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Impact of mutual thermal coupling on the performance of a single 90nm SiGe heterojunction bipolar transistor (HBT) due to the presence of power dissipating elements like other HBTs in near vicinity is presented in this paper. Mutual thermal resistance (Rth,mutual) has been computed as a function of spacing between the single HBT and a ring of HBTs surrounding the device. HBT structural design variations including device layout schemes, metal wire stack connected to the emitter, deep trench (DT) depth and emitter to DT spacing, for reduced self thermal resistance (Rth), have been explored in this paper. An updated thermal resistance model accounting for the heat flow through the metal wiring stack connected to the emitter is also reported.

High performance Schottky Barrier Diodes (SBDs) with cut-off frequency (fc) ~2.0 THz integrated into a 90nm SiGe BiCMOS technology for millimeter wave (mm-wave) applications are presented in this paper. To our knowledge, this is the highest reported fc for a SBD in a BiCMOS technology. The SBDs reported here have low reverse bias leakage with breakdown voltage of ~5V, and have been integrated in the base technology without the addition of any extra processing step. The affects of variation of critical process and device parameters - undoped silicon layer (n-epi) thickness, thermal cycle associated with deep-trench formation, cathode reach-through width, and anode area on device performance have also been investigated and are presented here.

Scaling both the fT and the fMAX of SiGe HBTs is quite challenging due to the opposing physical device requirements for improving these figures of merit. In this paper, millisecond anneal techniques, low temperature silicide and low temperature contact processes are shown to be effective in reducing the base resistance. These processes when combined with a novel approach to address the collector-base capacitance are shown to produce high performance SiGe HBT devices which demonstrate operating frequencies of 300/420GHz fT/fMAX. This is the first report of 90nm SiGe BICMOS with an fMAX exceeding 400GHz.