Very Low Cost Graded SiGe Base Bipolar Transistor for a High Performance Modular BiCMOS Process

We report a new super self-aligned graded SiGe base transistor that uses high-energy implantation, rather than epitaxial growth, to form the sub- collector region. This new inexpensive process yields a device with f sub T of 52 GHz and f sub (max) of 70 GHz with the addition of only 4 lithography levels over our 0.25 micron CMOS technology without any changes to the existing process steps. Also, we demonstrate 4:1 multiplexer and 1:4 demultiplexer circuits using this technology that show excellent performance at 10 Gbit/s.