A SiGe-base PNP ECL circuit technology

Abstract

In this work we present the first SiGe-base PNP ECL circuit results. The SiGe-base PNP circuit technology includes extended Ge-profile designs for low collector doping levels, a self-aligned transistor structure on deep and shallow trench isolation, and in-situ doped polysilicon emitter contacts. Circuit transistors are obtained wilh good Gummel characteristics, a current gain of 40, a low emitter resistance of 9 Ω, a pinched base sheet resistance of 9.5 kΩ/□, and a peak fT of 31 GHz at a VBC of 3 volts. The circuit transistors have low parasitics resulting in a peak fmax of 38 GHz at a VBC of 3 volts. An ECL ring oscillator delay of 44 ps was measured at 2.7 mW.