Performance boost of spiral inductors with thickness-controlled domain-patterned permalloy

In CMOS radio frequency integrated circuits, inductors are a barrier in achieving better monolithic solutions because of the large area occupied and the associated parasitics. For better performance of on-chip inductors, soft magnetic materials are incorporated with them. In an earlier work, it was shown that by tailoring the shape and size of the permalloy patterns, formation of magnetic domains can be controlled. When such domain patterns are incorporated with inductors, they have varied effects on inductor performance. In this paper, it is demonstrated that by depositing 60 nm thick domain-controlled permalloy patterns, better performance of inductors can be obtained at higher frequencies (>5 GHz). About 2× increment in inductance and 7× increment in quality factor is obtained at frequencies >5 GHz by incorporating appropriate domain-controlled permalloy patterns with inductors.