Blazed grating measurements of lithographic lens aberrations
US6091486A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 5, 1999 |
| Grant date | Jul 18, 2000 |
| Priority date | — |
| Expiry date | Jan 5, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70641
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Exposures of a photosensitive material through an array of blazed gratings illuminate a lens asymmetrically to detect effects of a plurality of azimuthal aberrations including coma, astigmatism, and three-leaf and four-leaf clover aberrations. A plurality of such exposures of the array of blazed gratings at slightly differing focus allows detection of focus shift due to any aberrations present in the lens. Upon development of the plurality of exposures, contrast of each area is measured, for example, by reflection or scattering from the relief in the developed photosensitive material and the aberrations thus detected can be simulated by effective summation of individual aberration effects.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.