High-performance Uniform Stepper-Based InP Double-Heterojunction Bipolar Transistor (DHBT) on a 3-Inch InP Substrate

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 stepperbased 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 WE = 0.6 mu m and LE = 15 mu m exhibits current gain (beta) = 50 at VCE = 1.0 V and an open-base common-emitter breakdown voltage (BVCEO) of 5.7 V at JC = 0.01 mA/mu m2 and 7.5 V at JC = 0.1 mA/mu m2, respectively. Moreover, the fabricated DHBTs with WE = 0.6 mu m and LE = 15 mu m show excellent fT of 244 GHz and fmax of 221 GHz at JC = 4.4 mA/mu m2 and VCE = 1.6 V. In order to evaluate the uniformity of the fabricated DHBTs, we measure current gain (beta) and high-frequency characteristics with WE = 0.6 mu m and LE = 15 mu m and the average values and standard deviation of the beta, fT, and fmax are beta = 49.3 +/- 1.9, fT = 241.4 +/- 3.8 GHz, and fmax = 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.