Bipolar transistor with improved reverse breakdown characteristics

摘要

A bipolar transistor (10) in an IC includes a semiconductor wafer defining a collector area (14) with a first conductivity type, a base area (20) with a second conductivity type formed in the collector area (14), and an emitter formed in the base area. A field oxide is positioned on the surface of the semiconductor wafer surrounding the emitter (30) and substantially covering the base area (20) and an implant of the second conductivity type is positioned in the base area (20) between and spaced from the emitter (30) and the outer periphery of the base area (20). The implant further has a heavier concentration of the second conductivity type than the base area to compensate for loss of the second conductivity type under the field oxide and to separate the transistor current path from the breakdown path, which improves the collector to emitter breakdown voltage (BVCEO) while still maintaining a high beta.