JPS60260153A - Semiconductor device - Google Patents

Abstract

PURPOSE:To form a lateral P-N-P transistor having the more superior characteristics by a method wherein a part of a collector provided in the circumference of an emitter is cut apart, and a diffusion layer for base contact and a contact window are formed at this part. CONSTITUTION:A collector region 15 is made as not to exist at the part whereat an emitter region 14 is facing with a base electrode connecting region 16, and the base electrode connecting the region 16 is provided in place of the collector region as to approach the emitter region 14. Because a part of the collector 15 is removed, and the base electrode connecting region 16 is provided, a base current is made to flow more easily to the part facing to the base electrode connecting region 16 of the emitter 14 than the part directly under the emitter 14. Accordingly, implantation of minority carriers from the mitter 14 is increased at the periphery of the metal 14, the distance to reach the collector is shortened, and the amplification factor of the current is increased. Moreover, base resistance is reduced also because the base electrode connecting region 16 is provided in the neighborhood of the emitter 14.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the structure of a PNP transistor constituting a semiconductor integrated circuit.

(Prior art) Semiconductor integrated circuits include NPN transistors, PNP transistors, resistors, diodes, and capacitors.

It is composed of FET, etc., but in linear integrated circuits it is NPN.
) Since transistors are mainly used, N
It is common to form a type epitaxial layer and form elements on the surface thereof. In this case, various efforts have been made to determine how to form a PNP transistor on the N-type epitaxial layer on which the device is to be formed.

A conventional PNP) transistor is based on an N-type epitaxial layer, and P-type impurities are selectively diffused into two places close to each other from the surface, and one of them is made into an emitter.

There is one in which the other is the collector. This transistor is called a lateral PNP transistor because current flows horizontally.

The structure of a conventional lateral PNP transistor is shown in FIG. FIG. 1(a) is a cross-sectional view showing the structure of a horizontal PNP transistor (FIG. 1(a) is a plan view).

In FIG. 1(a), 1 is a P-type semiconductor substrate, 2 is an N-type buried layer,
3 is the P-type assembly region, 4 is the emitter, and 5 is this.

The lid, 6 is an ohmic diffusion layer for the base electrode, 7 is an insulating layer on the surface, and 8, 9, and 10 are emitters.

0 power amplification factor (hrE), which is the collector and base electrodes.
), a collector 5 is often arranged around the emitter 4 so as to surround it.

In this, the N-type buried layer 2 prevents current from flowing from the emitter layer 4 to the P-type substrate 1, and connects the P-type base layer 1 and the emitter layer 4 to the P-type substrate 1.

This is to prevent a parasitic PNP transistor from occurring between the transistor and the transistor 4.

(Problem that the invention attempts to solve) However, the conventional structure has the following drawbacks.

One is that the current amplification factor is small, and the other is that the base resistance is large.

The reason why the hFE is small is that the emitter 4 and the collector 5 are arranged in a plane, and the distance between them is determined by the i space, so the distance cannot be made smaller, and the recombination occurs when a current flows through the surface. In addition, many carriers are injected from the emitter into the base region directly below the emitter, and therefore the proportion of carriers reaching the collector is small. Further, the reason for the large base resistance is that the base electrode 10 is connected to the base electrode diffusion layer 6 outside the collector 5, and the purpose is to provide a lateral PNP transistor with better characteristics.

(Means for Solving the Problems) The feature of the present invention is to divide a part of the collector installed around the emitter and ri, and form a diffusion and contact window for the base contact in that part. .

(Embodiment) Next, an embodiment of the present invention will be explained with reference to FIG. 2. In FIG.
3 is a P-type insulating region, 14 is an emitter, 15 is a collector,
16 is an ohmic diffusion layer for the base electrode, 17 is a surface insulating layer, and 18, 19, and 20 are ohmic, radial, collector, and base electrodes, respectively. The difference from the conventional structure is that conventionally, the pace electrode 20 is connected to the pace electrode connection region 6 outside the collector region 5, whereas in this embodiment, the emitter region 14 of the collector region 15 is connected to the base electrode connection region 16. Instead, the pace electrode connection region 16 is provided so as to be close to the emitter region 14.

Next, the reason why the present invention alleviates the conventional drawbacks will be described. Third
The figure shows the flow of base current in a conventional structure. The 9 base current that can be seen in this diagram is emmi.

The water flows intensively from the area around Ri4 and directly below Ri4. The distribution of the pace current is the same as the distribution of minority carriers from emitters and ri4, so many minority carriers are injected from emitters and ri4 directly under emitter 4 as well as around emitters and ri4. The minority carrier directly under RI 4 is collector 5.
The distance it takes to reach is long and it is easy to recombine. In other words, the current amplification factor is reduced. Furthermore, the base resistance becomes large because the distance between the pace electrode connection region 6 and the emitter 4 is long.

FIG. 4 shows the flow of pace current according to this embodiment. Since a portion of the collector 15 is removed and the pace electrode connection area 16 is left in place, the pace current easily flows from directly under the emitter 14 to the part of the emitter 14 facing the pace electrode connection area 16. Become.

For this reason, the minority carriers injected from the emitter 14 are concentrated around the emitter 14, and the distance to reach the collector is short, increasing the spot flow amplification factor. Also, the pace resistance is Emi,
The pace electrode connection area 16 is located near the wall 14 so that it is lowered.

[Brief explanation of the drawing]

Figure 1 shows a horizontal PNP transistor with a conventional structure, in which (a) is a plan view, and (b) is a line AA' in (a).
FIG. FIG. 2 shows a horizontal PNP transistor according to an embodiment of the present invention, in which (a) is a plan view and FIG. 2 (b) is a sectional view taken along line BB' in FIG. 2 (a). FIG. 3 shows a cross-sectional view of a horizontal PNP having a conventional structure, and FIG. 4 shows a cross-sectional view of a horizontal PNP according to an embodiment of the present invention, each of which shows the flow of pace current. 1.11...P-type semiconductor substrate, 2.12...
...N type buried layer, 3.13...P type insulation isolation region, 4゜14...Emitter region, 5.15.
... Collector region, 6.16 ... Pace electrode connection region, 7.17 ... Insulating film, 8.18
... Emi electrode, 9.19 ... Collector electrode, 10.20 ... Pace electrode. Pole 1vpr 2nd figure Pole 3I! gI $ 4 Leap

Claims (1)

[Claims] a semiconductor region of one conductivity type acting as a base region;
an emitter region of another conductivity type provided within the semiconductor region; and a collector region of the other conductivity type formed in the semiconductor region so as to surround the emitter region except for a portion thereof;
A semiconductor device comprising a base electrode connection region formed at a portion where the collector region is divided.