| 摘要 |
PURPOSE:To substantially shorten the period of time required for depositing a polycrystalline semiconductor layer, by welding a semiconductor foil layer to a polycrystalline semiconductor layer so as to provide a two-layer welded structure. CONSTITUTION:After a substrate 1 is provided with a groove by etching the substrate masked with a mask 2, a highly doped layer 3 and an oxide film 4 are formed on the whole surface. A polycrystalline silicon layer 5 is then formed on the whole surface by means of the CVD process. After that, a polycrystalline silicon plate 6 is put on and welded to the polycrystalline silicon layer 5. In this manner, the period of time required for depositing the silicon layer 5 by means of the CVD process can be decreased by that corresponding to the welded silicon plate. The substrate 1 is then polished until islands 8a and 8b are seperated from each other, and elements are provided on the islands 8a and 8b, respectively. Since the period of time required for forming the polycrystalline silicon layer can be decreased, possible residual stress in a wafer also can be decreased. Thus, warpage of the wafer is prevented.
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