Tunable metallization by assembly of metal nanoparticles in polymer thin films by photo- or electron beam lithography.
Tunable metallization by assembly of metal nanoparticles in polymer thin films by photo- or electron beam lithography.
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通过光或电子束光刻在聚合物薄膜中组装金属纳米颗粒来实现可调谐金属化。
DOI：
10.1021/la0511485
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
A. Takahara
中科院分区：
文献类型：
--
作者：
D. Yin;S. Horiuchi;M. Morita;A. Takahara
通过可控地将金属纳米颗粒组装成聚合物薄膜，在微米或纳米尺度上形成富金属结构的表面图案化技术。以钯(II)双(乙酰丙酮基)钯(Pd(Acac))(2)为前驱体，在氮气气氛中汽化，将钯纳米粒子引入到聚甲基丙烯酸甲酯(PMMA)薄膜中。根据剂量的不同，紫外光或电子束(EB)照射PMMA薄膜可增强其对Pd(Acac)(2)的还原能力。这种对剂量的依赖关系可用于控制钯纳米颗粒的形成和组装。使用该技术，可以通过通过二元光掩模照射聚合物的表面来简单地创建由聚合物薄膜中的富金属区域和贫金属区域组成的二元图案。除了创建二元图案外，还可以创建灰度图案，其中Pd纳米颗粒的密度可以通过使用连续调制强度的光来调节以提供灰色阴影。由于电子束还增强了PMMA对Pd(Acac)(2)的还原能力，因此有可能获得具有纳米图形特征的高度金属化的薄膜。可以通过氧等离子体处理或通过热解选择性地去除PMMA膜。因此，通过选择性地去除PMMA膜，可以获得具有二进制或灰度图案的高度金属化的表面。与裸露的硅表面相比，金属化区对Cf(4)等离子体具有相对较高的电阻率；因此，金属化表面图案可以通过Cf(4)等离子体处理转移到底层硅衬底上。由于金属纳米粒子的纳米效应，900℃的热处理明显低于块体Pd的熔融温度，通过结合组装的纳米粒子产生连续的金属特征。
The technique of patterning of surfaces with metal-rich structures on micro- or nanoscales was developed by 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 upon its dose, the irradiation of a PMMA film by UV light or an electron beam (EB) enhances its reducing capability against Pd(acac)(2). This dependency on dose can be used to control the formation and assembly of Pd nanoparticles. Using this technique, binary patterns consisting of metal-rich and metal-poor regions in the polymer film can be created simply by irradiating the surface of the polymer through a binary photomask. Besides the creation of binary patterns, it is also possible to create grayscale patterns where the density of Pd nanoparticles can be tuned to provide shades of gray by the use of light with continuously modulated intensity. Because the electron beam also enhances the reducing power of PMMA against Pd(acac)(2), it is thus possible to obtain highly metallized films with nanoscale pattern features. The PMMA film can be selectively removed by oxygen plasma treatment or by pyrolysis. Thus, highly metallized surfaces with binary or grayscale patterns can be obtained by selective removal of the PMMA films. The metallized regions possess relatively high resistivity against CF(4) plasma compared to the bare silicon surface; therefore, the metallized surface patterns can be transferred onto the underlying silicon substrate by CF(4) plasma treatment. Because of the nanosize effect of metal nanoparticles, the thermal treatment at 900 degrees C, which is significantly lower than the melting temperature of the bulk Pd, yields continuous metallic features by binding the assembled nanoparticles.