Bipolar transistor with field shields

Abstract

A bipolar transistor includes a substrate of semiconductor material having an expitaxial body of the semiconductor material on a surface thereof. The semiconductor body has a major surface. A collector region of one conductivity type is in the body at the major surface and a base region of the opposite conductivity type is in the collector region at the major surface and forms with the collector region a collector/base junction which extends to the surface. A plurality of emitter regions of the one conductivity type are in the base region and form with the base region emitter/base junctions which extend to the surface. At least some of the emitter/base junctions are adjacent to but spaced from the collector/base junction at the major surface. A layer of insulating silicon oxide is on the major surface and a layer of conductive polysilicon is on the insulating layer. The polysilicon layer includes strips which extend only over the area of the surface between the collector/base junction and the adjacent emitter/base junctions and resistor areas to which the strips are connected. The emitter regions are connected to the polysilicon layer. The bipolar transistor may be part of an integrated circuit which includes MOS transistors and the polysilicon layer also forms the gates of the MOS transistors.