Abstract
We evaluated structural changes of poly (methyl-methacrylate) (PMMA) surfaces after and before vacuum ultraviolet (VUV)-irradiation using X-ray photoelectron spectroscopy (XPS) and Fourier trans form infrared spectroscope reflection absorption Spectroscopy (FTIR-RAS). When the PMMA films were irradiated with VUV light under reduced pressure of 100Pa, XPS measurements showed that the O/C value decreased from 0.40 before VUV irradiation to 0.10 after irradiation at 100Pa for 10 min. FT-IR spectral results indicated that C=O and ester peaks, which are parts of PMMA structures, were reduced by the VUV-irradiation. These results showed that oxygen-groups existed on the PMMA surface were decom posed by VUV-irradiation at 100 Pa. However, these structural changes weren't observed when the PMMA was irradiated at 103 Pa. Furthermore, we confirmed that C=O and ester peaks were reduced by VUV-irradiation at N2 atmosphere. This result was the same as the case of VUV-irradiation at 100 Pa. Although unirradiated PMMA was removed by toluene rinsing, the cured PMMA by VUV-irradiation at 100 Pa could not dissolve. Utilizing these properties, we could prepare negative and positive-tone PMMA micropattems by VUV-light lithography through a photomask.
