High yield scalable dry etch process for indium basedheterojunction bipolar transistors

摘要

A dry etch process for fabricating high-performance In-basedheterojunction bipolar transistors is described. The 2 μm×4μm emitter was formed by electron cyclotron resonanceCH₄/H₂/Ar plasma etch, thus minimizing damage andproviding excellent pattern transfer of the emitter metal mask. In orderto minimize parasitics and insure high yields, an SiO₂-filledtrench base-mesa is used, under the self-aligned based contact pad, todefine the active base area. As a further yield enhancement and toenable eventual submicron scaling of devices, planarization and reactiveion etchback of Futurrex PC2-1500 polymer were performed to exposeemitter terminals. Devices with emitter sizes of 2 μm×4 μmdemonstrated current gains of 50 with f_T (cutofffrequency) and f_max (maximum frequency ofoscillation) values measured at >80 GHz and >60 GHz, respectively.By employing a two-stage collector structure, V_ceoin excess of 7 V is realized