Semiconductor device and manufacturing method thereof

A semiconductor device comprising:

• at least a first n-channel thin film transistor being formed in a display region over a substrate;
• and
• at least a second n-channel thin film transistor and at least a p-channel thin film transistor in a drive circuit each being formed in a periphery of the display region over the substrate;
• each of the second n-channel thin film transistor and the p-channel thin film transistor includes:
• gate electrodes formed over the substrate,
• a first insulating film formed over the gate electrodes,
• a second insulating film comprising silicon oxide formed over the first insulating film,
• a crystalline semiconductor film formed over the second insulating film,
• wherein a channel length of the p-channel thin film transistor is shorter than that of the second n-channel thin film transistor,
• wherein the first n-channel thin film transistor has at least first and second channel regions, and source and drain regions,
• wherein the crystalline semiconductor film of the second n-channel thin film transistor comprises a pair of LDD regions located between a channel region and source and drain regions respectively.