Dissolution Fundamentals
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Introduction
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At 65 nm node on-line in 2007, LER must be < 1.5 nm
Dissolution effectively controls LER
Interdependent processing steps many experimental methods
Extent of developer penetration? Interplay between swelling
and dissolution
Developer: Influence of ionization?
Additives: Source of modified film properties?
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Experimental Approach
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| Photoresists Ionize: Charge effects |
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| Quartz Crystal Microbalance: Mass Transport |
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| Neutron and X-ray Reflectivity: Depth profile |
Dry solid films
•Protection profile (NR)
•Mass density profile (XR)
Liquid Immersed films
•Water profile (NR)
•Aqueous base profile (NR)
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Results: Towards Improved Dissolution Models
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| Dissolution and Swelling: Kinetics |
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157 nm material shows different dissolution behavior
Either swells or swells and dissolves; make affect LER
Function of developer strength, but not salt concentration
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| Aqueous Base Profile: Neutron Reflectivity |
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First direct measurement of base profile
Broad solid-liquid interface early stages of development
Diffuse counterion profile at free surface
TMA concentration enhanced with base concentration
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| :Line-Edge Roughness: Bilayer Model |
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Reflectivity highlights developer effects on LER
Poor LER (74 Å) and CD control for swelling solvent
Broad solubility switch, unacceptable
Swelling expected only butanol
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NIST Contributors
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Vivek M. Prabhu*
Eric K. Lin
Wen-li Wu
Erin L. Jablonski
Bryan D. Vogt
Christopher L. Soles
Ronald L. Jones
David vanderHart
Michael Wang
Sushil Satija
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Collaborators:
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Dario L. Goldfarb(1) , Marie Angelopoulos (1), Hiroshi Ito
(2)
(1) IBM T. J. Watson Research Center, Yorktown Heights, NY
(2) IBM Almaden Research Center, San Jose, CA
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