PURPOSE: To shorten exhausting hours by introducing dry inert gas into a vacuum chamber after exhausting the inside of a vacuum chamber so that the pressure may become the fixed immediate pressure from the atmospheric pressure, and then by restarting exhaust, when the vacuum chamber is exhaust so as be in the vacuum state.
CONSTITUTION: When a vacuum chamber 1 made of aluminum, where an object to be vacuum-processed is put in/pulled out is exhausted up to its vacuum state, the inside of the vacuum chamber 1 is exhausted by driving an exhaust system 5 composed of a turbo molecule pump 3 and a hydraulic rotational pump 4 after releasing the vacuum chamber 1 to the atmosphere. And the connection to the exhaust system 5 is shutted off by closing a gate valve 2 when the internal pressure in the vacuum chamber 1 is decreased to about 1×10-1 Torr. Then the valve 6 is opened to introduce dry nitrogen gas into the vacuum chamber 1 as an inert gas until the pressure may become about the atmospheric pressure. After that, the gate valve 2 is opened as well as the valve 6 is closed, so as to perform exhaust by driving the exhaust system 5 again, thereby a vacuum pressure having, for example, about 8×10-8 Torr can be obtained.
TANIGAWA HISAO
MIKASA KAZU
