Shallow Boron‐Doped Layer Formation by Boron Diffusion from Poly‐Si Through Thin SiO2

Abstract

This paper discusses boron doping using metal oxide semiconductor structure . The thin layer acts as a stopper to poly‐Si removal after doping. When boron implantation is used for poly‐Si doping, shallow boron‐doped layers suitable for base application can be formed by wet drive‐in. When implantation is used, shallow boron‐doped layers can be formed even by drive‐in. The surface boron concentration of boron‐doped layers increases with dose and saturates, since boron concentration in poly‐Si in the region near the interface with also increases with dose and saturates. An estimate of the boron diffusion coefficient in , , shows that it increases by about one order of magnitude both for boron implantation with subsequent wet drive‐in and for implantation with subsequent drive‐in.