JPH0120547B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved lateral transistor.

Horizontal transistors have disadvantages, such as their frequency characteristics being inferior to vertical transistors, or their current amplification factor starting to decline from a relatively small collector current due to the low impurity concentration in the base region. An integrated circuit has the advantage that it can be realized without adding any special process, and that if it has a multi-collector structure, the ratio of each collector current can be changed arbitrarily by designing the planar dimensions. However, as a matter of course, there is the inconvenience that the collector area, which determines the collector current ratio, cannot be changed even if one wishes to do so later. The object of the present invention is to provide a novel lateral transistor that can adapt to a variety of usage conditions, in which the collector area, which has conventionally been fixed at the design stage, can be changed arbitrarily just by wiring operations according to actual operational requirements. is to provide. The lateral transistor of the present invention includes an emitter region consisting of a second conductivity type region selectively provided in the main surface of a first conductivity type semiconductor substrate, and a collector region facing a part of the emitter region. , an active base region whose main portion is a portion sandwiched between the emitter region and the collector region of the first conductivity type semiconductor substrate; an independent electrode made of a conductive film provided thereon;
and voltage application means for inducing an inversion layer on the main surface immediately below the independent electrode to increase the collector area.

Next, the present invention will be explained by examples.

FIG. 1 is a sectional view of an embodiment of the present invention. In the figure, N with an impurity concentration of about 10 ¹⁵ cm ^-3
A P-type emitter region 3, a P-type collector region 2, and a base region are formed on a silicon substrate 1 using known photolithography and diffusion techniques.
A contact region 4 for the base electrode contact of the mold substrate 1 is formed, and a collector electrode 5, an emitter electrode 6, and a base electrode 7 are connected to the corresponding regions through contact holes formed in the insulating film 8. The metal wiring is formed using, for example, a vapor-deposited film of aluminum. At this time, an independent electrode 9 made of a metal film is formed at the same time, with a portion overlapping the collector diffusion region 2 and the remaining portion extending over the N-type substrate 1.

In a lateral transistor having such a structure, for example, by applying a sufficiently low potential to the independent electrode 9 with respect to the base region during actual operation of the transistor, an inversion layer 10 connected to the collector region is formed on the surface of the base region. This increases the effective area of the base-collector junction.

As explained above, the present invention provides an independent electrode from just above the collector region of a lateral transistor to its periphery, and applies a voltage to the independent electrode to generate an inversion layer, thereby forming a base-collector junction. By increasing the effective area,
It is possible to electrically change the collector area to meet various usage conditions.

Although the above embodiments have described the case of a PNP type lateral transistor, it is clear that an NPN type can also be realized, and it goes without saying that the semiconductor material is not limited to silicon.

[Brief explanation of drawings]

FIG. 1 is a sectional view of one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... N-type semiconductor substrate, 2... P-type collector region, 3... P-type emitter region, 4... base electrode extraction part, 5... collector electrode, 6... emitter electrode, 7... base electrode, 8... Insulating film, 9... Independent electrode, 10... Inversion layer.

Claims (1)

[Claims] 1. An emitter region consisting of a second conductivity type region selectively provided in the main surface of the first conductivity type semiconductor substrate, a collector region facing a part of the emitter region, and the first conductivity type semiconductor. an active base region whose main portion is a portion sandwiched between the emitter region and the collector region of the base body; and a conductive film provided on the main surface from directly above the collector region to its periphery via an insulating film. 1. A lateral transistor comprising: an independent electrode; and voltage applying means for inducing an inversion layer on the main surface directly under the independent electrode to increase a collector area.