Illumination device for projection system and method for fabricating
US6466304B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Oct 21, 1999 |
| Grant date | Oct 15, 2002 |
| Priority date | — |
| Expiry date | Oct 21, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/26
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An illumination system for a microlithographic stepper has a light source that emits light of selected wavelength(s) along an optical path toward a photomask. An aperture mask is positioned in the path of the illumination light and between the light source and the photomask. The aperture mask has a dithered pattern of pixels. The intensity of the pattern controls the illumination of the photomask. The masking aperture pattern defines one or more zones of illumination. Each zone has elements that are patterned in accordance with a selected wavelength of incident light to diffract the incident light into an illumination pattern for illuminating a photomask. Each of the elements is constructed with a matrix of pixels. In the preferred embodiment the array of pixels is 8×8. The number of elements is generally greater than 3×3.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.