The RF characteristics of micromachined coplanar waveguide in 0.13 μm CMOS technology by CMOS compatible ICP dry etching

A coplanar waveguide (CPW) was implemented in 0.13 μm CMOS technology and then postprocessed by CMOS compatible inductivelycoupled plasma etching, which removed the silicon underneath the coplanar strips. Transmission line parameters such as characteristic impedance Z _O. attenuation constant α, substrate capacitance/conductance C/G, series inductance/resistance L/R, as a function of frequency were extracted It is found that α, C and G can be greatly improved after silicon removal. Specifically, a 0.45 dB/mm reduction (from 0.5 to 0.05 dB/mm) in α, a 1.6 mS/mm reduction (from 1.6 to ∼0 mS/mm) in G, and a 43.9% reduction (from 92.8 to 52.1 fF/mm) in C were achieved at 20 GHz. In addition, this work also investigates the dielectric loss α _d and conductive loss α _c of the CPW.