A method of making a semiconductor device, including the steps of forming, upon
a substrate, a semiconductor film, an insulating film, and a conductive film. Part
of the upper surface of the conductive film is covered with a resist pattern so
that the semiconductor film protrudes from the edges of the resist pattern. Then,
the conductive film is etched using the resist pattern as a mask to leave a patterned
conductive film, whereby side wall additives of reaction byproducts are generated.
Next, the insulating film is etched using the patterned conductive film and side
wall additives as a mask, and the side wall additives are removed. Then, impurities
are implanted in the semiconductor film using the patterned conductive film as
a mask so that impurities transmit through the insulating film, which expose on
both sides of the patterned conductive film after removing the side wall additives.
Finally, the resist pattern is removed.
