| 摘要 |
Disclosed is a method of forming a heterojunction bipolar transistor (HBT), comprising depositing a first stack comprising an polysilicon layer (16) and a sacrificial layer (18) on a mono-crystalline silicon substrate surface (10); patterning the first stack to form a trench (22) extending to the substrate; depositing a silicon layer (24) over the resultant structure; depositing a silicon-germanium-carbon layer (26) over the resultant structure; selectively removing the silicon-germanium-carbon layer (26) from the sidewalls of the trench (22); depositing a boron-doped silicon-germanium-carbon layer (28) over the resultant structure; depositing a further silicon-germanium-carbon layer (30) over the resultant structure; depositing a boron-doped further silicon layer (32) over the resultant structure; forming dielectric spacers (34) on the sidewalls of the trench (22); filling the trench (22) with an emitter material (36); exposing polysilicon regions (16) outside the side walls of the trench by selectively removing the sacrificial layer (18) of the first stack; implanting boron impurities into the exposed polysilicon regions (16) to define base implants; and exposing the resultant structure to a thermal budget for annealing the boron impurities. A HBT formed by this method is also disclosed.
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