MICROMACHINED COPLANAR WAVE-GUIDES IN CMOS TECHNOLOGY

Coplanar waveguides were fabricated in standard complimentary metal-ox ide semiconductor (CMOS) with postprocessing micromachining. IC's were designed with commercial CAD tools, fabricated through the MOSIS(1) s ervice, and subsequently suspended by maskless top-side etching, Absen ce of the lossy silicon substrate after etching results in significant ly improved insertion loss characteristics, dispersion characteristics , and phase velocity, Measurements were performed at frequencies from 1 to 40 GHz, before and after micromachining, These show improvement i n loss characteristics of orders of magnitude, For the micromachined l ine, loss does not exceed 4 dB/cm. Before etching, loss as high as 38 dB/cm is measured, Phase velocity nu(p) approximate to 0.8 . c is achi eved for the micromachined line.