| 摘要 |
PURPOSE:To prevent a substrate from dropping when the vacuum suction power of a suction means inside a low-pressure chamber becomes insufficient at a power failure. CONSTITUTION:An air supply line 19 for emergency use is installed at a low- pressure chamber 1 whose pressure is reduced by using a first vacuum pump 3 and which is maintained in a low-pressure helium gas atmosphere by means of helium gas supplied from an air supply line 4. At a power failure, a first valve 19a in the air-supply line 19 for emergency use is opened, and the air is introduced into the low-pressure chamber 1 so as to prevent a drop in the pressure of the low-pressure chamber 1. Consequently, the vacuum suction power of a wafer chuck 7, a detection-stand chuck 10 and individual suction hands 11a, 11b which have been installed inside the low-pressure chamber 1 does not become insufficient. |
