Low loss 67-GHz coplanar waveguides and spiral inductors on 100 kΩcm gold-doped high resistivity Cz-Silicon

In this paper, we demonstrate the ability of deep level doping to reduce the substrate losses in coplanar waveguides and spiral inductors. Room temperature resistivity of Au doped Czochralski-Si increases from 50Ωcm for n-type Si to 100 kΩcm for Au doped Si and temperature dependent Hall measurements show a six order increase in resistivity at lower temperatures which is entirely due to a decrease in free carrier concentration. The mobility is not affected and is determined by lattice scattering only. The resistivity follows theoretical models demonstrating that nearly 100% of the doped Au is electrically active. Coplanar waveguides show a reduction in attenuation at 67GHz from 0.88 dB/mm to 0.30 dB/mm. Spiral inductors fabricated in the compensated substrates show a 50% improvement in quality-factor with respect to high resistivity float zone wafers demonstrating the use of these substrates for integrated passive devices.