Crystal growth method

Claim 1

A method for producing film having large size crystal grains with a narrow grain size distribution, said method comprising the steps of: providing an amorphous film of a crystallizable material on a surface of a substrate; converting said amorphous film to a polycrystalline film by applying heat at an elevated temperature not higher than a melting point of said amorphous film; applying a patterned mask on a surface of said polycrystalline film, said mask covering first regions of said polycrystalline film but leaving second regions of said polycrystalline film exposed; irradiating said polycrystalline film with ions of said crystallizable material to inject said ions into said second regions to a penetration depth not less than the thickness of said polycrystalline film whereby said second regions are converted to an amorphous state having a disordered structure at each interface between each second region and said substrate; removing said mask; and growing a crystal grain from each first region by applying heat continuously at an elevated temperature not higher than the melting point of said amorphous film in an atmosphere of either hydrogen or nitrogen until each second region in said amorphous state is converted to a polycrystalline state consisting of crystal grains grown from said first regions.

Claim 2

A method for producing film having large size crystal grains with a narrow grain size distribution, said method comprising the steps of: providing an amorphous film of a crystallizable material on a surface of a substrate; converting said amorphous film to a polycrystalline film by applying heat at an elevated temperature not higher than a melting point of said amorphous film; applying a patterned mask on a surface of said polycrystalline film, said mask covering first regions of said polycrystalline film but leaving second regions of said polycrystalline film exposed; irradiating said polycrystalline film with ions of said crystallizable material to inject said ions into said second regions to a penetration depth not less than the thickness of said polycrystalline film whereby said second regions are converted to an amorphous state having a disordered structure at each interface between each second region and said substrate; removing said mask; and growing a crystal grain from each first region by applying heat continuously at an elevated temperature not higher than the melting point of said amorphous film in an atmosphere of either hydrogen or nitrogen until each second region in said amorphous state is converted to a polycrystalline state consisting of crystal grains grown from said first regions.

Claim 18

A method according to any of claims 1-12, wherein said crystallizable material is either silicon or germanium.