In a method for manufacturing a display device having a light emitting
element, a first base insulating film, a second base insulating film, a
semiconductor layer, and a gate insulating film are formed in this order
over a substrate. A gate electrode is formed over the gate insulating
film to overlap with at least a part of the semiconductor layer, and a
portion to be a pixel portion of the gate insulating film and the second
base insulating film is doped with at least one conductive type
impurities. An opening portion is formed by selectively etching the gate
insulating film and second base insulating film that are each doped with
impurities. The first base insulating film is exposed in a bottom face of
the opening portion. Subsequently, an insulating film is formed to cover
the opening portion, the gate insulating film, and the gate electrode,
and a light emitting element is formed over the insulating film to
overlap with at least a part of the opening portion.