is possible to absorb it by the nucleus or defect and improve the gettering effect.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

1 to 4 are diagrams for explaining a method for manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. 1 is a diagram for explaining a method for heat treatment of a silicon wafer according to a first embodiment of the present invention. ing.

Note that (a) is a characteristic diagram showing the relationship between heat treatment temperature θ [°C] and time T [minutes], and (b) is a state diagram in which silicon wafers are Q-treated in the initial stage. Figure (c)
2A and 2B respectively show state diagrams in which the silicon wafer is heat-treated in the subsequent manufacturing process.

In FIG. 5A, the vertical axis is the temperature θ [° C.], which is the heating temperature at which the silicon wafer is heat-treated.

The horizontal axis is time T (minutes), which indicates the processing time during which the silicon wafer is exposed to heat treatment.

Further, A is a thermal characteristic diagram at an initial stage, for example, a thermal characteristic diagram in which a silicon wafer is heat-treated before forming elements such as impurity diffusion regions and conductive regions on a semiconductor substrate in the manufacturing process of a semiconductor device.

In addition, B is a thermal characteristic diagram of the subsequent manufacturing process, for example, 95
It shows the oxidation thermal characteristics in the manufacturing process of gate oxide films of MOS and FET (': 4 field effect type 1 to transistor) which are subjected to heat treatment at 0 °C or higher, and the activation thermal characteristics in the activation process of impurity diffusion regions. .

In addition, C shown in the broken line circle is a temperature increase characteristic in which the silicon evaporator is heated from a low temperature range of 500 °C to 900 °C to a high temperature range of 950 °C to 1300 °C, and the temperature increase rate is kept below 14 °C/win. This is the part that stipulates.

In the figure (b), in the initial stage A, a solicon wafer 11 having a film thickness of, for example, about 500 to 600 (um) is heated to a temperature of 1100 in a dry nitrogen (N2) atmosphere.
Heat treatment is performed at a temperature of 30 minutes to 10 hours.

As a result, the oxygen 12 in the surface area of the silicon wafer U is out-diffused (C-out diffusion), and the surface area becomes a defect-free layer (defect-free layer) with a depth of about 10~30 (μm).
Knoepuit Zone (DZ) 13.

The relationship between the heat treatment conditions and the DZ width is shown in FIG.

Note that defect nuclei I4 contributing to the gettering effect grow slightly inside the silicon wafer 11, and oxygen 12 moves between the silicon crystal lattices as U! fJ is dissolved. In order to prevent the wafer surface from becoming rough due to this high temperature treatment, it may be coated with a protective film such as SiO□ in advance.

Next, in the same figure (b), when forming a 5i02 film 15 as a gate oxide film of a MOSFET, for example, the temperature increase rate is specified to 14°C/1Iin or less in a dry oxygen (island) atmosphere, and the temperature is increased from a low temperature range of 750°C, for example. High temperature range 1000゛C
The heat treatment equipment is adjusted so that the temperature increase rate is 3° C./sin, and the temperature increase treatment is performed. Next, heating temperature 100
After reaching 0°C, an oxidizing atmosphere is maintained at an oxidation temperature of 1000°C, and oxidation treatment is performed for 5 minutes to form a 5iO1 film I5 with a thickness of about 350 to 400 (people) on the defect-free layer 136. Thereafter, the growth conditions are changed from the ozW atmosphere to the dry N7 atmosphere, and the temperature of the silicon wafer 11 is lowered.The temperature lowering rate is not particularly specified, but it is preferably 14°C/l1in or less, for example, the temperature lowering rate is 5°C/l1in. Temperature cooling treatment is performed at

Thereby, many defect nuclei 14 can be grown inside the silicon wafer 11 while maintaining the defect-free layer 13.

This makes it possible to form de-nuptoid zones and crystal defects that provide a gettering effect in the manufacturing process of semiconductor devices without dividing the oxygen concentration.

FIG. 2 is a diagram illustrating a silicon wafer heat treatment method according to a second embodiment of the present invention, and FIG. figure,
FIG. 5B shows a state diagram in which an epitaxial silicon layer is grown on a silicon wafer, and FIG.

The difference from the first embodiment is that in the second embodiment, an epitaxial layer 5ili 23 is formed on the silicon wafer 21, so the initial stage heat treatment according to the first embodiment is omitted.

Therefore, in FIG. 3A, the thermal characteristic diagram A at the initial stage disappears, and the thermal characteristic diagram in the subsequent manufacturing process becomes similar to the characteristic diagram of the first embodiment.

In addition, in FIG. 2(b), a silicon wafer 21 is coated with a film having a thickness of [1] by a CVD method on top of a state in which oxygen 22 mixed into the silicon crystal by the CZ method is solidly dissolved between the silicon crystal lattices.
An epitaxial layer of about [μm] is formed.

Note that, in FIG. 2C, a Sing film 25 is grown as a gate oxide film of the MOSFET by heat treatment in the same manner as in the first embodiment. As a result, the epitaxial Si layer 2
3 is maintained, and many defect nuclei 24 can be formed in the silicon wafer 21.

FIG. 3 is a diagram illustrating another temperature increase rate according to each embodiment of the present invention.

In the figure, C5 is a part that defines the temperature increase process from a low temperature range of 500°C to 900″C to a high temperature range of 950°C to 1300″C to a temperature increase rate of 5°C or less.

This is particularly effective when forming a thin denomination zone (DZ), which is an element formation region of a semiconductor device, or as a heat treatment for forming many crystal defects inside a substrate.

FIG. 4 is a diagram illustrating the relationship between the 02 width and the high temperature heat treatment time according to the practical example of the present invention.

In the figure, the vertical axis is the day-neutral zone width [μm
], and the horizontal axis indicates the high temperature heat treatment time [Hour]. In addition, the figure shows a heating temperature of 950°C as a heating condition.
It is a characteristic curve showing the relationship between the DZ width and the processing time when the temperature is increased from 1200° C. to 1200° C. every 50° C.

Ru.

In this way, according to the first embodiment, in the initial stage of semiconductor Lit, the heating temperature 11 of the silicon wafer 11 is
By performing heat treatment at 00°C for a processing time of about 30 minutes to 10 hours, oxygen 1 in the surface area of the silicon wafer If is removed.
2 can be out-diffused to form defect-free N(DZ) 1.3 with extremely low oxygen concentration,
In the subsequent manufacturing process that requires heat treatment at 950°C or higher, for example, in the manufacturing process of the gate oxide film of a MOS FET, the heating rate of the heat treatment from a low heating temperature range of 750°C to a high temperature range of 1000°C is 3. C/win, it is possible to control oxygen precipitation and grow many defect nuclei or defects 14 inside the wafer while maintaining the DZ 13, and to form a SiO2 film 15 on the DZ 13. Become.

Further, according to the second embodiment, an epitaxial layer 5ii 123 is provided on the silicon wafer 21.

Therefore, compared to the first embodiment, the 950"C
As described above, the heat treatment step of 10 minutes or more can be omitted,
By performing the heat treatment for forming defect nuclei 24 in the silicon wafer 21 in the same manner as in the first embodiment, it is possible to perform the heat treatment also as a process for manufacturing a gate oxide film, for example.

Furthermore, according to the third embodiment, the low temperature range of 500°C to 900°C according to the 1.2 embodiment is changed to 950°C to 13°C.
The temperature increase rate at 00°C is set to 5°C/sin or less.

Therefore, the distance in the depth direction of the element formation region, for example, the DZ 13 or the epitaxial layer 23, can be made thinner, so that no contamination, heavy metals, etc. can get into the silicon evaporators 11 and 21 during the subsequent resist film stripping process. , the defect core or the defects 14 and 24 absorb them, making it possible to further improve the gettering effect.

〔Effect of the invention〕

As explained above, according to the present invention, heat treatment can be performed in the semiconductor device manufacturing process under the same heat treatment conditions, regardless of the oxygen concentration of the silicon semiconductor substrate.
It becomes possible to control oxygen precipitation.

Therefore, it is possible to improve the efficiency of the heat treatment process.

Further, according to the present invention, it is possible to prevent the occurrence of slip lines in the silicon wafer, to eliminate the occurrence of warpage, and to further improve the intrinsing gentering effect. This makes it possible to improve the production yield of semiconductor elements and to manufacture semiconductor devices that are highly multi-sized and lightweight.

[Brief explanation of the drawing]

FIGS. 1(a) to (c) are diagrams illustrating a silicon wafer heat treatment method according to a first embodiment of the present invention, and FIGS. FIG. 3 is a diagram illustrating another temperature increase rate according to each embodiment of the present invention. FIG. FIGS. 5(a) to 5(c) are diagrams illustrating the relationship between width and high-temperature heat treatment time, and FIGS. 5(a) to 5(c) are diagrams illustrating a conventional method for manufacturing a semiconductor device. (Explanation of symbols) 1.11.21...Silicon wafer (silicon half 1 (
[Mutan), 2.12.22...Oxygen, 3.13...Defect-free region (De Noop India Zone, DZ) 23...Epitaxial 5ili (epitaxial silicon layer) 4.14.24. ...Defect nucleus (crystal defect), 15.25
...5iO1 film (gate oxide film), A...Thermal characteristics diagram at the initial stage, B...Thermal characteristics diagram of the subsequent manufacturing process, C...Temperature rise rate set to 4℃/win or less The part to do,
C3: Part where the temperature increase rate is set to 5°C + min or less.

Claims (3)

[Claims] (1) A heat treatment method for a manufacturing process of a semiconductor device using a silicon semiconductor substrate, which comprises:
℃ or more for 10 minutes or more, and in the subsequent manufacturing process that requires heat treatment at 950℃ or more, from a low temperature range of 500℃ to 900℃ to 95℃.
The temperature increase rate from 0℃ to 1300℃ is 14℃/m.
A method for manufacturing a semiconductor device, characterized in that the substrate is heat-treated at a temperature of less than 100 m. (2) A heat treatment method for the manufacturing process of a semiconductor device using a silicon semiconductor substrate having an epitaxial silicon layer, in which the process requires heat treatment at 950°C or higher.
A method for manufacturing a semiconductor device, characterized in that the substrate is heat-treated at a temperature increase rate of 14° C./min or less from a low temperature range of 900° C. to 950° C. to a high temperature range of 950° C. to 1300° C. (3) The method for manufacturing a semiconductor device according to claim 1 or 2, wherein the rate of temperature increase from a low temperature range of 500°C to 900°C to a high temperature range of 950°C to 1300°C is 5°C/min or less. .