JPH04264718A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a manufacture method of a semiconductor device which does not damage a semiconductor substrate. CONSTITUTION:An electrode is formed on a semiconductor substrate (1), and first and second insulating films (31, 32) are deposited all over. Since there is a difference in etching rate of the insulating films, one insulating film can selectively be removed. Therefore, the substrate (1) is not damaged since it is possible to make the other insulating film selectively remain and to use it as a stopper layer during etching.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device.

0002

2. Description of the Related Art Japanese Patent Publication No. 2-49012 is known as a method for forming a Schottky junction electrode. In Figure 2,
An example is shown below. For example, when forming a Schottky junction electrode, first, a heat-resistant metal is patterned into a desired shape on the active layer of the substrate 1 (as shown in FIG. 4A). Next, an insulating film 3 is deposited on the entire surface of the substrate 1 so as to cover the heat-resistant metal 2 (as shown in FIG. It is left only on the side (as shown in figure (c)).

0003

In the above manufacturing method, as shown in FIG. 2, only one layer of an insulating film is formed on the surface of the patterned heat-resistant metal and the substrate. Therefore, when the insulating film is etched to remove unnecessary portions, the substrate surface is damaged by plasma irradiation or the like.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing a semiconductor device that solves the above-mentioned problems.

[0005]

[Means for Solving the Problems] The present invention includes a first step of patterning a heat-resistant metal on a substrate into a desired shape, and etching the patterned heat-resistant metal and the entire surface of the substrate with the same etchant. a second step in which a first insulating film and a second insulating film are sequentially deposited at different rates; and a third step in which the second insulating film is anisotropically etched and left only on the sides of the refractory metal. and a fourth step of removing the exposed first insulating film by etching.

[0006]

[Operation] According to the present invention, since the etching rates of the first and second insulating films are different for the same etchant,
The first insulating film functions as a stopper layer when etching the second insulating film. Therefore, by selectively removing only the first insulating film and then using a method that does not damage the substrate surface when etching the second insulating film,
It is possible to avoid adversely affecting the active layer of the substrate.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of each step of the manufacturing method according to the embodiment. First, a heat-resistant metal is deposited on the substrate 1, and a mask pattern (not shown) is formed on the top surface. The heat-resistant metal is etched through this mask pattern to form a desired shape on the active layer of the substrate (see figure (a)).
(Illustrated). Next, a first insulating film 31 and a second insulating film 32 are sequentially deposited on the entire surface of the substrate 1 and the patterned heat-resistant metal 2 (as shown in FIG. 2B). These first and second
The etching rates of the first insulating films 31 and 32 are different with respect to the etchant used in anisotropic etching, and the etching rate of the first insulating film 31 is smaller. Therefore, when etching the second insulating film, the first insulating film 31
will function as a stopper layer. Therefore, by anisotropically etching the second insulating film 32 until the first insulating film 31 is exposed, the second insulating film 32 can be left only on the sides of the heat-resistant metal 2. , the surface of the substrate 1 is not damaged by plasma irradiation or the like (as shown in FIG. 1(c)). Next, the exposed first insulating film 31 is etched with an etchant that does not damage the substrate 1 to expose the surface of the substrate 1 and the surface of the heat-resistant metal 2, thereby forming the desired structure. A semiconductor device can be obtained (as shown in the same figure (d))
.

Next, a specific example based on the above-mentioned manufacturing method will be explained.

First, a heat-resistant metal 2 is patterned on a substrate 1 (as shown in FIG. 1(a)). As the heat-resistant metal used here, a metal material containing W (tungsten) (for example, WSi, WAl, WN, WSiN, etc.) is generally used. When patterning, a dry etching method such as RIE (reactive ion etching) or PE (plasma etching) that allows anisotropic etching is preferable, but a lift-off method may also be used.

[0011] Next, a first layer made of SiO2 is coated on this entire surface.
An insulating film 31 (hereinafter referred to as SiO2 film) is deposited to a thickness of 500 angstroms, and then SiO
A second insulating film 32 (hereinafter referred to as a SiON film) made of N is deposited to a thickness of 3000 angstroms (as shown in FIG. 2B). Thereafter, the SiON film is removed by RIE using an etchant containing CF4 as a main component until the SiO2 film is exposed (as shown in FIG. 4(c)). At this time, the etching rate of the SiO2 film is higher than that of the SiON film.
slower than membranes. As a result, only on the side of the heat-resistant metal 2,
A SiON film remains deposited to a thickness of 1500 angstroms.

[0012] Here, the SiO2 film and SiO
Although N films were used as the first and second insulating films, both insulating films may be SiO2 films. In this case, the film quality is changed by changing the film forming temperature when forming each SiO2 film, so it is possible to change the etching rate of films of the same composition as necessary.

Next, the exposed SiO2 film is etched to expose the surfaces of the substrate 1 and the heat-resistant metal 2 (
Figure (d) shown). Although PE was performed here so as not to damage the substrate 1, HF-based wet etching may also be performed. In that case, the wet etching rate of the SiO2 film is more than four times that of the SiON film, so
Only the O2 film can be selectively removed.

By the method described above, the side walls of the insulating film 3 can be formed only on the sides of the heat-resistant metal 2 without adversely affecting the substrate 1.

[0015]

[Effects of the Invention] As explained above, according to the present invention, the first
Since the etching rate of the second insulating film differs depending on the etchant used in each step, a highly self-aligned manufacturing method can be obtained. Furthermore, since the first insulating film is formed on the substrate and functions as an etching stopper layer, damage caused by etching is not directly applied to the substrate. Therefore, a semiconductor device with good characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an element according to steps of a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an element by process according to a conventional manufacturing method.

[Explanation of symbols]

1...Substrate 2...Heat-resistant metal 31...First insulating film 32...Second insulating film

Claims (2)

[Claims] 1. A first step of patterning a heat-resistant metal into a desired shape on a substrate, and a first step of patterning the patterned heat-resistant metal and the entire surface of the substrate at different etching rates with the same etchant. a second step of sequentially depositing an insulating film and a second insulating film;
a third step of etching the insulating film anisotropically and leaving it only on the sides of the heat-resistant metal; and a fourth step of removing the exposed first insulating film by etching. A method for manufacturing a semiconductor device. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the fourth step uses an etching method that does not damage the surface of the substrate.