Illumination source and method for microlithography
US5453814A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 13, 1994 |
| Grant date | Sep 26, 1995 |
| Priority date | — |
| Expiry date | Apr 13, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70583
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A light source having a solid state laser emitting a beam that is separated into a number of segments. Each segment is frequency shifted by a different amount so that the segments do not substantially overlap in the frequency domain. Each segment passes through a short focal length lens element of a fly's eye array to be dispersed onto a mask plane for evenly illuminating a mask. The lens elements of the fly's eye array are contained within a small region in comparison to the width of the dispersed beam segments, such that each beam segment contributes illumination to the entirety of a common portion of the mask. The apparatus may include a beam expander to permit the frequency shifting cells to be positioned in an array entirely circumscribed by the diameter of the expanded beam, or may alternatively include an arrangement of beam splitters used to generate a branching beam path, with the branches passing through different numbers of frequency shifting cells to generate a diversity of frequencies in the resulting beam segments. A half- or quarter-wave plate may be used to shift or change the polarity of some of the beam segments, or of portions of all of the beam segments, reducin…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.