| AVS 56th International Symposium & Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS-TuA |
| Session: | Fundamentals of Plasma-Surface Interactions I |
| Presenter: | T.-Y. Chung, University of California, Berkeley |
| Authors: | T.-Y. Chung, University of California, Berkeley D.G. Nest, University of California, Berkeley G.K. Choudhary, University of California, Berkeley J.J. Végh, University of California, Berkeley D.B. Graves, University of California, Berkeley F. Weilnboeck, University of Maryland, College Park G.S. Oehrlein, University of Maryland, College Park E.A. Hudson, Lam Research Corp. M. Li, Dow Electronic Materials D. Wang, Dow Electronic Materials |
| Correspondent: | Click to Email |
Previous vacuum beam studies showed that PMMA-based 193 nm photoresist (PR) will roughen due to the synergistic effects of ion bombardment, vacuum ultraviolet (VUV) photon flux and substrate heating [1]. FTIR measurements show that VUV photons break C-O bonds to a depth of about 100 nm in this PR. Using the same vacuum beam apparatus, we show that electron beam exposure (energies ~ 103 eV) of this PR results in similar C-O bond breaking. However, the effect of e-beams on PR roughening is very different from that of VUV photons. Electron beams can either promote or inhibit roughening with simultaneous ion and VUV photon exposure, depending on electron fluence. At high electron fluence, simultaneous e-beam/VUV/ion exposure appears to suppress VUV/ion-induced roughening. By contrast, lower fluence e-beams amplify the synergistic effects of ions and VUV photons, increasing roughness. It is known from electron beam resist studies that low fluence e-beams scission PMMA, but higher electron fluences induce cross-linking [2]. We tentatively conclude that any effect that amplifies PR scissioning during ion bombardment increases roughening, whereas any effect that induces cross-linking will suppress roughening. Finally, we discuss the nature of the dynamic changes occurring within the PR during separate and simultaneous exposures of ions, VUV photons and electrons.
[1] Nest, D., et al., Synergistic effects of vacuum ultraviolet radiation, ion bombardment, and heating in 193 nm photoresist roughening and degradation. Applied Physics Letters, 2008, 92(15).
[2] Hatzakis, M., Electron resists for microcircuit and mask production. Journal of the Electrochemical Society, 1969. 116(7): p. 1033.