JPS5940580A - Manufacture of semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To obtain a gate film of high withstand voltage by a method wherein an oxide film is formed on a thin film by vapor growth, thereafter changed into a gate oxide film by heat treatment in oxidizing atmosphere which contains chloric gas, on an IC composed of an MOSFET wherein an amorphous semiconductor or polycrystalline semiconductor thin film is used as a substrate. CONSTITUTION:A vapor grown SiO2 film 12 is formed on the quartz glass substrate 11, a P type crystal Si layer 13 is deposited thereon and selectively etched into a fixed shape. Next, an SiO2 film 14 is produced over the entire surface including that likewise by vapor growth and heat-treated in the oxidizing atmosphere which contains chloric gas, resulting in the formation of a gate oxide film 15. Thereafter, gate electrode wiring 16 is provided thereon, ion is implanted from above, and accordingly the layer 13 at the part uncovered with the wiring 16 is changed into an N<+> type layer 17. Then, windows are opened by adhereing an SiO2 film 18 over the entire surface, and then Al wirings 19 are mounted at the regions 17. Thus, a gate oxide film 15 of high quality without projections, etc. is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor integrated circuit having an MO8 field effect transistor as a component using a thin film semiconductor as a substrate, and relates to a method for forming an oxide film formed on the thin film semiconductor.

Research and development of MO3i14 field effect transistors using amorphous thin film semiconductors or polycrystalline thin film semiconductors as substrates is being actively conducted. This is because if it becomes possible to realize a semiconductor integrated circuit device using thin film MO8 type field effect transistors as a component, various great advantages will emerge. For example, we can expect large-scale stop-downs, and the realization of large-sized ICs and multilayer ICs, which will create a wide range of applications for ICs.

This thin film MO3 is currently being researched and developed everywhere.
There are also some major problems with field effect transistors and integrated circuit devices.

Some of the major problems include a reduction in gate film breakdown voltage, an increase in leakage current, a state that applies a threshold voltage, and charge injection into the oxide film, which affect characteristics and reliability. We are in a state where stable mass production is not possible.

Examples of conventional manufacturing methods are shown in FIGS. 1 to 3.

These will be listed and explained below.

As shown in FIG. 1, a vapor phase growth 5102 film 2 is formed on a quartz glass substrate 1, and a P-type polycrystalline silicon layer 3 is formed thereon and selectively etched.

As shown in FIG. 2, a gate oxide film 4 is formed thereon to form a gate 'NJ electrode pattern m5. Furthermore, an N diffusion layer 6 is formed by +inane implantation.

As shown in FIG. 6, after forming a vapor phase grown 5102 film 7, a contact hole is bored by photoetching, and then At vapor deposition is performed and selective etching is performed to form Aj.
Wiring 8 is formed.

As described above, a thermal oxide film, particularly a dry thermal oxide film that is oxidized in an 02 gas atmosphere, is generally used as the gate oxide film. And the oxidation temperature is also 1100℃~12
It requires a high temperature of 00℃. Oxidation at low temperatures or humid oxidation at high temperatures will cause the substrate to become polycrystalline, causing protrusions called asbilites to grow protruding from the substrate into the gate oxide film, causing electric field concentration there and deteriorating breakdown voltage. Although the pressure has deteriorated, we are currently investigating a better method for forming an oxide film.

Other methods are being considered, such as growing an 8102 film by vapor phase growth and using it as a gate film by thermal annealing, but instability of the characteristics is a problem.

Furthermore, there is a strong demand for lowering the oxidation temperature from the viewpoint of the material of the substrate on which the thin film is placed and the equipment and jigs such as oxidation furnaces and boats.

The present invention is an improvement on the drawbacks such as blow-up, and the purpose of the present invention is to form a gate film with excellent voltage resistance characteristics.Another purpose of the present invention is to reduce the oxidation temperature. be.

The present invention will be described below with examples shown in FIGS. 4 to 6.

As shown in FIG. 4, a vapor phase grown 5102 film 12 is formed on a quartz glass substrate 11, and a P-type polycrystalline silicon layer 13 is formed thereon and selectively etched. A vapor-phase grown 5102 film 14 is formed thereon to a thickness thinner than the required gate film thickness, and then thermally oxidized in an oxidizing atmosphere to form a gate oxide film of a predetermined thickness as shown in FIG. Get 15. A gate electrode arrangement m16 is formed thereon, and ions are implanted from above to form an N diffusion layer 17. As shown in FIG. 6, a vapor phase grown 5102 film 18 is formed, a contact hole is bored by photoetching, and then At is deposited and selectively etched to form an At wiring 19.

As described above, according to the method of the present invention, since the vapor-phase grown Sin is formed before thermal oxidation, it is possible to prevent crystallization that occurs when heat is applied, and to prevent aspiration ( Helps prevent the occurrence of bumps). Therefore, it has sufficient pressure resistance.

Furthermore, in thermal oxidation, oxidizing agents such as oxygen diffuse through the vapor-phase grown 8102 and reach the surface of the thin film semiconductor, oxidizing the surface of the thin film semiconductor and forming an oxide film, which improves the film quality. It also has the same quality as an oxide film formed by thermal oxidation alone.

Incidentally, asabilities (protrusions) tend to occur and grow at low temperatures, but according to the method of the present invention, they are difficult to generate and grow even at low temperatures, and a high-quality gate oxide film can be obtained even if the oxidation temperature is lowered.

Although an example using a P-type polycrystalline silicon substrate is shown as an example of the method of the present invention, the same applies to an lq-type polycrystalline silicon substrate, and the same applies to an amorphous silicon substrate. The same applies to polycrystalline substrates and amorphous substrates of other elemental compositions.

[Brief explanation of drawings]

1 to 6 are schematic cross-sectional views of the manufacturing process according to the conventional method. 4 to 6 are schematic cross-sectional views of the manufacturing process according to the method of the present invention. The following is as follows. 1.11... Quartz glass substrate 2.12.14... Vapor phase growth 5102 film 6.16...
・P-type polycrystalline silicon layer 4.15... Gate oxide film 5.16... Gate electrode wiring 6.17... N+ diffusion layer 7, 18... Vapor phase growth 5102 film 8.19... At wiring and above Applicant: Suwa Seikosha Co., Ltd.

Claims (1)

[Scope of Claims] 1) A semiconductor integrated circuit device comprising a MOS field effect transistor using an amorphous semiconductor thin film or a polycrystalline semiconductor thin film as a substrate, the amorphous semiconductor thin film or the polycrystalline semiconductor thin film A method for manufacturing a semiconductor integrated circuit device, comprising forming an oxide film thereon by vapor phase growth, and then forming a gate oxide film by thermally oxidizing the film in an oxidizing atmosphere. 2) A method for manufacturing a semiconductor integrated circuit device according to claim 1, characterized in that the oxidizing atmosphere contains hydrochloric acid gas.