Patent ID: 7723167

Claim:
A laser annealing process for performing laser annealing of a nonmonocrystalline semiconductor film by scanning and irradiating the nonmonocrystalline semiconductor film with continuous-wave laser light so as to increase crystallinity of a laser-annealed area of the nonmonocrystalline semiconductor film in such a manner that crystallinity of a part of the laser-annealed area is higher than crystallinity of other parts of the laser-annealed area, comprising the steps of: (a) scanning and irradiating, with said continuous-wave laser light, a first section of a bandlike area of said nonmonocrystalline semiconductor film so as to produce a first fused region having a substantially uniform width in the first section of the bandlike area, where the bandlike area contains a predetermined portion which is required to have higher crystallinity than other portions of the bandlike area, and the first section is apart from the predetermined portion; (b) solidifying at least a portion of said first fused region which is last fused in said step (a); (c) re-fusing at least a subportion of said at least a portion of the first fused region solidified in the step (b) in such a manner that said at least a subportion of said at least a portion of the first fused region has a width smaller than said substantially uniform width of said first fused region; (d) uninterruptedly after the operation in said step (c), scanning and irradiating, with said continuous-wave laser light, a second section of said bandlike area so as to produce a second fused region in the second section of the bandlike area in such a manner that the second fused region has a width which stepwise or continuously increases from said width of said at least a subportion of said at least a portion of the first fused region at a boundary between said first section and the second section, where the second section is located between the first section and said predetermined portion, and abuts the first section; and (e) uninterruptedly after the operation in said step (d), scanning and irradiating, with said continuous-wave laser light, a third section of said bandlike area so as to produce a third fused region in the third section of the bandlike area in such a manner that the third fused region has a width which is substantially identical to said width of the second fused region at a boundary between said second section and the third section, where the third section abuts the second section, and contains said predetermined portion.