Effect of Patterned Magnetic Shields on High-Frequency Integrated Inductors

Abstract

Understanding the losses in magnetic integrated inductors is essential for attaining optimal performance. Integrated inductors with thick magnetic shield (MS) with eddy current inhibiting slots were fabricated to understand the losses due to the MS, patterning, and eddy currents. An increase in the quality factor was measured for inductors with patterned magnetic shields. We further measured a) only a partial inhibition of eddy currents in films, and b) an increased in the expected frequency response of the magnetic material (in-situ). We found that patterning the MS with wide patterns (36 /spl mu/m wide) is not entirely sufficient for eliminating eddy currents, and the pattern should be refined; however studies of arrays of bars show that refining the pattern leads to dramatically different high frequency behavior that must be accounted for when optimizing the quality factor.