US Patent 7332793 Semiconductor device

A transistor region is a region where a plurality of MOS transistors, including an MOS transistor, are formed, and a dummy region is a region lying under a spiral inductor. In the dummy region, a plurality of dummy active layers are disposed in the main surface of an SOI substrate and a plurality of dummy gate electrodes are disposed covering the respective dummy active layers. The arrangement pattern of the dummy active layers and the arrangement pattern of the dummy gate electrodes nearly match, so that the dummy gate electrodes are aligned accurately on the dummy active layers.