| 摘要 |
Vacuum equipment for use in fabrication of a semiconductor device is provided to easily adjust pressure of a vacuum pump by changing an analog type ballast valve into a digital type ballast valve. A chamber(50) is adapted to perform wafer processing therein. The chamber is connected to a vacuum pump(40) via a pump line to maintain a high vacuum state in the chamber. A digital ballast valve(30) supplies a ballast gas into the vacuum pump to prevent damage of the vacuum pump. The ballast gas is nitrogen gas, and is supplied by a ballast gas supply.
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