Designing Photoresist Systems for Carbon Dioxide

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Designing Photoresist Systems for Carbon Dioxide

• Bryant Suitte1, Devin Flowers2, and Joseph M.
  Desimone1,2,3,4
• 1North Carolina At State University
• 2University North Carolina at Chapel Hill
• 3Micell Integrated Systems
• 4North Carolina State University

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IntroductionMicrolithography

• Printing process for integrated circuits
• Increase performance while decreasing cost

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Photoresist Requirements

• SENSITIVITY- efficiency of the resist to
  radiation
• CONTRAST- change in dissolution rate
• RESOLUTION- smallest useful image formed
• ETCH RESISTANCE- ability to withstand liquid or
  plasma etching
• PURITY- free of contamination

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Advantages of CO2 in Microlithography

• CO2 Solutions
• Eliminating or reducing waste
• Prevent image collapse
• Materials _at_157nm will be fluorinated

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Project Goals

• Obtain viscosity measurements of 193nm resist
  systems
• Improve Synthesis of Trifluoromethacrylate
  monomers

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193nm Resist Acrylate System

• Viscosity measurements
• Find a relative MW
• ensure consistent solubility
• spin coating parameter
• Inconsistent retention times
• Changed solvents
• Changed polymers
• Added cooling system
• Electronics shop

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193nm ResistNB/MA System

• Must copolymerize Norborenes
• Fluorinated NB/MA copolymers insoluble in CO2
• Replacement needed for MA

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Maleic Anhydride Replacement Monomer

• TFM shown to copolymerize with NB
• Expected higher solubility in CO2
• R group variables

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Monomer SynthesisTrifluoromethacrylate
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Monomer SynthesisTrifluoromethacrylate

• Experimental Procedure
• Distilled under vacuum (dry ice/2-propanol bath)
• 1HNMR

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Acrylic Acid Reactions

• Experimental Procedure
• Pyridine as solvent
• Distilled under vacuum in (dry ice/2-propanol)
• 1HNMR

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Acrylic Acid Reaction
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Summary

• Viscosity
• Instrumentation failure
• constant temp, repair, design of coolant system
• Synthesis of TFM
• Increased yields
• Increased percent desired product

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Acknowledgements

• Dr. Joseph M. DeSimone
• Devin Flowers
• DeSimone Group
• Morken Group
• NSF for funding