Characterization of new aromatic polymers for 157-nm photoresist applications

Fender, Nicolette; Brock, Phillip J.; Chau, Weilun; Bangsaruntip, Sarunya; Mahorowala, Arpan P.; Wallraff, Gregory M.; Hinsberg, William D.; Larson, Carl E.; Itô, Hiroshi; Breyta, Gregory; Burnham, Kikue S.; Truong, Hoa D.; Lawson, P.; Allen, Robert D.

doi:10.1117/12.436873

Cited by 10 publications

(13 citation statements)

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“…Although the a-trifluorination of PMMA significantly decreases the absorption at 157 nm as reported by Brodsky et al [7] and Ito et al [18,19], the calculated absorptions of (c) and (d) are only 20-30 % smaller than those of (a) and (b). For estimating absorbance in the solid state, calculated oscillator strengths should be divided by molecular volume.…”

Section: Methodsmentioning

confidence: 59%

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DFT Calculations of Photoabsorption Spectra in the VUV Region for Design of Photoresist Materials for 157 nm Lithography.

Ando

Fujigaya

Ueda

2002

J. Photopol. Sci. Technol.

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Time-dependent density functional theory (TD-DFT) calculations using the B3LYP hybrid functional were performed to investigate the transparencies of organic molecules and polymers in the vacuum ultraviolet (VUV) region. The calculated photoabsorption spectra obtained from the combination of geometry optimization using the 6-3110(d) basis set and subsequent calculations of transition energies and oscillator strengths using the 6-311++G(d,p) basis set agree well with the experimental spectra. This method is a useful to infer the transparency of polymers in the VUV region, and in particular helpful for design of photoresist materials for F2 lithography (157 nm). The transparencies of the model compounds relating to the representative polymer platforms were estimated, and the calculated spectra demonstrate the effectiveness of judicious introduction of -F and -CF3 groups in reducing optical absorption at the wavelength. In addition, the absorption spectra of model compounds having a sulfonyl fluoride (-S02F) and sulfonyl ester (-S020R) groups, which were proposed by the present authors as novel resist platforms, were calculated and compared with the experimental spectra of corresponding homopolymers.

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Section: Methodsmentioning

confidence: 59%

“…Figs. 2, 4, and 11 demonstrate the effectiveness of the judicious introduction of -CF3 group and support the good transparency of poly(MTFMA) at 157 nm [18,19]. Fig.12 shows the calculated spectra of the esters of propionic acid (a-d) and 3,3,3-trifluoropropionic acid (e-h).…”

Section: Calculation Of Photoabsorption Spectra Of Model Compounds Fomentioning

confidence: 99%

DFT Calculations of Photoabsorption Spectra in the VUV Region for Design of Photoresist Materials for 157 nm Lithography.

Ando

Fujigaya

Ueda

2002

J. Photopol. Sci. Technol.

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“…While PF2-ESCAP is hydrophilic due to a high concentration (>50 mol%) of STHFA [2,4], the TBTFMA copolymer with NBHFA is highly hydrophobic due to the high concentration of TBTFMA (60-70 mol%). Aqueous base developer cannot wet the P(TBTFMA-NBHFA) film (contact angle 87-88 °) and therefore the copolymer resist does not develop well.…”

Section: Blending Of Copolymers With Pnbhfamentioning

confidence: 99%

“…We have proposed four platforms for 157 nm resist systems (Scheme I) [2]. 4-(1,1,1,3,3,3-Hexafluoro-2-hydroxypropyl)styrene (STHFA) can be copolymerized by radical initiation with t-butyl 2-trifluoromethylacrylate (TBTFMA) and with t-butyl methacrylate (TBMA) to form PFZ-ESCAP and PF-ESCAP, respectively [2,4]. Because PFz-ESCAP is more transparent than PF-ESCAP at 157 nm (3.2-3.6 vs. 4.0-4.21µm), we have placed more emphasis on PF2-ESCAP, while others have produced good images in PF-ESCAP also [5].…”

Section: Introductionmentioning

confidence: 99%

Fluoropolymers for 157/193 nm Lithography: Chemistry, New Platform, Formulation Strategy, and Lithographic Evaluation.

Itô

Truong

Okazaki

et al. 2002

J. Photopol. Sci. Technol.

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A copolymer of t-butyl 2-trifluoromethylacrylate (TBTFMA) and norbornene bearing hexafluoroisopropanol (NBHFA) as an acid group, which is prepared by radical copolymerization, is employed in our 157 nm resist. The radical copolymerization of 2-trifluoromethylacrylic monomers with norbornene derivatives has been shown to follow the penultimate model much better than the commonly employed terminal model. These copolymers (containing >50 mol% TBTFMA) are too lipophilic to provide good imaging. Blending a NBHFA homopolymer with an optical density (OD) of 1.7/µm at 157 nm into the copolymers (OD=2.5-2.7/µm) results in increased hydrophilicity and reduced OD (2.2-2.0/µm) and provides high resolution images. A copolymer of TBTFMA with vinyl ethers has been identified as a new platform, which can be prepared facilely by common radical polymerization. Certain vinyl ether copolymers are also compatible with the NBHFA homopolymer and thus blending improves their OD and aqueous base development. Because these fluoropolymers are highly transparent at 193 nm as well, they are evaluated as 157/193 dual wavelength resists.

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“…A similar observation was also made by the IBM group at Almaden [3] who reported an absorbance of 3.2µm"1 for the HFIP derivatized polymer. This base-developable, fluoroalcohol group has been adopted by most research groups as the replacement for the phenols and carboxylates used at longer wavelengths, including analogous modified ESCAP formulations with HFIPstyrene [3,14,15].…”

Section: Introductionmentioning

confidence: 99%