Slide 31 of 64
This slice pictorially shows the cross section of a SiGe HBT. The dark blue region is the SiGe alloy. SiGe enhances the performance of the device through bandgap engineering. Improvements of 1.7x in speed are possible in spite of high doping levels in the base. This boost has provided enough incentive for IBM, Hitachi and Daimler-Benz to aggressively scale the bipolar device to make it competitive with contemporary CMOS dimensions. Emitter stripe widths are 0.5 microns in IBM's present baseline process. Applications for wireless have attracted attention. But a key issue is the scaling of the emitter.