Lithographic approach to pattern self-assembled nanoparticle multilayers
Lithographic approach to pattern self-assembled nanoparticle multilayers
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DOI：
10.1021/la025856r
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发表时间：
2002-08-20
期刊：
影响因子：
3.9
通讯作者：
Lvov, Y
中科院分区：
文献类型：
--
作者：
Hua, F;Cui, TH;Lvov, Y
通过交替吸附极性相反的组分（线性多离子、纳米粒子和酶），超薄膜的纳米组装允许在垂直于表面的方向上形成具有几纳米精度的组分层。自从Decher等人的演示1,2以来，它已经在光电器件、生物相容性覆盖和生物反应器中得到了应用。1-7逐层自组装的典型过程如下：将预处理过的硅衬底浸入阳离子溶液中10分钟，在衬底上形成单层阳离子聚电解质。然后冲洗基材。然后，将其浸入聚阴离子溶液中10分钟，吸附一层阴离子聚电解质。这个过程可以无限重复；唯一的条件是正负成分的适当交替。在逐层组装（LbL）中经常使用的线性多离子有阳离子聚乙亚胺（PEI）、聚二甲基二烯丙胺氯化铵（PDDA）、聚丙烯胺盐酸盐（PAH）、聚赖氨酸、壳聚糖、阴离子聚苯乙烯磺酸钠（PSS）和聚硫酸乙烯基、聚丙烯酸和DNA。酶和带电纳米粒子也被用于LbL组装。为了在器件中使用LbL多层，不仅要在垂直方向上而且要在平面方向上提供薄膜排序。这对于纳米器件的生产至关重要，比如纳米电子芯片或纳米机电系统。8-15在二维（2D）图案上应用逐层组装的作品。16-21它们主要基于硫醇化合物在金上的微缩印刷，以及在带电荷的图案上进一步组装聚离子多层膜，由Hammond等人开发。16-19这种策略旨在通过在基片上冲压具有不同功能的化学物质（即聚离子粘合剂或抗性）来产生图案。多离子只被引导到带电的“吸引”区域，而被排斥在电阻区域。Whitesides等人利用聚二甲基硅氧烷（PDMS）微模塑技术将20个乳胶颗粒在毛细管通道中结晶，并制作了分辨率约为1 μm的450纳米球体的三维（3D）集成。在另一种方法中，21聚（吡咯）和聚（苯乙烯磺酸）通过等离子体处理在含氟聚合物上产生的二维带电微图上进行lbl组装。所描述的三种方法都非常成功，但由于基材（金、含氟聚合物）或特殊塑料印章的必要性，在应用上受到限制。本文提出了一种利用硅基光刻技术实现自组装多层膜二维图案化的方法，这是一种成熟的工业工艺。开始时，通过标准紫外线照射程序通过掩模对光刻胶进行图案化（图1）。然后采用逐层交替的方法在衬底上完全覆盖多晶硅层，得到所需的多层结构。因此，聚离子膜覆盖整个表面（而不仅仅是促进吸附的区域，就像用硫醇微印一样），然后去除部分膜。通过使用这种策略（图1），可以避免故意的选择性沉积控制。溶解光刻胶，在溶解过程中，在选定的区域从衬底上去除多离子多层膜。纳米粒子或多离子多层可以通过这种方法进行微图案化。光刻微制造方法在工业上被广泛接受，它提供了更大的工艺通用性和高的图案分辨率。因为这两种平版印刷…
Nanoassembly of ultrathin films through alternate adsorption of oppositely charged components (linear polyions, nanoparticles, and enzymes) allows formation of layers with component location precision of a few nanometers in the direction perpendicular to the surface. Since its demonstration by Decher et al., 1, 2 it has found applications in electro-optical devices, biocompatible coverage, and bioreactors. 1-7 The typical procedure of layer-by-layer self-assembly is as follows: A pretreated silicon substrate is immersed in a cationic solution for 10 min, forming a single layer of cationic polyelectrolytes on the substrate. The substrate is then rinsed. Next, it is immersed in a polyanion solution for 10 min to adsorb a layer of anionic polyelectrolyte. The process can be repeated indefinitely; the only condition is a proper alternation of positive and negative components. Linear polyions frequently used in the layer-by-layer (LbL) assembly are cationic poly (ethyleneimine)(PEI), poly-(dimethyldiallylammonium chloride)(PDDA), poly (allylamine hydrochloride)(PAH), polylysine, chitosan, and anionic sodium poly (styrenesulfonate)(PSS) and poly-(vinyl sulfate), poly (acrylic acid), and DNA. Enzymes and charged nanoparticles were also used in the LbL assembly. 5 To use LbL multilayers in devices, one has to provide film ordering not only in a vertical direction but also in the planar direction. This is critical for nanodevice production, such as nanoelectronic chips or NEMS (nanoelectromechanical systems). 8-15 There are works on application of the layer-by-layer assembly on two-dimensional (2D) patterns. 16-21 They are based mostly on the microprinting of thiol compounds on gold and further assembly of the polyion multilayers on charged patterns, and they were developed by Hammond et al. 16-19 This strategy is designed to produce patterns by stamping onto substrates chemicals with different functionalities, that is, polyion adhesive or resisting. The polyions were directed only to charge “attractive” regions and were repelled from the resistant regions. Whitesides et al. 20 crystallized latex particles in capillary channels produced by poly (dimethylsiloxane)(PDMS) micromolding and made three-dimensional (3D) ensembles of 450-nm spheres with a resolution of ca. 1 μm. In another approach, 21 poly (pyrrole) and poly (styrenesulfonate) were LbL-assembled on the 2D charged micropattern produced on a fluoropolymer by plasma treatment. The three methods described were quite successful but restricted in applications by substrate materials (gold, fluoropolymers) or by necessity of special plastic stamps. In this paper, we present an approach to realize 2D patterning of selfassembled multilayers by silicon-based lithographical technology, which is a well-established industrial process. At the beginning, a photoresist was patterned through a mask by the standard UV-irradiation procedure (Figure 1). Then the substrate was entirely covered with polyion layers with the alternate layer-by-layer method to get the desired multilayer structure. Therefore, polyion film covers the entire surface (not only the adsorption-promoting region as in the work with thiol microprinting17) followed by removal of part of the film. By using this strategy (Figure 1), the deliberate selective deposition control is avoided. The photoresist was dissolved, and during the dissolution, polyion multilayers were removed from the substrate at the selected areas. Nanoparticle or polyion multilayers can be micropatterned by this process. The lithographic micromanufacturing approach is widely accepted in industry, and it offers larger versatility of the process and high pattern resolution. Since both lithography …