EFFECT OF CONTACTS ON ADVANCED BIPOLAR DEVICE CHARACTERISTICS.

In order to realize the full performance potential of bipolar devices in scaling, the vertical dimensions, i. e. base width, epi thickness, etc. , must be reduced in a coordinated manner with the horizontal dimensions. Current gains of three bipolar transistors having identical shallow emitter and base profiles but different emitter contacts are presented. The large current gain provided by the polysilicon emitter contact allows bipolar transistors to be scaled down to submicron dimensions without having to worry about emitter-collector punch through problems. Potential problems due to interfacial layers can be monitored by monitoring the emitter series resistance, which can be determined from the measured I-V characteristics, and then plotted as shown.