Illumination system for illuminating a mask in a microlithographic projection exposure apparatus
US8164046B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 16, 2009 |
| Grant date | Apr 24, 2012 |
| Priority date | — |
| Expiry date | Oct 20, 2030 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70116
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An illumination system for illuminating a mask in a microlithographic projection exposure apparatus includes an array of mirrors or other beam deflecting elements. Each beam deflecting element produces on the surface a projection light spot at a position that is variable by changing a deflection angle produced by the beam deflecting element. A spot shape measuring unit measures the shapes of spots which are produced on the spot measuring unit by the beam deflecting elements. The spot shape measuring unit is arranged outside of every possible path projection light is allowed to take between the array and the mask. A control unit controls the beam deflecting elements such that, at a given instant during an exposure operation of the apparatus, at least one beam deflecting element directs projection light exclusively on the spot shape measuring unit, and at least some beam deflecting elements direct projection light exclusively on the surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.