Patent ID: 7456433

Claim:
A display device which forms a first thin film transistor which is formed in a first region and has a first threshold value, and a second thin film transistor which is formed in a second region and has a second threshold value which differs from the first threshold value, wherein the first thin film transistor has a first silicon semiconductor film, the second thin film transistor has a second silicon semiconductor film which has different crystal structure than the first silicon semiconductor film, at least one of a particle size and a shape of the first silicon semiconductor film is different from that of the second silicon semiconductor film, first impurities and second impurities are implanted into both of a channel region of the first thin film transistor and a channel region of the second thin film transistor, the first impurities are substantially 100% activated in both of the channel region of the first thin film transistor and the channel region of the second thin film transistor, and 50% or less of the second impurities are activated in the channel region of the first thin film transistor and substantially all of the second impurities are activated in the channel region of the second thin film transistor.