JPS6414919A - Chucking device - Google Patents

Abstract

PURPOSE:To prevent a liquid material, such as resist or the like from being introduced to the rear face of a material by providing a rear side cover separably provided from the support on the rear face of a support for a chuck body and having a flange in close contact with an extended rear face of the material at the side of the support when the chuck body approaches the support. CONSTITUTION:Since a substrate 8 is larger than the support 1a of a chuck body 1, its peripheral edge is supported in a state that it is extended outside from the edge of the support 1a. The substrate 8 is fixedly supported onto the surface of the support 1a through an O-ring 7 for attracting the substrate. The differential pressure in a cylinder bore 12a from the atmosphere overcomes the energizing force of a coiled spring 18 so that a piston member 14 is attracted into the bore 12a, a rear side cover 10 approaches the support 1a, and the upper face of a flange 10a is brought into close contact with the rear face 8a of the perlpheral edge of the substrate 8. Liquid resist is dropped on the substrate 8, which is rotated at a high speed and coated therewith. The rear face 8a of the substrate 8 is completely covered by the flange 10a to prevent the resist from being introduced to the rear face 8a of the substrate 8.