JPS60110142A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enhance the reliability by forming an insulating film on the side of an electrode layer, forming the stepwise difference of a smooth film surface, thereby preventing an overhung portion from forming on an interlayer insulating film and preventing the stepwise disconnection of metallic wirings. CONSTITUTION:After an aluminum film 3 is formed as an electrode wiring layer through an insulating film 2 on a semiconductor substrate 1, a silicon dioxide film 5 is formed by a CVD process as the second layer, the film 5 is anisotropically etched, and the film 3 is etched to produce an undercut. A silicon nitride film 6 is formed by a plasma CVD process on a pattern having a T-shaped sectional shape formed in this manner, plasma etched to allow the silicon nitride 6 to remain only on the side wall of the layer 3, thereby flattening the stepwise portion. Thus, the surface of the film 4 to be formed thereafter becomes smooth, a preferable insulating film having no overhang is obtained, and the stepwise disconnection of the aluminum film used for upper electrode wirings can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and in particular to a multilayer wiring technology for MO8 type integrated circuits.

J114 formation of the conventional example and its problems FIG. 1 is an enlarged sectional view of the main part of the conventional example showing the process completed immediately before the deposition of the upper aluminum electrode layer of a semiconductor device having a two-layer aluminum wiring structure. For the sake of simplicity, the process of forming the first aluminum electrode layer is shown first. In the figure, 1 is a semiconductor substrate, 2 is a surface insulating film, 3 is a first layer metal film made of aluminum or aluminum alloy, and 4 is an insulating film, which is connected to a second layer metal wiring (not shown). This serves as an interlayer insulating film. Conventionally, after forming the first layer metal film 3, a phosphorus-doped SiO2 film by normal pressure or low pressure CVD method or a silicon nitride film by plasma CVD method is formed as the interlayer insulating film 4 with the second layer metal film. It was formed by a method. in this way,
The current status of the insulation WX4 at the stepped portion of the first layer metal film 3 is as follows:
As shown in a of FIG. 1, the shape has a severe overhang. In the insulating film 4 having such a cross-sectional shape, as shown in the figure, there is a problem in that the film quality deteriorates and cracks easily occur due to changes in stress, making it impossible to ensure dielectric strength. In addition, there is a problem in that the aluminum used for mutual wiring in a and b in the figure tends to cause breakage.

Purpose of the Invention The present invention has been made to solve the above-mentioned problems, and is intended to prevent the formation of an overparts ring in an interlayer insulating film, and to prevent the formation of an overparts ring in the interlayer insulating film, and to prevent the formation of an overparts ring in the interlayer insulating film. The present invention provides a method for manufacturing a semiconductor device that can eliminate localized stress corrosion of metal film wiring such as aluminum due to stress imbalance, prevent breakage of metal wiring and glands, and improve reliability. .

Structure of the Invention The present invention can be summarized by forming an electrode layer directly or via an insulating film on a semiconductor substrate, and then forming a second layer having a lower lateral processing speed than the electrode layer, Next, using a predetermined resist pattern as a mask, etching is performed on the electrode layer and the second layer so that the cross-sectional shape of the etching becomes a T-shape. After that, an insulating film that can be formed at a low temperature is formed, and then the entire surface of the insulating film is etched. This is a method for manufacturing semiconductor devices that includes a process of isotropic etching. According to this method, the stepped portions of the subsequently formed vapor-deposited insulating film are made into smooth film surfaces, making it convenient for multilayer wiring structures. Realized.

Actually, Explanation of Fear-1 The details of the present invention will be explained with reference to examples. FIG. 2 is a cross-sectional view showing essential parts of a semiconductor device manufactured by a method according to an embodiment of the present invention, in which the same numbers as in FIG. 1 indicate the same parts. It differs from the structure in Figure 1 in that it has the following.

Hereinafter, embodiments of the present invention will be described in order.

Figure 3 shows an aluminum film 3 of approximately 1 μm as an electrode wiring layer.
This is a new view of a stage in which a silicon dioxide film 5 is formed to a thickness of 3000 mm as a 21-th film by the CVD method, and a predetermined resist pattern 7 is formed. Thereafter, the silicon dioxide film 5 is anisotropically etched by reactive ion etching using Freon-based gas using mask I for the resist 7, and then the aluminum 1-layer film 3 is etched using chlorine-based gas plasma. . At this time, the aluminum film 3 causes an undercut of about 0.3 μm below the silicon dioxide film 5. The upper part of the pattern having a T-shaped cross section formed in this way, plasma CVD
FIG. 4 shows a cross-sectional view of the silicon nitride film 6 formed by the method. After that, the entire surface of the semiconductor substrate is subjected to plasma etching using Freon gas, leaving the silicon nitride film 6 only on the side wall portions of the electrode layer 3, and the cross-sectional view at the stage where the stepped portions are flattened is shown below. It is shown in FIG. As a result, the entire surface of the insulating film to be formed thereafter becomes sloped, and a good insulating film without overhang can be obtained. The aluminum film 3 subsequently used for the upper north pole wiring can be formed very reliably without any gaps 7, and the reliability of the semiconductor device is dramatically improved. Although the silicon dioxide film 6 was used as the second layer in this embodiment, it may be made of any other material as long as it has a lower lateral processing speed than the electrode layer 3, or it may be made of a conductive material. It doesn't matter.

As described above, according to the present invention, an LSI having a multilayer metal wiring structure
Alternatively, it is particularly suitable as a method for manufacturing a VLSI element structure, and has high industrial value.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram of main parts of a conventional semiconductor device, FIG. 2 is a cross-sectional structural diagram of main parts of a semiconductor device according to the present invention, and FIG.
Figures 5 to 5 are cross-sectional views of the process of the present invention. DESCRIPTION OF SYMBOLS 1... Semiconductor substrate, 2... Surface insulating film, 3... Metal film, 4... Insulating film, 5...
... silicon dioxide film, 6 ... plasma silicon nitride film, 7 ... photoresist. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure fJa Figure 4

Claims (3)

[Claims] (1) After forming a predetermined electrode layer on the semiconductor substrate,
a second layer whose etching rate in the lateral direction is lower than that of the electrode layer;
Then, using a predetermined resist pattern as a mask, the 'electrode layer and the second layer are sequentially etched to form a pattern, and then both layer patterns are covered with an insulating layer that can be formed at a low temperature. A method for manufacturing a semiconductor device comprising the step of subjecting the insulating film to an isotropic etching process after forming the film. (2) '1'jl: The method of manufacturing a semiconductor device according to claim 1, wherein the pole layer is made of polycrystalline silicon, a high melting point metal, a high melting point metal silicide, aluminum, or an aluminum alloy. (3) The method for manufacturing a semiconductor device according to claim 1, wherein the insulating film that can be formed at low temperature is formed by a low pressure CVD method or a plasma CVD method.