Transistor with an airgap for reduced base-emitter capacitance and method of forming the transistor

Abstract

Disclosed are embodiments of a transistor, which incorporates an airgap for low base-emitter capacitance (C). Each embodiment of the transistor has a monocrystalline base and, within the monocrystalline base, an intrinsic base region and an extrinsic base region positioned laterally adjacent to the intrinsic base region, wherein the intrinsic and extrinsic base regions have co-planar top surfaces. An essentially T-shaped emitter in cross-section has a lower emitter region on the intrinsic base region and an upper emitter region above the lower emitter region. Each embodiment of the transistor further has an airgap, which is positioned laterally adjacent to the lower emitter region so as to be between the extrinsic base region and the upper emitter region. Thus, the entire airgap is above the co-planar top surfaces of the intrinsic base region and the extrinsic base region. Also disclosed herein are methods of forming the transistor embodiments.