NOVELTY - The method involves processing a plasma treatment by either depositing a thinfilm e.g. n-type silicon thinfilm (55), on a surface of a transparent substrate (5) i.e. glass substrate, or treating the surface of the substrate with a source gas in plasma. A silicon nanoparticle (54) is arranged by arranging nanoparticles on the surface of the substrate, which is subjected to the treatment processing by spraying a nanoparticle-containing fluid onto the surface of the substrate, where the treatment processing and the nanoparticle arranging in a same chamber are defined as one cycle.    USE - Method for deposing a thinfilm e.g. semiconductor film such as n-type silicon thinfilm, p-type silicon thinfilm and i-type silicon thinfilm, of a thinfilm semiconductor device e.g. thin-film silicon-based solar cell such as amorphous silicon-based and nanocrystalline silicon-based solar cells, and polycrystalline silicon-based solar cell, by a thinfilm deposition apparatus (all claimed). Can also be used for thinfilm transistor.    ADVANTAGE - The method allows spraying a nanoparticle-containing medium that contains nanoparticles on the surface of the substrate such that the nanoparticles are arranged at desired areas, thus forming the thinfilm in which the nanoparticles are evenly arranged at the same time. The method allows separating a nanoparticle supplying chamber from which the nanoparticles are sprayed, from a plasma treatment chamber for depositing the thinfilm, so that the nanoparticles are kept from penetrating into the plasma treatment chamber without depositing the nanoparticles on the thinfilm even if the plasma is extinguished. The thinfilm is not formed by the spray to prevent an alteration of base coating or the substrate due to a thermal energy. The thinfilm contains the silicon nanoparticles to increase the spectral sensitivity in a long-wavelength range compared to a case of without the nanoparticles, and using the wavelength range of the sunlight to increase the efficiency of the solar cell.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a thinfilm deposition apparatus comprising a substrate holding unit for holding a substrate while heating a part or whole of the substrate    (2) a thinfilm semiconductor device comprising an electrode formed on a substrate.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross section of a thinfilm silicon-based solar cell.    Transparent substrate (5)    Electrodes (51, 52)    Silicon nanoparticle (54)    N-type silicon thinfilm (55)    Backside transparent conductive film (57)