Position difference detecting device and method thereof
US5917601A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 1, 1997 |
| Grant date | Jun 29, 1999 |
| Priority date | — |
| Expiry date | Dec 1, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/342
- WIPO fieldMeasurement
- WIPO sectorInstruments
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.