JPH04181732A - Silicon dioxide film formation method - Google Patents

Abstract

PURPOSE:To obtain a good quality silicic dioxide film at a low temperature by a method wherein a film formation temperature is held at a specific temperature and oxygen plasma is emitted to a non-monocrystal silicone film. CONSTITUTION:A microwave is introduced into a reacting chamber 102 through a wave introducing space 101, oxygen is introduced from a gas introducing pipe 103 to produced oxygen plasma. An external coil 104 is provided outside the reacting chamber 102 to generate a magnetic field to the oxygen plasma. A substrate 105 is placed perpendicularly to the plasma and a temperature of a substrate 1 is held at 300 deg.C by a heater 106. The oxygen plasma is emitted to a groundwork film layer, whereby all or a part of the groundwork film layer and/is oxidized to obtain a silicic dioxide film. Thus, the silicic dioxide film having good qualities at a low temperature can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for forming a high-quality silicon dioxide film at a relatively low temperature, and is applicable to the field of manufacturing silicon-based semiconductor devices such as three-dimensional LSI devices and thin film transistors. It is something used for.

[Prior Art] Conventionally, there are three widely known methods for forming a silicon dioxide film (S i Ox ii): a silicon film thermal oxidation method and a chemical vapor deposition method (CVD method). In the former thermal oxidation method, the base silicon thin film is exposed to oxygen (02), laughing gas (
The surface layer of the silicon film is oxidized by heat treatment at a high temperature of about 700°C to 1000°C or higher in an oxidizing atmosphere containing water vapor (H□0) and water vapor (H□0). There is a method to obtain a membrane. The latter CVD method combines silicon-containing liquid or gaseous compounds such as silane (SiH4), disilane (Si*H-), or Teos (Si-(0-C18,)) and oxides such as oxygen in a gas phase or This method involves depositing a silicon dioxide film on the substrate by causing a chemical reaction on the surface of the substrate. This CVD method is a normal pressure CVD method.

There is a low pressure CVD method, and other known methods include a plasma CVD method, an ECR plasma CVD method, and a photoCVD method.

[Problems to be Solved by the Invention] However, in the conventional method described above, the u1 point has been pointed out for many years. First, in the Si film formation method based on the thermal oxidation method of the silicon film, the formation time is at least 70%.
Since high-temperature heat treatment of 0°C or higher is required, the heat resistance of the substrate becomes a major issue. This conflict remains an essential problem in the manufacture of a three-dimensional multilayer LSI, for example, in that the lower layer LSI must be protected when the upper layer LSI is created. Furthermore, when manufacturing semiconductor devices such as thin film transistors on glass substrates, the thermal oxidation method cannot be used due to the insufficient heat resistance of glass.

On the other hand, although the SiO□ film deposited by the CVD method can be deposited at a relatively low temperature, there is a feeling that the film quality is extremely poor, as shown by, for example, a high etching rate. Therefore, up to now, there has been no method for forming high-quality Sin films at low temperatures.

The present invention is among such conventional SiO2 film forming methods.

The purpose is to provide a method for forming a high quality 5i02 film at low temperatures.

[Means for Solving the Problems] The present invention is based on spraying oxygen plasma onto the base film layer.
The method is characterized in that a silicon dioxide film is obtained by oxidizing all or part of the base film layer.

[Example 1] The present invention will be described in detail below, but the present invention is not limited to the following examples.

In this Example I, the substrate has a diameter of 76.2 mm and a thickness of 40 mm.
Three n-type single crystal silicon wafers having a <100> crystal plane orientation of 0LLm were used. This substrate was doped with phosphorus and had a resistivity of 3.00 Ωcm.The substrate was immersed in boiling 60% nitric acid for 5 minutes to remove dirt on the substrate surface. 6 Next, the liquid temperature is 25°C]
The surface natural oxide film was removed by troweling the substrate in a 67% hydrofluoric acid aqueous solution for 20 seconds, followed by washing in pure water with nitrogen bubbles for 15 minutes and drying with a spin dryer. , immediately atmospheric pressure vapor phase chemical deposition (
The underlying 6S i O2 film was deposited using the APCVD method (APCVD method).
The substrate temperature when A is deposited and the underlying SiO2 film is deposited is 300.
'C, 600SCCM of silane/nitrogen mixed gas diluted to 20% according to N vote, 840SC
CM(7) was diluted with about 140 SLM of nitrogen along with oxygen and flowed into an APCVD furnace to deposit base 51021i. The deposition rate of SiO*Mi at this time was 3.33A7sec. These different steps were carried out in order to stabilize the quality of the silicon film that would be deposited later, regardless of the nature of the substrate material.

Next, on the 5iO2tlN formed in this way, a low pressure vapor phase chemical deposition method (
747 people deposited non-single-crystal silicon films using the LPCVD method (LPCVD method) The LPCVD equipment used in Example 1 was a hot-tub type, and a soaking zone with a length of about 350 mm was installed in the vertical direction near the center of the reactor. The volume of one reactor in which is expanded is 1
At 84.54, the substrate was inserted into the reactor near the center with the front side facing upward. The deposition temperature of the non-monocrystalline silicon film is 550℃.
``C, 305 CCM of monosilane, which is a raw material gas, was flowed. No diluent gas was used at all. By adjusting the opening and closing of the conductance valve in the exhaust system, the internal pressure of the reactor during deposition was maintained at 300.0 mTorr1. The deposition rate at this time was 14.93 A/min. After the non-bonding silicon film was deposited, one of the substrates (Sample 1-1) was heated to a temperature of 24°C.
C. Leave it in a room at a temperature of 45% to 50% for 10 days, then dry it for several days. When the thickness of the natural oxide film on the surface was measured using i-long dispersion ellipsometry (multi-wavelength spectroscopic ellipsometry - Nisobra Co., Ltd., 11055-ES4G), four types of SiO2 were observed.

Next, one of the substrates after the non-single crystal silicon film was deposited (Sample 1-
2) was immersed in a 167% hydrofluoric acid aqueous solution for 20 seconds to remove the natural oxide film on the surface.

Immediately electron cyclotron resonance plasma cvoiffi
(ECR-PECVD equipment) A non-single-crystal silicon film was irradiated with oxygen plasma. EC used in Example 1.
An outline of the R-PECVD apparatus is shown in FIG. 1. Oxygen plasma is generated by introducing 2.45 GHz microwaves into the reaction chamber 102 through a waveguide 101, and introducing 100 SCCU of oxygen from a gas introduction pipe 103 to generate oxygen plasma. Ta. At this time, the pressure inside the reaction chamber was 1.80 mTorr, and the microwave output was 100 OW.
A Gaussian magnetic field is applied to make the electrons in the plasma satisfy the ECR conditions. The substrate 105 is placed perpendicular to the plasma, and the substrate temperature is maintained at 300° by the heater 106.
C is maintained. Under these conditions, sample 1-2
Oxygen plasma was irradiated for 10 minutes. Similarly to sample 1-2, sample 1-3 was immersed in 167% hydrofluoric acid for 20 seconds to remove the natural oxide film on the surface, and then immediately subjected to test It 1-2.
ECR-PECV
Oxygen plasma was irradiated using D apparatus. At this time, plasma irradiation was performed under the same conditions as Sample 1-2, except that the microwave output was 2500 W and the plasma irradiation time was 8 minutes and 20 seconds.

The thickness of the surface oxide film of Sample 1-2 and Sample 1-3 thus prepared was determined using multi-wavelength dispersive ellipsometry.
93 and 112 SiO films were confirmed, respectively6.
Next, these samples 1-1.1-2.1-3 and the above-mentioned AP
The etching rate of the underlying SiO□ film deposited by the CVD method was measured. A 1.67% hydrofluoric acid aqueous solution was used as the etching solution.

The liquid temperature was 25°C. The etching rate of the native oxide film of Sample 1-1 was 0.76 people/sec.

Samples 1-2 and 1- created by oxygen plasma irradiation
The etching speed of the 5iO- films in No. 3 is 4.35 people/s.
ec and 4,29 people/sec. On the other hand, AP
The etching rate of SiO,l[ deposited by the CVD method was 21.40 people/sec. In this way, it is possible to form a 5102 film by irradiating a non-single-crystal silicon film with oxygen plasma, and the film quality is higher than that of 5i deposited by the conventionally widely used APCVD method at the same substrate temperature.
Osll! much better than.

[Example 2] The possibility of oxidation of the non-single-crystal silicon film due to oxygen plasma irradiation was investigated using the same steps as in Example 1 except for the step of depositing the non-single-crystal silicon film.

In this Example 2, the same three substrates as in Example 1 were used, and the base material 5i
The steps up to the step of forming the Oz film were exactly the same as in Example 1. After forming the base Si○2, disilane (Sl
The LPCVD furnace in Example 2 was the same as the LPCVD furnace in Example 1, in which 839A of non-single-crystal silicon film was deposited by the LPCVD method. The deposition temperature of the non-single crystal silicon pus was 450° C., and disilane as a raw material gas was flowed at 11,005 CC. Purity 99.0 as diluent gas.
9999% helium was used and it was flowed at 11003 CC. Additionally, by adjusting the opening and closing of the conductivity valve in the exhaust system, the reactor internal pressure during deposition was reduced to 298.7 mTorr.
was maintained. At this time, the deposition rate of the non-single crystal silicon film +
-: 16.78 people/min. After depositing non-monocrystalline silicon M, one of the substrates (sample 2-1) was rotated once at 24°.
When the specimens were left in a room with a C1 humidity of 45% to 50% for 10 days and the thickness of the natural oxide film on the surface was measured using multi-wavelength dispersive ellipsometry, 5iO- was found in 5 people.

Next, one of the substrates after the non-single crystal silicon film was deposited (Sample 2-
2) was immersed in a 1.67% hydrofluoric acid aqueous solution for 20 seconds to remove the surface natural oxide film.

Oxygen plasma irradiation was immediately performed using the ECR-PECVD apparatus used in Example 1. The plasma irradiation conditions at this time were as strict as sample 1-2 in Example 1! matches. For sample 2-3, after removing the native oxide film on the surface of the non-single crystal silicon film using the same method as sample 2-2, the sample 2-3 was immediately exposed to oxygen under the completely same oxygen plasma irradiation conditions as sample 1-3 of Example 1. Plasma irradiation was performed.

The film thicknesses of the surface oxide films of Sample 2-2 and Sample 2-3 thus created were determined using multi-wavelength fractional ellipsometry.
The etching rates of these samples 2-1, 2-2, and 2-3, in which 102 and 119 SiO□ films were confirmed, respectively, were measured. The measurement conditions were all the same as in Example 1. As a result, the etching rate of the native oxide film of sample 2-1 was 1.06 A/sec, and the etching rate was 1.06 A/sec. sample 2-2 and 2
-3 SiO2 film etching speed was 481 people/
sec and 4.59A/sec. By irradiating the non-single crystal silicon film with oxygen plasma in this way,
The substrate temperature is as low as 300°C, and the film quality of Si is much better than that of S10, which was created by CVD.
C) I was able to create aMJN.

[Effect of the invention] As described above, according to the present invention, the temperature of 11M can be reduced to 3
By irradiating a non-single-crystal silicon film with oxygen plasma, it is possible to form a high-quality silicon dioxide film even at temperatures as low as 00°C. It has a great effect of improving performance 6

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an outline of an electron cyclotron resonance plasma CVD apparatus used for oxygen plasma irradiation in an embodiment of the present invention. 1, 01 ・ ・ Micro i skin guidance (Zanyuki 102...
Reaction chamber 103...Oxygen gas introduction pipe 104...External coil 105...Substrate 106...Heater and above Applicant: Seiko Epson Corporation

Claims (3)

[Claims] (1) A method for forming a silicon dioxide film, characterized in that a silicon dioxide film is obtained by oxidizing all or part of the base film layer by irradiating the base film layer with oxygen plasma. (2) The silicon dioxide forming method according to claim 1, wherein the base film layer is a non-monocrystalline silicon film layer. (3) The method for forming a silicon dioxide film according to claim 1, wherein the surface layer of the base film layer is a non-monocrystalline silicon film layer.