US Patent 7391063 Display device

A display device has C-MOS p-Si TFTs which enable high integration by reducing spaces for P-MOS TFTs and N-MOS TFTs in a driving circuit or the like thereof. A self-aligned C-MOS process is adopted, which uses a half tone mask as an exposure mask for manufacturing the C-MOS p-Si TFTs mounted on the display device. With the use of the half tone mask, the alignment or positioning at a bonding portion between a P-MOS portion and an N-MOS portion becomes unnecessary, and, hence, the number of photolithography steps can be reduced and high integration of C-MOS TFT circuits can be realized.