Semiconductor device and manufacturing method thereof

A method of manufacturing a semiconductor device comprising the steps of:

• forming a base insulating film on a substrate;
• forming an amorphous semiconductor film on the base insulating film;
• doping a metallic element promoting crystallization of the amorphous semiconductor film and crystallizing the amorphous semiconductor film to form a crystalline semiconductor film;
• forming a gate insulating film on the crystalline semiconductor film;
• forming a gate electrode on the gate insulating film;
• doping an impurity element in a selected region of the crystalline semiconductor film to form a source region and a drain region;
• forming an interlayer insulating film on the gate electrode;
• forming a contact hole in the interlayer insulating film, the contact hole reaching the source region or the drain region;
• forming a film containing an impurity element belonging to the group 15 of the periodic table in the contact hole reaching the source region or the drain region and on the interlayer insulating film;
• gettering by thermal annealing the metallic element contained in the crystalline semiconductor film;
• and
• forming a conductive film on the film containing an impurity element belonging to the group 15 of the periodic table.