The development of the high performance parallel-stacked RF spiral inductor

In this work, deep sub-micron CMOS process compatible high Q on chip spiral inductors with air- gap structure and parallel stacked inductor have been fabricated with 0.18 mum CMOS compatible process. In the design the electromagnetic solver, SONNET, and the finite element program, ANSYS, were used for electrical-characteristics and maximum mechanical strength, respectively. Experimental results show that measured peak Q and peak-Q frequency attain 7.06 and 1.8 GHz for the structure of four metal layers parallel and metal width of 15 um at 5.5 turns, respectively and 5.2 and 1.6 GHz for the suspending spiral inductor. Besides, the experimental results also shows the parallel stacked structure saves the chip area significantly and reduces resistance to obtain high Q value at low frequency significantly.