REACTIVE ION ETCHING-INDUCED DAMAGE STUDIES AND APPLICATION TO SELF-ALIGNED INP INGAAS HETEROJUNCTION BIPOLAR-TRANSISTOR TECHNOLOGY/

A self-aligned InP/InGaAs heterojunction bipolar transistor (HBT) tech nology which makes use of a combination of CH4/H2/Ar reactive ion etch ing (RIE) and wet chemical etching to reduce the base-emitter separati on is described. Surface damage and contamination induced by the CH4/H 2/Ar discharge can, if not properly removed, degrade the current gain or lead to device failure. Surface analysis techniques, such as electr on spectroscopy for chemical analysis and secondary ion mass spectrome try have been used to examine dry-etched surfaces. Submicron I-bar str uctures with varying InP air-bridge channel widths were defined by ele ctron beam lithography and used for the analysis of vertical sidewall damage. Based on these studies, a RIE process has been defined and inc orporated in the development of a self-aligned HBT technology. By elim inating the damaged regions and creating an overhang in the emitter la yer using wet chemical etching, damage-free self-aligned HBTs with exc ellent characteristics were fabricated and their properties are report ed.