| 摘要 |
PURPOSE:To hold a work, such as a wafer, etc., of different shape and size with a sufficient strength and correct properly it flatness by using a porous material in the adsorption area of a chuck body. CONSTITUTION:A water chuck body 5 has 6 adsorption members in its inner side and also 6 adsorption members in its outer side 6b, 6e, 6h, 6k, each of them having a separate and independent adsorption surface. Each adsorption member is formed with a porous material of calcined porous metal for example, and is fixed and supported on each of grooves 6b', 6e', 6h', 6k' formed on the body 5. These grooves are each connected to the vacuum pumps through respective pipe lines 10b, 10e, 10h, 10k and respective electromagnetic valves 8b, 8e, 8h, 8k. Based on the electric signals from vacuum gauges 7b, 7e, 7h, 7k, the electromagnetic valves are open/close-controlled by an arithmetic operation control circuit 9 to adjust the degree of vacuum of each adsorption member independently and exclucively, and a wafer W of different shape and size is held by the chuck body 5 in the state that its flatness is corrected. |
