Scanning exposure method accounting for thermal transformation of mask
US6416913B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 27, 2000 |
| Grant date | Jul 9, 2002 |
| Priority date | — |
| Expiry date | Nov 27, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7003
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Points for calculation are set at uniform intervals on an ideal lattice set over a pattern area on a reticle. An amount of light incident on a slit-shaped illumination area on a lens is measured with an integrator sensor. An amount of heat absorbed by the reticle according to the position in a scanning direction is calculated on the basis of a pattern presence ratio on the reticle, and an amount of thermal expansion at each point for calculation is calculated on the basis of the calculated amount of heat absorbed. A change in the magnification of a projected image is obtained from the calculated amount of thermal expansion. At the same time, a change in the projection magnification caused by a projection optical system itself is also calculated according to the position in the scanning direction of the reticle. The projection magnification of the projection optical system is corrected through a magnification correction mechanism so as to cancel both the magnification changes thus calculated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.