JPH03225826A - Manufacture of silicon oxide film for semiconductor device - Google Patents

Abstract

PURPOSE:To make it possible to manufacture an SiO2 film at a lower temperature than tetraethoxysilane and improve the qualities of the film such as the capabilities of covering steps, planarization, compactness, resistance against cracking, and insulating quality by using triethoxysilane SiH(OC2H5)3 as a liquid raw material in manufacturing the SiO2 film for a semiconductor device by a CVD method. CONSTITUTION:When an SiO2 film for a semiconductor device is formed using a liquid raw material and by a CVD method, triethoxysiliane is used as the liquid raw material. Triethoxysilane has a higher vapor pressure than the one of tetraethoxysilane, and can make an SiO2 film at a lower temperature than the one of tetraethoxysilane. Also, in the molecule of triethoxysilane, H is easy to break away from is and O is easy to enter it, and therefore, since triethoxysilane is easier to generate the intermediate condensate of a dimer and trimmer than tetraethoxysilane, it is excellent in the capabilities of covering steps and planarization. Further, the film grown by the CVD method using triethoxysilane is very excellent too in the qualities of the film such as compactness, resistance against cracking, and insulating quality. Thereby, the SiO2 film can be manufactured at a lower temperature, and the qualities of the film such as the capabilities of covering steps, planarization and compactness can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is a method of forming a Sio2 film by CVD using a new liquid raw material.
The present invention relates to a method for manufacturing a silicon oxide film for a semiconductor device formed by a method.

(Prior Art) The CVD method is a method in which one or more compound gases consisting of elements constituting a thin film are sent to the surface of a substrate and chemically reacted on the surface of the substrate to form a desired thin film.

Traditionally, SiH4 has been used as a 5102-based CVD film forming material.
Gaseous feedstocks have been used.

However, the pattern dimensions used in integrated circuits have been becoming smaller and smaller year by year as the density of circuit patterns has increased, and we have now entered the submicron era. Further, as LSIs become smaller and more highly integrated, the area occupied by wiring on a chip becomes larger, and the number of layers of wiring is increasing. Furthermore, in future multilayer wiring, the aspect ratio of the wiring will increase due to the need to maintain low wiring resistance, and as a result, the unevenness of the substrate surface will become more and more severe. Therefore, planarization of an insulating film such as SiO2 has become an indispensable technology.

In the conventional CVD process using the 5iHa gaseous raw material, it is not possible to flatten the steps and unevenness on the substrate.

Further, in this CVD process, voids are formed in narrow gaps between electrodes and in gate trenches, significantly degrading film characteristics.

Furthermore, 5iHa is a self-igniting and extremely dangerous raw material.

In order to overcome the above drawbacks, tetraethoxydisilane Si (○
The CVD method using C2H5)a has been put into practical use and is becoming popular.

This vaporizes tetraethoxysilane and introduces it into the CVD reaction chamber.

Films grown by the CVD method using tetraethoxysilane have excellent step coverage and flattening properties, and tetraethoxysilane does not self-ignite, making it an extremely safe raw material for semiconductor device manufacturing processes. .

Further, as a feature of the planarized CVD film, a void-free planarized film can be achieved by reflow processing even in a high-density pattern portion.

However, films grown by the CVD method using tetraethoxysilane still have problems with film quality such as density, crack resistance, and insulation, and there are ways to form films to alleviate these problems. Requires substrate heating to 600-700°C.

Therefore, when a SiO2 film is formed on aluminum wiring by the CVD method using tetraethoxysilane, there is a drawback that the aluminum wiring is significantly deteriorated.

For this reason, there has been a desire for a CVD liquid raw material that does not require high-temperature substrate heating and can form a SiO2 film at a lower temperature than tetraethoxysilane.

(Problems to be Solved) The present invention can form a SiO2 film at a lower temperature than tetraethoxysilane, has excellent step coverage, flattening properties, etc., and has excellent density, crack resistance, and insulation properties. The present invention aims to provide a method for manufacturing SiO2 films for semiconductor devices using a novel liquid raw material with excellent film quality.

(Means for Solving the Problems) The present invention provides a method for producing SiO2 films for semiconductor devices using the CVD method, using Trie I and xysilane S as novel liquid raw materials.
It is characterized by using iH(OC2H5)3.

Tetraethoxysilane has a structure in which four ethoxy groups are attached to Si, while triethoxysilane has a structure in which three ethoxy groups and one hydrogen are attached to Si, and is a colorless and transparent liquid at room temperature.

Tetraethoxysilane has a boiling point of 16B and a viscosity of 5°C and 0.
7 mPa, s, whereas triethoxysilane has a boiling point of 131.5° C. and a viscosity of 0.512 mPa, s, and triethoxysilane has a lower boiling point and lower viscosity than tetraethoxysilane.

Further, the vapor pressures of triethoxysilane and tetraethoxysilane are as follows.

S i )l(OC2H5)3 S i (OC
2) +5) 425°C 4.9 Torr 0.
9 Torr50°C23Torr 6 Torr
rrlooooC240Torr 85 Torr
As mentioned above, it was found that triethoxysilane has a higher vapor pressure than tetraethoxysilane, and that a SiO2 film can be formed at a lower temperature than tetraethoxysilane.

Furthermore, triethoxysilane has a characteristic of being easily decomposed because of its SiH bond.

The process of tetraethoxysilane becoming SiO2 is S at once.
Instead of becoming iO2, (H5C20) 3 S iO3i (OC2H5)
3, (H5C20)3siO3i (○C2H3)20S
It is known that SiO2 is formed through an intermediate condensate of dimers and trimers of tetraethoxysilane such as i(○C2H5) 3, and because this intermediate condensate has fluidity, it has good properties. It is considered to have excellent step coverage and flattening properties.

In triethoxysilane, H in the molecule easily leaves and O enters.
Therefore, it is easier to form intermediate condensates of dimers and triplets than tetraethoxysilane, so it has excellent step coverage and flattening properties.

Furthermore, it was found that the film grown by the CVD method using triethoxysilane has extremely excellent film qualities such as denseness, crack resistance, and insulation properties.

Further, like tetraethoxysilane, triethoxysilane is an extremely safe raw material in the manufacturing process of semiconductor devices.

(Example) An S1 substrate was placed in a plasma CVD apparatus, and the substrate was heated to 400°C.

Triethoxysilane was bubbled with He carrier gas at 25° C. and introduced into a plasma CVD apparatus, mixed with oxygen in the apparatus, and an SiO2 film was formed on a Si substrate by plasma. The gas pressure at this time was 10 Torr.

Plasma CVD using this film and tetraethoxysilane
As a result of comparing the hardness of the film with the film using a hardness meter, it was found that the plasma CVD film using triethoxysilane had greater hardness and was a sufficiently dense film.

(Effects of the Invention) According to the present invention, Si can be formed at a lower temperature than tetraethoxysilane.
It is possible to form an O2 film, and the film has excellent step coverage and flattening properties, as well as excellent film quality such as density.

Additionally, it has the feature of extremely high safety in the manufacturing process of semiconductor devices.

Claims (1)

[Claims] CVD of SiO_2 film for semiconductor devices using liquid raw materials
1. A method for manufacturing a silicon oxide film for a semiconductor device, characterized in that when the film is formed by a method, triethoxysilane is used as the liquid raw material.