| 摘要 |
<p>PURPOSE:To meet the requirement for a wafer in large diameter and improve the supporting performance by providing a blow-off hole for gas and a suction hole for gas at a supporting part supporting the wafer in non-contact. CONSTITUTION:The inside of a groove 15 of a supporting part 13 which supports a wafer in contact by performing vacuum discharge from a vacuum discharge port 22 leading to a vacuum path 17 is turned into vacuum state for suction of a wafer 10. At the same time, a dry air is supplied from a gas supply port 23 leading to a gas supply path 19 and is suctioned from a gas discharge port 24 leading to a gas discharge path 21 to enable gas to flow from a gas blow-off hole 18 to a gas suction hole 20 within a gap between a supporting part 14 which supports the wafer in non-contact and the wafer 10. Gas flows within the gap G at some speed even if static pressure is approximately 1 atmospheric pressure near the gas blow-off port so that pressure is reduced lower than 1 atmospheric pressure according to the Bernoulli's theorem, thus enabling the wafer 10 to be suctioned. Thus, the wafer 10 is suctioned and retained by suction force between the supporting parts 13 and 14.</p> |
