JPH0462920A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent simply and easily a fault, which is generated in an upper conductive layer, from being generated by a method wherein the contact part of a resist film situated at a position, in where a contact hole is inclined to form, to an insulating film is exposed in a defocused manner and a taper is formed on the sidewall of the lower, part, which is situated in the contact hole, of the resist film. CONSTITUTION:An insulating film 2 consisting of a silicon oxide film is formed on the surface of a lower conductive layer 1 by a CVD method and a resist film 3 is applied and formed on the surface of the film 2. Then, the contact part of the film 3 situated at a position, in where a contact hole is inclined form, to this film 2 is exposed in such a way that an exposure to the contact part becomes the exposure of a defocus and after the exposed contact part is developed, a taper is formed on the sidewall of the lower part, which is situated in an opening window 3a, of this film 3. Then, the film 2 is etched by a reactive ion etching method, the contact hole 4 formed with the taper is formed and the film 3 is removed. An upper conductive layer 5 consisting of Al is formed by a PVD method in such a way that it is extendedly provided ranging from the bottom and inner wall of the hole 4 to the surface of the film 2.

Description

[Detailed Description of the Invention] [Summary] Concerning an improvement in the method for forming a contact hole in a semiconductor device, the present invention relates to a method for forming a contact hole that can simply and easily prevent damage occurring in the L conductive layer. A method for forming a contact hole in an insulating film formed between a lower conductive layer and an upper conductive layer, the method comprising forming a resist film on the surface of the insulating film formed on the surface of the lower conductive layer. In the process, the contact portion between the resist film and the insulating film at the position where the contact hole is to be formed is exposed to light in a defocused manner, and the resist film is developed to form a side wall at the bottom of the opening window. a step of forming a taper, and using the resist film in which a taper is formed on the lower side wall of the opening window as a mask, simultaneously etching the resist film and the insulating film to form a contact hole having a tapered side surface. The structure includes a step of forming.

[Industrial application field]

The present invention relates to an improvement in a method for forming contact holes in semiconductor devices.

In recent years, a method of forming a contact hole in an insulating film between a lower conductive layer and an upper conductive layer has been adopted, in which the insulating film is removed by anisotropic etching to form a contact hole. The aspect ratio of contact holes has increased as semiconductor devices have become smaller due to higher integration, and contact holes with vertical sidewalls created by anisotropic etching have poor coverage of wiring formed in these contact holes, resulting in disconnection of wiring. or poor contact between conductive layers.

Under the above circumstances, there is a need for a method of manufacturing a semiconductor device that does not cause disconnections or contact failures in wiring layers formed in contact holes.

[Conventional technology]

A conventional method for manufacturing a semiconductor device will be explained in detail step by step with reference to FIG.

First, as shown in FIG. 2(a), an insulating film 12 made of a silicon oxide film is formed on the surface of the lower conductive layer 11 by the CVD method, and a resist film 13 is applied to the surface.

Next, as shown in FIG. 2(b), a resist film 1 is placed at a position where a contact hole is to be formed in this insulating film 12.
3, an opening window 13a having a side wall perpendicular to the surface of the insulating film 12 is formed using photolithography technology.

Next, as shown in FIG. 2(C), anisotropic etching with a large ratio of the etching rate of the resist film 13 to the etching rate of the insulating film 12, that is, a high selectivity, is performed to form a pattern perpendicular to the insulating film 12. A contact hole 14 having side walls is formed.

Finally, as shown in FIG. 2(d), the contact hole 1
The upper conductive layer 1 made of aluminum and having a thickness of 1.0 μm extends from the bottom surface and inner wall of the insulating film 12 to the surface of the insulating film 12.
5 is formed by the PVD method.

[Problem to be solved by the invention]

In the conventional semiconductor device manufacturing method described above,
Since a contact hole having a side wall perpendicular to the surface of the insulating film is formed in the insulating film on the surface of the lower conductive layer, such a contact hole 1 is formed as shown in FIG.
If the upper conductive layer 15 is formed in the insulating film 12, the coverage of the contact hole 14 will be poor, and the upper conductive layer 15 and the lower conductive layer 11 extending from the bottom and inner wall to the surface of the insulating film 12 will deteriorate.
There was a problem in that the contact with the upper conductive layer 15 was poor, and in the thinner portions of the upper conductive layer 15, film breakage occurred and the wire was disconnected.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention aims to provide a method for forming a contact hole that can simply and easily prevent problems occurring in the upper conductive layer.

[Means for Solving the Problems] A method for manufacturing a semiconductor device of the present invention is a method for forming a contact hole in an insulating film formed between a lower conductive layer and an upper conductive layer, the method comprising: The process of forming a resist film on the surface of the insulating film formed on the surface, and the exposure so that the contact area between the resist film and this insulating film at the position where the contact pole is to be formed is defocused. Then, there is a step of developing this resist film to form a taper on the lower side wall of the opening window, and a step of developing this resist film and forming a taper on the lower side wall of the opening window. The structure includes a step of simultaneously etching this insulating film to form a contact hole having a tapered side surface.

[Effect]

That is, in the present invention, an insulating film is formed on the surface of the lower conductive layer, a resist film is formed on the surface, and a contact portion between the resist film and this insulating film is formed at a position where a contact hole is to be formed. Exposure is performed so that the exposure is defocused, and development is performed to form a taper on the lower side wall of the contact hole in this resist film, so that a taper is formed on the lower side wall of the contact hole.

Using this resist film as a mask, the insulating film is etched by anisotropic dry etching in which the ratio of the etching rate of the resist film to the etching gray of the insulating film is equal to the taper of this contact hole, so that the insulation 1 pattern is vertical. As the resist 1 to the tapered part of the film is etched in this direction, the opening window becomes wider and the inner diameter of the contact hole becomes larger. It becomes possible to form a forward tapered contact hole that is larger than the inner diameter of the bottom.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained in detail in the order of steps with reference to FIG.

First, as shown in FIG. 1(a), an insulating film 2 made of a silicon oxide film is formed on the surface of a lower conductive layer 1 by the CVD method, and a resist film 3 is applied to the surface.

Next, the contact area between the resist film 3 and the insulating film 2 at the position where the contact hole is to be formed is exposed to light in a defocused manner, and after development, as shown in FIG.
), a taper is formed on the lower side wall of the resist film 3 within the opening window 3a.

Next, the etching rate of the resist film 3 and this insulating film 2
Anisotropic active ion etching is performed under the following conditions in which the ratio of the etching rate to the etching rate, that is, the selectivity is equal to the taper of the contact hole 4 to be formed.

Reaction gas ----------------------CF4. CHF
3. Argon reaction gas flow rate----------------------
------------1, 100s CCM reaction chamber pressure-----1-----------
---------4,7Torr substrate heating temperature----
−−−−−−−−−−−−−−−−−−−−−−−−−
-----------1, 5°C high frequency power supply frequency------
−−−−−−−−−−−−−−−−−400KHz high frequency power output−−−−−−−−−−−−−−−−−−−−−
---------- 800W When the insulating film 2 is etched by active ion etching in this way, the inner diameter of the bottom of the contact hole 4 is reduced as shown in FIG. 1(C). ), a tapered contact hole 4 is formed which is equal to the inner diameter of the base of the opening window 3a of the resist film 3 and whose inner diameter of the surface of the insulating film 2 is equal to the inner diameter of the upper part of the opening window 3a of the resist film 3. When the film 3 is removed, the formation of the contact hole 4 is completed.

When an upper conductive layer 5 made of aluminum is formed by the PVD method so as to extend from the bottom surface and inner wall of the contact hole 4 thus formed to the surface of the insulating film 2,
As shown in Figure 1(d), it is possible to prevent problems such as poor contact between the upper and lower conductive layers and film breakage of the conductive layer at the edges, which occur in conventional contact holes. becomes.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the shape of the opening window of the resist film used for etching the insulating film is formed into a different shape, and by selecting the etching material, a forward taper shape can be obtained very easily. It is possible to provide a method for manufacturing a semiconductor device which has the advantage of being able to form a contact hole having the same structure, and which can be expected to have significant economical and reliability improvement effects.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing a method for manufacturing a semiconductor device according to an embodiment of the present invention in the order of steps; FIG. 2 is a side sectional view showing a conventional method for manufacturing a semiconductor device in order of steps; FIG. 3 is a sectional view of a conventional semiconductor device. FIG. 3 is a side cross-sectional view showing the problem of the method of manufacturing the device; In the figure, (2) indicates a lower conductive layer, 2 indicates an insulating film, 3 indicates a resist film, 3a indicates an opening window, 4 indicates a contact hole, and 5 indicates an upper conductive layer. Park area

Claims (1)

[Scope of Claims] A method for forming a contact hole (4) provided in an insulating film (2) formed between a lower conductive layer (1) and an upper conductive layer (5), comprising: ) of forming a resist film (3) on the surface of the insulating film (2) formed on the surface of the insulating film (2), and forming a resist film (3) and the insulating film (2) at the position where the contact hole (4) is to be formed. ) and developing the resist film (3) to form a taper on the lower side wall of the aperture window (3a); ) using the resist film (3) with a tapered lower side wall as a mask, the resist film (3) and the insulating film (2) are simultaneously etched to form a contact hole ( 4) A method for manufacturing a semiconductor device, comprising the steps of: