Patent ID: 6542839
Filing Date: 2003-04-01
Classification: H01L

Abstract:
An apparatus for calibrating the position of a cassette indexer in a semiconductor process machine comprising:a base plate having a rectangular shape, a uniform thickness and parallel upper and lower surfaces; a top plate having a uniform thickness and parallel upper and lower surfaces, said top plate having the same shape and size of said base plate; at least two support members for rigidly attaching said top plate to said base plate in a parallel relationship, said two support members being positioned opposite to each other forming a cavity therein; at least two spaced-apart rows of distance sensors each having at least five distance sensors mounted on said lower surface of said top plate for sensing a distance in said cavity, wherein a sensor in a front row and a corresponding sensor in a back row sense a front-to-back tilt while two adjacent sensors in the same row sense a side-to-side tilt of a wafer blade extended into said cavity of the apparatus; and a processor for receiving signals from said distance sensors and for calculating said front-to-back and said side-to-side levelness of said wafer blade such that a levelness of said cassette indexer is determined.