| 摘要 |
A collector (204) is deposited and a base (222) grown on the collector (204), for example, epitaxially depositing either silicon or silicon germanium. An emitter (230) is fabricated on the base (222) followed by implant doping an extrinsic base region (224), using for example, boron. The extrinsic base region (224) doping diffuses out during subsequent thermal processing steps in chip fabrication, creating an out diffusion region (226) in the device, which can adversely affect various operating characteristics, such as parasitic capacitance and linearity. Counter doping using arsenic or phosphorus controls the out diffusion. Also the counter doping can be formed using tilt implanting or, alternatively, by region by implant doping the counter doped region (228) and forming a spacer (not shown) on the base (222) prior to implanting the extrinsic base region (224).
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