High-Q integrated inductors on trenched silicon islands

An implementation of high quality factor (Q) copper (Cu) inductors on CMOS-grade silicon substrates using a fully CMOS-compatible process is presented. A low-temperature fabrication sequence is employed to reduce the loss of Si wafers at RF frequencies using micromachining technique. This method does not require air suspension of the inductors, resulting in mechanically-robust structures that are compatible with any packaging technology. An InH inductor fabricated on this low-loss micromachined Si substrate exhibits a high peak Q of 51 at 1.0GHz (40 at 2.4GHz) with a self-resonant frequency larger than 10GHz.