Submicron, fully self-aligned HBT with an emitter geometry of 0.3 μm

A new fully self-aligned heterojunction bipolar transistor (HBT) process has been developed to fabricate submicron emitter geometries for applications requiring ultra low-power consumption and very high-speed performance. In this novel process approach the emitter, base and collector ohmic contacts are all self-aligned to the emitter mesa. Furthermore, the three ohmic contacts, i.e., emitter, base, and collector are defined and deposited in a single metalization step thereby simplifying the fabrication process. Using this new process we have fabricated HBT emitter geometries as small as 0.3 μm² with RF performance of over 130 GHz. To our knowledge, this is the smallest HBT ever reported.