High-performance uniform stepper-based InP double-heterojunction bipolar transistor (DHBT) on a 3-inch InP substrate

초록

In this paper, InP Double-Heterojunction Bipolar Transistors (DHBTs) on a 3-inch InP substrate is demonstrated through stepper-based photolithography. The performance of the fabricated InP DHBTs such as DC characteristics, high-frequency characteristics, and uniformity of the 3-inch wafer is investigated to verify the stepper-based fabrication process. To improve the high-frequency characteristics, the self-aligned base-emitter contact is realized by using the high height-to-width ratio and vertical sidewall emitter profile of the Au electroplating process. The fabricated DHBTs with W<inf>E</inf> = 0.6 μm and L<inf>E</inf> = 15 μm exhibits current gain (β) = 50 at V<inf>CE</inf> = 1.0 V and an open-base common-emitter breakdown voltage (BV<inf>CEO</inf>) of 5.7 V at J<inf>C</inf> = 0.01 mA/µm2 and 7.5 V at J<inf>C</inf> = 0.1 mA/µm2, respectively. Moreover, the fabricated DHBTs with W<inf>E</inf> = 0.6 μm and L<inf>E</inf> = 15 μm show excellent f<inf>T</inf> of 244 GHz and f<inf>max</inf> of 221 GHz at J<inf>C</inf> = 4.4 mA/μm2 and V<inf>CE</inf> = 1.6 V. In order to evaluate the uniformity of the fabricated DHBTs, we measure current gain (β) and high-frequency characteristics with W<inf>E</inf> = 0.6 μm and L<inf>E</inf> = 15 μm and the average values and standard deviation of the β, f<inf>T</inf>, and f<inf>max</inf> are β = 49.3 ± 1.9, f<inf>T</inf> = 241.4 ± 3.8 GHz, and f<inf>max</inf> = 221.5 ± 4.0 GHz, respectively. Thanks to the optimized stepper-based fabrication process, the fabricated InP DHBTs exhibit well-balanced high-frequency characteristics and excellent uniformity. © 2024 Elsevier Ltd

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