To provide a technology for fabricating a bottom gate type TFT by steps having
high mass production performance, an insulating film whose major component is silicon
is formed on an active layer, the insulating film is patterned and openings are
formed at portions thereof constituting source and drain regions at later steps,
a resist is provided right above a portion for forming a channel forming region
at later steps, a step of adding an impurity is carried out and in this case, the
patterned insulating film is utilized as a doping mask.
