Stacked barrier-diffusion source and etch stop for double polysilicon BJT with patterned base link

摘要

A bipolar transistor (100) and a method for forming the same. A base- link diffusion source layer (118) is formed over a portion of the collector region (102). The base-link diffusion source layer (118) comprises a material that is capable of being used as a dopant source and is capable of being etched selectively with respect to silicon. A barrier layer (119) is formed over the base-link diffusion source layer (118). A base electrode (114) is formed over at least one end portion of the barrier layer (119) and base-link diffusion source layer (118) and the exposed portions of the barrier layer (119) and underlying base-link diffusion source layer (118) are removed. An extrinsic base region (110) is diffused from the base electrode (114) and a base link-up region (112) is diffused from the base-link diffusion source layer (118). Processing may then continue to form an intrinsic base region (108), emitter region (126), and emitter electrode (124).