Optimization of fully-implanted NPNs for high-frequency operation

With a very straightforward (low-cost) process flow as basis, fully-implanted washed-emitter-base (WEB) NPNs have been optimized for operation in the 10-30 GHz range. Above 20 GHz the best overall performance is achieved by heavy doping of the epi. A low-stress silicon rich nitride layer is proven effective as surface isolation before contact window dip-etch.