| 摘要 |
<p>PROBLEM TO BE SOLVED: To hold and suck a substrate while the flatness of the substrate is maintained, by providing plural suction parts sucking and holding the substrate in different positions, and controlling the suction operation in accordance with a result obtained by detecting the suction state. SOLUTION: A substrate P is transferred to a substrate holding face PH1 provided with porous areas A, B and C and a vacuum pump 2 is operated. At that time, valves 3B and 3C are set in a wholly closed state. The peripheral part of the substrate P on the porous area A is sucked to the substrate holding face PH1 with the vacuum suction 2. When a pressure sensor 6A detects that the pressure of a piping 1A is reduced to a prescribed value, the valve 3B is opened and the peripheral part of the substrate P on the porous area B is sucked to the substrate holding face PH1. At the same time, the valve 3C is opened by the detection result of the pressure sensor 3B, and the peripheral part of the substrate P on the porous area C in is sucked. Thus, the substrate P is chucked for respective parts at optimum timing, and the substrate can securely be sucked and held.</p> |
