PURPOSE: To grow epitaxially amorphous silicon on a wafer without warping the wafer by shifting one of a plurality of tubular lamps for heating the wafer to the side of a path for the wafer.

CONSTITUTION: Plural tubular lamps 100 are arranged parallel, one 100a of the lamps 100 is shifted to the side of a path for a wafer 8, and the wafer 8 is moved in a direction perpendicular to the axes of the lamps 100, 100a. The wafer 8 is preheated before it reaches a position just below the lamp 100a, it is heated to a temp. above the m.p. at the position, and the epitaxial growth of amorphous silicon or polycrystalline silicon 11 on the wafer 8 is linearly carried out in the longitudinal direction of the lamp 100a. The growth proceeds linearly and partially at the position just below the lamp 100a, and finally the growth is completed all over the region.