A technique of reducing fluctuation between elements is provided in which a
semiconductor film having a crystal structure is obtained by using a metal
element that accelerates crystallization of a semiconductor film and then
the metal element remaining in the film is removed effectively. A barrier
layer is formed on a semiconductor film having a crystal structure by
plasma CVD from monosilane and nitrous oxide as material gas. In a step of
forming a gettering site, a semiconductor film having an amorphous
structure and containing a high concentration of noble gas element,
specifically, 1.times.10.sup.20 to 1.times.10.sup.21 /cm.sup.3, is formed
by plasma CVD. The film is typically an amorphous silicon film. Then
gettering is conducted.
