Method of processing workpieces using a vessel with a low pressure space surrounding a processing space for the purpose of preventing the leakage of atmosphere into the processing space

A processing method of processing a workpiece comprising the steps of:

• placing the workpiece in a processing system comprising:
• a processing vessel having a vessel body defining a processing space for receiving the workpiece and processing the same therein, and a lid for covering an opening formed in the vessel body to seal the processing space, the processing space being surrounded by a low-pressure space that is settable at a pressure lower than that of the processing space and that has a volume not smaller than that of the processing space;
• a first sealing member sealing a joint between a part of the vessel body and a part of the lid to separate the low-pressure space from the processing space;
• and a second sealing member sealing a joint between a part of the vessel body and a part of the lid on the outer side of the first sealing member to separate the low-pressure space from an external space surrounding the processing vessel, by carrying the workpiece through the opening;
• covering the opening by the lid of the processing vessel to close the process space, and creating a normally sealed state where the external space surrounding the processing vessel, the low-pressure space and the processing space are isolated from each other with each having its own pressure;
• evacuating the low-pressure space to a pressure such that when the processing space and the low-pressure space communicate with each other due to an internal leakage state, the pressure in the processing vessel is not higher than the pressure in the external space;
• and
• processing the workpiece placed in the processing space.