Process characterisation of hot-carrier-induced beta degradation in bipolar transistors for BiCMOS

This paper investigates the effect of various process parameters on the var iation in forward current gain lifetime caused by hot carrier generation of BiCMOS bipolar transistors. Statistical process control and statistical de signed experiments were used in this evaluation. The device lifetime in rev erse bias operation was calculated from the forward current gain. Various p rocess parameters were examined in this work, i.e., the intrinsic base impl ant dose and energy, selective collector implant dose, collector plug dose, spacer etch ratio, overetch thickness of nitride spacer and emitter poly e tch time. It was deduced that high current gain lifetime can be obtained wi th high base implant doses. high base implant energies, long bulk nitride e tch times and short emitter poly etch times. (C) 1999 Elsevier Science Ltd. All rights reserved.