| 摘要 |
<p>PURPOSE:To greatly reduce refuses sticked on one wafer after unloading, by providing a by pass piping with a needle valve for flowing the work gas in a small quantity at all times to a chuck head with its mounting on the main valve of the piping. CONSTITUTION:A work gas N2 in a small quantity is flowed to a chuck head 4 through a by pass pipe 5 with a needle valve 6 even excepting the wafer 8 suction time of a chuck head 4 which flows the work gas. The entrainment sticking of a floating refuse into the chuck head 4 and piping 5 is thus prevented and consequently the refuse sticking to the wafer 8 is prevented.</p> |
