Fabrication of very high resistivity Si with low loss and crosstalk

We have used proton and As⁺ implantation to increase the resistivity of conventional Si (10 Ω-cm) and Si-on-quartz substrates, respectively. A high resistivity of 1.6 MΩ-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 ~1 ps carrier lifetime stable even after a 400°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 Å oxides