Buried-metal Self-aligned Process for SiGe HBT

Aiming at improving accuracy of photoetching technology in conventional double-mesa process,this article introduced buried-metal layers and developed silicon based buried-metal self-aligned process in order to increase the mesa area utilization efficiency.Novel process has advantages of smaller junction area,larger met- al-semiconductor contact area and fewer pinhole fabrication defects,with no increase of fabrication difficulties or advancement of photolithography equipments.