Characterization of high-Q spiral inductors on thick insulator-on-silicon

This paper reports on the fabrication and characterization of high quality factor (Q) copper (Cu) inductors with thick insulator on standard silicon (Si) substrate (rho = 10-20 Omega cm). The thickness and the area of the insulating layer are optimized for high Q by fabricating inductors on very thick (similar to 50 mu m) embedded silicon dioxide (SiO2) islands and 4-20 mu m thick PECVD SiO2 coated standard Si substrate. The effect of the dielectric permittivity is verified by comparing the performances of identical inductors fabricated on 20 mu m thick SiO2 and 20 mu m thick low-k polymer coated standard Si substrate. Measurement results show saturation behavior for the inductor Q versus the area and the thickness of the insulating layer. A 0.9 nH inductor fabricated on a 50 mu m thick embedded oxide island (OI) exhibits a high peak Q of 53 at 2 GHz. The Q of an identical inductor on 20 mu m thick PECVD SiO2 is 45 at 2 GHz.