JPS61264763A - Manufacture of semiconductor element - Google Patents

Abstract

PURPOSE:To prevent a gate insulating film from being broken by ion implantation, by adhering a polycrystalline silicon film on the whole surface of a substrate after the formation of a gate electrode, implanting ions from over the polycrystalline silicon film and thermally oxidizing the film. CONSTITUTION:A field oxide film 2 of silicon dioxide and a gate insulation film 3 of silicon dioxide are adhered in respective positions on the principal face of a silicon substrate 1. A polycrystalline silicon film to be a gate electrode 4 is then adhered thereon, and a silicon dioxide film 5 is adhered on the surface of the polycrystalline silicon film by thermal oxidation. After that, the polycrystalline silicon film is removed by means of the photo etching technique, except the part thereof to be the gate electrode 4 in the further. A polycrystalline silicon film 6 is then adhered. Boron atoms are implanted in a source region 7 and a drain region 8 by means of the ion implantation technique. The silicon substrate 1 is then subjected to thermal oxidation so that the polycrystalline silicon film 6 is converted into a silicon dioxide film 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing an eight-edge gate field effect semiconductor device.

[Conventional technology]

Axes (a) and (b) of FIG. 2 are cross-sectional views showing a conventional semiconductor device, for example, an insulated gate field effect semiconductor device. In this figure, 1 is a silicon substrate, 2 is a field oxide film, 3 is a gate insulating film, 4 is a gate electrode, 5 is an insulating film, for example, a silicon dioxide film, and T and 8 are source and drain regions, respectively. .

Next, the Vclll construction method will be explained. First, the 2nd ry!
As shown in J(a), polycrystalline silicon is deposited via the gate insulating film SV using a -conductivity type silicon substrate/plate 1'%. Thereafter, the polycrystalline silicon chip is removed by a 7-to-etching method, leaving a polycrystalline silicon chip only in the portion that will later become the gate electrode 4. This photoresist (not shown) was used as a mask for impurity ion implantation in the source region 7. is introduced into the drain region 8.

Thereafter, a silicon dioxide film 5 is deposited on the entire surface of the silicon substrate 1 as shown in FIG. 2(b).

[Problem that the invention seeks to solve]

As described above, in the conventional manufacturing method of an insulated gate type field effect semiconductor device, ions are implanted from above the gate electrode 4 connected to the silicon substrate 1 through the gate insulation II1. Therefore, a large electric field is applied to the gate insulating film 3, resulting in frequent breakdown of the insulating film.

This promise was made in order to solve the above-mentioned problems, and by reducing the electric field applied to the gate insulating film during ion implantation, an insulated gate field effect semiconductor can be prevented from being destroyed. The purpose is to provide a method for manufacturing the device.

[Means for solving problems]

The method for manufacturing an insulated gate field effect semiconductor device according to the present invention is to cover the entire surface of the substrate with a polycrystalline silicon film after forming the gate electrode, implant ions over the film, and perform thermal oxidation treatment to activate impurities. At the same time, the polycrystalline silicon film is oxidized.

[Function] In the present invention, by electrically connecting the gate electrode and the semiconductor substrate, charges are prevented from being accumulated on the gate electrode during ion implantation, and damage to the gate insulation film is prevented.

〔Example〕

One embodiment of this invention Vat diagrams (a), (b), (c
) Vc is shown. First, a field oxide film 2 made of a silicon dioxide film with a thickness of 8000 Å and a gate insulating film 3t made of a silicon dioxide film with a thickness of 400 Å are coated on the main surface of a silicon substrate 1 made of conductive material, for example Nu, at predetermined positions. wear it. Next, a polycrystalline silicon film that will later become the gate electrode 4 is deposited to a thickness of 5000 Å, and then a silicon dioxide film 5 oxidized by 2000 Å is deposited on the surface of the polycrystalline silicon film by thermal oxidation. Then, by photo-etching, the polycrystalline silicon film that will become the gate electrode 4, the silicon dioxide film above it, and the silicon dioxide film that will become the gate insulating film 3 are left only in the part that will later become the gate electrode 4, and the rest is removed. do. This state is shown in Figure 1 (&)
It is.

Next, as shown in FIG. 1(b), a K polycrystalline silicon film 6 is deposited to a thickness of IGOOA. After that, by using the ion implantation method, the acceleration energy was set to 40 @V and the dose was 5 x 10"/c.
Boron atoms are implanted into the source region 1 and drain region 8 under conditions of t.
Make it. During this process, source region 7 and drain region 8
porons are activated. The semiconductor device v#It that was formed in this way is shown in FIG.

In this embodiment, source region 7 and drain region 8
When introducing impurities using ion implantation method.

Since the gate insulating film 3 is surrounded by the polycrystalline silicon film 6, no electric field is applied to the gate insulating film 3.
Destruction of the gate insulating film 3 does not occur.

In the above embodiment, the case where a silicon dioxide film is used as the gate insulating film 3 has been described, but a silicon nitride film or a phosphorus glass film may also be used.

〔Effect of the invention〕

As explained above, in this invention, since ion implantation is performed through a polycrystalline silicon film, the gate electrode is not insulated from the semiconductor substrate when forming the source and drain regions, which prevents the breakdown of the gate insulating film due to ion implantation. It has the effect of preventing

[Brief explanation of drawings]

1(a)(b) and (c) are explanatory diagrams of the manufacturing process showing one embodiment of the present invention, and FIGS. 2(a) and (b) are explanatory diagrams of the manufacturing process of a conventional semiconductor device. In the figure, 1 is a silicon substrate, 3 is a gate insulating film, and 4 is a silicon substrate.
is a gate electrode, 5 and 9 are silicon dioxide films, 6 is a polycrystalline silicon film, 7 is a source region, and 8 is a drain region. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent: Masuo Oiwa (2 others) Figure 1 Figure 2 Mu procedural amendment (voluntary) 1. Indication of the case Patent application Sho EO-TOESTS No. 26
Title of the invention: Method for manufacturing a semiconductor device 3; Person making the amendment 5; Drawings to be amended; Contents of the amendment; Figures 1(b) and 1(C) are amended as shown in the attached sheet. that's all

Claims (1)

[Claims] A process of sequentially forming a gate insulating film, a polycrystalline silicon film, and a silicon dioxide film on a semiconductor substrate, and after removing each of the above films on the source region and drain region to form a gate electrode, a polycrystalline silicon film is formed on the entire surface. ion implantation into the source and drain regions through this polycrystalline silicon film, and then thermal oxidation treatment to activate the implanted impurities and at the same time remove the polycrystalline silicon film. A method for manufacturing a semiconductor device, the method comprising: oxidizing a semiconductor device.