Semiconductor device

摘要

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.