PURPOSE: To acquire a C-MOS transistor of a small leak current without applying a channel dope process by forming a non-single crystal silicon film of a specified value or loss which is used as a semiconductor active layer.

CONSTITUTION: In a thin film transistor which uses a non-single crystal silicon film as a semiconductor active layer, a thickness of the non-single crystal silicon film is made 600 or loss. For example, a poly-Si film of a film thickness of 950 is formed on a quartz substrate 1 and an island-like pattern 2 is formed. Then, a gate oxide film 3 of a film thickness of 750 is formed by dry-oxidation method; a film thickness of the poly-Si film becomes 560. Then, a poly-Si film 4 is formed and patterned after B+-implantation to form a gate electrode 5. Boron is introduced to a source-drain region 7 of P-channel TFT. After phosphorus is introduced to a source/drain region 8 of N-channel TFT, an NSG film 9 is formed. Impurities introduced to the gate electrode 5 and the source/drain regions 7, 8 are activated.