Wafer stage with reference surface
US5285142A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 9, 1993 |
| Grant date | Feb 8, 1994 |
| Priority date | — |
| Expiry date | Feb 9, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/682
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
An electromagnetic sub-stage and an electromagnetic monolithic stage coupled such that one follows the other having a single reference surface positioned therebetween. A sub-stage having linear motors for movement in the X-Y direction is mounted by a U bracket to a monolithic stage. The monolithic stage is suspended by flat electromagnetic coils providing precise motion of the body of the monolithic stage in X, Y, Z, and rotation about the Z axis or .theta.. Follow control means links or tracks the movement of the monolithic stage to the sub-stage such that the monolithic stage positioning coils are centered in their respective magnetic structure. Adjustable mechanical stops attached the monolithic stage in combination with air bearings riding on the reference surface limit travel of the monolithic stage in the focus or Z direction. The single reference surface extends over the entire range of motion of the monolithic stage. This improves position accuracy, and cleaning and servicing of the apparatus. The modular nature of the monolithic stage permits easy removal for inspection and repair.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.