Propagation of picosecond electrical pulses on a silicon-based microstrip line with buried cobalt silicide ground plane

A microstrip line with a highly conducting cobalt silicide (CoSi2) ground plane buried 7 μm below the surface of a single-crystal silicon wafer is presented. This new transmission line shows significantly reduced dispersion up to 100 GHz bandwidth compared to a conventional microstrip line with the ground plane on the back of the substrate, while being able to support active devices in the silicon dielectric. After propagating 5 mm, the rise time (10%–90%) of an electrical pulse increases only from 2.5 to 3.7 ps as opposed to an increase from 2.7 to 11.3 ps on a conventional microstrip line.