Radiation imagery chemistry: process – composition – or product th – Radiation modifying product or process of making – Radiation mask
Patent
1993-02-02
1994-09-20
Rosasco, Steve
Radiation imagery chemistry: process, composition, or product th
Radiation modifying product or process of making
Radiation mask
430322, 430324, G03F 900
Patent
active
053488261
ABSTRACT:
A phase-shifted reticle with patterns proximate each other having inverted phases for the features and phase-shifting elements, and methods of fabricating the reticle. Each of the patterns and inverted patterns are structurally identical with regard to the direction of phase shift, so that any focal shift due to phase error is in the same direction for all patterns. In a preferred embodiment, the structurally identical inverted reticle is used to form an array of closely spaced contact or via openings. For a first pattern on the reticle, the feature will be the 0.degree. phase and the phase-shifting rim surrounding that feature will be the 180.degree. phase. All patterns surrounding the first pattern have phase-shifting rims of the 0.degree. phase and features of the 180.degree. phase. In this way, each pattern can form below conventional resolution features in the resist. Additionally, there will not be exposure of the regions between the closely spaced features since radiation transmitted through the closely spaced phase-shifting rims of the two patterns is 180.degree. out of phase. Also, since each pattern is structurally identical, any focal shift due to phase error is in the same direction for all patterns, so that an acceptable depth of field is maintained for a substrate exposed with the reticle.
REFERENCES:
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patent: 5045417 (1991-09-01), Okamoto
Conjugate Twin Shifter for the New Phase Shift Method to High Resolution Lithography (Miyagi OKI Electric Co., LTD, 1991).
N. Hasegawa, A. Imai, T. Terasawa, T. Tanaka, F. Murai. The Japan Society of Applied Physics and Related Societies "Extended Abstracts 29 p-ZC-3, Submicron Lithography Using Phase Mask (9): Halftone Phase Shifting Mask" 1991.
K. Nakagawa, N. Ishiwata, Y. Yanagishita, Y. Tabata. The Japan Society of Applied Physics and Related Societies "Extended Abstracts 29 p-ZC-2, Phase-Shifting Photolithography Applicable to Real IC Patterns" 1991.
Lin, Burn J. "The Attenuated Phase-Shifting Mask" Solid State Technology Jan. 1992.
Dao Giang T.
De Qian Qi
Fujimoto Harry H.
Gaw Eng T.
Tam Nelson N.
Intel Corporation
Rosasco Steve
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