Bicmos process with low temperature coefficient resistor (TCRL)

摘要

A method for forming a polysilicon resistor with a relatively low temperature coefficient of resistance (TCRL) resistor (141). As a first step, a protective oxide (140) is deposited over the epi layer (11). This layer protects any exposed emitter polysilicon layer (132) from etching when the TCRL regions are defined. A polysilicon layer (142) is deposited in the opening. Next, the polysilicon layer is implanted with a BF2 implant (143). Finally, the TCRL (141) is covered with a photoresist and etched to its suitable size. The TCRL layer (141) is then covered with a protective oxide. The oxide is suitably patterned and masked to protect the underlying portion of the TCRL (141).