Process integration of isolated emitter transistors with commonemitter heterojunction bipolar transistor circuits

摘要

The process of integrating two types of AlGaAs-GaAs emitter-downHBTs (heterojunction bipolar transistors), one with isolated emitter andone with grounded emitter, on a common n+ substrate isdescribed. The use of a selective p- implanted regionfollowed by MOCVD (metalorganic chemical vapor deposition) overgrowthhas resulted in junction isolation with an emitter-to-emitter blockingvoltage greater than ~12 V. The characteristics of such integrated HBTsare examined. The advantages and limitations of the isolated emitter HBTto enhance I/O interfaces and introduce linear circuits to an allemitter-down HBT technology are addressed