Concave-suspended high-Q solenoid inductors with a post-CMOS MEMS process in standard wafers

We report on concave-suspended high-Q solenoid inductors with a post-CMOS MEMS process in low-resistivity silicon substrate. The 3-mask processes include copper electroplating, photo-resist spray-coating and XeF₂ gaseous etching. The peak Q-factor value is measured as 47 at 5.3 GHz with 2.96 nH inductance. A compact and four curving layouts of inductors are fabricated and tested. Both finite element simulation and shock testing results show that the suspended inductor is almost free of influence from environmental vibration and shock. Featuring the high-Q value and the good robustness, the novel solenoid inductors are promising for high-performance RF IC applications.