BICMOS PROCESS FOR COUNTER DOPED COLLECTER

摘要

In a BICMOS circuit the bipolar transistor base region is formed in an n-type well serving as the collector of the transistor. Boron ions are implanted at two different energy levels to form the base region (26) and to counter dope the well to form a region (34) below the base region which is more lightly doped than the remainder of the well. The ion implantation counter doping the well may comprise two energy levels. Such counter doping reduces the electric field at the collector base junction and reduces collector base capacitance.