FIG 17 is a schematic cross sectional diagram of a vacuum pump unit attached to the LPCVD apparatus of a ninth embodiment of the present embodiment, and FIG 18 is a graph illustrating {HEAD ~ output characteristics} of {TAIL ~ a vacuum pump unit} 
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FIG 17 is a schematic cross sectional diagram of a vacuum pump unit attached to the LPCVD apparatus of a ninth embodiment of the present embodiment , and FIG 18 is a graph illustrating { HEAD ~ output characteristics } of { TAIL ~ a vacuum pump unit }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL