Missing or broken wafer sensor
US4513430A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 24, 1982 |
| Grant date | Apr 23, 1985 |
| Priority date | — |
| Expiry date | May 24, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/67259
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
Apparatus for sensing a missing or broken wafer in an automated wafer transfer system. The apparatus includes means for moving a wafer transfer mechanism from a first position along a prescribed path. A counter coupled to an oscillator is enabled when the wafer transfer mechanism and a wafer are moved away from the first position. A photosensor senses the presence of the wafer at a second position along the prescribed path and inhibits the counter. The count stored in the counter is compared with a predetermined count corresponding to the time required for movement of an unbroken wafer to the second position. If the counts do not agree, a missing or broken wafer is indicated and corrective action is taken.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.