Narrow Base High Performance Bipolar Structure
Original Publication Date: 1980-Feb-01
Included in the Prior Art Database: 2005-Feb-13
In the bipolar transistor structure, as the depth is reduced to improve the device performance, control of the integrated base doping and base width in the intrinsic region while maintaining a low sheet resistance in the extrinsic region becomes increasingly difficult. To achieve an optimized device structure, the doping formed in the intrinsic and extrinsic base regions has to be done by separate, independent processes. That is, a high dose boron implant cannot be doped the (intrinsic base) emitter region. The controllable and reproducible narrow intrinsic base should be formed "in place" by a low-dose implant after high temperature emitter drive-in diffusion. To mask the high dose boron implant from getting into the emitter region, a self-aligned mask covering the emitter contact is required.