Nanofacility Piemonte, Istituto Nazionale di Ricerca Metrologica , Strada delle Cacce 91, Torino 10135, Italy.
Dipartimento di Scienze e Innovazione Tecnologica (DIST), Università del Piemonte Orientale "A. Avogadro", INSTM , Viale T. Michel 11, Alessandria 15121, Italy.
ACS Appl Mater Interfaces. 2017 May 10;9(18):15685-15697. doi: 10.1021/acsami.7b00509. Epub 2017 Apr 26.
The self-assembly (SA) of diblock copolymers (DBCs) based on phase separation into different morphologies of small and high-density features is widely investigated as a patterning and nanofabrication technique. The integration of conventional top-down approaches with the bottom-up SA of DBCs enables the possibility to address the gap in nanostructured lateral length standards for nanometrology, consequently supporting miniaturization processes in device fabrication. On this topic, we studied the pattern characteristic dimensions (i.e., center-to-center distance L and diameter D) of a cylinder-forming polystyrene-b-poly( methyl methacrylate) PS-b-PMMA (54 kg mol, styrene fraction 70%) DBC when confined within periodic SiO trenches of different widths (W, ranging between 75 and 600 nm) and fixed length (l, 5.7 μm). The characteristic dimensions of the PMMA cylinder structure in the confined configurations were compared with those obtained on a flat surface (L = 27.8 ± 0.5 nm, D = 13.0 ± 1.0 nm). The analysis of D as a function of W evolution indicates that the eccentricity of the PMMA cylinders decreases as a result of the deformation of the cylinder in the direction perpendicular to the trenches. The center-to-center distance in the direction parallel to the long side of the trenches (L) is equal to L measured on the flat surface, whereas the one along the short side (L) is subjected to an appreciable variation (ΔL = 5 nm) depending on W. The possibility of finely tuning L maintaining constant L paves the way to the realization of a DBC-based transfer standard for lateral length calibration with periods in the critical range between 20 and 50 nm wherein no commercial transfer standards are available. A prototype transfer standard with cylindrical holes was used to calibrate the linear correction factor c(Δx') of an atomic force microscope for a scan length of Δx' = 1 μm. The relative standard uncertainty of the correction factor was only 1.3%, and the second-order nonlinear correction was found to be significant.
两亲嵌段共聚物（DBC）通过相分离自组装（SA）形成具有小尺寸和高密度特征的不同形态，被广泛研究作为一种图案化和纳米制造技术。将传统的自上而下方法与 DBC 的自下而上 SA 相结合，使得有可能解决纳米计量学中纳米结构横向长度标准的差距，从而支持器件制造中的小型化过程。在这个主题上，我们研究了受限在不同宽度（W，范围在 75 到 600nm 之间）和固定长度（l，5.7μm）周期性 SiO 沟槽内的圆柱形成聚苯乙烯-b-聚（甲基丙烯酸甲酯）PS-b-PMMA（54kgmol，苯乙烯分数 70%）DBC 的 PMMA 圆柱结构的特征尺寸（即中心到中心距离 L 和直径 D）。将受限结构中 PMMA 圆柱结构的特征尺寸与在平面上获得的特征尺寸（L=27.8±0.5nm，D=13.0±1.0nm）进行了比较。D 作为 W 演化函数的分析表明，由于圆柱在垂直于沟槽的方向上的变形，PMMA 圆柱的偏心率减小。平行于沟槽长边方向的中心到中心距离（L）等于在平面上测量的 L，而沿短边方向的距离（L）则会发生明显变化（ΔL=5nm），这取决于 W。通过保持 L 不变来精细调整 L 的可能性为基于 DBC 的横向长度校准转移标准铺平了道路，该标准的周期处于 20 到 50nm 的关键范围内，目前尚无商业转移标准可用。使用具有圆柱形孔的原型转移标准来校准原子力显微镜的线性校正因子 c(Δx')，对于扫描长度Δx'=1μm。校正因子的相对标准不确定度仅为 1.3%，并且发现二阶非线性校正非常显著。
