Absorption Coefficient and Sensitivity of Positive and Negative Resists in the Vacuum Ultraviolet Region

Abstract

We classify super-symmetric solutions of the minimal N = 2 gauged Euclidean supergravity in four dimensions. The solutions with an anti-self-dual Maxwell field give rise to anti-self-dual Einstein metrics given in terms of solutions to the SU (∞) Toda equation and more general three-dimensional Einstein-Weyl structures. Euclidean Kastor-Traschen metrics are also characterized by the existence of a certain supercovariantly constant spinor.

Interfacial Chemistry of Poly(methyl methacrylate) Arising from Exposure to Vacuum-Ultraviolet Light and Atomic Oxygen

“…The quantum yield was calculated to be 0.11 ± 0.03, for 110 nm thick films ( d ), and the absorption coefficient, α, was 1.2 × 10 −5 cm −1 at 160 nm . Quantum yield varies with the wavelength of the VUV light source, and previous studies have shown that the quantum yield is 0.053 at 185 nm, 0.03 at 215−230 nm, and ∼0.92 at 254 nm …”

“…PMMA strongly absorbs ultraviolet radiation at wavelengths less than 160 nm (C−C bonds in the polymer backbone) and near 180 and 210 nm (C−O π−π* and n-π* transitions in the ester moieties). The high absorption coefficient of PMMA restricts the penetration of the VUV radiation to a very shallow surface layer, around 150 nm thick for 160 nm light. Primary UV photochemical reactions in PMMA are wavelength dependent ,, and give rise to a variety of chemical reactions such as cross-linking or Norrish reactions as depicted in Figure .…”

“…The film thickness was determined to be 110 ± 10 nm by AFM and ellipsometry. This thickness was significantly thinner than the penetration depth of VUV radiation, which is 150 nm for 157 nm light and is 192 nm for 160 nm light . The VUV light is therefore interacting with the entire sample, not just the outermost layer.…”