Laser irradiation apparatus

1. A laser irradiation apparatus comprising:

first and second flotation units configured to each blow a gas upward and float a workpiece of a plate shape, and aligned at a predetermined interval; and

a laser irradiation unit configured to irradiate the workpiece with a laser beam from an upper side in a gap between the first flotation unit and the second flotation unit, the workpiece being floated and conveyed from the first flotation unit to the second flotation unit in a conveyance direction, wherein

each of the first and second flotation units includes:

a base, and

a porous plate bonded to an upper surface of the base by an adhesive layer,

the base includes a rising portion protruding upward at an outer periphery facing at least the gap, and the porous plate includes a cutout portion configured to fit to the rising portion, the cutout portion reducing a width of the porous plate along an upward direction, wherein a length of the porous plate in the conveyance direction is the same as a length of the base including the rising portion in the conveyance direction, and

the adhesive layer is formed along an inner wall of the rising portion having fitted to the cutout portion,

wherein the rising portion is formed at the entire outer periphery of the base, and

wherein the porous plate overlaps an upper surface of the rising portion.

2. The laser irradiation apparatus according to claim 1 , wherein

each of the first and second flotation units further includes an intermediate plate accommodated inside the base in parallel to the porous plate,

a plurality of second through-holes respectively connected to a plurality of first through-holes formed in the porous plate are formed in the intermediate plate, and

a pressurizing chamber configured to pressurize the gas blown from the porous plate, and a depressurizing chamber configured to suction the gas through the pluralities of first and second through-holes are partitioned by the intermediate plate.

3. The laser irradiation apparatus according to claim 2 , wherein

a cavity configured to form the depressurizing chamber is formed in the base, and

a counterbored groove is formed at a periphery of the cavity, and the intermediate plate is fitted and adhered to the counterbored groove.

4. The laser irradiation apparatus according to claim 2 , wherein the porous plate is made of a ceramic.

5. The laser irradiation apparatus according to claim 4 , wherein

the intermediate plate is made of a metal, and

diameters of the second through-holes are smaller than diameters of the first through-holes.

6. The laser irradiation apparatus according to claim 5 , wherein

the diameters of the first through-holes are larger than 1 mm, and

the diameters of the second through-holes are 1 mm or less.

7. The laser irradiation apparatus according to claim 4 , wherein the porous plate is divided into a first plate and a second plate in a longitudinal direction.

8. The laser irradiation apparatus according to claim 7 , wherein

a protrusion portion is formed on a lower side of a butting end surface of the first plate with respect to the second plate, and a protrusion portion is formed on an upper side of a butting end surface of the second plate with respect to the first plate, and

the first plate and the second plate are adhered between the protrusion portion of the first plate and the protrusion portion of the second plate.

9. The laser irradiation apparatus according to claim 1 , wherein

the workpiece is a substrate including an amorphous silicon film formed on an upper surface, and

the laser irradiation apparatus is an excimer laser annealing apparatus configured to irradiate the amorphous silicon film with the laser beam to polycrystallize.

10. A laser irradiation apparatus comprising:

first and second flotation units configured to each blow a gas upward and float a workpiece of a plate shape, and aligned at a predetermined interval; and

a laser irradiation unit configured to irradiate the workpiece with a laser beam from an upper side in a gap between the first flotation unit and the second flotation unit, the workpiece being floated and conveyed from the first flotation unit to the second flotation unit in a conveyance direction, wherein

each of the first and second flotation units includes:

a base, and

a porous plate bonded to an upper surface of the base by an adhesive layer,

the base includes a rising portion protruding upward at an outer periphery facing at least the gap, and the porous plate includes a cutout portion configured to fit to the rising portion, and

the adhesive layer is formed along an inner wall of the rising portion having fitted to the cutout portion,

wherein

the porous plate is divided into a first plate and a second plate in a longitudinal direction,

a protrusion portion is formed on a lower side of a butting end surface of the first plate with respect to the second plate, and a protrusion portion is formed on an upper side of a butting end surface of the second plate with respect to the first plate, and

the first plate and the second plate are adhered between the protrusion portion of the first plate and the protrusion portion of the second plate.

11. The laser irradiation apparatus according to claim 10 , wherein

each of the first and second flotation units further includes an intermediate plate accommodated inside the base in parallel to the porous plate,

a plurality of second through-holes respectively connected to a plurality of first through-holes formed in the porous plate are formed in the intermediate plate, and

a pressurizing chamber configured to pressurize the gas blown from the porous plate, and a depressurizing chamber configured to suction the gas through the pluralities of first and second through-holes are partitioned by the intermediate plate.

12. The laser irradiation apparatus according to claim 11 , wherein

a cavity configured to form the depressurizing chamber is formed in the base, and

a counterbored groove is formed at a periphery of the cavity, and the intermediate plate is fitted and adhered to the counterbored groove.

13. The laser irradiation apparatus according to claim 11 , wherein the porous plate is made of a ceramic.

14. The laser irradiation apparatus according to claim 13 , wherein

the intermediate plate is made of a metal, and

diameters of the second through-holes are smaller than diameters of the first through-holes.

15. The laser irradiation apparatus according to claim 14 , wherein

the diameters of the first through-holes are larger than 1 mm, and

the diameters of the second through-holes are 1 mm or less.