Out-of-pocket detection system using wafer rotation as an indicator
US6950774B2 · kind B2 · utility
11Cited by
22References
22Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jan 16, 2003 |
| Grant date | Sep 27, 2005 |
| Priority date | — |
| Expiry date | Jan 16, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01C9/00
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical substrate placement device is disclosed employing light from the surface of a rotating substrate in order to generate a signal component which oscillates at the frequency of rotation of the substrate. The magnitude of another signal resulting from filtering the signal component at the frequency of rotation, when processed, reveals whether the substrate is misplaced or “out-of-pocket.” Preferred embodiments employ reactor heat lamps as the light source. Methods of detecting whether a substrate is misplaced are also provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.