JPS63181449A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent a resist from remaining by a method wherein a stepped part and conductor layers traversing this stepped part are formed at an insulating film on a semiconductor substrate and a protruding part is formed at the stepped part near the conductor layers. CONSTITUTION:A silicon oxide film as an insulating film is formed on a semiconductor substrate. The thickness of the oxide film on a base region is thinner than the thickness at the part other than this film; the difference in level of about 0.7 mum is formed on the surface of the oxide film at the peripheral part of the base region. A protruding part 4 is formed at the recessed part of this stepped part. If aluminum as an electrode material remains at this recessed part of this stepped part, an emitter electrode 31 is short-circuited with a base electrode 32. It is possible to prevent this short circuit if the protruding part 4 is formed. That is to say, if a photoresist is exposed, it can penetrate into the recessed part at the stepped part; it is possible to prevent the resist from remaining; a conductor layer does not remain.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a semiconductor device.

BACKGROUND ART As shown in the cross-sectional view of FIG. 2(a), there is a step in the insulator layer 2 on the semiconductor substrate 1, and when wiring is to be formed across this step, the insulator layer 2 is first As shown in FIG. 2(b), a conductor layer 3 made of wiring material is formed on the surface, and then this conductor layer 3 is formed into wiring using a photoresist pattern.

At this time, if the photoresist is a positive resist, during exposure to form the same resist pattern, the light absorbed by the resist will be uniform in the flat parts, but it will be reflected in the concave parts of the step. This reduces the amount of light that enters the recessed area, reducing the effective amount of exposure of the recessed portion. Then, the resist 11 remains in the stepped opening portion as shown in FIG. 2(c). Because of this residual resist 11, even when etching the conductor that will become the wiring, the wiring material, that is, the conductor material remains in the step recess without being etched. When such residual conductor material occurs, and when there is a plurality of wirings crossing the step, the remaining conductor material 3 as shown in the perspective view of FIG.
The respective wirings 3.3 are short-circuited by a.

If such a short-circuit portion is formed as described above, a semiconductor device will be produced which cannot operate normally, resulting in a problem of lower yield.

Problems to be Solved by the Invention As mentioned above, when there is a step in the insulator on the surface of a semiconductor substrate, when wiring is formed across this step, if the wiring pattern is formed using a positive resist, the step will be Resist remains and the conductor remains in the step recess when etching the conductive material that will become the wiring, and if there are multiple wirings, they may be short-circuited. The present invention solves these problems.

Means for Solving the Problems The present invention has an insulating film on a semiconductor substrate having a stepped portion and a conductor layer that crosses the stepped portion, and a protrusion is provided in the stepped portion near the conductive layer. It is something.

According to the present invention, the exposure light to the photoresist is diffusely reflected by the protrusions provided at the step portion, and as a result, the remaining resist in the recesses of the same step portion, and therefore the remaining conductor layer, is also eliminated at the protrusion portions. Ru.

Embodiment FIG. 1 is a perspective view of a main part of an embodiment in which the present invention is applied to a discrete element. The actual device is formed by implanting and diffusing an n+ layer as an emitter and a p layer as a base into a semiconductor substrate, and a silicon oxide film is present as an insulating film on the semiconductor substrate. The oxide film on the base region is thinner than other parts, and there is a step difference of 0.7 um on the oxide film surface in the peripheral part of the base region. FIG. 1 shows the general shape of this oxide film 2. As shown in FIG. At this time, if aluminum, which is the electrode material, remained in the recessed part of the stepped portion, the emitter electrode 31 and the base electrode 32 would be short-circuited, but by forming the protrusion 4, such a short-circuit as described above could be prevented.

Effects of the Invention According to the present invention, the projections provided on the stepped portions of the insulating film allow the exposure of the photoresist to penetrate into the stepped recesses, eliminating any remaining resist and, therefore, eliminating any remaining conductor layers.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the main parts of an embodiment of the present invention, Figures 2 (a) to (
c) is a cross-sectional view showing the conventional example in the order of steps, and FIG. 3 is a perspective view of the main part thereof. 2... Oxide film, 31.32... Electrode,
4... Protrusion of insulator film. Name of agent: Lawyer Nakao, Toshio and one other person? -Oxide film 4-Protrusion 31-Dou” heavy Figure 1 3? Figure 2?

Claims (1)

[Claims] 1. A semiconductor device comprising: a step portion in an insulating film on a semiconductor substrate; and a conductor layer crossing the step portion; and a protrusion provided at the step portion near the conductor layer.