NOVELTY - A semiconductor device comprises: a substrate (31) having a surface which functions as an electrode; a copper (Cu) plating film (24) over the substrate; a barrier film (26) on the Cu plating film; a single crystal silicon film on the barrier film; and an electrode layer (36) over the single crystal silicon film.    USE - The semiconductor device and methods are useful for manufacturing a photoelectric conversion device, and a solar cell (all claimed).    ADVANTAGE - The semiconductor device is highly reliable and efficient, and has low resistance and improved bonding.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are:    (1) a photoelectric conversion device comprising the semiconductor device;    (2) a solar cell comprising: a substrate having a surface which functions as an electrode; a Cu plating film over the substrate; a barrier film on the Cu plating film; a photoelectric conversion layer on the barrier film; and an electrode layer over the photoelectric conversion layer, where the photoelectric conversion layer is formed of silicon film, and where the electrode layer is formed with a transparent conductive material; and    (3) a method for manufacturing a semiconductor device, comprising: forming an embrittled layer in a single crystal silicon substrate by doping a surface of the single crystal silicon substrate with ions which are generated from a hydrogen gas; forming a barrier film on the single crystal silicon substrate; forming the Cu plating film on the barrier film; preparing a metal substrate; bonding the single crystal silicon substrate and the metal substrate to each other with the Cu plating film interposed between it by thermocompression bonding of the Cu plating film and the metal substrate; forming a single crystal silicon film over the metal substrate with the Cu plating film interposed between it by separating part of the single crystal silicon substrate along the embrittled layer through heat treatment; and forming an electrode layer over the single crystal silicon film.    DESCRIPTION OF DRAWING(S) - The drawings show a perspective view and a cross-sectional view of a semiconductor device.    Cu plating film (24)    Barrier film (26)    Substrate (31)    Metal film (32)    Single crystal silicon film (34)    Electrode layer (36)