PURPOSE: To provide a large radiation beam spot even when the diameter of electron beam is small when a semiconductor layer is annealed by irradiation with an electron beam.

CONSTITUTION: A point-like electron beam 9 is made to fall on the surface of a semiconductor layer 3 at a low angle θ (presumably five degrees or less). Then, irradiation beam spot 14 enlarges. Therefore, even the diameter d of the point-like electron beam 9 is small, the irradiation beam spot 14 can be enlarged. As a result, when scanning speed, beam intensity, etc., are identical with those of irradiation in the vertical direction, temperature rising at a unit area and time can be smaller. Further, the time required for annealing, while the entire semiconductor layer 3 is scanned, can be shortened.