Semiconductor device having a plurality of crystalline thin film transistors

A semiconductor device comprising:

• a substrate;
• a first circuit comprising a p-channel thin film transistor and an n-channel thin film transistor formed on said substrate;
• and
• a second circuit comprising thin film transistors of only one of p-channel or n-channel types formed on said substrate,
• wherein each of said transistors of both said first and second circuits has a crystalline semiconductor film comprising silicon as an active region, and the thin film transistors of said second circuit contains a crystallization promoting material at a higher concentration than the thin film transistors of said first circuit.

A semiconductor device comprising:

• a substrate
• a first thin film transistor comprising a first crystalline silicon film formed on said substrate;
• and
• a second thin film transistor comprising a second crystalline silicon film formed on said substrate,
• wherein said first thin film transistor is doped with a catalyst metal which is capable of promoting a crystallization of said first crystalline silicon film while said second crystalline silicon film is not doped with said catalyst metal.