Fabrication of very high resistivity Si with low loss and cross talk

We have used proton and As/sup +/ implantation to increase the resistivity of conventional Si (10 /spl Omega/-cm) and Si-on-quartz substrates, respectively. A high resistivity of 1.6 M/spl Omega/-cm is measured that is close to intrinsic Si and semi-insulating GaAs. Very low loss and cross coupling of 6.3 dB/cm and -79 dB/cm (10 μm gap) at 20 GHz are measured on these samples, respectively. The very high resistivity and improved rf performance are due to the extremely fast /spl sim/1 ps carrier lifetime stable even after a 400/spl deg/C annealing for 1 h. Little negative effect on gate oxide integrity is also observed as evidenced by the comparable stress-induced leakage current and charge-to-breakdown for 30 /spl Aring/ oxides.