Abstract: A partial oxide film (31) with well regions formed therebeneath isolates transistor formation regions in an SOI layer (3) from each other. A p-type well region (11) is formed beneath part of the partial oxide film (31) which isolates NMOS transistors from each other, and an n-type well region (12) is formed beneath part of the partial oxide film (31) which isolates PMOS transistors from each other. The p-type well region (11) and the n-type well region (12) are formed in side-by-side relation beneath part of the partial oxide film (31) which provides isolation between the NMOS and PMOS transistors. A body region is in contact with the well region (11) adjacent thereto. An interconnect layer formed on an interlayer insulation film (4) is electrically connected to the body region through a body contact provided in the interlayer insulation film (4). A semiconductor device having an SOI structure reduces a floating-substrate effect.

Abstract: A method of processing a semiconductor wafer that has circuits in each of a plurality of regions sectioned by a plurality of streets on the front surface and has a coating layer formed on the front surface having the circuits to a predetermined thickness, the method comprising a stress-reducing step of reducing the stress of the coating layer by forming a plurality of grooves in the coating layer formed on the front surface of the semiconductor wafer; and a grinding step of processing the back surface of the semiconductor wafer by grinding to a predetermined thickness after the stress-reducing step.