Novel annular illumination using controlled phase and transparency

An off axis illumination is valid to enlarge resolution limit and depth of focus (DOF) for narrow pitch patterns. While in wide pitch patterns, the DOF is remarkably inferior to conventional illumination. A novel annular illumination has been achieved by amplitude superposition of off axis and on ax...

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Bibliographic Details
Published inProceedings of 1994 VLSI Technology Symposium pp. 95 - 96
Main Authors Sugihara, T., Mori, S., Fukushima, T., Takagi, J.
Format Conference Proceeding
LanguageEnglish
Published IEEE 1994
Subjects
Chemical lasers
Chromium
Delay
Lighting
Linearity
Lithography
Optical filters
Paper technology
Resists
Stability
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Summary:An off axis illumination is valid to enlarge resolution limit and depth of focus (DOF) for narrow pitch patterns. While in wide pitch patterns, the DOF is remarkably inferior to conventional illumination. A novel annular illumination has been achieved by amplitude superposition of off axis and on axis illuminations which are controlled inverse phases with appropriate transmittance. It has been confirmed, using a new optical filter, that this method can improve the DOF over wide range of pattern pitches maintaining resolution capability of under 0.25 /spl mu/m.< >
ISBN:9780780319219
0780319214
DOI:10.1109/VLSIT.1994.324438