JPH0680680B2 - Multi-cell type transistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention assembles a large number of small transistors such as a multi-emitter type and a mesh emitter type, and an emitter stabilizer resistor is connected to the emitter electrode of each transistor. And a macticel transistor.

[Conventional technology]

It is known that a stabilizing resistor is connected in series to the emitter of each cell of a multi-cell type transistor in which transistors each having a minute emitter are assembled in order to increase the current, the switching speed and the frequency of the transistor.
Fig. 2 shows a conventional multi-cell transistor, NPN
The emitter extraction electrode 4 is in contact with the N ⁺ emitter layer 12 provided in the P base layer 11 of the transistor in the connection hole 3 formed in the oxide film 2 on the silicon substrate. The emitter extraction electrode 4 is provided on the substrate surface in parallel with the base extraction electrode 6 and an emitter common electrode 5 and a polycrystalline Si film resistor 7 are provided.
As a result, two resistors 7 are connected in parallel as a stabilizing resistor between the common electrode 5 and each emitter.

[Problems to be Solved by the Invention]

The polycrystalline Si film resistor 7 shown in FIG. 2 is connected to the electrodes 4 and 5 by depositing an Al layer on the pattern of the polycrystalline Si film previously formed on the insulating film 2 to form the polycrystalline Si film at the connection portion. It is done by stacking on a membrane. As a result, for example, as shown in the plan view of FIG. 3A, the Al common electrode 5 overlaid on the polycrystalline Si film resistor 7 having a thickness of about 1 μm has a cross-sectional view of FIG. 3B. As shown in FIG. As the miniaturization of each cell progresses, the width W of the common emitter electrode 5 becomes narrower, causing the following problems.

(1) A resistance is generated in the step portion 51, the resistance up to the tip of the common emitter connecting electrode 5 is increased, and a potential difference is generated between the emitter common electrode 5 and the root portion. Destruction occurs at.

(2) When the overcurrent flows, the step portion 51 is melted.

(3) Failure due to electromigration is likely to occur and reliability is lowered.

An object of the present invention is to solve the above problems and provide a multi-cell transistor in which a step is not generated in a connecting portion between a polycrystalline Si film as a resistor connected in series to an emitter and a common electrode for external connection. To do.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the present invention has a plurality of emitter regions on one semiconductor substrate, and covers the other end of a resistance film whose one end is in contact with an electrode in ohmic contact with each emitter region In a multi-cell transistor provided with an emitter common electrode for connection, each resistance film is assumed to be a part of a film having a connecting portion in contact with the surface of the common electrode on the substrate side.

[Action]

The resistance film connected in series with the emitter does not end below the common electrode of the emitter, but is formed with the connecting part below the connection electrode, so there is no step at the connection between the resistance film and the common electrode. .

〔Example〕

FIG. 1 shows an embodiment of the present invention, in which the same parts as those in FIGS. 2 and 3 are designated by the same reference numerals. In this embodiment, when patterning the polycrystalline Si film formed on the insulating film 2, as shown in FIG. 2, they are connected to the portion 7 acting as a resistor connected to the emitter extraction electrode 3. part
70 and 70 are integrally formed. Therefore, no step is formed on the common electrode 5 laminated thereon by vapor deposition patterning of Al. FIG. 4 shows another embodiment. In FIG. 1, the common electrode 5 covers the polycrystalline Si film connecting portion 70, whereas in this embodiment, the polycrystalline Si film connecting portion 70 is common. Since it is formed with a width wider than the width W of the electrode, a part thereof is exposed.

Although the resistor is formed of a polycrystalline silicon film in the above-mentioned embodiments, the present invention can be implemented in the case of a resistor using another material, for example, a metal film.

〔The invention's effect〕

According to the present invention, the step formed at the connection portion of the common electrode, which is connected to the resistor connected in series to each emitter of the multi-cell type transistor and through which a large current flows, is common to the films forming each resistor. This can be solved by being integrated with the connecting portion that contacts the lower surface of the electrode, and the step coverage problem of the common electrode can be solved. As a result, disconnection of the common electrode or occurrence of a potential difference in the common electrode can be prevented without increasing the number of steps and complicating, and a highly reliable multi-cell transistor can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a plan view of a connecting portion between an emitter stabilizing resistor and an emitter common electrode according to an embodiment of the present invention, FIG. 2 is a perspective view of an example of a conventional multi-cell transistor, FIG. 3 (a),
(B) shows a connecting portion between a stabilizing resistor and a common emitter electrode of a conventional multi-cell transistor, (a) is a plan view,
(B) is a cross-sectional view taken along the line AA of (a), and FIG. 4 is a plan view of a similar connection portion of another embodiment of the present invention. 4 ... Emitter extraction electrode, 5 ... Emitter common electrode, 7
...... Polycrystalline Si film resistor, 70 ...... Polycrystalline Si film connection part.

Claims (1)

[Claims] 1. A semiconductor substrate is provided with a plurality of emitter regions, and a common electrode for external connection is provided by covering the other end of a resistive film, one end of which contacts each electrode that makes ohmic contact with each emitter region. A multi-cell transistor, wherein each resistance film is a part of a film having a connecting portion in contact with the surface of the common electrode on the substrate side.