| Abstract
| - The technique of patterning of surfaces with metal-rich structures on micro- or nanoscales was developedby assembling metal nanoparticles into a thin film of polymer in a controllable way. Palladium (Pd)nanoparticles were incorporated into a thin film of poly(methyl methacrylate) (PMMA) using palladium(II) bis(acetylacetonato), Pd(acac)2, as a precursor vaporized in a nitrogen atmosphere. Depending uponits dose, the irradiation of a PMMA film by UV light or an electron beam (EB) enhances its reducingcapability against Pd(acac)2. This dependency on dose can be used to control the formation and assemblyof Pd nanoparticles. Using this technique, binary patterns consisting of metal-rich and metal-poor regionsin the polymer film can be created simply by irradiating the surface of the polymer through a binaryphotomask. Besides the creation of binary patterns, it is also possible to create grayscale patterns wherethe density of Pd nanoparticles can be tuned to provide shades of gray by the use of light with continuouslymodulated intensity. Because the electron beam also enhances the reducing power of PMMA againstPd(acac)2, it is thus possible to obtain highly metallized films with nanoscale pattern features. The PMMAfilm can be selectively removed by oxygen plasma treatment or by pyrolysis. Thus, highly metallizedsurfaces with binary or grayscale patterns can be obtained by selective removal of the PMMA films. Themetallized regions possess relatively high resistivity against CF4 plasma compared to the bare siliconsurface; therefore, the metallized surface patterns can be transferred onto the underlying silicon substrateby CF4 plasma treatment. Because of the nanosize effect of metal nanoparticles, the thermal treatmentat 900 °C, which is significantly lower than the melting temperature of the bulk Pd, yields continuousmetallic features by binding the assembled nanoparticles.
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