Structure and stability of patterned self-assembled films of octadecyltrichlorosilane formed by contact printing
Structure and stability of patterned self-assembled films of octadecyltrichlorosilane formed by contact printing
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DOI：
10.1021/la970166m
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发表时间：
1997-06-25
期刊：
影响因子：
3.9
通讯作者：
Nuzzo, RG
中科院分区：
文献类型：
--
作者：
Jeon, NL;Finnie, K;Nuzzo, RG
用X射线光电子能谱（XPS）、椭圆偏振光谱仪、反射吸收红外光谱（RAIRS）、扫描电子显微镜（SEM）和原子力显微镜（AFM）研究了十八烷基三氯硅烷（OTS）在Al和SiO2/Si表面的接触印刷和吸附薄膜的结构。的OTS膜的结构被发现是强烈的影响所使用的制备方法。通过用OTS“油墨”接触印刷30 a形成的膜由紧密堆积的、主要是几乎垂直于表面排列的全反式烷基链组成，而通过从可比浓度的溶液中吸附OTS 30 s形成的膜由稀疏吸附的和更随机取向的链组成。对于通过浸没在含OTS的溶液中制备的样品，随着反应时间的增加（例如，在ImM溶液中15-30分钟），观察到膜结构的大变化（从构象无序、取向差到填充良好、高度取向的烃链）。另一方面，通过接触印刷制备的膜在仅30埃的基材与用10 mM OTS己烷溶液上墨的弹性体印模接触后就达到或超过了完整的单层质量覆盖。通过接触印刷形成的OTS膜在高温和侵蚀性反应条件下是稳定的，这对于它们分别通过MOCVD和溶胶-凝胶方法在引导金属和陶瓷薄膜的选择性沉积中用作分子抗蚀剂是必要的。在本文中，我们展示了OTS油墨浓度和印模接触时间等因素如何影响微接触印刷OTS薄膜的图案化。我们发现，在不与印模接触的图案区域中的OTS域的反应性扩散和岛形成限制了在小于几微米的尺寸下进行的图案化的保真度。我们讨论了介导这些影响的物理处理的几个方面，并提出了消除或大大减少它们的可能方法。
The structures of thin films of octadecyltrichlorosilane (OTS) formed by contact printing and adsorption from solution on Al and SiO2/Si surfaces have been investigated by X-ray photoelectron spectroscopy (XPS), ellipsometry, reflection-absorption infrared spectroscopy (RAIRS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The structures of the OTS films were found to be strongly influenced by the method of preparation used. The films formed by contact printing for 30 a with an OTS ''ink'' are composed of close-packed, predominantly all-trans alkyl chains aligned nearly perpendicular to the surface, while films formed by adsorption of OTS for 30 s from a solution of comparable concentration are made up of sparsely adsorbed and more randomly oriented chains. Large changes in the film structure (from conformationally disordered, poorly oriented to well-packed, highly oriented hydrocarbon chains) were observed as the reaction time was increased for samples prepared by immersion in an OTS-containing solution (e.g. 15-30 min in a 1 mM solution). On the other hand, films prepared by contact printing reached or exceeded full monolayer mass coverages after only 30 a of substrate contact with an elastomeric stamp inked with a 10 mM solution of OTS in hexane. The OTS films formed by contact printing are stable at the high temperatures and aggressive reaction conditions necessary for their use as molecular resists in directing the selective deposition of metal and ceramic thin films by MOCVD and sol-gel methods, respectively. in this paper we show how such factors as the OTS ink concentration and stamp contact time influence the patterning of OTS thin films by microcontact printing. We find that reactive spreading and island formation of OTS domains in regions of the pattern not in contact with the stamp limit the fidelity of the patterning carried out at dimensions less than a few microns. We discuss several aspects of the physical processing which mediate these effects and propose possible methods for eliminating or greatly reducing them.