| 摘要 |
PURPOSE:To prevent fine particles of ammonium chloride from adhering to wafer surface and to improve product yield, by providing with a gas trap at the top of an oil filter, and by connecting the gas trap with the exhausting tube of a rotary pump. CONSTITUTION:A gas trap 17 is mounted at the top of an oil filter, with the lower section of the gas trap 17 communicated with the upper section of a filter housing, and is connected with the exhausting tube 10 of a rotary pump 8. In such an oil circulating system, ammonia gas in an oil 22 is trapped in the upper section of the gas trap 17 and is exhausted through a connecting tube from an exhausting tube 10 of the rotary pump 8. Therefore, the ammonia gas which is produced by decomposition of the ammonium chloride adhering to the filter elements 19 and the inside of the filter housing 18 of the oil filter, can be removed outside the system before it is fed into the rotary pump 8. |
