| 摘要 |
PURPOSE:To make it possible to check for the presence of a work, existence of dust, the positional deviation of a work, etc. by providing a detecting means to detect independently the degree of vacuum in each adsorption area of a chuck body. CONSTITUTION:When a wafer is not put on a wafer chuck body 5, since the wafer does not cover each adsorption part of adsorption grooves 6a-6d, the degree of vacuum of the adsorption grooves 6a-6d or pipe lines 7a-7d does not get higher than the standard level; therefore, electromagnetic valves 9a-9d are all turned off and the pipe lines 7a-7d are all closed. When there is some dust between the water chuck body 5 and the wafer W placed on it and the gap between the wafer W and each adsorption surface of the adsorption grooves 6a-6d is large, the evacuation by a vacuum pump not shown in the figure is stopped and the pipe lines 7a-7d are closed to stop the adsorption of the wafer W through the adsorption grooves 6a-6d. |
