Method and apparatus for variable polarization control in a lithography system
US7271874B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 2, 2004 |
| Grant date | Sep 18, 2007 |
| Priority date | — |
| Expiry date | Nov 2, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70566
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A polarization control device for a lithography system selectively polarizes light in horizontal, vertical and/or circular orientations. A pair of relatively rotatable quarter-wave plates move to provide the desired polarization. When the quarter-wave plates are at a relative angle of 45 degrees, the polarization is circular. When the quarter-wave plates are both at zero or 45 degrees, the resulting polarization is vertical or horizontal. The polarization is selected based on the orientation of an image to be projected. Horizontal polarization is preferably used for images with a strong horizontal orientation, and vertical polarization is selected for images with a strong vertical orientation. Circular orientation is selected when the image has no strong horizontal or vertical orientation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.