Jpn. J. Appl. Phys. 31 (1992) pp. 4126-4130 |Next Article| |Table of Contents|
|Full Text PDF (823K)| |Buy This Article|
A New Pupil Filter for Annular Illumination in Optical Lithography
Central Research Laboratory, Hitachi Ltd., Kokubunji, Tokyo 185
(Received July 23, 1992; accepted for publication October 17, 1992)
Several super-resolution photolithography techniques are investigated. In annular illumination, both the resolution and depth of focus (DOF) are enhanced most effectively when 0.6<σ<0.7, whether or not contrast enhancement techniques, such as pupil filters or edge-enhancing phase-shift masks (PSMs), are used. Various contrast enhancement techniques are investigated from the viewpoint of spatial frequency characteristics, since flat characteristics are required for good mask-to-image fidelity. We propose a new high-spatial-frequency enhancing filter for annular illumination system which meets this requirement. We also optimize edge-enhancing PSMs for use with annular illumination. It is shown that both methods can improve the resolution/DOF characteristics while maintaining good mask-to-image fidelity. A practical resolution analysis shows that 0.2 (0.3) µm patterns can be delineated with a DOF of ±0.6 (±0.75) µm, if a KrF (i-line) stepper with an NA0.5 lens and high-contrast resist materials are used, with few restrictions on the pattern layout.
KEYWORDS:photolithography, resolution, depth of focus, super-resolution, spatial frequency characteristics, phase-shift mask, pupil filtering, annular illumination, quadrupole illumination
- M. D. Levenson, N. S. Viswanathan and R. A. Simpson: IEEE Trans. Electron Devices ED-29 (1982) 1828.
- H. Fukuda, T. Terasawa and S. Okazaki: J. Vac. Sci. & Technol. B9 (1991) 3113.
- D. L. Fehrs, H. B. Lovering and R. T. Scruton: KTI Microelectronics Seminar INTERFACE' 89 (KTI Chemicals, Inc., San Diego, 1990) p. 217.
- K. Kamon, T. Miyamoto, Y. Myoi, H. Nagata, M. Tanaka and K. Horie:
Jpn. J. Appl. Phys. 30 (1991) 3021[JSAP].
- M. Noguchi, M. Muraki, Y. Iwasaki and A. Suzuki:
Proc. SPIE's 1992 Symp. on Microlithography SPIE-1674 (1992) 105[AIP Scitation].
- N. Shiraishi, S. Hirukawa, Y. Takeuchi and N. Magome:
Proc. SPIE's 1992 Symp. on Microlithography SPIE-1674 (1992) 741[AIP Scitation].
- S. Matsuo, K. Komatsu, Y. Takeuchi, E. Tamechika, Y. Mimura and K. Harada: IEDM '91 Technical Digest (IEEE, New York, 1991) p. 970.
- M. Noguchi, Y. Yoshitake, Y. Kembo:
Proc. SPIE's 1992 Symp. on Microlithography SPIE-1674 (1992) 622[AIP Scitation].
- K. Kamon, T. Miyamoto, Y. Myoi, M. Fujinaga, H. Nagata and M. Tanaka: 1992 Symp. VLSI Technol. Digest of Papers (IEEE and Jpn. Soc. of Appl. Phys, Washington, 1992) p. 108.
- T. Terasawa, N. Hasegawa, H. Fukuda, S. Katagiri:
Jpn. J. Appl. Phys. 30 (1991) 2991[JSAP].
- K. Nakagawa, M. Taguchi and T. Ema: IEDM '90 Technical Digest (IEEE, New York, 1991) p. 817.
- H. Fukuda, A. Imai, T. Terasawa, and S. Okazaki: IEEE Trans. Electron Devices ED-38 (1991) 67.