JPH0590628A - Semiconductor device - Google Patents

Abstract

PURPOSE:To reduce an appearance defect rate by preventing aluminum blister in a heating process after the growth of a plasma nitride film through slit- patterning the aluminum electrode of a large area of a phototransistor to contrive to subdivide the area and to enlarge a peripheral length. CONSTITUTION:The thermal diffusion of impurity showing P-type is performed after the P-type impurity diffusion window of a light-receiving face 1 is opened in the N-type semiconductor substrate. After that, a base layer is formed. Then, after N-type impurity diffusion window 2 is formed, the thermal diffusion of impurity showing N-type is conducted to form an emitter layer. Subsequently, after an emitter part contact layer 3 and base part contact layer 7 are formed, aluminum is vapor-deposited all over the surface. Thereafter, an aluminum electrode 4 with many slits 10 formed therein and base aluminum electrode 8 are formed into patterns. Then, a passivation film is applied all over the surface by the growth of plasma nitride film. After that, circular emitter bonding part 5 and base bonding part 6 are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a pattern of an aluminum (hereinafter referred to as aluminum) electrode of a phototransistor.

[0002]

2. Description of the Related Art FIG. 3 shows a product pattern of a conventional phototransistor. First, a P-type impurity diffusion window of the light-receiving surface 1 is opened in the N-type semiconductor substrate by a usual photo-etching method, and then a P-type impurity is thermally diffused. Then, high temperature heat treatment is performed to form a base layer.

Next, after the N-type impurity diffusion window 2 is formed by a normal photo-etching method, the N-type impurity is thermally diffused, and then a high temperature heat treatment is performed.
Form an emitter layer. Next, the contact opening layer 3 and the base contact layer 7 of the emitter are formed by the usual photo-etching method.
After forming, the aluminum is vapor-deposited on the entire surface. Thereafter, the aluminum other than the aluminum electrode portion 4 and the base portion aluminum electrode 8 of the emitter is removed by etching by a normal photo-etching method.

Next, a passivation film is applied to the entire surface by plasma nitride film growth. After that, a circular emitter bonding portion 5 and a base bonding portion 6 are formed by a normal photo-etching method to expose a part of the aluminum electrode portion and form a bonding lead portion.

In the phototransistor, it is necessary to increase the area of the light receiving surface 1 in order to improve the electrode conversion efficiency, and the product pattern is also large accordingly.

[0006]

In a phototransistor in which a plasma nitride film is passivated on an aluminum electrode, if there is a heat addition step at a temperature of, for example, 480 ° C. after the growth of the plasma nitride film, the aluminum and the plasma nitride film will be separated from each other. There was a problem that hydrogen gas was generated at the interface and the appearance of aluminum blister became poor.

[0007]

According to the present invention, in a semiconductor device such as a phototransistor in which a plasma nitride film is passivated on an aluminum electrode, a high area aluminum electrode pattern is provided with slits to subdivide the area and the periphery of the aluminum electrode. It is characterized by a long expansion, and as a result, it is possible to prevent the occurrence of aluminum swelling in the heat addition process at about 480 ° C. after the growth of the plasma nitride film.

That is, when the area of the aluminum electrode is subdivided, the hydrogen gas is dispersed, and as a result, it is possible to prevent aluminum swelling. Further, if the peripheral length is increased, the efficiency of hydrogen gas release from the side surface of aluminum during annealing is increased, and aluminum blistering is prevented as described above.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing an embodiment in which the present invention is applied to an aluminum electrode portion of an emitter of a phototransistor.

First, the P-type impurity diffusion window of the light-receiving surface 1 is opened in the N-type semiconductor substrate by the usual photo-etching method in the same manner as in the conventional manufacturing method, and then the P-type impurity is thermally diffused. Then, high temperature heat treatment is performed to form a base layer.

Next, an N-type impurity diffusion window 2 is formed by a usual photo-etching method, and then an N-type impurity is thermally diffused. Thereafter, a high temperature heat treatment is performed to form an emitter layer. Next, after the emitter contact layer 3 and the base contact layer 7 are formed by the usual photo-etching method, aluminum is deposited on the entire surface. Thereafter, the aluminum electrode portion 4 and the base aluminum electrode portion 8 having a large number of slits 10 formed therein are patterned by a usual photo-etching method.

Next, a passivation film is applied to the entire surface by plasma nitride film growth. After that, a circular emitter bonding portion 5 and a base bonding portion 6 are formed by a normal photo-etching method.

As described above, also in the embodiment shown in FIG. 2, the same effect as that of the embodiment of FIG. 1 can be obtained by changing the contact and aluminum patterns and subdividing the aluminum electrode area.

[0014]

As can be seen from the above embodiments, according to the present invention, a wide area aluminum electrode portion of a phototransistor is formed into a slit pattern so as to subdivide the area and increase the peripheral length. Aluminum blistering was prevented in the heat addition process, and as a result, it became possible to significantly reduce the appearance defect rate (about 90%).

[Brief description of drawings]

FIG. 1 is a plan view of a product pattern of an embodiment when the present invention is applied to a phototransistor.

FIG. 2 is a plan view of a product pattern according to another embodiment of the present invention.

FIG. 3 is a plan view of a product pattern of a conventional phototransistor.

[Explanation of symbols]

 1 Light-receiving surface 2 N-type impurity diffusion window 3 Emitter contact window 4 Emitter aluminum electrode 5 Emitter bonding part 6 Base bonding part 7 Base contact window 8 Base aluminum electrode 10 Slit 11 Hollow out

Claims (2)

[Claims] 1. In a semiconductor device having a plasma nitride film passivation on an aluminum electrode, by forming slits or hollows in the pattern of the aluminum electrode, the area of the aluminum electrode is subdivided and the peripheral length is enlarged. A semiconductor device characterized by being designed. 2. The semiconductor device according to claim 1, wherein the semiconductor device is a phototransistor.