Apparatus for holding workpiece by suction

Abstract

Suction apparatus for holding workpieces such as semiconductor substrates or wafers having different diameters comprises a table having an upper surface with a plurality of concentric circular air grooves having different diameters and a plurality of sleeves in radial arcuately spaced bores, respectively, for selectively switching a vacuum source to all or less than all of the grooves. In a preferred embodiment, each sleeve is rotatable about its axis and has a plurality of axially spaced holes which communicate with the vacuum source through the central axial passage in the sleeve. Correspondingly axially spaced holes in the table connect the respective grooves with the bore and are registerable with the sleeve holes through selective rotation of the sleeve to connect the vacuum source and the grooves. The respective sleeves control different numbers of grooves as each is rotated between operating and non-operating positions so as to hold wafers of correspondingly different diameters to the table without necessitating costly and time consuming replacement of major structural components.

Dependencies are inferred from the claim text.