JPH05175132A - Manufacture of silicon oxide film of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a silicon oxide film increasing in reaction rate and being excellent in flattening properties by using alkoxysilane and 0.01-10% water vapor and catalyst gas in the case of forming the SiO2 film for semiconductor device through plasma CVD method or ozone CVD method. CONSTITUTION:A surface-irregular silicon substrate is placed in a plasma reaction chamber and heated to a temperature of 200 deg.C. Then, 10cc/min Si(OC2H5)4, 300cc/min He, 100cc/min O2, 30cc/min water vapor and 11cc/min HC are introduced into the reaction chamber and a high frequency is set at 13.56MHz and the pressure in the reaction chamber, at 20Torr. After this film-forming reaction is previously continued for 1 minute, plasma is generated for 7 seconds and the liquid condensation film of alkoxysilane is generated on the substrate. Then, 20cc/min O2, is introduced into the reaction chamber, the pressure in the reaction chamber is brought to 1Torr and plasma is generated for 10 seconds at a high frequency of 100kHz so that the liquid film on the substrate is changed into SiO2 film. This process is repeated 10 times so that the SiO2 film of 0.5mum thickness is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a silicon oxide film of a semiconductor device, which is formed by using a CVD method.

[0002]

_2. Description of the Related Art Conventionally, SiH ₄ gas raw material has been used as a SiO ₂ type CVD film forming material. However, the pattern size used for integrated circuits has been becoming finer year by year with the increase in the density of circuit patterns, and is now in the submicron era. Also, with the miniaturization and high integration of LSI, the area occupied by the wiring chip increases,
Wiring multilayering is becoming more and more advanced. Further, in the future multi-layer wiring, the aspect ratio of the wiring becomes large because it is necessary to keep the wiring resistance small, and as a result, the unevenness of the substrate surface becomes more and more severe. Therefore, S
Flattening of an insulating film such as iO ₂ is an indispensable technique.

The conventional CVD process using SiH ₄ gas raw material cannot flatten the steps and irregularities on the substrate. In order to overcome this drawback, recently, a CVD method using a liquid raw material such as tetraethoxysilane instead of SiH ₄ has been put into practical use and has become popular. Si grown by the CVD method using such a liquid raw material as compared with SiH ₄
The O ₂ film is extremely excellent in step coverage and flatness.

When forming a SiO ₂ film by a CVD method using such an alkoxysilane as a raw material gas, it is a general technique to use an oxygen source such as oxygen or ozone. However, this method has a drawback in that an alkyl group or a tar-like component obtained by polycondensation of an alcohol and a carboxylic acid remains in the formed SiO ₂ film, resulting in poor film characteristics.

To form a film to reduce this problem, 6
Substrate heating of 00 to 700 ° C. is required. Therefore,
When the SiO ₂ film is formed on the aluminum wiring by the CVD method using tetraethoxysilane, there is a drawback that the aluminum wiring is significantly deteriorated.

The present inventors have studied the use of water vapor in such a CVD method. According to this method, an alkyl group and tar-like components or OH group does not remain in the SiO ₂ film was deposited, Si with very that high quality SiO ₂ film is obtained, the reaction of SiO ₂ and water vapor generated ( O
H) ₄ is produced, and this reaction is a reversible reaction.
Since H) ₄ is volatile, it was found that it has the effect of facilitating the movement of the SiO ₂ component on the film growth surface and densifying the film quality, and that densification treatment can be performed at low temperature. Filed a patent (Japanese Patent Application No. 1-10698)
6, Japanese Patent Application No. 1-330881, Date of application December 6, 1991
Day reference number P9112-022).

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to an improvement of the above-mentioned invention, and provides a method for producing a silicon oxide film of a semiconductor device which uses a catalyst gas to increase the reaction rate and is excellent in planarization. It is the one we are trying to provide.

[0008]

According to the present invention, a SiO ₂ film for a semiconductor device is formed by plasma CVD or ozone CVD.
When formed by the method, the alkoxysilane is added with 0.01 to 10
% Steam and catalyst gas are used.

The catalyst gas is a halogen such as F ₂ , Cl ₂ or Br ₂ , or an interhalogen compound such as ClF,
Alternatively, a hydrogen halide such as HF, HCl or HBr, a halogenoxy acid such as HClO, HClO ₂ or HClO ₃ or a carbon halide such as CCl ₄ or CF ₄ , or SiF ₄ or H ₂ SiF ₆ Such as silicon fluoride and its acid, or N ₂ O, N
Oxides such as O, NO ₂ , N ₂ O ₅ , HNO ₃ and their acids, or phosphorus oxides such as P ₂ O ₃ , P ₂ O ₅ , H ₃ PO ₄ and their acids, or HCOOH, CH
₃ Organic acids such as COOH.

In Japanese Patent Application No. 1-106986, steam and hydrogen were used. However, if hydrogen and oxygen sources are used at the same time, there are safety problems, and it is not preferable to use a common exhaust piping system.

According to the present invention, it is not necessary to use hydrogen because the catalytic gas promotes smooth condensation of the alkoxysilane with water vapor. In addition, for example, the process in which tetraethoxysilane and water vapor react to produce SiO ₂ is represented by the following chemical formula.

[0012]

[Chemical 1]

Therefore, when the above chemical formulas are totaled, the heat of reaction goes in and out of -9 KJ, which is an endothermic reaction.
It is known that when a silica sol is prepared and hydrochloric acid is added to water and tetraethoxysilane as a catalyst to hydrolyze, heat is generated. This is the heat of dilution generated when HCl is dissolved in water, and the above formula is used. Is not inconsistent with.

Hydrolysis of tetraethoxysilane is generally slow, but the reaction rate can be increased by using a catalyst, and the supply of active oxygen energy by plasma or ozone is effective.

Therefore, even if the substrate heating temperature is lowered, the reaction proceeds continuously to form a SiO ₂ film. In addition, an alkyl group, a tar-like component, an OH group, and the like do not remain in the formed SiO ₂ film, and thus extremely high-quality dense Si
An O ₂ film is obtained.

The concentration of the catalyst gas to be added is determined by the molecular form of the catalyst. A catalyst containing oxygen in the molecule may have a high concentration, but a catalyst containing no oxygen in the molecule preferably has a low concentration.

[0017]

Example A silicon substrate having surface irregularities was placed in a plasma reaction chamber and heated to a substrate temperature of 200 ° C. Si in the reaction chamber
(OC ₂ H ₅ ) ₄ 10 cc / min, He 300 cc /
min, O ₂ 100 cc / min, steam 30 cc / m
In, HCl 1 cc / min was introduced. High frequency is 1
The pressure inside the reaction chamber was set to 3.56 MHz and to 20 Torr.

After the film formation reaction was continued for 1 minute in advance, the conditions such as plasma intensity were found so that a liquid film could be recognized on the concave surface of the substrate, and then plasma was generated for 7 seconds to generate a liquid of alkoxysilane on the substrate. A condensation film was produced.

Next, 20 cc / min of O ₂ was introduced into the reaction chamber, the pressure inside the reaction chamber was set to 1 Torr, and 100 KH.
Plasma was generated at a high frequency of z for 10 seconds to change the liquid film on the substrate to a SiO ₂ film. The substrate temperature at this time is 200
It was ℃.

The above operation is repeated 10 times to obtain a film thickness of 0.5.
A μm SiO ₂ film was produced.

The SiO ₂ film thus prepared was excellent in flatness filling the recess of the silicon substrate extremely flat. Further, as a result of measuring an infrared absorption spectrum of this film, an alkyl group, a reaction polymer, an OH group and the like were not detected.

[0022]

EFFECTS OF THE INVENTION According to the present invention, since a catalyst gas is used for the reaction, the reaction rate can be remarkably increased, and a SiO ₂ film having an extremely excellent flatness can be formed. Further, there is a feature that an alkyl group, a tar-like component, or an OH group does not remain in the formed SiO ₂ film, and an extremely high-quality densified SiO ₂ film can be obtained.

Claims (2)

[Claims] 1. When a SiO ₂ film for a semiconductor device is formed by a plasma CVD method or an ozone CVD method, alkoxysilane, steam of 0.01 to 10% and a catalyst gas are used. Manufacturing method of silicon oxide film of. 2. The catalyst gas is a halogen such as F ₂ , Cl ₂ , Br ₂ or an interhalogen compound such as ClF, a hydrogen halide such as HF, HCl or HBr, or HClO, HClO ₂ or HClO. Halogenoxy acids such as ₃ , or halogenated carbons such as CCl ₄ and CF ₄ , or SiF ₄ and H ₂ SiF ₆
And its acid such as N ₂ O, N
Oxides such as O, NO ₂ , N ₂ O ₅ , HNO ₃ and their acids, or phosphorus oxides such as P ₂ O ₃ , P ₂ O ₅ , H ₃ PO ₄ and their acids, or HCOOH, CH
_{3. The} method for manufacturing a silicon oxide film of a semiconductor device according to claim 1, wherein the organic acid is ₃ COOH.