Apparatus and method for generating partially coherent illumination for photolithography
US5920380A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 19, 1997 |
| Grant date | Jul 6, 1999 |
| Priority date | — |
| Expiry date | Dec 19, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/702
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The present invention relates an apparatus and method for creating a bright, uniform source of partially coherent radiation for illuminating a pattern, in order to replicate an image of said pattern with a high degree of acuity. The present invention introduces a novel scatter plate into the optical path of source light used for illuminating a replicated object. The scatter plate has been designed to interrupt a focused, incoming light beam by introducing between about 8 to 24 diffraction zones blazed onto the surface of the scatter plate which intercept the light and redirect it to a like number of different positions in the condenser entrance pupil each of which is determined by the relative orientation and the spatial frequency of the diffraction grating in each of the several zones. Light falling onto the scatter plate, therefore, generates a plurality of unphased sources of illumination as seen by the back half of the optical system. The system includes a high brightness source, such as a laser, creating light which is taken up by a beam forming optic which focuses the incoming light into a condenser which in turn, focuses light into a field lens creating Kohler illumination i…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.