There is provided a method in which a TFT with superior electrical
characteristics is manufactured and a high performance semiconductor
device is realized by assembling a circuit with the TFT. The method of
manufacturing the semiconductor device includes: a step of forming a
crystal-containing semiconductor film by carrying out a thermal annealing
to a semiconductor film; a step of carrying out an oxidizing treatment to
the crystal-containing semiconductor film; a step of carrying out a laser
annealing treatment to the crystal-containing semiconductor film after
the oxidizing treatment has been carried out; and a step of carrying out
a furnace annealing treatment to the crystal-containing semiconductor
film after the laser annealing. The laser annealing treatment is carried
out with an energy density of 250 to 5000 mJ/cm.sup.2.