Optimization of Pupil Filters for Increased Depth of Focus
- 1 December 1993
- journal article
- Published by IOP Publishing in Japanese Journal of Applied Physics
- Vol. 32 (12S) , 5850
- https://doi.org/10.1143/jjap.32.5850
Abstract
The use of pupil filtering in optical lithography raises the question of an appropriate optimization method for such filters. We have suggested a pattern-independent procedure based on optimal energy concentration. Here, we discuss several different methods of implementing pupil filters in lithographic projection systems. We have assembled a simple telecentric test system and fabricated three filters optimized according to the suggested procedure. The results are shown to be in close agreement with predictions. We also present extensions of our calculations to large numerical apertures and non-unity magnification.Keywords
This publication has 8 references indexed in Scilit:
- Derivation and Simulation of Higher Numerical Aperture Scalar Aerial ImagesJapanese Journal of Applied Physics, 1992
- Depth of focus enhancement in optical lithographyJournal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1992
- Extending scalar aerial image calculations to higher numerical aperturesJournal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1992
- Axial Image Superposing (Super-FLEX) Effect Using the Mask Modulation Method for Optical LithographyJapanese Journal of Applied Physics, 1991
- Spatial filtering for depth of focus and resolution enhancement in optical lithographyJournal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1991
- Convolution relation within the three-dimensional diffraction imageJournal of the Optical Society of America A, 1991
- Mathematical Theory of OpticsPublished by University of California Press ,1964
- Generalized Aperture and the Three-Dimensional Diffraction ImageJournal of the Optical Society of America, 1964