Ren J, Ocola L E, Divan R, Czaplewski D A, Segal-Peretz T, Xiong S, Kline R J, Arges C G, Nealey P F
University of Chicago, Institute for Molecular Engineering, 5640 S Ellis Ave ERC 229, Chicago, IL 60637, USA.
Nanotechnology. 2016 Oct 28;27(43):435303. doi: 10.1088/0957-4484/27/43/435303. Epub 2016 Sep 23.
Full characterization of the three-dimensional structures resulting from the directed self-assembly (DSA) of block copolymers (BCP) remains a difficult challenge. Transmission electron microscope (TEM) tomography and resonant soft x-ray scattering have emerged as powerful and complementary methods for through-film characterization; both techniques require samples to be prepared on specialized membrane substrates. Here we report a generalizable process to implement BCP DSA with density multiplication on silicon nitride membranes. A key feature of the process developed here is that it does not introduce any artefacts or damage to the polymer assemblies as DSA is performed prior to back-etched membrane formation. Because most research and applications of BCP lithography are based on silicon substrates, process variations introduced by implementing DSA on a silicon nitride/silicon stack versus silicon were identified and mitigated. Using full-wafers, membranes were fabricated with different sizes and layouts to enable both TEM and x-ray characterization. Finally, both techniques were used to characterize structures resulting from the DSA of lamella-forming BCP with density multiplication.
对嵌段共聚物（BCP）定向自组装（DSA）所产生的三维结构进行全面表征仍然是一项艰巨的挑战。透射电子显微镜（TEM）断层扫描和共振软X射线散射已成为用于全膜表征的强大且互补的方法；这两种技术都需要在专门的膜基板上制备样品。在此，我们报告了一种可推广的工艺，用于在氮化硅膜上实现具有密度倍增的BCP DSA。此处开发的工艺的一个关键特征是，由于DSA是在背蚀刻膜形成之前进行的，因此不会对聚合物组件引入任何伪影或造成损坏。由于BCP光刻的大多数研究和应用都基于硅基板，因此确定并减轻了在氮化硅/硅堆栈上与在硅上实施DSA所引入的工艺变化。使用整片晶圆制作了具有不同尺寸和布局的膜，以实现TEM和X射线表征。最后，这两种技术都用于表征由具有密度倍增的层状BCP DSA产生的结构。
