| 摘要 |
PROBLEM TO BE SOLVED: To employ a serial-transmission encoder for a rotation detection unit that provides rotation information of a wafer mounting stage that rotates while holding a wafer, to thereby allow a notch to be positioned highly precisely even when the rotation information is provided only intermittently, in a wafer prealignment apparatus. SOLUTION: When the rotation information from a rotation detection unit 101 is transmitted over serial transmission that permits transmission at a predetermined interval, a calculation processing unit 4 is configured to seek rotation information when a change signal 471 is obtained by calculating rotation information (461), immediately before the change signal 471 from a rotation detection unit 101 is obtained, and a time 431 from when the change signal 471 is obtained until a rotation information 462 immediately thereafter is obtained. COPYRIGHT: (C)2008,JPO&INPIT |
