MANUFACTURE OF THIN FILM TRANSISTOR

PURPOSE: To form a good polycrystalline Si film on a substrate by creating crystal nuclei in an amorphous Si film on the substrate at specified high temp. or more and separating a step of growing crystal grains at a specified low temp. or less to crystallize it. CONSTITUTION: On a wafer 31 having a silicon oxide film 32 an amorphous Si film 33 is formed and heat-treated at 600 deg.C or more for a short time to create crystal nuclei of adequate density and size in a quickly heat-treating chamber, crystal grains already created in an electric furnace are grown at 600 deg.C or less to form a good polycrystalline Si. When the crystal grain growth is made at 600 deg.C or lower, because the temp. dependence of the crystal nucleus creating is higher than that of the crystal grain growth, new crystal nucleus generation is fully suppressed to form a good polycrystal Si film 33 uniform in the crystal grain.