BiCMOS devices

摘要

A BiCMOS process which provides both low voltage (digital) and high voltage (analog) CMOS devices. The high voltage NMOS devices have a compensated drain formed by the NPN and PNP base implants. The PNP base plus the high voltage NMOS drain carrier concentrations are both optimized by adjustment of the two variables N base implant dose and P base implant dose; this determines the NPN base carrier concentration which turns out to provide good NPN characteristics. Low voltage NMOS source and drain implants employ a higher dose and may also be used for the high voltage NMOS source. The NPN emitter doping may also be used for a contact to the high voltage NMOS drain contact.