Ghoshal Tandra, Holmes Justin D, Morris Michael A
School of Chemistry and Tyndall National Institute, University College Cork, Cork, Ireland.
AMBER and Department of Chemistry, Trinity College Dublin, Dublin, Ireland.
Sci Rep. 2018 May 8;8(1):7252. doi: 10.1038/s41598-018-25446-0.
In an effort to develop block copolymer lithography to create high aspect vertical pore arrangements in a substrate surface we have used a microphase separated poly(ethylene oxide) -b- polystyrene (PEO-b-PS) block copolymer (BCP) thin film where (and most unusually) PS not PEO is the cylinder forming phase and PEO is the majority block. Compared to previous work, we can amplify etch contrast by inclusion of hard mask material into the matrix block allowing the cylinder polymer to be removed and the exposed substrate subject to deep etching thereby generating uniform, arranged, sub-25 nm cylindrical nanopore arrays. Briefly, selective metal ion inclusion into the PEO matrix and subsequent processing (etch/modification) was applied for creating iron oxide nanohole arrays. The oxide nanoholes (22 nm diameter) were cylindrical, uniform diameter and mimics the original BCP nanopatterns. The oxide nanohole network is demonstrated as a resistant mask to fabricate ultra dense, well ordered, good sidewall profile silicon nanopore arrays on substrate surface through the pattern transfer approach. The Si nanopores have uniform diameter and smooth sidewalls throughout their depth. The depth of the porous structure can be controlled via the etch process.
为了开发嵌段共聚物光刻技术以在衬底表面创建高纵横比的垂直孔排列,我们使用了一种微相分离的聚环氧乙烷-b-聚苯乙烯(PEO-b-PS)嵌段共聚物(BCP)薄膜,其中(且非常不寻常的是)形成圆柱相的是PS而非PEO,且PEO是主要嵌段。与之前的工作相比,我们通过将硬掩膜材料引入基体嵌段来放大蚀刻对比度,从而能够去除圆柱状聚合物,使暴露的衬底进行深度蚀刻,进而生成均匀、有序、直径小于25 nm的圆柱形纳米孔阵列。简而言之,将选择性金属离子引入PEO基体并进行后续处理(蚀刻/改性)以创建氧化铁纳米孔阵列。氧化物纳米孔(直径22 nm)呈圆柱形,直径均匀,且模仿了原始的BCP纳米图案。通过图案转移方法,氧化物纳米孔网络被证明是一种用于在衬底表面制造超密集、排列良好、侧壁轮廓良好的硅纳米孔阵列的抗蚀掩膜。硅纳米孔在整个深度上具有均匀的直径和光滑的侧壁。多孔结构的深度可通过蚀刻工艺进行控制。