| CPC H01L 21/67784 (2013.01) [B23K 26/0006 (2013.01); B23K 26/083 (2013.01); B23K 26/12 (2013.01); B23K 26/354 (2015.10); B65G 49/05 (2013.01); B65G 49/065 (2013.01); B65G 53/02 (2013.01); C03B 25/02 (2013.01); C03C 17/30 (2013.01); H01L 21/268 (2013.01); H01L 21/67115 (2013.01); H01L 21/6776 (2013.01); B65G 2249/04 (2013.01); B65G 2249/045 (2013.01); C03C 2218/32 (2013.01)] | 7 Claims |

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1. A laser irradiation apparatus comprising:
(a) a laser oscillator configured to emit a laser beam to be irradiated on a workpiece of a plate shape; and
(b) a flotation unit configured to float the workpiece by blowing and suctioning a gas, and including:
(b1) a base including a pressurizing through-hole and a depressurizing through-hole formed therein;
(b2) a porous plate located on an upper surface of the base and including a plurality of first through-holes formed therein; and
(b3) an intermediate plate made of a metal located below the porous plate, accommodated inside the base and including a plurality of second through-holes formed therein, wherein
the intermediate plate is shorter along a conveyance direction than the porous plate and the base,
the porous plate is bonded to the base by a first adhesive layer, and the intermediate plate is bonded to the base by a second adhesive layer,
the porous plate is disposed facing the workpiece,
a pressurizing chamber configured to pressurize a gas is formed in a space between the porous plate and the intermediate plate,
a depressurizing chamber configured to depressurize the gas is formed in a space between the base and the intermediate plate,
the pressurizing through-hole is connected to the pressurizing chamber,
each of the plurality of first through-holes is connected with a corresponding one of the plurality of second through-holes,
the depressurizing through-hole and the second through-holes are connected to the depressurizing chamber,
the gas is blown through the pressurizing through-hole and a pore of the porous plate,
the gas is suctioned through the depressurizing through-hole, and the pluralities of first and second through-holes, and
diameters of the plurality of first through-holes are larger than diameters of the plurality of second through-holes.
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