200-nm InGaAs/InP type I DHBT employing a dual-sidewall emitter process demonstrating ƒmax ≫ 800 GHz and ƒτ = 360 GHz

• Main Authors: Lobisser, E., Griffith, Z., Jain, V., Thibeault, B.J., Rodwell, M.J.W., Loubychev, D., Snyder, A., Ying Wu, Fastenau, J.M., Liu, A.W.K.
• Format: Conference Proceeding
• Language: English
• Subjects: Chromium; Current density; Cutoff frequency; Double heterojunction bipolar transistors; Dry etching; Heterojunction bipolar transistors; Indium gallium arsenide; Indium phosphide; InP heterojunction bipolar transistor; Protection; Wet etching
• ISSN: 1092-8669
• DOI: 10.1109/ICIPRM.2009.5012408

Type I InP/InGaAs/InP double heterojunction bipolar transistors were fabricated using a simple mesa structure, where emitter junction widths have been scaled from 250 nm to 200 nm. These devices exhibit f max in excess of 800 GHz, and f tau = 360 GHz. Greater than fifty percent device yield was obtained by employing two 25 nm SiN x sidewalls to protect and anchor the refractory metal emitter contact to the emitter semiconductor. A hybrid dry and wet etch process is used to form a vertical emitter mesa, causing reductions in both the emitter-base gap resistance R gap and the spreading resistance beneath the emitter R b,spread , leading to an expected and observed increase in f max . Peak HBT current gains beta ap 21-33, BV ceo ~ 4 V, BV cbo ~ 5 V, and J e at low V cb is over 10 mA/mum 2 .