Optical reduction method with elimination of reticle diffraction induced bias
US7031077B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 8, 2004 |
| Grant date | Apr 18, 2006 |
| Priority date | — |
| Expiry date | Nov 8, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70358
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An optical reduction system for use in the photolithographic manufacture of semiconductor devices having one or more quarter-wave plates operating near the long conjugate end. A quarter-wave plate after the reticle provides linearly polarized light at or near the beamsplitter. A quarter-wave plate before the reticle provides circularly polarized or generally unpolarized light at or near the reticle. Additional quarter-wave plates are used to further reduce transmission loss and asymmetries from feature orientation. The optical reduction system provides a relatively high numerical aperture of 0.7 capable of patterning features smaller than 0.25 microns over a 26 mm×5 mm field. The optical reduction system is thereby well adapted to a step and scan microlithographic exposure tool as used in semiconductor manufacturing. Several other embodiments combine elements of different refracting power to widen the spectral bandwidth which can be achieved.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.