Vacuum exhaust system

Abstract

A vacuum exhaust system is provided which can reduce a size of a pump or a valve, and can thin the pipe diameter, and can perform highly efficient exhaust making the best use of exhaust characteristics of the pump from high vacuum to the large flow region. The process gas used in a vacuum chamber passes through a regulating valve, and reaches a first branch pipe. The passage on the side indicated with A in the drawing of the first branch pipe is connected with an inlet port of a second pump. On the other hand, the passage indicated with B in the drawing of the first branch pipe is provided with a bypass valve. Then, the downstream of an outlet port of the second pump and the downstream of the bypass valve are connected with a first pump via a second branch pipe. In the low and medium vacuum regions (at the time of large flow rate exhaust), the bypass valve is opened. At this time, the gas is exhausted through both the passage A including the second pump therethrough and a passage B. Then, when exhaust under medium and high vacuum conditions lower than that is performed, the bypass valve is closed, thereby performing exhaust through the passage A. As a result of this, the pipe of the passage B can be thinned.

Dependencies are inferred from the claim text.