초록 ▼

An apparatus and method for holding a thin workpiece such as a semiconductor wafer for operations which require the workpiece to have a high degree of planarity such as photolithographic printing includes positioning the workpiece onto a planar holding face comprising the points of a multiplicity of

An apparatus and method for holding a thin workpiece such as a semiconductor wafer for operations which require the workpiece to have a high degree of planarity such as photolithographic printing includes positioning the workpiece onto a planar holding face comprising the points of a multiplicity of regularly spaced-apart substantially parallel pins with a thin rim encompassing all pins to contain a vacuum in the region adjacent to the workpiece. The small abutting area of each pinpoint abutment reduces the probability of dirt particles collecting on the holding face and provides a high thrust pressure to dislodge dirt particles interposed between the abutment and the workpiece. A small amount of lateral motion is imparted to the workpiece when it first contacts the holding face to brush off any dirt particles on the abutments.

대표청구항 ▼

A vacuum apparatus for holding and planarizing a thin workpiece on a holding face which minimizes the interposition of dirt particles between said workpiece and said holding face, said apparatus comprising: (a) a baseplate having a rigid raised rim which includes a smooth planar edge surface adapted

A vacuum apparatus for holding and planarizing a thin workpiece on a holding face which minimizes the interposition of dirt particles between said workpiece and said holding face, said apparatus comprising: (a) a baseplate having a rigid raised rim which includes a smooth planar edge surface adapted to support a workpiece having front and back surfaces, said edge surface being adapted to contact the periphery of said back surface to make a substantially airtight seal thereto, thus forming an evacuable chamber enclosed by said baseplate, said rim, and said back surface; (b) a plurality of regularly spaced-apart rigid support members disposed within said chamber, each providing a localized pinpoint abutment with said back surface, said abutments together with said edge surface forming a holding face which is substantially planar, each of said abutments having an area sufficiently small to reduce the probability of dirt particles collecting thereon, evacuation of said chamber producing a pressure difference between said front and back workpiece surfaces forcing said back surface to conform to said holding face, the spacing between adjacent ones of said abutments and the spacing between said abutments nearest said rim and said edge surface being sufficiently small to prevent significant distortion of the unsupported regions of said workpiece.