| 摘要 |
PROBLEM TO BE SOLVED: To prevent troubles in conveying a wafer or damages to the wafer due to the deformation of an arm by detecting the deformation of the arm in advance when the wafer is taken out of a carrier. SOLUTION: A semiconductor wafer conveying device comprises a rotary encoder which is synchronized with a ball screw for moving the arm up and down, and a reflection type photoelectric sensor 6 for detecting if the arm has reached a detecting position 18 while being sent down from a starting point 17 which is the altitudinal position of the arm when a normal arm is inserted into the carrier. In the case the arm has the deformation when a deformed arm 2a starts descent, the rotary encoder simultaneously starts to output pulses. Once the detecting signal from the reflection type photoelectric sensor 6 is received, the number of the pulses in the rotary encoder (900 or 1100 pulses) is compared with the number of the pulses of the normal arm, thereby detecting the deformation of the arm. COPYRIGHT: (C)2004,JPO |
