JPH05308071A - Manufacture of silicon oxide film of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing silicon oxide film of a semiconductor device for forming SiO2 film by the CVD method using a new liquid raw material. CONSTITUTION:One out of Si[OC(CH3)3](OC2H5)3, Si(OCOCH3)(OC2H5)3, Si(NH2)(OC2H5)3, Si[OC(CH3)3]2(OC2H5)2, Si(OCOCH3)2(OC2H5)2), and Si(NH2)2(OC2 H5)2 is used as a new liquid raw material. Therefore, neither OH group nor an organic content remain within generated SiO2 film not only by the ozone CVD method and the oxygen plasma CVD method where activated oxygen coexists but also by the CVD method where no activated oxygen coexists, thus obtaining SiO2 film with a superb film quality. Also, a film which is superb in flat property can be obtained at a low reaction temperature.

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, in which a SiO ₂ film is formed by a CVD method using a novel liquid raw material.

[0002]

2. Description of the Related Art Conventionally, C of SiO ₂ film for semiconductor devices has been used.
A SiH ₄ gas raw material has been used as a VD film forming material. However, as semiconductor devices become highly integrated, the unevenness of the substrate surface becomes more and more intense, and the steps and unevenness on the substrate cannot be flattened by the CVD process using this SiH ₄ gas source, and narrow gaps between electrodes or trenches in the gate are formed. There are drawbacks such as the formation of voids and the deterioration of film characteristics, and SiH ₄ being a self-igniting and extremely dangerous raw material.

In order to overcome the above drawbacks, recently, a CVD method using tetraethoxysilane Si (OC ₂ H ₅ ) ₄ which is a liquid raw material in place of SiH ₄ has been put into practical use and has become popular. ..

This vaporizes tetraethoxysilane,
It is introduced into the CVD reaction chamber to form a SiO ₂ film on the substrate. The film grown by the CVD method using tetraethoxysilane has excellent step coverage and flattening property, and tetraethoxysilane has no self-ignitability and is a very safe raw material in the manufacturing process of semiconductor devices. Further, as a characteristic of the flattening CVD film, a void-free flattening film can be achieved by reflow processing even in a high-density pattern portion.

However, C using tetraethoxysilane
The SiO ₂ film grown by the VD method has a drawback that OH groups and organic components are likely to remain in the film. In addition, since tetraethoxysilane has a high thermal decomposition temperature during film formation, S by the thermal decomposition CVD method.
When forming an iO ₂ film, there is a drawback that a high temperature of 700 ° C. or higher is required. Therefore, when the SiO ₂ film is formed on the aluminum wiring by the CVD method using tetraethoxysilane and the reflow is performed, there is a drawback that the aluminum wiring is significantly deteriorated.

Therefore, it is possible to form a SiO ₂ film at a lower temperature than that of tetraethoxysilane without the need for heating the substrate at a high temperature.
In addition, a CVD raw material in which OH groups and organic components do not remain in the formed film and which is also excellent in flatness has been desired.

[0007]

DISCLOSURE OF THE INVENTION The present inventors have found that S of a semiconductor device using triethoxysilane SiH (OC ₂ H ₅ ) ₃ as a novel CVD raw material satisfying such demands.
I applied for a patent for a method for manufacturing an io ₂ film (Japanese Patent Application No. 2-201
21).

This is because triethoxysilane has a higher vapor pressure than tetraethoxysilane and can form a SiO ₂ film at a lower temperature than tetraethoxysilane. Since triethoxysilane has SiH bonds in its molecule, it decomposes more than tetraethoxysilane. It is easy to do, and in the case of triethoxysilane, H in the molecule is easily desorbed and O is easily introduced. Therefore, since it is easier to produce an intermediate condensate such as a dimer or trimer than tetraethoxysilane, step coverage and flatness are improved. It is based on features such as being excellent.

However, CV using triethoxysilane
It has been found that the D method has drawbacks that H groups and OH groups are likely to remain in the generated SiO ₂ film unless active oxygen coexists, and a skeleton of Si—Si bonds is easily formed. Therefore, the ozone CVD method or the oxygen plasma CVD method can form an extremely excellent film, but the CVD method using water vapor in which active oxygen does not coexist has a drawback that a good film cannot be formed.

Therefore, the present invention relates to an improvement in the method for producing this SiO ₂ film, which is a CV using water vapor.
The method D is also intended to provide a method for producing a SiO ₂ film having good film quality.

[0011]

According to the present invention, when a silicon oxide film for a semiconductor device is formed by a CVD method using a liquid raw material, triethyl tert-butyl silicate Si [OC (CH ₃ )] is used as the liquid raw material. ₃ ] (OC ₂ H ₅ ) ₃ , triethoxyacetoxysilane Si (OCOCH ₃ ) (OC
₂ H ₅ ) ₃ , triethoxyaminosilane Si (NH ₂ ).
(OC ₂ H ₅ ) ₃ , diethyl tert-butyl silicate Si [OC (CH ₃ ) ₃ ] ₂ (OC ₂ H ₅ ) ₂ , diethoxydiacetoxysilane Si (OCOCH ₃ ) ₂ (O
C ₂ H ₅ ) ₂ , diethoxydiaminosilane Si (N
At least one of H ₂ ) ₂ (OC ₂ H ₅ ) ₂ is used.

SiH (OC ₂ H ₅ ) ₃ is Si (OC ₂ H 5
₅ ) Although only one side chain of ₄ is substituted with an H group to enhance reactivity, the liquid raw material according to the present invention is SiH (OC ₂
H ₅ ) ₃ or SiH ₂ (OC ₂ H ₅ ) ₂ H groups are replaced by OC
(CH ₃ ) ₃ groups, OCOCH ₃ groups, NH ₂ groups and the like are substituted.

Since the reaction is fast in the ozone CVD method and the plasma CVD method, OC (CH ₃ ) ₃ groups, OCOCH ₃ groups, N
It is desirable that the number of side chains such as H ₂ groups that are easily thermally decomposed is one, but two such side chains may be present because the reaction is slow in the steam decomposition method.

Since these groups are decomposed at a temperature lower than that of the OC ₂ H ₅ group in this manner, there is a feature that an ethoxy group is left to be polymerized and a Si source can be deposited on the substrate. In the CVD method using a liquid raw material, the present inventors provide a standing time of not applying plasma for at least 1 second or more at the stage when the alkoxysilane condensation polymer is formed on the substrate surface,
A patent was filed for a method for producing a SiO ₂ laminated film by repeating the operation of applying a stronger plasma to form a SiO ₂ film several tens of times (Heisei 2-127592). When this manufacturing method is applied to the present invention, there is a feature that the effect of the present invention can be extremely enhanced.

Further, there is a feature that a SiO ₂ film having an excellent film quality can be obtained because H groups, OH groups and organic components do not remain in the SiO ₂ film formed by the CVD method in which active oxygen does not coexist. Furthermore, since a skeleton of Si—O—Si bond is formed without forming a skeleton of Si—Si bond, a film having excellent flatness can be obtained.

[0016]

Example A Si substrate was placed in a CVD reaction chamber and the temperature of the substrate was set to 250 ° C. Si heated to 60 ° C
2000cc of [OC (CH ₃ ) ₃ ] (OC ₂ H ₅ ) ₃
Mixed with gas generated by bubbling with / min of _{N 2,}
A mixed gas generated by bubbling pure water at 25 ° C. with N ₂ at 1500 cc / min was introduced into the reaction chamber for 1 second. Next, the introduction of the raw material into the reaction chamber was stopped, and 2000
After introducing only cc / min of N ₂ gas into the reaction chamber for 1 second, the introduced gas is 100 cc of oxygen containing 10% of ozone.
/ Min, the gas was introduced for 7 seconds, and then the introduced gas was changed to N ₂ gas and 2000 cc / min was introduced for 1 second to form a SiO ₂ film on the substrate. The above operation 6
The SiO ₂ film was laminated by repeating 0 times.

As a result of analyzing the deposited SiO ₂ film by infrared absorption spectroscopy, it was found that OH groups and alkyl groups were not detected and the film was extremely good. Further, the substrate was changed to an Al pattern Si substrate, a SiO ₂ film was deposited by the same operation, and the film was observed. As a result, it was found that the film was extremely flat. From the above experiment, it was found that the substrate temperature was extremely low and a good film was obtained.

In this embodiment, Si [OC (CH ₃ )
₃ ] (OC ₂ H ₅ ) ₃ is being flown, plasma is applied, ozone, N ₂ O, etc. are flowed, and a component having a catalytic property for polycondensation is flowed to further improve the reaction efficiency. I found out that I can also do it.

[0019]

According to the present invention, OH groups and organic components remain in the SiO ₂ film produced not only by the ozone CVD method and oxygen plasma CVD method in which active oxygen coexists but also in the CVD method in which active oxygen does not coexist. The feature is that a SiO ₂ film having excellent film quality can be obtained without doing so. Further, there is a feature that a film having excellent flatness can be obtained at a low temperature.

Claims (1)

[Claims] 1. When a silicon oxide film for a semiconductor device is formed by a CVD method using a liquid raw material, Si is used as the liquid raw material.
[OC (CH ₃ ) ₃ ] (OC ₂ H ₅ ) ₃ , Si (OCO
_{CH 3) (OC 2 H 5} ) 3, Si (NH 2) (OC 2 H
₅ ) ₃ , Si [OC (CH ₃ ) ₃ ] ₂ (OC
₂ H ₅ ) ₂ , Si (OCOCH ₃ ) ₂ (OC
_A method of manufacturing a silicon oxide film of a semiconductor device, wherein at least one of ₂ H ₅ ) ₂ and Si (NH ₂ ) ₂ (OC ₂ H ₅ ) ₂ is used.