JPS62244173A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve the current capacity of a transistor and to attain high breakdown withstanding voltage by forming the number of lattices of the emitter of a transistor of previous stage more than that of the emitter of a transistor of rear stage to accelerate transistors connected in a Darlington. CONSTITUTION:The number of lattices of a transistor 3 of previous stage in a semiconductor device 1 having transistors 3, 9 including a latticelike emitter structure connected in Darlington transistors is increased more than that of the transistor 9 of rear stage. For example, the transistor 3 of the previous stage has an N-type epitaxial layer 2 operating as a collector, a P<-> type base region 4, and an N<+> type mesh emitter region 5, and many multibase regions 6,.., 6 are disposed insularly in the region 5. The transistor 9 of the rear stage is also similarly formed, and integrated so that the pectinated second emitter electrode 8 of the previous stage are electrically connected with the pectinated second base electrode 7' of rear stage.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention forms a plurality of transistors in a semiconductor substrate,
This invention relates to a semiconductor device formed by Darlington connection, and particularly relates to a semiconductor device with improved operating speed and current capacity when Darlington connection is made.

(b) Prior Art Darlington transistors have a high current amplification factor and are therefore used for switching large currents.

In general, the Darlington transistor
As in Publication No. 390 (Figures 2 and 3), the collector and base of the transistor (22) (output transistor) in the subsequent stage are connected between the collector and emitter of the transistor (21) (driver transistor) in the previous stage, Diffused resistors were formed between the bases and emitters of the transistors (21) and (7) at the front stage and between the base and emitter of the transistor (22) at the rear stage, respectively, and Darlington connections were made.

(c) Problems to be Solved by the Invention In the above-mentioned Darlington transistor, a semiconductor capable of passing a higher current is required. In addition, high-current semiconductor devices are required to have higher switching speeds and improved breakdown resistance.

(d) Means for Solving the Problems The present invention has been made in view of the problems such as layer structure, and is a semiconductor device equipped with transistors (3) and (9) having a grid-like emitter structure connected to Darlington transistors. (1
) is solved by forming the number of lattices of the transistor (3) at the front stage to be larger than the number of lattices of the transistor (9) at the rear stage.

(*) Effect With the lattice-like emitter structure as described above, there are many island-like base regions (6)...(6) and emitter regions (5).
The unit transistors operate in parallel, allowing a large current to flow.

Also, the lattice-like emitter structure in the previous stage, here it is a case.

If the dimensions of the emitter region (5) (the dimensions of the unit transistor) are made smaller by increasing the number of children, the traveling distance of the minority carriers becomes shorter and the switching speed can be increased. Therefore, the transistor in the next stage can be brought into a fast<ON state. Furthermore, by reducing the size of the unit transistor of the transistor (3) in the previous stage, a larger number of unit transistors can be arranged in the previous stage than before, so the emitter peripheral length becomes longer than before and the current capacity improves.

Furthermore, the switching speed of the subsequent transistor (9) is slow due to the large size of the unit transistor, but current concentration is less likely to occur. Furthermore, the resistance to breakdown is improved due to the fact that the resistance generated between the emitter and base junction is greater than that between the base contact and the like.

(F) Example An example of the present invention will be described below with reference to FIG.

The Darlington transistor connected transistor (1) according to the present invention can be formed by connecting two or more stages of transistors on a silicon semiconductor substrate (2). Here, the explanation will be made in two stages as shown in FIG.

First, the structure of the transistor (3) at the front stage is formed by an N''' type silicon semiconductor substrate, an N type epitaxial layer (2) covering the semiconductor substrate and serving as a collector, and the epitaxial layer (2). The emitter region (5) includes a P-type base region (4) shown by a dotted line and an N0-type mesh emitter region (5) provided on the surface of the base region (4). ), and the multi-base regions (6>...(6) are arranged in the form of multiple islands completely surrounded by the emitter region (5).

Next, on the silicon oxide film on the surface of the substrate (2), a first
A first base electrode and a first emitter electrode of the first layer, which are omitted in the figure, are formed, and the first base electrode makes ohmic contact with the multi-base regions (6)...(6), respectively, and the first emitter electrode The electrode is located in the mesh emitter region (5
) and forms a mesh shape by making ohmic contact with almost the entire surface of the surface. Subsequently, the first base electrode and the first
The emitter electrode is covered with an interlayer insulating film such as a silicon nitride film or polyimide, and on the interlayer insulating film there is a second base electrode (7) in the second layer and a second emitter electrode (8) as shown by the solid line in FIG. ) is formed. The second base electrodes (7) are formed to extend in one direction in a comb-teeth shape, making ohmic contact with each of the first base electrodes scattered in an island shape. Further, the second emitter electrode (8) is a mesh-like first emitter electrode (8).
It makes ohmic contact with the emitter electrode, and extends in a comb-teeth shape like the second base electrode (7).

- The transistor in the subordinate stage is formed in the same way as the transistor in the previous stage, and furthermore, the comb-shaped second emitter electrode (8) in the former stage and the comb-shaped second base electrode (7゛) in the latter stage are formed. As shown in FIG. 1, they are integrally formed by vapor deposition so as to be electrically connected. Also, the base region (4) of the transistor in the previous stage is replaced by the base region (4') of the transistor in the latter stage.
are integrated and use separate areas.

This configuration is the first feature of the present invention, and as described above, having the lattice-like emitter structure has a large number of island-like base regions (6)...(6), (6')... (6')
and an emitter region (5), the unit transistors operate in parallel, and the Darlington transistor-connected transistor of the present invention can conduct a large current.

Next, the former stage transistor (3) is replaced by the latter stage transistor (3).
The emitter (5) structure having a smaller size than the emitter (5') size of 9) is formed by increasing the number of gratings.

This configuration is the second feature of the present invention, in which the dimensions of the emitter (5) of the transistor (3) in the previous stage (dimensions of the unit transistor) are the dimensions of the emitter (5') of the transistor (9) in the subsequent stage (unit transistor).・Transistor dimensions)

For example, here, the cell size is 273 to 1/4. In other words, the traveling distance of the minority carriers becomes shorter, and the switching speed can be increased. Therefore, the transistor in the next stage can be brought into a fast<ON state.

Furthermore, by reducing the dimensions of the unit transistor in the front stage, more unit transistors can be placed in the front stage than before, which increases the emitter peripheral length.
Improves current capacity. By improving the current capacity of the previous stage, the current capacity of the Darlington transistor also improves. On the other hand, since the unit transistor size of the subsequent transistor (9) is large, the switching speed is slow, but current concentration is less likely to occur. In addition, the breakdown resistance is improved because the resistance generated between the emitter and base junction is greater than that between the base contact and the like. Darlington
The breakdown capability of a transistor is determined primarily by the breakdown capability of the subsequent stage through which a large current flows, so the breakdown capability of a Darlington transistor is improved. Furthermore, since the vertical profile of the transistor is the same in both the front and rear stages, it can be formed in one process, so the number of steps can be kept the same as in the past.

(g) Effect of the invention As is clear from the above explanation, the transistor in the previous stage (3
) is the size of the lattice-shaped emitter region (5') of the subsequent transistor (9) (
By making the size of the unit transistor smaller, the speed of Darlington-connected transistors can be increased, and further, the current capacity and breakdown resistance can be improved.

[Brief explanation of drawings]

FIG. 1 is a plan view of a semiconductor device connected with Darlington transistors, which is an embodiment of the present invention, FIG. 2 is a plan view of a conventional semiconductor device connected with Darlington transistors, and FIG. 3 is a plan view of a semiconductor device connected with Darlington transistors. FIG. (1) is a Darlington transistor connected transistor, 2) is a silicon semiconductor substrate, (3) is a previous stage transistor, (4) is a base region, (5) is an emitter region, (6) is a multi-base region, (7) is a second base electrode, (8) is a second emitter electrode, and (9) is a subsequent transistor.

Claims (1)

[Claims] (1) A semiconductor device including a transistor having a lattice-like emitter structure connected to a Darlington transistor, characterized in that the number of lattices of the preceding transistor is greater than the number of lattices of the subsequent transistor. Device.