SiGe HBTs in 90nm BiCMOS Technology Demonstrating f_T/f_MAX 285GHz/475GHz through Simultaneous Reduction of Base Resistance and Extrinsic Collector Capacitance

Abstract

Development of SiGe HBTs in BiCMOS technology with both high f T and f MAX faces significant challenges. To increase f T, thinning the base and collector thickness is generally the first step to reduce the carrier transit times, but this increases the base resistance and the collector-base capacitance, which impacts f MAX negatively. Increasing collector doping is also often employed to increase f T, but this increases collector-base capacitance, which drives f MAX down. To overcome these limits, millisecond anneal techniques, low temperature silicide and low temperature contact processes are employed to reduce the base resistance. Concurrently a novel approach to reduce the extrinsic collector-base capacitance is developed, without affecting the manufacturability and integration with CMOS. The simultaneous reduction of both base resistance and collector capacitance enables high performance SiGe HBT devices in 90nm BiCMOS Technology with operating frequencies of 285/475GHz f T/f MAX.

Advanced Heterojunction Bipolar Transistor for Half-THz SiGe BiCMOS Technology

“…The current state-of-the-art performance level for the DPSA design is represented, for example, by STMicroelectronics' 55 nm SiGe BiCMOS technology featuring peak f T /f max /gate-delay values of 320 GHz/370 GHz/ 2.34 ps [1]. By the help of non-standard technology elements the feasibility of f max values around 500 GHz could be shown [6]- [9]. The recently proposed SEG HBT process in which an epitaxial base link (EBL) is formed after emitter fabrication [7] offers a potential way to overcome limitations of the classical DPSA technology in forming a more conductive baselink suitable for ongoing lateral scaling.…”

(Invited) Integration of an Epitaxial-Base-Link HBT Device with fT = 300GHz, fmax 480GHz in 90nm CMOS

“…HBT architectures in volume production today are limited to an fmax of up to 400GHz (1),( 2),(3),(4), (5), (6). Alternative HBT architectures to overcome this limitation have been proposed (7), (8), (9), (10).…”