In a manufacturing process of a semiconductor device using a substrate
having low heat resistance, such as a class substrate, there is provided a
method of efficiently carrying out crystallization of a semiconductor film
and gettering treatment of a catalytic element used for the
crystallization by a heating treatment in a short time without deforming
the substrate. A heating treatment method of the present invention is
characterized in that a light source is controlled in a pulsed manner to
irradiate a semiconductor film, so that a heating treatment of the
semiconductor film is efficiently carried out in a short time, and damage
of the substrate due to heat is prevented.
