TW238410B - Process for lateral bipolar transistor - Google Patents

Abstract

A process for lateral bipolar transistor includes: 1. after implanting the second conductive well mask and ion on the first conductive Si semiconductor substrate, then forming the pad oxide and Si3N4 sequentially, then through one field mask and oxidization to form active region and field oxide on the surface of Si semiconductor substrate and forming the second conductive well; 2. depositing one polysilicon layer and doping it with high density and etching to form the emitter of bipolar transistor, and the etching step including the over etching makes the Si substrate etched to form collector trench; 3. depositing one dielectric layer and etching back to remain dielectric space on the sidewall of collector trench, then implanting the first conductive mask and dopant ion to form the collector of bipolar transistor; 4. implanting the second conductive mask and dopant ion to form the base of bipolar transistor; 5. through one high temperature drive in step to make the first conductive dopant in the polysilicon of emitter expand outside to form emitter expansion area; 6. by separately controlling the depth of collector trench and the width of dielectric space and the structrue of collector trench to achieve the increase of current gain and component density.