Display device and manufacturing method thereof

A method for manufacturing a display device comprising the steps of:

• forming a gate electrode;
• forming a gate insulating film over the gate electrode;
• forming a microcrystalline semiconductor film;
• forming a channel protective layer over and in contact with a channel formation region of the microcrystalline semiconductor film;
• forming a doped semiconductor film over the microcrystalline semiconductor film and over the channel protective layer;
• forming a conductive film over the doped semiconductor film;
• forming a source electrode and a drain electrode, by etching the conductive film;
• forming a source region and a drain region, by etching the doped semiconductor film;
• forming a doped region by adding an impurity element to the channel formation region through the channel protective layer, using the source electrode and the drain electrode as masks;
• and
• irradiating the doped region with laser light through the channel protective layer, using the source electrode and the drain electrode as masks,
• wherein the impurity element imparts either p-type conductivity or n-type conductivity to the microcrystalline semiconductor film.

A method for manufacturing a display device comprising the steps of:

• forming a gate electrode;
• forming a gate insulating film over the gate electrode;
• forming a microcrystalline semiconductor film;
• forming a channel protective layer over and in contact with a channel formation region of the microcrystalline semiconductor film;
• forming a doped semiconductor film over the microcrystalline semiconductor film and over the channel protective layer;
• forming a conductive film over the doped semiconductor film;
• forming a source electrode and a drain electrode, by etching the conductive film;
• forming a source region and a drain region, by etching the doped semiconductor film;
• forming a doped region by adding an impurity element to the channel formation region through the channel protective layer, using the source electrode and the drain electrode as masks,
• wherein the impurity element imparts either p-type conductivity or n-type conductivity to the microcrystalline semiconductor film, and
• wherein dry etching is used in the step of etching the conductive film and in the step of etching the doped semiconductor film.