Double-polysilicon self-aligned SiGe HBT architecture based on nonselective epitaxy and polysilicon reflow

This paper describes a self-aligned SiGe heterojunction bipolar transistor (HBT) based on a standard double-polysilicon architecture and nonselective epitaxial growth (i.e. DPSA-NSEG). Emitter-base self-alignment is realized by polysilicon reflow in a hydrogen ambient after emitter window patterning. The fabricated self-aligned SiGe HBTs, with emitter widths of 0.3-0.4 μm, exhibit 20% lower base resistance and 15% higher maximum oscillation frequency f
_max
than non-self-aligned reference devices. The minimum noise figure of a Ku-band low-noise amplifier is reduced from 0.9 to 0.8 dB by emitter-base self-alignment.