| 摘要 |
<p>PURPOSE:To correct the eccentricity of a wafer quickly and with high accuracy for positioning by a method wherein the variation curve of a pixel number detected by a linear sensor in regard to the circumference of the wafer and an angle signal are processed. CONSTITUTION:A detection signal is outputted from a pixel detected in accordance with the circumferential radial position in regard to the rotation center of a wafer 1 and the signal is inputted to a pixel number detecting circuit 7. The outputted pixel number is inputted to a microprocessor 4 together with an angle signal from an angle detector 8 and the angle of the center of the orientation flat(OF) of the wafer 1, the angle of the eccentricity of the wafer 1 from the center of the OF and the eccentricity are calculated and stored in a memory 4a. In accordance with the stored data read out of the memory 4a, the wafer 1 is turned until the angle of the center OFc of the OF agrees with a reference angel and stopped by a rotation control circuit 5 and a spindle motor 6a. Then the wafer 1 is attracted by an attracting mechanism 10 are shifted to the direction of the eccentricity. The shift distance can be obtained by multiplying the stored eccentricity by a suitable factor.</p> |
