Simulations of SiGe HBT's to obtain high ft and fmax

Julian, Engelin Shintadewi; Hartanto, Djoko

doi:10.1109/smelec.2002.1217821

Cited by 1 publication

(1 citation statement)

References 15 publications

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“…The design of Ge profile to get t Bmin in SiGe HBTs (without analyzing the p-type base doping profile effect) has been studied comprehensively in References [5][6][7][8][9][10][11][12][13][14][15][16][17]. Salmon et al OE8 and Kim et al OE9 considered a non-uniform base doping profile (resembling Gaussian) while analyzing the Ge profile effect on f t .…”

Section: Introductionmentioning

confidence: 99%

A novel approach for justification of box-triangular germanium profile in SiGe HBTs

Khanduri¹,

Panwar²

2015

J. Semicond.

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This work presents a unique and robust approach for validation of using the box-triangular germanium profile in the base of SiGe heterojunction bipolar transistors, where the methodology considers the simultaneous optimization of the p-type base doping profile in conjunction with the germanium profile in the base. The study analyses the electron motion across the SiGe base in SiGe HBTs, owing to different accelerating electric fields. The analysis first presents a figure of merit, to achieve the minimum electron transit time across the base in conjunction with the increased current gain in n-p-n-SiGe HBTs, which shows a general trend vis-à-vis the advantage of a trapezoid germanium profile, but with additional accuracy as we considered simultaneously optimized p-type base doping. The effect of minority carrier velocity saturation is then included to make the study more detailed. The analysis then investigates the shifted germanium profile in the base to further minimize the base transit time. Finally, it is shown that a shifted germanium profile eventually evolves into a box-triangular Ge-profile in the SiGe base, which could simultaneously minimize the base transit time and reduce emitter delay by virtue of the high current gain. The analysis verifies that for an average Ge-dose of 7.5% Ge across the base, a box-triangular germanium profile in conjunction with an optimum base doping profile has an approximately identical base transit time and a 30% higher current gain, in comparison with an optimum base doping and triangular Ge-profile across the whole base.

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