| 摘要 |
<p>PURPOSE:To obtain the title device to which foreign matters are hard to attach and which can prevent the deterioration of flatness of the upper surface of a wafer, by constituting the equipment with dense and uniform fine ceramics, wherein the number of voids which exist at least on substrate sucking surfaces, and have the maximum size larger than or equal to 10mum is made smaller than a specified value per mm<2>. CONSTITUTION:A substrate sucking device WH is provided with sucking surfaces to suck and fix a thin plate type wafer W, and constituted by using dense and uniform fine ceramics, wherein the number of voids which exist at least on a substrate sucking surface, and have the maximum size larger than or equal to 10mum is made smaller than or equal to 300 per mm<2>. For example, a wafer holder WH, wherein a plurality of concentric annularly protruding parts 1 and annularly recessed parts 2 are radially formed in a rim type, is made of dense and uniform fine ceramics. The voids exist at least on the whole part of the wafer sucking surface, i.e., the upper end surface 1a and the side surface 1b of the annularly protruding part 1 and the bottom surface of the annularly recessed part 2. Among those voids existing on said surfaces, the number of voids, whose maximum size is 10mum or more in any one direction, is made equal to or smaller than 300 per mm<2>.</p> |
