National Semiconductor Corporation

Victor K Liang

James L Dunkley

A collector diffused isolation transistor wherein the normal buried layer in the substrate of the device is utilized as a collector region, an isolation region of the same conductivity type as the buried layer being formed by ion implantation of suitable atoms in the buried layer region with a second similar ion implantation in the surface of the epitaxial layer of second conductivity type grown over the substrate and buried layer, the collector diffused isolation region being formed by the up diffusion of the lower ion implanted region into the grown layer and the down diffusion of the upper ion implanted region into the grown layer so that the up and down diffusions overlap. Complimentary devices such as PNP and NPN devices are made on the same substrate utilizing this novel technique.

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Phoenix, AZ, United States of America

Victor K Liang