Patent ID: 8809133

Claim:
A method of manufacturing a semiconductor device comprising: forming an island-like single crystal portion by patterning a semiconductor film on silicon oxide; heating the island-like single crystal portion at a temperature of 900 to 1200° C. in a reducing atmosphere; oxidizing a surface of island-like single crystal portion to form an insulating film; and forming a gate electrode over the island-like single crystal portion with the insulating film interposed therebetween, wherein concentrations of carbon, nitrogen and oxygen in the island-like single crystal portion are 5 ×10 18 atoms/cm 3 or less, 5 ×10 18 atoms/cm 3 or less and 1.5 ×10 19 atoms/cm 3 or less, respectively, and wherein a concentration of oxygen or an oxide compound in the reducing atmosphere is not higher than 10 ppm.