JPS5839034A - Forming method for electrode - Google Patents

Abstract

PURPOSE:To form an electrode pattern by lift-off method by forming grooves of electrode pattern on the protective surface under the pattern before forming an electrode material in a semiconductor device. CONSTITUTION:A protective film 5 exposed by a resist film 6 is partly wet etched from the surface with an etchant of fluoric acid series, and overhangs 7, 7,... are formed at the ends of the film 6. Subsequently, aluminum 8 is deposited on the surface of the substrate 1. The film 8 is not almost coated on the side surface of the film 6, the side surface of the film 5 and the overhangs 7, 7, thereby forming air gaps 9, 9,.... The film 8 is slightly etched to completely expose the side surface of the film 6, thereby removing the film 6. As a result, the film 8 is also removed, only the film 8 on the gate electrode 4 and the film 5 remain, becoming the electrodes of the semiconductor device. Since the overhangs are formed at the surface protective film, the electrode material can be readily isolated, thereby enabling the microminiaturization of wire and the like.

Description

[Detailed description of the invention] The present invention relates to a method for forming electrodes in semiconductor devices.

Lift-off processing is known as a method suitable for miniaturizing electrodes by reducing the difference between the pattern drawn with resist and the actually formed electrode pattern, that is, the conversion difference when forming electrodes of aluminum etc. on semiconductor devices. ing. However, in the case of using aluminum as the electrode material or using foot-scanning, the resist film thickness must be extremely thick and there must be overhangs, etc., and as a result, there are problems in the current state of the art.

The present invention has been made in view of these problems, and involves forming grooves for the electrode pattern on the surface protection of the lower part before forming the electrode material, and forming the electrode pattern by a 7-to-7 process. be.

The present invention will become clearer from the following description with reference to the drawings.

The present invention is based on a semiconductor device having the structure shown in FIG. In the figure, (1) is a silicon substrate, (2) is a field oxide film, (3) is a gate insulating film, (4) is a gate electrode, and (5) is a surface protection film that protects the surface of the semiconductor device. It is made of a silicon oxide film, PSG, or the like. (6)
is a resist film provided on this surface protection film (5),
The skeleton protective film (sounds 5 times) according to the pattern in which the electrodes are to be formed.

In the first step of the present invention, as shown in FIG. 2, a part of the resist film (6) is wet-etched using a V-tone etchant, and at the same time, the protective film immediately below the edge of the resist film (6) is removed, and the resist film (6) is 6) Forms an eave part (force (force...) at the end.

The next step is to sputter aluminum (8) from the surface of the substrate (1) shown in Figure 2 without EB deposition! Vapor deposition (Figure 6). During this vapor deposition process, the step coverage of the aluminum film (8) is slightly deteriorated by increasing the vapor deposition rate without heating the substrate (1). Aluminum film (8)
is hardly adhered to the side surfaces of the resist film (6), the side surfaces of the surface protection film (5), and the eaves (7) of the same protection film (5), and as a result, this eaves ( 7) (7)... has an empty 1!1 (91(9)...).

Subsequently, the aluminum film (8) is slightly etched to completely expose the side surfaces of the C resist film (6), and then the resist film (6) is removed using a resist release agent. the result,
As shown in FIG. 4, the aluminum film (8) present on the resist film (6) was also removed at the same time, and the gate electrode (4)
Only the aluminum film (8) on the top and surface protection film (5) remains, which will eventually become the electrode of the semiconductor device.

Since the protective film has an overhang, it is possible to easily separate the electrode material, making it possible to miniaturize wiring, etc.

[Brief explanation of the drawing]

1 to 4 are cross-sectional views showing the method of forming an electrode according to the present invention in the order of steps, in which (1) is a substrate, (5) is a surface protective film, (6) is a strip film, ( 7) shows the eave portion, and (8) shows the aluminum film.

Claims (1)

[Claims] 1) A resist film exposing the reflective film is provided according to a pattern for forming an electrode on a surface protective film that protects the surface of a semiconductor device, and a part of the surface of the protective film exposed by the resist film is etched. The resist film is characterized by removing the retained MW directly under the edge of the resist film to make the resist film into an eave-like shape, depositing an electrode material directly above the eave-like resist film, and then removing the resist film. Electrode formation method.