Radiation imagery chemistry: process – composition – or product th – Radiation modifying product or process of making – Radiation mask
Patent
1993-12-23
1996-07-02
Rosasco, S.
Radiation imagery chemistry: process, composition, or product th
Radiation modifying product or process of making
Radiation mask
430313, 430314, 430322, 430323, 1566431, 1566441, 1566461, 1566531, 428137, G03F 900
Patent
active
055320899
ABSTRACT:
A simplified method of forming a phase shift structure for a lithographic mask includes the conformal deposition of a phase shift material, preferably having an index of refraction similar to that of the mask substrate, over a patterned layer of opaque material and exposed areas of the mask substrate corresponding to the pattern. The thickness of the opaque patterned layer, in combination with the conformal deposition preferably establishes a differentially altered optical path length to produce a phase shift which enhances contrast and increases illumination and resolution in fine patterns. In variant forms of the invention, the conformal deposition of either phase shift material or a sidewall spacer material is followed by an anisotropic removal of material to form the phase shift structure. The application of phase shift material over the mask surface increases durability of the mask and also enhances contrast of images produced with other phase-shift mask feature structures, such as Levenson-type shifters.
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patent: 4937129 (1990-06-01), Yamazaki
patent: 5045417 (1991-09-01), Okamoto
patent: 5194345 (1993-03-01), Rolfsen
patent: 5262282 (1993-11-01), Hieda et al.
patent: 5276551 (1994-01-01), Nakagawa
"Methods for Manufacturing Self-Aligning Phase-Shift Masks"; S. P. Bajuk et al.; Research Disclosure, Feb. 1992, No. 334, Kenneth Mason Publications Ltd, England.
"New Phase Shifting Mask with Self-aligned Phase Shifters for a Quarter Micron Photolithography"; Akihiro Nitayama et al.; Toshiba Corporation; ULSI Research Center; IEEE Sep. 1989; pp. 3.3.1 through 3.3.4.
Adair William J.
Brunner Timothy A.
Dove Derek B.
Hsu Louis L.
Yuan Chi-Min
International Business Machines - Corporation
Petraske Eric W.
Rosasco S.
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