Semiconductor device based on transistors with low, high, breakdown voltages e.g. for controlling a motor-vehicle airbag, has breakdown voltage transistor formed with emitter zone of second conductivity type formed on the main surface

摘要

The current gain spread of transistors with low and high breakdown voltages is suppressed to avoid complications during the manufacturing process and has the transistors formed on a main surface of a semiconductor substrate. The low voltage breakdown transistor has a field insulation layer (12) formed on the main surface. A first base-impurity zone (2b) of a first conductivity type is formed on a first zone of the main surface, and the high voltage breakdown transistor has a fourth base-impurity zone (2b) of a first conductivity type formed in the main surface.