PURPOSE: To carry out the crystallization of a semiconductor thin film by heat treatment and the passivation by hydrogenation at a low temperature and in a short time by irradiating an energy beam which is easily be absorbed by the semiconductor thin film in an atmosphere which contains hydrogen.

CONSTITUTION: A hydrogenized amorphous Si film, i.e., a-Si:H film 2 is formed on a glass substrate 1 by plasma CVD. The substrate 1 is set at a specified position in a vacuum chamber 3. Hydrogen gas or hydrogen gas plasma is introduced from a glass tube 5 and space within the vacuum chamber 3 is made to provide a hydrogen atmosphere. A laser beam of a wavelength which is strongly absorbed by Si is irradiated on the a-Si:H film 2 from the outside. Then, a polycrystalline Si film 8 consisting of large crystal grains as large as approx. 1,000 in diameter is formed. The total Si film 8 is also hydrogenized.