Well-Ordered Thin-Film Nanopore Arrays Formed Using a Block-Copolymer Template
Well-Ordered Thin-Film Nanopore Arrays Formed Using a Block-Copolymer Template
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DOI：
10.1002/smll.200900053
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发表时间：
2009-07-17
期刊：
影响因子：
13.3
通讯作者：
Ross, Caroline A.
中科院分区：
文献类型：
--
作者：
Jung, Yeon Sik;Ross, Caroline A.
遵循摩尔定律，晶体管密度和集成电路的计算能力随着时间呈指数级增长然而，在过去半个世纪里支撑摩尔定律的光学光刻技术，在图案分辨率上已经达到了极限。因此，需要非常规的光刻技术来实现下一代微电子器件的制造。关键要求是可扩展性、高吞吐量、低成本以及与现有制造技术的兼容性。在过去的十年中，自组装二嵌段共聚物（bcp）薄膜在光刻应用中引起了极大的关注，因为它们可以通过热力学驱动的微相分离产生尺寸小于30 nm的有序微畴[2-16]。在这种应用中，需要二维阵列或单层微畴来促进图案转移。[4,7,13,14,17]通常，自组装BCP微畴阵列只具有短程有序，因此，为了制造具有远程有序和精确配准的技术上有用的结构，BCP可以使用另一种光刻技术形成的特征进行模板化。最常见的模板是化学模板[5,15,19,20]或地形模板[4,8,9,13,14,17]，这些模板由电子束光刻或光学光刻定义。在由面外圆柱体或片层组成的BCP膜中，化学模板可以高精度地调节BCP微畴的方向和位置[5,15,19,20]，其中两个块都与化学图案衬底接触。地形模式，无论是否具有衬底表面功能化，都利用空间限制在多种形态的bcp中施加远程有序，包括平面内圆柱体和球体，[4,8,9,13,14,17]，也可以形成3D组件，[21-24]，包括环状、螺旋、圆盘和空心圆柱体等形态，而这些形态在散装中是找不到的。[21 - 23,25,26]最重要的是能够将嵌段共聚物的图案以良好的保真度转移到各种材料中，包括可能难以干蚀刻的金属。在本文中，我们描述了一种使用自组装嵌段共聚物光刻和图案转移工艺制造具有有序纳米孔（反点阵列）的薄膜的简单方法。利用刷涂一维形貌模板和溶剂退火，实现了球嵌段共聚物的远程有序，并通过图案反转工艺将球用于制备纳米多孔图案。给出了Ti、Pt、Ta、W、二氧化硅和磁性Co和Ni反点阵列的例子。第二次图像反转过程被用来形成Ni点阵列。这种通用的方法可以用来制作各种各样的纳米模式薄膜，这些薄膜可以用于集成电路、滤波器、等离子体和光子带隙结构、催化剂、模板、传感器和太阳能电池中的通孔形成。[27-35]纳米多孔金属薄膜的制备工艺如图1所示。采用球形聚苯乙烯-聚二甲基硅氧烷（PS-PDMS） BCP制备纳米级点阵列。与其他常用的bcp相比，PS-PDMS（图1a）由于其较大的Flory-Huggins相互作用参数而具有优异的微域有序性。由于PDMS中的无机成分（Si），它在两个块之间具有良好的蚀刻选择性。[13,14,26]使用紫外干涉光刻系统制作深度为40nm的1.2 mm周期线性沟槽（图1b），然后用PDMS刷处理。制备了30 nm厚的无序PS-PDMS薄膜。
Following Moore’s law, the transistor density and hence the computing power of integrated circuits have scaled exponentially with time.[1] However, optical lithography technology, which has sustained Moore’s law over the last half century, is reaching a limit in pattern resolution. Unconventional lithography techniques are therefore required to enable the next generations of microelectronic device fabrication. The critical requirements are scalability, high throughput, low cost, and compatibility with existing fabrication techniques. During the past decade, films of self-assembled diblock copolymers (BCPs) have attracted significant attention for lithography applications because they can generate ordered microdomains with sizes below 30 nm by thermodynamically driven microphase separation [2–16] In this application, 2D arrays or monolayers of microdomains are desirable to facilitate pattern transfer.[4, 7, 13, 14, 17] Typically, self-assembled BCP microdomain arrays possess only short-range order, and thus to make technologically useful structures with long-range order and accurate registration, BCPs may be templated using features formed by another lithography technique.[4, 5, 9, 10, 13–15, 17, 18] The most common templates are chemical [5, 15, 19, 20] or topographic [4, 8, 9, 13, 14, 17] patterns defined by electron beam lithography or optical lithography. Chemical templates can regulate the orientation and position of BCP microdomains to high precision [5, 15, 19, 20] in BCP films consisting of out-of-plane cylinders or lamellae, in which both blocks contact the chemically patterned substrate. Topographic patterns, with or without substrate surface functionalization, use spatial confinement to impose long-range ordering in BCPs of many morphologies including in-plane cylinders and spheres,[4, 8, 9, 13, 14, 17] and can also form 3D assemblies,[21–24] including morphologies such as rings, spirals, disks, and hollow cylinders that are not found in bulk.[21–23, 25, 26] Of key importance is the ability to transfer patterns with good fidelity from block copolymers into a variety of materials, including metals that may be difficult to dry-etch. In this communication, we describe a simple route to fabricate thin films with well-ordered nanopores (antidot arrays) using selfassembled block-copolymer lithography and pattern transfer processes. Long-range ordering of a sphere-forming block copolymer is accomplished using a brush-coated 1D topographic template and solvent annealing, and the spheres are used to make nanoporous patterns through a pattern reversal process. Examples of Ti, Pt, Ta, W, silica, and magnetic Co and Ni antidot arrays are presented. A second image reversal process was used to form Ni dot arrays. This general method may be used to make a diverse range of nanoatterned films that can be useful in applications including via formation in integrated circuits, filters, plasmonic and photonic bandgap structures, catalysts, templates, sensors, and solar cells.[27–35] The fabrication process for nanoporous metallic thin films is illustrated in Figure 1. A sphere-forming polystyrene-bpoly (dimethylsiloxane)(PS-PDMS) BCP was used to make nanoscale dot arrays. PS-PDMS (Figure 1a) has excellent microdomain ordering due to its large Flory–Huggins interaction parameter compared to other commonly used BCPs. It also has good etch selectivity between the two blocks due to the inorganic component (Si) in the PDMS.[13, 14, 26] An UV interference lithography system was employed to make 1.2-mm-period linear trenches with a depth of 40nm (Figure 1b) that were then treated with a PDMS brush. A disordered 30-nm-thick PS-PDMS thin film was …