Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Nano Lett. 2009 Dec;9(12):4364-9. doi: 10.1021/nl902646e.
Self-assembly provides the ability to create well-controlled nanostructures with electronic or chemical functionality and enables the synthesis of a wide range of useful devices. Diblock copolymers self-assemble into periodic arrays of microdomains with feature sizes of typically 10-50 nm, and have been used to make a wide range of devices such as silicon capacitors and transistors, photonic crystals, and patterned magnetic media(1-3). However, the cylindrical or spherical microdomains in diblock copolymers generally form close-packed structures with hexagonal symmetry, limiting their device applications. Here we demonstrate self-assembly of square-symmetry patterns from a triblock terpolymer in which one organometallic block imparts high etch selectivity and etch resistance. Long-range order is imposed on the microdomain arrays by self-assembly on topographical substrates, and the orientation of both square lattices and in-plane cylinders is controlled by the substrate chemistry. Pattern transfer is demonstrated by making an array of square-packed 30 nm tall, 20 nm diameter silica pillars. Templated self-assembly of triblock terpolymers can generate nanostructures with geometries that are unattainable from diblock copolymers, significantly enhancing the capabilities of block copolymer lithography.
自组装提供了创建具有电子或化学功能的良好控制的纳米结构的能力，并能够合成广泛的有用设备。两亲性嵌段共聚物自组装成具有通常为 10-50nm 的特征尺寸的微区的周期性排列，并且已经被用于制造各种设备，例如硅电容器和晶体管、光子晶体和图案化磁介质（1-3）。然而，两亲性嵌段共聚物中的圆柱状或球状微区通常形成具有六方对称性的密堆积结构，限制了它们的器件应用。在这里，我们展示了一种由三嵌段共聚物自组装形成的正方形对称图案，其中一个有机金属嵌段赋予了高的刻蚀选择性和耐刻蚀性。通过在形貌基底上自组装对微区阵列施加长程有序，并且正方形晶格和平面圆柱的取向都由基底化学控制。通过制造 30nm 高、20nm 直径的二氧化硅柱的正方形密堆积阵列来证明图案转移。三嵌段共聚物的模板自组装可以生成无法通过两亲性嵌段共聚物获得的几何形状的纳米结构，显著增强了嵌段共聚物光刻的能力。
