JPH01123440A - Semiconductor device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and particularly to an electrode structure of a flip-chip transistor.

[Conventional technology]

FIG. 2 is a cross-sectional view of the electrode part of a conventional flip-chip NPN) transistor. In the figure, 1 is the N-collector layer of the transistor, 2 is the P diffusion layer forming the base region of the transistor, and 3 is the P diffusion layer. 2 is the A1 layer which is the conductor wiring, 4 is the silicon oxide film layer that insulates the N-layer 1 and A1 layer 3, 5 is the glass layer that protects the surface of the transistor chip, and 6 is the copper that forms the bump electrode of the base. Layer 7 is a solder layer forming bumps.

Next, the electrode portion will be explained in detail.

Above A! 1ii3 is formed so as to maintain ohmic contact with the P diffusion layer 2, and the steel 1i16 is formed so as to be electrically conductive with the A1 layer 3. Naturally, the steel N6 and the solder layer 7 are also electrically conductive. It is a good conductor.

That is, the P diffusion N2 is electrically connected to the copper layer 6 and the solder layer 7, and the copper N6. The solder layer 7 serves as an electrode for the base region, which is the P diffusion 712. Further, a silicon oxide film N4 is formed between the copper layer 6 and the N-collector layer 1.
Al153 wiring in the base area and N-collector Fi
It is electrically insulated from ll.

[Problem that the invention seeks to solve]

However, such an electrode structure has the following problems.

FIG. 3 is an enlarged view of the vicinity of the copper layer 6 in FIG. If it does not reach layer 1, insulation is maintained initially, but copper layer 6
The pinhole 8 may develop due to external stress from the pinhole 8, and the collector N-1 and the base electrode A1 layer 3 may become electrically connected, resulting in a problem of low reliability.

This invention was made to solve the above problems, and even if a pinhole in the silicon oxide film layer reaches the low concentration collector layer due to stress from the copper layer, the connection between the low concentration collector layer and the base An object of the present invention is to obtain a semiconductor device having an electrode structure that can maintain an electrically insulated state from the A1 layer, which is an electrode, and can improve reliability.

[Means for solving problems]

The semiconductor device according to the present invention includes a semiconductor diffusion layer of a conductivity type opposite to that of the collector layer in the low concentration collector layer immediately below the bump electrode copper layer.

[Effect]

In this invention, since a semiconductor diffusion layer of a conductivity type opposite to that of the collector layer is provided in the low concentration collector layer directly under the bump electrode copper layer, there is no insulation between the collector layer and the wiring layer of the bump electrode. Even if a pinhole in the film reaches the collector layer due to stress from an upper layer, the collector layer and the wiring layer above the semiconductor diffusion layer are kept in an insulated state by a P-N junction between the collector layer and the semiconductor diffusion layer. Can be done.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the electrode structure of a flip-chip transistor according to an embodiment of the present invention, in which the same reference numerals as in FIG. This is the formed P diffusion layer.

Next, the effects will be explained.

In such a flip-chip transistor, the pinhole 8 existing in the silicon oxide film layer 4 directly under the copper N6
reaches the P diffusion N9 due to the stress from the copper layer 6, AlN3
When the P diffusion layer 9 and P diffusion layer 9 become electrically conductive, the P diffusion layer 2 as the base and the P diffusion layer 9 become at the same potential,
In the active region, the potential of the N- collector layer 1 is higher than that of the P diffusion layer 9.
In other words, the PN junction is reverse biased, and as a result, the A1 layer 3 and the collector N1 can be electrically insulated.

Also, in the saturation region, the potential of the N-collector N1 is lower than the potential of the P-diffusion layer 9, but since the potential of the P-diffusion layer 2, which is the base, is lower than the potential of the N-collector N1, the area of the base region is expanded. It has no effect on the characteristics.

In the above embodiment, the bump electrode at the base of the NPN l-transistor was shown, but this could also be the emitter electrode (it goes without saying that the same effect can be obtained.Also, the transistor may be of the PNP type. In this case, if an N diffusion layer is provided directly under the copper layer in the P-collector layer, the same effect as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the electrode structure of the semiconductor device according to the present invention, the semiconductor diffusion layer of the conductivity type opposite to that of the core layer is provided in the low concentration collector layer immediately below the W4 layer forming the bump electrode. Even if a pinhole in the silicon oxide film layer between the low concentration collector layer and the copper layer reaches the layer below it due to stress from the copper layer, the low concentration collector layer and the bump electrode are electrically insulated. As a result, reliability can be improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the electrode structure of a semiconductor device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the electrode structure of a conventional flip-chip transistor, and FIG. 3 is a problem with the electrode structure of a conventional transistor. FIG. 3 is a cross-sectional view for explaining the points. 1... N-collector layer, 3... A1 layer, 4... silicon oxide film layer, 6... copper layer, 9... P diffusion layer. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1) In a semiconductor device having a bump electrode formed on a semiconductor layer via an insulating film, a semiconductor of a conductivity type opposite to that of the semiconductor layer is diffused in a region directly under the bump electrode of the semiconductor layer. A semiconductor device characterized by having a layer.