JPS6254427A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the degree of integration from deteriorating by a method wherein, after impressing a semiconductor substrate with bias to form the second insulating film by sputtering process, the second insulating film on the specified opening is removed by etching treatment using a mask. CONSTITUTION:After coating a silicon substrate 1 with the first insulating film, a photoresist film 3 is formed on the first insulating film 2 and then an opening is made by photolithography. Next the silicon oxide film 2 is removed by reactive ion etching treatment using the photoresist film 3 as a mask and then the photoresist 3 is removed. The silicon substrate 1 is impressed with negative bias to form the second insulating film 4; a gradient angle alpha at step part is freely changed by changing the level of bias impressed upon the silicon substrate 1 to form another photoresist film 5 again forming an opening 5a for an etching mask by patterning. Finally the photoresist film 5 is removed to form an aluminium film 6. Through these procedures, the sectional shape of lower opening side can be made almost perpendicular to the semiconductor substrate, which is optimum for minute processing, to prevent the degree of integration from deteriorating.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device,
.

The present invention relates to a method for manufacturing a semiconductor device having wiring in an insulating film that does not cause disconnection in the opening.

[Conventional technology]

Conventionally, there has been a method of filling an opening for electrode extraction in an insulating film on a semiconductor substrate on which an element is formed, and in addition, when the wiring is multilayered, openings for interlayer connections are formed in the insulating film between the metal wirings. The formation method is to form a resist film having a predetermined opening on the insulating film, to etch the insulating film exposed in the opening at once, and then to remove the resist film.
As shown in FIG. 2 (al), a predetermined opening 3t was provided in the insulating film 2 on the semiconductor substrate 1. Next, as shown in FIG.
As shown in FIG.
was forming.

[Problem that the invention seeks to solve]

An opening is provided in the insulating film on the conventional semiconductor substrate described above,
To form the wiring, the insulating film at the opening is removed by -i etching, resulting in a steep cross-section of the opening and the aluminum wiring deposited on the first layer is difficult to form at the step of the opening. The film thickness becomes thinner.

Eventually, this will cause disconnection of the wiring, reducing the reliability of the semiconductor device.

In addition, one way to prevent wire breakage is to make the slope of the stepped part of the opening in the insulating film gentler, but as the slope becomes gentler, the processing accuracy decreases, and the area occupied by the slope part increases. becomes larger and reduces the degree of integration. Another method to prevent wire breakage is to increase the thickness of the wiring metal, but this method also makes it difficult to miniaturize and increases the cost of integration.
It has the disadvantage of lowering

[Ninth way to solve the problem]

The method for forming an opening in an insulating film in the method for manufacturing a semiconductor device of the present invention includes forming a predetermined opening in a first insulating film by photolithography, and then forming a second insulating film by a sputtering method. However, during this sputtering, by applying a bias to the semiconductor substrate, the first step part can have a desired slope. Further, the openings are etched again by photolithography to form predetermined openings, and through these openings the underlying conductor is connected to the substrate to form wiring.

〔Example〕

Next, the present invention will be explained using examples.

FIGS. 1A to 1F are t-th cross-sectional views illustrating a method for forming an aluminum wiring according to an embodiment of the present invention in the order of steps. First of all, as shown in FIG. The silicon oxide film 2 is then formed by reactive ion etching using the photoresist film 3 as a mask.
After removing the photoresist film 3t by etching, the photoresist film 3t is removed, resulting in the state shown in FIG. Next, silicon substrate 1];
Applying a negative bias, the second insulating film 1, for example, a silicon oxide film 4t-1000 to 1, is formed by sputtering.
Formed to a thickness of 1 in 0,000, for example 6,000 people.

As shown in Fig. 1 fc). At this time, the inclination angle α at the step portion can be freely changed by changing the magnitude of the bias applied to the silicon substrate. Next, as shown in FIG. 1(d), a photoresist film 5t is formed again.

The opening 5a for an etching mask is formed by buttering by photolithography. Next, the silicon oxide film 4 formed by the sputtering method as described above is etched away by the reactive ion etching method, and then the photoresist film 5 is removed to form the state shown in FIG. Next, as a wiring metal, for example, an aluminum film 6 is formed by sputtering, and the aluminum film 6 is coated on the side surface of the opening to the same thickness as the flat part. I'm wearing it.

Note that the mask used when etching away the silicon oxide film formed by the sputtering method is the first one.
The mask used for the second etching may be the same as or different from the companion mask, and the openings do not necessarily have to be the same size. In addition to the silicon oxide film, the second insulating film is made of
A silicon nitride film or an aluminum oxide film can also be used.

Although this embodiment describes the case of connecting a semiconductor substrate and a wiring metal, the same applies to the case of forming an opening for connecting a semiconductor substrate and polycrystalline silicon, or wiring metal to wiring metal. be.

〔Effect of the invention〕

As explained above, in the method for forming an opening in an insulating film according to the present invention, the cross-sectional shape of the opening widens at a certain slope at the upper part of the side surface. When deposited, an aluminum film is formed on the side surfaces of the opening to the same thickness as the flat portion, preventing wiring breakage and improving reliability. Furthermore, since the cross-sectional shape of the lower part of the side surface of the opening is substantially perpendicular to the semiconductor substrate and is suitable for miniaturization, there is no reduction in the degree of integration.

[Brief explanation of the drawing]

Figure 1 (al to f) is a cross-sectional view of the process order for explaining the aluminum wiring forming process according to an embodiment of the present invention, and Figure 2 (fat) and (b) are illustrating the conventional aluminum wiring forming process. FIG. DESCRIPTION OF SYMBOLS 1...Silicon substrate, 2...First insulating film, 3°5...Photoresist film, 4...
...Second insulating film. 6...Aluminum film. Agent Patent Attorney Susumu Uchihara (b) (e) 0
゛′ Australia 1ヅ °f) (i, Figure 2 cb)

Claims (4)

[Claims] (1) In a method of manufacturing a semiconductor device that includes forming an opening in an insulating film on a semiconductor substrate, a first forming an insulating film, and providing a predetermined opening in this first insulating film by etching using a mask;
Next, the step includes applying a bias to the semiconductor substrate to form a second insulating film by a sputtering method, and then removing the second insulating film in the predetermined opening by etching using a mask. A method for manufacturing a semiconductor device, characterized in that: (2) The method for manufacturing a semiconductor device according to claim 1, wherein a silicon oxide film, a silicon nitride film, or an aluminum oxide film is used as the second insulating film. (3) The thickness of the first insulating film is 500 to 8000 Å,
2. The method of manufacturing a semiconductor device according to claim 1, wherein the second insulating film has a thickness of 1,000 to 10,000 Å. (4) The method for manufacturing a semiconductor device according to claim 1, wherein anisotropic etching is used as a method for etching away the insulating film in the opening.