| 摘要 |
<p>PURPOSE:To correctly detect the position of a wafer by a method wherein peripheral position data of the wafer is collected by a one-dimensional image sensor while the wafer position is detected based on selection of a sampling point, with which the maximum value is realized, among the peripheral position data. CONSTITUTION:At the time of sampling of peripheral position data of a water W, a pulse motor 2 drives the wafer W in steps at a specific angle based on an instruction from a rotation driving and controlling means. A CPU 9 controls data collection timing so that peripheral position data at the time when step driving is stopped is collected among peripheral position data continuously output from a one-dimensional image sensor 3. The collected peripheral position data is stored in a RAM 10 according to the displacement angle at each sampling point. The CPU 9 selects the sampling point having maximum peripheral position data among the peripheral position data stored in the RAM 10 to appropriately select two sampling points interposing the above sampling point and calculates displacement angle from the reference point on a perpendicular line, from the rotation center to an orientation flat, based on respective displacement angles at two sampling points and peripheral position data.</p> |
