Nippon Telegraph and Telephone Public Corporation

Hitachi, Ltd.

Oki Electric Industry Co., Ltd.

Tetsuma Sakurai

Tatsuya Kamei

Yoshitaka Sugawara

Kotaro Kato

Taiji Usui

Tetsuya Takayashiki

A lateral transistor having a high breakdown voltage and operable with an improved current amplification factor and an improved cut-off frequency comprises in a semiconductor substrate of one conductivity type, a base layer of the one conductivity type and an emitter layer of the other conductivity type formed in the base layer. A first collector layer of the other conductivity type is formed in the one principal surface of the substrate apart from the base layer and a second collector layer of the same conductivity type having an impurity concentration lower than that of the first collector layer is formed between the first collector layer and the base layer in contact with the latter layers. Emitter, base and collector electrodes make ohmic contact with the emitter, base and first collector layers respectively. The emitter electrode extends on a passivation film covering the one principal surface of the substrate to terminate at a point on the second collector layer.

Semiconductor device

Spaced recesses are formed in a surface of a low impurity concentration P type single-crystal substrate by using a mask. A P type impurity is diffused at a high concentration into an entire surface of the substrate including the recesses to form a P type diffused layer, and an N type layer is epitaxially grown on the P type diffused layer. Then, mask layers are formed on bottom surfaces of the recesses in the epitaxially grown N type layer and this N type layer is anisotropically etched by using the mask layers to form island regions in the recesses. After removing the mask layers, N type diffused layers are formed to cover the island regions. An insulating film (SiO.sub.2) acting to isolate completed transistor elements is formed on the P and N type diffused layers, and a polycrystalline silicon layer acting as a support of a dielectrically isolated integrated circuit device is formed on the insulating film. Then, the rear surface of the single-crystal silicon substrate is ground off to expose the insulating film. MOS or bipolar type transistor elements are formed in the island regions to obtain a dielectrically isolated semiconductor integrated device.

Method of manufacturing semiconductor integrated circuit devices

The semiconductor device is provided with semiconductor elements having the complementary characteristics and high breakdown strength. These semiconductor elements are formed in N and P islands respectively each having an inverted frustum shape. Surfaces of the frustum are inclined by an angle determined by semiconductor crystal structure. Side and bottom surfaces of the islands are formed adjacent to an insulating layer and both islands are supported part from the polycrystalline semiconductor layer. All side and bottom surfaces of the islands adjacent the insulating layer are made of high impurity substance of the same type as respective islands.

Method of manufacturing semiconductor device provided with complementary

Growing community of inventors

Hachioji, Japan

Tetsuma Sakurai