Materials Science and Engineering Division, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
ACS Nano. 2014 Aug 26;8(8):8426-37. doi: 10.1021/nn5029289. Epub 2014 Aug 6.
The directed self-assembly (DSA) of block copolymers (BCP) is an emerging resolution enhancement tool that can multiply or subdivide the pitch of a lithographically defined chemical or topological pattern and is a resolution enhancement candidate to augment conventional lithography for patterning sub-20 nm features. Continuing the development of this technology will require an improved understanding of the polymer physics involved as well as experimental confirmation of the simulations used to guide the design process. Both of these endeavors would be greatly facilitated by a metrology, which is capable of probing the internal morphology of a DSA film. We have developed a new measurement technique, resonant critical-dimension small-angle X-ray scattering (res-CDSAXS), to evaluate the 3D buried features inside the film. This is an X-ray scattering measurement where the sample angle is varied to probe the 3D structure of the film, while resonant soft X-rays are used to enhance the scattering contrast. By measuring the same sample with both res-CDSAXS and traditional CDSAXS (with hard X-rays), we are able to demonstrate the dramatic improvement in scattering obtained through the use of resonant soft X-rays. Analysis of the reciprocal space map constructed from the res-CDSAXS measurements allowed us to reconstruct the complex buried features in DSA BCP films. We studied a series of DSA BCP films with varying template widths, and the internal morphologies for these samples were compared to the results of single chain in mean-field simulations. The measurements revealed a range of morphologies that occur with changing template width, including results that suggest the presence of mixed morphologies composed of both whole and necking lamella. The development of res-CDSAXS will enable a better understanding of the fundamental physics behind the formation of buried features in DSA BCP films.
定向自组装（DSA）嵌段共聚物（BCP）是一种新兴的分辨率增强工具，可以增加或减小光刻定义的化学或拓扑图案的节距，是一种增强常规光刻技术以实现小于 20nm 特征图形的分辨率增强候选技术。继续开发这项技术需要更好地了解所涉及的聚合物物理，以及对用于指导设计过程的模拟进行实验验证。这两个方面都可以通过一种能够探测 DSA 薄膜内部形态的计量技术得到极大的促进。我们已经开发出一种新的测量技术，即共振临界尺寸小角 X 射线散射（res-CDSAXS），用于评估薄膜内部的 3D 埋入特征。这是一种 X 射线散射测量技术，其中通过改变样品角度来探测薄膜的 3D 结构，同时使用共振软 X 射线来增强散射对比度。通过使用 res-CDSAXS 和传统的 CDSAXS（使用硬 X 射线）对同一样品进行测量，我们能够证明使用共振软 X 射线获得的散射显著增强。对从 res-CDSAXS 测量中构建的倒空间图谱的分析使我们能够重建 DSA BCP 薄膜中的复杂埋入特征。我们研究了一系列具有不同模板宽度的 DSA BCP 薄膜，并且将这些样品的内部形态与单链在平均场模拟中的结果进行了比较。测量结果揭示了随模板宽度变化而出现的一系列形态，包括表明存在由完整和颈缩层片组成的混合形态的结果。res-CDSAXS 的发展将使我们更好地理解 DSA BCP 薄膜中埋入特征形成背后的基本物理。
