JPS6194346A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent disconnections at stepped sections on processing and the generation of voids, and to improve the degree of integration by etching a first film shaped onto a substrate twice or more, forming two steps of more of stepped sections and shaping second and third films. CONSTITUTION:An impurity, etc. are diffused selectively to the surface of an Si substrate 1 to form a predetermined semiconductor region. An SiO2 film 6 is shaped. A photo-resist 7 is applied, the photo-resist 7 at a position to be etched is removed, and the film 6 is etched only by approximately half thickness of the thickness of the film 6. The film 6 is etched again until the substrate 1 is exposed to shape two stepped sections. A passivation film 2 is formed onto the whole surface, and a film 5 electrically connected to the semiconductor region is shaped onto the film 2. Accordingly, disconnections at stepped sections on processing and the generation of voids are prevented, and the degree of integration can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION 0) Industrial Field of Application The present invention relates to a method for manufacturing a semiconductor device that forms a good film on a semiconductor substrate having a step in film formation other than thermal oxidation.

(b) Conventional technology Aluminum (AI) has traditionally been used in semiconductor integrated circuits.
Problems include disconnection of electrodes and a drop in withstand voltage.

Generally, the insulating film is formed by a thermal oxidation method, a CVD method, or the like. However, as the final process approaches (according to which high processing temperatures such as thermal oxidation methods cause characteristic changes, insulating films are formed using CVD methods that can form films at low temperatures. However, with this CVD method, semiconductor integration When an insulating film is formed on a circuit and an aluminum electrode is formed on the insulating film by vapor deposition or the like, problems arise such as breakage and deterioration of characteristics such as withstand voltage.

An example of this is LSI Process Handbook 323-P, 324 Figure-18 published by Science Forum.
Semiconductor substrate t61) shown in (a) and (d)
This is the case where the AI film is applied to the edge (64) of the contact hole formed in 62, and a passivation film is formed on the surface of the above passivation film (silicon substrate 61), for example, S J Ot Jl! '8'J was formed by a method other than thermal oxidation, a contact hole was formed 5 inches above by etching, and an AI electrode was formed thereon by vapor deposition or the like.

Further, as shown in Japanese Unexamined Patent Publication No. 57-26432 (FIG. 5), a contact hole 183) is formed by etching the insulating film. A viscous insulating material such as polyimide resin or 5OG (glass powder dissolved in an inorganic agent) or the like is applied thereon (FIG. 5(f)). After that, the viscous insulating material (material) is etched to make the steep edges of the contact hole (c) into a gentle shape (Fig. 5 (b)).

Finally, it was formed by removing AI(c) (FIG. 2(c)).

(c) Problems to be solved by the invention In the semiconductor device formed as described above, Sin,
If the membrane trowel is thick, when forming the contact hole, the cross section of the membrane trowel will be in an overhanging state, resulting in
In the film (4 at the edge of 6e), the AI film (to) is thinner, so disconnection is likely to occur. The shadow of the atom that also arrives
Due to the ing effect, the density of the film on the side surface of the step of the contact hole is lower than that of the flat part, and in wet etching, the etching speed is high, resulting in step breaks and voids during processing, deteriorating the properties of the film itself. In actual devices, the electrostatic breakdown point is not at the flat part [F]η of the film but at the edge.
is concentrated on.

In addition, in the method of forming a viscous insulating material (material) as shown in Fig. 5 and forming the steep edge □ of the contact hole* smoothly, the thickness of the SiO film eη increases,
W shown in FIG. 3(c) becomes wide, making it impossible to achieve a high degree of integration.

The present invention aims to provide a method for manufacturing a semiconductor device that prevents disconnection of the AI film [F] 9, improves its characteristics, and improves the degree of integration. 1) The problem can be solved by selectively etching the first film (6) formed on the upper surface and etching it again at least once to form two or more steps in the first film (6). That is.

(e) First film (6) formed on the surface of the working semiconductor substrate (1)
By etching at least twice, at least two steps are formed. Therefore, the thickness of this film (6) is thinner than that of the conventional film (6), making it possible to reduce the shadowing phenomenon. As a result, it becomes possible to eliminate defective parts within the area to be protected, which was conventional. It also prevents overhangs from forming.

(F) Embodiment An embodiment of the semiconductor device according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a method for manufacturing a semiconductor device, and the first step is as shown in FIG.
io, a film (6) is formed by a CVD method or the like, and a photoresist is applied to the entire surface to form a step by etching.

Resist (remove force).

In the second step, as shown in FIG. 1(b), the semiconductor substrate (1) formed in the previous step is etched by a predetermined method. Conventionally, etching was performed until the semiconductor substrate (1) was exposed, but here, etching is performed by approximately 1/2 of the thickness of the first film (6).

In the third step, as shown in FIG. 1(C), the first film (6), which has been etched by about 1/2 of its thickness, is etched again until the semiconductor substrate (1) is exposed. At this point, two steps are formed. A passivation film (2) is then formed to cover the entire semiconductor substrate (1). Furthermore, a second film (2) is electrically connected to the semiconductor region formed in the first step.
A third film (5) is formed on top.

Here, the second process and the third process are the characteristics of the present invention, and the first film (6) is etched at least twice to reduce the number of steps (if the number of steps is 2 or more, shadowing phenomenon may occur). The height of the film that gives the shadow is low (Shadowi
Since the NG phenomenon is reduced, the density of the film becomes almost uniform on the side surfaces of the step and the flat portion, thereby preventing step breaks and voids from occurring during processing. As a result of the above, electrostatic damage caused by AI migration can be prevented in the device. Also the fifth
As shown in the figure, since there is no need to form the steep edges of the contact hole smoothly, high integration is possible.

(g) Effects of the invention As is clear from the above description, the present invention provides a semiconductor substrate (1
) is etched at least twice to form at least two or more steps in the first film. As a result, when forming the second film (2), third film (5), etc., Sh
The adowing phenomenon is reduced, and the generation of step breaks and voids during machining can be prevented. Therefore, electrostatic damage caused by AI migration or the like can be prevented.

In addition, since the steep edge (4) of the contact hole (3) is smoothed, there is no need to apply a viscous insulating material, allowing for high integration.

[Brief explanation of drawings]

1(a) to 1(c) are cross-sectional views illustrating a method of manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a semiconductor device according to an embodiment of the present invention. cross-sectional view,
FIG. 3 is an enlarged cross-sectional view of a conventional semiconductor device, FIGS. 4(A) to 4(C) and FIGS.
C) is a sectional view illustrating a conventional semiconductor device. Explanation of the main drawing numbers: (1) is the semiconductor substrate, (2) is the second film, (3) is the contact hole, (4) is the edge, (5) is the third film,
(6) is the first film; -) Figure 2 Figure 3 Figure 4 (B) Figure 4 (C)

Claims (1)

[Claims] (1) A first film formed on the surface of the semiconductor substrate is selectively etched to form a second film so as to cover the entire surface of the semiconductor substrate, and the second film is electrically connected to a predetermined region within the semiconductor substrate. 1. A method of manufacturing a semiconductor device in which a third film is formed on a second film connected to the second film, the first film being formed in two or more stages.