| 摘要 |
PROBLEM TO BE SOLVED: To easily and surely detect the abnormal leak of an H gas, when a semiconductor wafer is laid on a holder in a vacuum chamber and a thermally conductive gas, e.g. He gas is fed to a gap between the wafer and holder to make a film forming process or etching, while maintaining the wafer at a specified temp. SOLUTION: A dielectric, e.g. Al nitride constituting a holder has a surface of mirror finish surface, a wafer W is attracted to the holder with an attraction force of 1 kg/cm2 or more by an electrostatic chuck, an H gas from a gas feed line 5 is sealed at the back side of the wafer W, a flow-meter 54 is provided at the gas feed line 5 and comparator 6 compares the measured flow rate thereof with a threshold, corresponding to the flow rate at abnormal gas leaking, at the back side of the wafer W.
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