Characteristics of Self-Aligned InP/InGaAs Heterojunction Bipolar Transistor Assisted by Silicon Nitride Sidewall
A reliable fabrication method for providing close spacing between the emitter mesa and the base contact metal of InP-based heterojunction bipolar transistor is disclosed. The silicon nitride sidewall was formed on the emitter electrode and mesa periphery. It was used as a mask for emitter mesa etching and also as an overhang to self-align the base contact with respect to the emitter mesa. The self-aligned device fabricated by this technique exhibited better high-frequency performances with fT of 138 GHz and fmax of 143 GHz, respectively, superior to the re-aligned one on the same epitaxy wafer.
Byung Tae Ahn, Hyeongtag Jeon, Bo Young Hur, Kibae Kim and Jong Wan Park
B. G. Min et al., "Characteristics of Self-Aligned InP/InGaAs Heterojunction Bipolar Transistor Assisted by Silicon Nitride Sidewall", Solid State Phenomena, Vols. 124-126, pp. 97-100, 2007