High speed, high voltage transistor

Claim 1

A transistor comprising: a semiconductor body having first and second opposed major surfaces and thin internal and thick peripheral portions; said thin internal portion being of substantially uniform thickness of greater than about 28 microns and having opposed surfaces each of greater than about 0.10 cm2 in area, and said thick peripheral portion being of thickness greater than 150 microns and having a radial width greater than about 10 microns but less than the corresponding radial dimension of the internal portion; an emitter region of high impurity concentration adjoining first major surface and being at least partially in the internal portion of the body; a collector region of impurity concentration less than 8 X 1014 atoms/cm3 formed by the same conductive type as the impurities of the emitter region adjoining second major surface at both the internal and peripheral portions, having a width at the internal portion of greater than 20 microns, having a reach-through voltage at the internal portion less than breakdown voltage, and having a width at the peripheral portion at least 20 percent greater than the width at the internal region; a base region of impurity concentration of conductive type opposite to the impurities of emitter and collector region provided partially in interior of the body between the emitter and collector regions and forming separate PN junctions therewith, and having a minority carrier diffusion length at the internal portion at least an order of magnitude greater than the width of the base region at the internal portion; and metal contacts affixed to the major surfaces of the body to make separate ohmic contact with the emitter and collector regions at least at the internal portion and with the base region at the peripheral portion.