Device design considerations for an ultra-high voltage (>1600 volts) high frequency switching transistor

A 1600-volt switching transistor has been developed for use in an electronic gyro suspension system. This paper describes the design criteria and processes for this NPN silicon device. The major requirements for this transistor are to obtain a stable collector-base breakdown voltage of > 1600 volts, a collector-emitter saturation voltage of < 4.0 volts and an ftspecification of 40MHz. Two methods have been used for fabricating the transistor. One method employs a deep double diffused structure and the other uses an epitaxial grown base layer and a diffused emitter structure. Both methods utilize an etched mesa junction with oxide passivation and have produced devices which meet the required specification.