PURPOSE: To achieve high gettering capability by including a polycrystalline silicon film formed on a single crystal silicon substrate, a silicon oxide film formed within the polycrystalline silicon film and another single crystal silicon substrate.

CONSTITUTION: A polycrystalline silicon film 2 is formed on a p+-type single crystal silicon substrate 1, and a silicon oxide film 3 is formed on the entire surface thereof. The silicon oxide film 3 is patterned to obtain islands of the silicon oxide film 3, and then a polycrystalline silicon film 2 is formed thereon again. A p-type single crystal silicon substrate is bonded to the resultant substrate on the device formation region side. Grooves for element isolation are formed in the bonded substrate, and filled with a silicon oxide film 5 to form element isolation regions. This provides the polycrystalline silicon film 2 to be a gettering site in an extended region under the device formation region, and the silicon oxide film 3 partly buried, which effectively getters the p+-type single crystal silicon substrate 1.