JPH0282523A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To insure sufficient peeling property after performing ion implantation by forming a double film in such a manner that its film comprises a photoresist film with which a region that does not require ion implantation is coated as a lower layer as well As an aluminum film as an upper layer. CONSTITUTION:After an N-type well 3 is formed in a P<-> type substrate 5 and a thick part 4 of an oxide film is formed, a polysilicon layer is formed and then, a polysilicon part 6 which forms a gate electrode and wiring is patterned. After a thin oxide film is formed with a thermal oxide film, a positive photoresist film 2 is applied to the foregoing thin film and then, an aluminum film 1 is formed. In this way, the formation of a photoresist layer 2 as a lower layer allows the surface of a photoresist to be approximately flat. Even though the aluminum layer 1 is formed on the upper layer of the photoresist 2, the aluminum layer may have a nearly uniform thickness. After that, a region which requires ion implantation is exposed and further it is developed. Then the photoresist is removed. Subsequently, a double film consisting of the left aluminum film 1 and the photoresist 2 prevents, for example, <75>As<+> from performing ion implantation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for forming a diffusion layer of a complementary field effect transistor (hereinafter referred to as CMO8) by an ion implantation method. The present invention relates to a membrane that blocks ion implantation.

[Conventional technology]

Conventionally, when forming this type of diffusion layer of two conductivity types (0MO8) by ion implantation, the region where ions are not implanted is covered with a vapor-deposited or sputtered aluminum film as shown in Figure 3, and an ion implantation blocking film is used. or the fourth
As shown in the figure, one of the manufacturing methods was to use a photoresist film as a blocking film.

[Problem to be solved by the invention]

The conventional manufacturing method described above has the following drawbacks. First, as shown in Figure 3, the polysilicon that will become the gate electrode is subjected to a photoresist process and an etching process, and after buttering, several hundred thin oxide films are applied to the surface of the polysilicon film by thermal oxidation, and then vapor deposition is performed. Or, by applying an aluminum film to the entire surface of the substrate by sputtering,
A photoresist process and an etching process are performed to remove the aluminum film in the portion where impurity ion implantation (in this case, 7"As") is to be performed, and the aluminum film is left in the portion where impurity ion implantation is not desired. (FIG. 3) At this time, the gate polysilicon has a thickness of 4000 to 6000 mm, and its sides are steep. When such a step exists, current aluminum film forming methods (evaporation or sputtering) have poor coverage of the step, and the aluminum may become extremely thin in some areas. When the conditions worsen, there is almost no aluminum, and even the ion implantation of heavy A s+ atoms cannot be prevented, and 22
There is a drawback that an N+ diffusion layer is formed.

Another conventional technique, as shown in FIG. 4, is a method in which 23 photoresist is left in areas where ions are not desired to be implanted. In this case, the type of ion implanted impurity (for example, "
Depending on the type of As''), there is a drawback that the peelability after ion implantation is poor.

[Means for Solving the Problems] A method for manufacturing a semiconductor device according to the present invention is a method for forming two diffusion layers of P+N+ by ion implantation of impurities of two conductivity types of 0MO3. For at least one of the ion implantations, the double film has a photoresist film as a lower layer and an aluminum film as an upper layer, covering the region where ions are not desired to be implanted.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) to 1(c) are longitudinal cross-sectional views of one embodiment of the present invention.

In FIG. 1(a), an N-well 3 is formed on a P-substrate 5, and a thick oxide film portion 4 is formed by selective oxidation.
A polysilicon layer with a thickness of 6,000 nm is formed, a photoresist process and an etching process are performed, the polysilicon part 6 that will become the gate electrode and wiring is buttered, a thin oxide film is formed by thermal oxidation, and then a positive photoresist is formed. membrane 2
Apply to a thickness of 1.5 to 2.0μ, then apply 0.5 to 2.0μ thick.
FIG. 2 is a longitudinal cross-sectional view immediately after forming an aluminum film 1 with a thickness of 1.1 μm. In this way, the photoresist layer (positive)
By using No. 2 as the lower layer, the surface of the photoresist becomes nearly flat, and is not affected by the unevenness of the underlying layer. Therefore, even if the aluminum layer 1 is formed on the photoresist 2, the aluminum layer can have a substantially uniform thickness. Thereafter, as shown in FIG. 1(b), a photoresist (positive) 7 is applied to the upper layer of the aluminum layer 1.
The area desired for ion implantation is exposed, developed, and the photoresist is removed. Thereafter, as shown in FIG. 1(c), the aluminum film 1 is etched using the photoresist 7 as a mask, and then the entire surface is exposed and developed, or
Plasma treatment is performed to remove the photoresist film 7 and the photoresist film 2 in the area where ions are to be implanted using the aluminum film 1 as a mask, and the remaining double film of the aluminum film 1 and the photoresist film 2 is ionized with, for example, As+. Used as a blocking film during implantation.Since ion implantation is blocked by the aluminum film 1 with a uniform thickness, ions are not implanted into the photoresist film 2, and the peelability of the aluminum film 1 and photoresist film 2 is also reduced. It is sufficient and there is no problem, and both the ion implantation blocking property and the peeling property are compatible.

FIGS. 2(a) to 2(c) are longitudinal cross-sectional views of other embodiments of the present invention. In this case, first, photoresist (positive) 11 is applied, and then photoresist (negative) 10 is applied.
The upper layer is coated (FIG. 2(a)). After that, the area where you want to implant ions is exposed and developed, and the photoresist (
Negative) 10 is left only in a predetermined area, and then aluminum film 1 is applied.
2 by vapor deposition or sputtering, (second
Figure (b)) By using the lift-off method, only the remaining photoresist (negative) 10 and the aluminum film on top of it are peeled off, and then the entire surface is exposed and developed to remove the aluminum film 12. The photoresist (positive) 11 in the remaining area is removed (FIG. 3(C)), and then a predetermined impurity is ion-implanted (for example, "A s ").
. In this case as well, since the aluminum film 12 is formed on the photoresist (positive) film 11 which is flat regardless of the unevenness of the base, the aluminum film 12 has a uniform thickness.
It blocks ion implantation and ensures both blocking properties and later peelability.

〔Effect of the invention〕

As explained above, the present invention provides a manufacturing method for forming two diffusion layers of P+N+ by ion implantation of two conductivity type impurities of 0MO8. By using a double film with a photoresist film on the bottom layer and an aluminum film on the top layer, the photoresist film can be used to cover areas where there is no surface area, regardless of the unevenness of the underlying surface.
By flattening the surface and eliminating variations in the thickness of the aluminum film at the stepped portions, the aluminum film has sufficient blocking ability during ion implantation. Since it is injected, it has the effect of being able to secure a sufficient amount.

2(a) to (c) are longitudinal sectional views of another embodiment of the present invention, and FIG. 3 is an example of a conventional manufacturing method, in which an aluminum film is FIG. 4 is a vertical cross-sectional view of the case in which a photoresist film is used in an example of the conventional manufacturing method.

1.12.20...aluminum, 2,7,11,2
3...Photoresist (positive), 3,13...
...N well, 4,16... Thick oxide film,
5,15...P-substrate, 6,14...Polysilicon, 8.17...Group-thin oxide film, 9,18,2
1, 25... River/N+ diffusion layer, 24... Altered photoresist.

Agent: Patent Attorney Susumu Uchihara

[Brief explanation of the drawing]

FIGS. 1(a) to 1(c) show the manufacturing process of the semiconductor device of the present invention.
Figure (b) Figure 1 CC) Figure 2 (S

Claims (1)

[Claims] An island-like region of a second conductivity type, which is an opposite conductivity type to the first conductivity type, is formed on a substrate of a first conductivity type, and the island-like region is 1st to
In the method for manufacturing a semiconductor device, in which a diffusion layer of a conductivity type is formed and a diffusion layer of a second conductivity type is formed on the substrate, during ion implantation to form the diffusion layers of the two conductivity types. 1. A method for manufacturing a semiconductor device, characterized in that in at least one of the steps, a region where ion implantation is not desired is covered with a double film having a photoresist film as a lower layer and an aluminum film as an upper layer.