Substrate holding system and exposure apparatus having the same
US5586159A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 28, 1995 |
| Grant date | Dec 17, 1996 |
| Priority date | — |
| Expiry date | Mar 28, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/707
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A substrate holding system includes a holding mechanism for holding a substrate through vacuum attraction, a vacuum evacuating device for supplying a vacuum to the holding mechanism, a first voltage source for supplying electric power to the vacuum evacuating device, a second voltage source, separate from the first voltage source, for supplying electric power to the vacuum evacuating device, and a controller for energizing the vacuum evacuating device at a higher evacuation capacity level, when the first voltage source is in operable order, and for energizing the vacuum evacuating device at a lower evacuation capacity level, when the second voltage source supplies electric power to the vacuum evacuating device, and the first voltage source is not in operable order.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.