For manufacture of a semiconductor device using a low heat resistant
substrate such as a glass substrate, a method of heat treatment for
activating an impurity element that is used to dope a semiconductor film
and for performing gettering on the semiconductor film in a short period
of time without deforming the substrate, is provided. Also provided is a
heat treatment apparatus for carrying out the above heat treatment. The
heat treatment method of the present invention involves irradiating an
object with light emitted from a lamp light source, and is characterized
in that the lamp light source emits light for 0.1 to 20 seconds at a time
and that light from the lamp light source irradiates the object several
times. The method is also characterized in that the irradiated region is
subjected to pulsating light from the lamp light source such that the
irradiated region holds the temperature to its highest for 0.5 to 5
seconds. The method is also characterized in that the amount of coolant
to be supplied is increased or reduced in accordance with blinking of the
lamp light source to enhance the effect of the heat treatment on the
semiconductor film and to prevent a heat-induced damage to the substrate.