Submicrometer Si and Si-Ge epitaxial-base double-poly self-aligned bipolar transistors

The fabrication, device profiles, and electrical characteristics of epitaxial-base double-poly self-aligned bipolar transistors are presented. The intrinsic-base regions in the present device structures reside above the silicon surface and were formed using a boron-doped low-temperature epitaxially (LTE)-grown Si or Si-Ge layer to achieve a narrow intrinsic-base width (⩽60 nm) and a low base pinch resistance (<5 kΩ/□) simultaneously. As a result of the raised base using LTE and the preservation of the integrity of this layer by minimizing the dopant diffusion during the subsequent processing steps, walled-emitter devices with excellent electrical characteristics were obtained