Reaction mechanism of fluorinated chemically amplified resists

The halogenation of resist materials is a well-known strategy for the improvement in resist performance particularly in electron beam and x-ray resists. However, for chemically amplified resists, the halogenation of polymers requires particular caution because halogenated polymers may interfere with acid generation. In this work, acid generation in poly[4-hydroxystyrene-co-4-(1,1,1,3,3,3-hexafluoro-2-hydroxypropyl)-styrene] films was investigated using steady-state spectroscopy and pulse radiolysis. Acid yield decreased with an increase in the ratio of hexafluoroalcohol units. It was found that the reactivity of polymers with low-energy electrons (∼thermal energy) correlates to the decrease in acid yield.

[1]  Saburo Imamura,et al.  Chloromethylated Polystyrene as a Dry Etching‐Resistant Negative Resist for Submicron Technology , 1979 .

[2]  Nigel P. Hacker,et al.  Photochemistry of triarylsulfonium salts , 1990 .

[3]  J. Chien,et al.  Radiolysis of resist polymers. 1. Poly(methyl-alpha-haloacrylates) and copolymers with methylmethacrylate. Technical report. [Gamma radiation] , 1983 .

[4]  Reaction Mechanisms of Brominated Chemically Amplified Resists , 2005 .

[5]  K. Asmus,et al.  Reactions of fluorinated benzenes with hydrated electrons and hydroxyl radicals in aqueous solutions. , 1973 .

[6]  S. Kashiwagi,et al.  Synchronization of femtosecond UV-IR laser with electron beam for pulse radiolysis studies , 2005 .

[7]  Takahiro Kozawa,et al.  Radiation and photochemistry of onium salt acid generators in chemically amplified resists , 2000, Advanced Lithography.

[8]  S. Tagawa,et al.  Dependence of Outgassing Characters at a 157 nm Exposure on Resist Structures , 2003 .

[9]  William P. Jencks,et al.  General base catalysis, structure-reactivity interactions, and merging of mechanisms for elimination reactions of (2-arylethyl)quinuclidinium ions , 1982 .

[10]  Roger F. Sinta,et al.  A Novel Photometric Method for the Determination of Photoacid Generation Efficiencies Using Benzothiazole and Xanthene Dyes as Acid Sensors , 1997 .

[11]  R. D. Allen,et al.  Development of 157 nm positive resists , 2001 .

[12]  Hiroki Yamamoto,et al.  Proton Dynamics in Chemically Amplified Electron Beam Resists , 2004 .

[13]  F. Schué,et al.  Poly-4-bromostyrene, a high-performance negative electron resist , 1986 .

[14]  Monte Carlo Simulation of Electron Thermalization Distribution in Liquid Hydrocarbons: Effects of Inverse Collisions and of an External Electric Field , 2001 .

[15]  S. Tagawa,et al.  Modeling and simulation of chemically amplified electron beam, x-ray, and EUV resist processes , 2004 .

[16]  Roger F. Sinta,et al.  Exploratory approaches to the study of acid diffusion and acid loss from polymer films using absorption and fluorescence spectroscopy , 1999, Advanced Lithography.

[17]  H. Mohan,et al.  Radiolysis of aqueous solutions of dihalobenzenes: studies on the formation of halide ions by ion chromatography , 2005 .

[18]  Yoshio Taniguchi,et al.  Iodinated polystyrene: An ion‐millable negative resist , 1980 .

[19]  Takahiro Kozawa,et al.  Radiation-Induced Acid Generation Reactions in Chemically Amplified Resists for Electron Beam and X-Ray Lithography , 1992 .

[20]  Hiroki Yamamoto,et al.  Proton and anion distribution and line edge roughness of chemically amplified electron beam resist , 2005 .

[21]  Hiroki Yamamoto,et al.  Study on acid generation from polymer , 2005 .

[22]  C. F. Cook,et al.  Synthesis, Radiation Degradation, and Electron Beam Resist Behavior of Fluorine‐Containing Vinyl Polymers , 1981 .

[23]  G. A. Coquin,et al.  Sensitive chlorine-containing resists for X-ray lithography , 1977 .

[24]  Takahiro Kozawa,et al.  Development of subpicosecond pulse radiolysis system , 2000 .

[25]  S. Tagawa,et al.  Polymer screening method for chemically amplified electron beam and X-ray resists , 2003, Digest of Papers Microprocesses and Nanotechnology 2003. 2003 International Microprocesses and Nanotechnology Conference.

[26]  Gerd Pohlers,et al.  Intrazeolite Photochemistry. 22. Acid−Base Properties of Coumarin 6. Characterization in Solution, the Solid State, and Incorporated into Supramolecular Systems , 1998 .

[27]  F. Jou,et al.  SOLVENT DEPENDENCE OF THE OPTICAL ABSORPTION SPECTRUM OF THE SOLVATED ELECTRON. , 1971 .

[28]  H. Truong,et al.  Fluoropolymer Resists: Progress and Properties , 2003 .

[29]  Studies on Reaction Mechanisms of EB Resist by Pulse Radiolysis , 2000 .

[30]  S. Tagawa,et al.  Study on radiation-induced reaction in microscopic region for basic understanding of electron beam patterning in lithographic process (I) - Development of subpicosecond pulse radiolysis and relation between space resolution and radiation-induced reactions of onium salt , 2001, Digest of Papers. Microprocesses and Nanotechnology 2001. 2001 International Microprocesses and Nanotechnology Conference (IEEE Cat. No.01EX468).

[31]  H. Orthner,et al.  Radical Cations of Sterically Hindered Phenols as Intermediates in Radiation-Induced Electron Transfer Processes , 1996 .

[32]  Takahiro Kozawa,et al.  Radiation-induced reactions of chemically amplified x-ray and electron-beam resists based on deprotection of t-butoxycarbonyl groups , 1997 .