Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States.
ACS Nano. 2010 Nov 23;4(11):6527-34. doi: 10.1021/nn101616d. Epub 2010 Oct 19.
We report the design of a direct electron beam patternable buffer layer to spatially control the orientation of the microdomains in an overlaying polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) block copolymer (BCP) film. The buffer layer consists of a surface anchored low molecular weight PS-b-PMMA, with the PMMA segment anchored to the surface and a short PS block at the buffer layer/BCP interface. The block architecture of the buffer layer combines the essential features of "bottom up" and "top down" approaches as it functions as a nonpreferential layer to dictate perpendicular orientation of BCP domains from the substrate interface and as an e-beam resist to allow top-down lithographic process to spatially define the buffer layer on the substrate. The composition of the buffer layer can be tuned by changing the relative block lengths to create a nonpreferential surface which effectively induces perpendicular orientation of domains in an overlying BCP film. The grafted block copolymer can be locally shaved by e-beam lithography resulting in spatial control of domain orientation in the BCP film. The direct patterning approach reduces the number of steps involved in forming chemical patterns by conventional lithography.
我们设计了一种直接电子束可图案化的缓冲层，以空间控制覆盖的聚苯乙烯-聚甲基丙烯酸甲酯（PS-b-PMMA）嵌段共聚物（BCP）膜中微区的取向。缓冲层由表面锚定的低分子量 PS-b-PMMA 组成，PMMA 段锚定在表面上，缓冲层/BCP 界面处有一个短的 PS 块。缓冲层的嵌段结构结合了“自下而上”和“自上而下”方法的基本特征，因为它作为非优先层，从基底界面上控制 BCP 畴的垂直取向，并且作为电子束抗蚀剂，允许自上而下的光刻工艺在基底上空间定义缓冲层。通过改变相对嵌段长度来调整缓冲层的组成，以形成非优先表面，从而有效地诱导覆盖的 BCP 膜中畴的垂直取向。接枝的嵌段共聚物可以通过电子束光刻局部刮除，从而导致 BCP 膜中畴取向的空间控制。直接图案化方法减少了通过传统光刻形成化学图案所需的步骤数量。
