| 摘要 |
<p>PURPOSE: To improve the accuracy of detecting whether or not a foreign matter is present between a workpiece and an electrostatic chuck, by providing a constitution such that an insulating layer is formed in an attracting surface of an electrostatic chuck main unit to arrange a plurality of pairs of electrodes independently of each other along the insulating layer and to be capable of connecting a DC power supply selectively to an arbitrary electrode. CONSTITUTION: For instance, a switch 61 having a power supply switching part 6 is operated, to connect all the electrodes 52A to 52H to a positive or negative electrode of a DC power supply 31. Then, electrostatic power is generated between a workpiece 1, opposed through an insulating layer 51, and the electrodes 52A to 52H, to attract the workpiece 1 to an attracting surface. On the other hand, in a power supply device 7, between the DC power supply 31 and an electrostatic chuck main unit 5, a transformer 33 and a detecting resistor 34 are provided in series, and a voltage detecting circuit 8 converts across-terminal AC voltage of the detecting resistor 34 into DC voltage, input to a control circuit 9. In the control circuit 9, its voltage is compared with reference voltage, to decide foreign matter presence and its position. By a signal of the control circuit 9, the electrodes 52A to 52H are selected by the power supply switching part 6.</p> |
