Patent ID: 7838397

Claim:
A laser annealing process for performing laser annealing of a nonmonocrystalline semiconductor film by scanning and irradiating the nonmonocrystalline semiconductor film with 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 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) uninterruptedly after the operation in said step (a), scanning and irradiating, with said 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 decreases from said width of the first fused region, where the second section is located between the first section and said predetermined portion, and abuts the first section; (c) uninterruptedly after the operation in said step (b), scanning and irradiating, with said 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 stepwise or continuously increases from said width of the second fused region at a boundary between said second section and the third section, where the third section is located between the second section and said predetermined portion, and abuts the second section; and (d) uninterruptedly after the operation in said step (c), scanning and irradiating, with said laser light, a fourth section of said bandlike area so as to produce a fourth fused region in the fourth section of the bandlike area in such a manner that the fourth fused region has a width which is substantially identical to said width of the third fused region at a boundary between said third section and the fourth section, where the fourth section abuts the third section, and contains said predetermined portion, wherein: steps (a) through (d) are continuously executed while continuously changing the irradiation width of the laser light by changing the irradiation energy of the laser light.