Patent ID: 9490180
Filing Date: 2016-11-08
CPC Classification: B24B,G01B,H01L

Claim Text:
1. A method for processing a wafer by inserting the wafer into a holding hole of a carrier to hold the wafer, and interposing the carrier holding the wafer between an upper turn table and a lower turn table to process both surfaces of the wafer at the same time, the method comprising the steps of: before processing the wafer, detecting a height position of the upper turn table by a laser displacement sensor while interposing the carrier holding the wafer between the upper turn table and the lower turn table; and determining that the wafer is not normally held to redo the holding of the wafer by inserting the wafer into a holding hole of a carrier if a difference between the detected height position and a reference position exceeds a threshold, wherein: the laser displacement sensor is a CCD laser micrometer of a transmission type, and a sensor dog is disposed in a shaft that is movable upward and downward along an up and down movement of the upper turn table, and the sensor dog is positioned to block a laser of the CCD laser micrometer of a transmission type when the carrier holding the wafer is interposed between the upper and lower turn table.