TUNNEL NITRIDE FOR IMPROVED POLYSILICON EMITTER

摘要

A method is disclosed for reproducibly and controllably enhancing the current gain of a bipolar junction transistor. Prior to depositing an extrinsic emitter region of polycrystalline silicon, the surface of a monocrystalline silicon substrate (65) is nitridized to grow a layer of silicon nitride (55) thereon. The interfacial layer of silicon nitride (75) functions as a tunnel insulator to enhance the current gain of the transistor and as a diffusion barrier to prevent thickening of the tunnel insulator due to the growth of a native oxide (80) layer while exposed to an oxygen-containing atmosphere. The ubiquitous native silicon oxide (80) on the surface of the monocrystalline silicon substrate (65) may be optionally removed either before nitridation or after nitridation.