Position difference detecting device and method thereof

Details Position difference detecting device and method thereof Position difference detecting device and method thereof

1997-12-01

1999-06-29

Kim, Robert H.

Optics: measuring and testing

By polarized light examination

With light attenuation

356400, G01B 1114, G01B 1100

Patent

active

059176016

ABSTRACT:
An R-.theta. robot moves a wafer between chambers according to an instruction issued by a robot controller. An optical sensor detects two edge positions of the wafer which stands still in a hand of the R-.theta. robot when the R-.theta. robot is in a predetermined stationary state. The robot controller obtains the length and the middle position of a chord of the wafer based on the two edge positions. This data is compared with the data of the length and the middle position of the chord which should be obtained when the wafer is placed in a reference position in the hand of the R-.theta. robot, so that a position difference of the wafer to be moved from the reference position is detected. The robot controller controls the operations of the R-.theta. robot in order to correct the detected position difference.

REFERENCES:
patent: 5483138 (1996-01-01), Shmookler et al.
U.S. Patent Application Serial No. 07/985,197, filed on Nov. 12, 1992, Shmooker et al.

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