Fabrication of hierarchical nanostructures using free-standing trilayer membrane
Fabrication of hierarchical nanostructures using free-standing trilayer membrane
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DOI：
10.1116/1.4821655
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发表时间：
2013-11-01
影响因子：
1.4
通讯作者：
Choi, Chang-Hwan
中科院分区：
文献类型：
--
作者：
Du, Ke;Liu, Yuyang;Choi, Chang-Hwan
分层纳米结构通常是通过在预先图案化的微米或纳米结构上进行多个光刻步骤来制造的。然而，这种传统的多重光刻步骤导致覆盖率和均匀性较差，尤其是在高深宽比微米或纳米结构上进行图案化时。在这项工作中，作者提出了一种新的制造方法，即使在高纵横比预图案上也可以使用独立式三层膜制造分层纳米结构。通过激光干涉光刻、反应离子蚀刻和电子束沉积在平面硅基板上形成由金属/光刻胶/抗反射涂层组成的纳米多孔三层复合薄膜。然后，使用氨 (NH3)、过氧化氢 (H2O2) 和水 (H2O) 的定制溶液将复合膜从支撑基板上剥离。然后将独立式复合膜转移到预先图案化的硅基板上。膜表面没有显示出重大缺陷，柔性和柔软的三层膜可以与预图案的顶面良好、均匀的接触，并在硅的深反应离子蚀刻（DRIE）工艺中用作坚固的蚀刻掩模，以制造分层纳米孔结构。由于膜无缝地覆盖预图案的顶表面，因此在蚀刻过程中膜的纳米孔图案以极高的保真度转移到顶表面上。该膜还可用作沉积工艺的模板。例如，通过剥离工艺通过纳米多孔膜沉积金属。然后，转移的金属纳米点图案在 DRIE 工艺中用作蚀刻掩模，以实现高深宽比的分层纳米柱结构。与制造分级纳米结构的传统方法相比，所引入的新方法更加可靠和通用，可以使用相同的单膜在纳米孔和纳米柱阵列中实现均匀性良好的大面积分级纳米结构。 (C) 2013 年美国真空协会。
Hierarchical nanostructures are typically fabricated with multiple lithography steps on prepatterned micro-or nanostructures. However, such conventional multiple lithography steps result in poor coverage and uniformity, especially when patterning on high-aspect-ratio micro- or nanostructures. In this work, the authors present a new fabrication method which can make hierarchical nanostructures even on high-aspect-ratio prepatterns, using a free-standing trilayer membrane. The nanoporous trilayer composite films, consisting of metal/photoresist/antireflective coating, is created on a planar silicon substrate by using laser interference lithography, reactive ion etching, and e-beam deposition. Then, a customized solution of ammonia (NH3), hydrogen peroxide (H2O2), and water (H2O) is used to release the composite film from the supporting substrate. The free-standing composite membrane is then transferred on a prepatterned silicon substrate. Showing no major defects on the membrane surface, the flexible and soft trilayer membrane allows a good, uniform contact with the top surface of the prepatterns and is utilized as a robust etch mask in the deep reactive ion etching (DRIE) process of silicon to fabricate hierarchical nanopore structures. Since the membrane covers the top surfaces of the prepatterns seamlessly, the nanopore patterns of the membrane are transferred onto the top surfaces with great fidelity during the etching process. The membrane can also be used as a stencil for deposition processes. For example, metal is deposited through the nanoporous membrane by a lift-off process. Then, the transferred metal nanodot patterns are used as an etch mask in the DRIE process to achieve high-aspect-ratio hierarchical nanopillar structures. Compared to conventional methods to fabricate hierarchical nanostructure, the introduced new approach is more reliable and versatile to realize large-area hierarchical nanostructures with a good uniformity, in both nanopore and nanopillar array by using the same single membrane. (C) 2013 American Vacuum Society.