Hybrid illumination system for use in photolithography
US5631721A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 24, 1995 |
| Grant date | May 20, 1997 |
| Priority date | — |
| Expiry date | May 24, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70358
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An illumination system for use in photolithography having an array optical element near the formation of a desired illumination field. Light or electromagnetic radiation from an illumination source is expanded and received by a multi-image optical element forming a plurality of secondary illumination sources in a plane. A condenser receives the light from the plurality of illumination sources. A array or diffractive optical element is placed on or near the focal point of the condenser. The illumination plane formed at the focal point of the condenser is within the near field diffraction pattern of the array or diffractive optical element. There is no condenser following the array or diffractive optical element. The use of the array or diffractive optical element permits the use of a condenser between the multi-image optical element and the array or diffractive optical element having a smaller numerical aperture than the emergent numerical aperture of the diffractive optical element, and generates a desired angular distribution with little dependance on the illumination source profile.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.