Determining the Resolution Limits of Electron-Beam Lithography: Direct Measurement of the Point-Spread Function

• Published in: Nano letters 2014-08, Vol.14 (8), p.4406-4412
• Main Authors: Manfrinato, Vitor R, Wen, Jianguo, Zhang, Lihua, Yang, Yujia, Hobbs, Richard G, Baker, Bowen, Su, Dong, Zakharov, Dmitri, Zaluzec, Nestor J, Miller, Dean J, Stach, Eric A, Berggren, Karl K
• Format: Article
• Language: English
• Subjects: Collective excitations (including excitons, polarons, plasmons and other charge-density excitations); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Lattice dynamics; Materials science; Methods of nanofabrication; Nanolithography; Phonons in low-dimensional structures and small particles; Physics; Surface and interface electron states
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl5013773

One challenge existing since the invention of electron-beam lithography (EBL) is understanding the exposure mechanisms that limit the resolution of EBL. To overcome this challenge, we need to understand the spatial distribution of energy density deposited in the resist, that is, the point-spread function (PSF). During EBL exposure, the processes of electron scattering, phonon, photon, plasmon, and electron emission in the resist are combined, which complicates the analysis of the EBL PSF. Here, we show the measurement of delocalized energy transfer in EBL exposure by using chromatic aberration-corrected energy-filtered transmission electron microscopy (EFTEM) at the sub-10 nm scale. We have defined the role of spot size, electron scattering, secondary electrons, and volume plasmons in the lithographic PSF by performing EFTEM, momentum-resolved electron energy loss spectroscopy (EELS), sub-10 nm EBL, and Monte Carlo simulations. We expect that these results will enable alternative ways to improve the resolution limit of EBL. Furthermore, our approach to study the resolution limits of EBL may be applied to other lithographic techniques where electrons also play a key role in resist exposure, such as ion-beam-, X-ray-, and extreme-ultraviolet lithography.