Etching with Low Te Plasmas

Monday, 2 October 2017: 10:20
Chesapeake L (Gaylord National Resort and Convention Center)
S. G. Walton (U.S. Naval Research Laboratory), D. R. Boris (U. S. Naval Research Laboratory), S. C. Hernandez (Naval Research Laboratory), S. G. Rosenberg (ASEE Postdoctoral Fellow - residing at NRL), H. Miyazoe, A. V. Jagtiani, S. U. Engelmann (IBM, T.J. Watson Research Center), and E. A. Joseph (IBM Research Division, T.J. Watson Research Center)
Processing with atomic layer precision requires the ability to not only add, remove or modify one monolayer of material but to also leave adjacent layers unchanged. This requires fine control over the flux of species and energy deposition at the surface. The appropriate threshold and process windows are certainly material specific but it is reasonable to assume many applications require low energy ions. Electron beam-generated plasmas are generally characterized by high charged particle densities (1010- 1011 cm-3), low electron temperatures (0.3 - 1.0 eV), and in reactive gas backgrounds, a relatively low radical production rate compared to discharges. The flux at the surface will thus be characterized by a comparatively large amount of ions whose energies are < 5 eV, a value commensurate with the bond strength of most materials. As such, these sources are well-suited to explore processing space not commonly found in industrial tools. In this work, we discuss SiN etching using pulsed, electron beam generated plasmas produced in SF6 backgrounds. We pay particular attention to the etch rates, selectivity (vs. carbon films, Si and SiO2), and patterning as function of operating parameters such as relative gas concentration, operating pressure, and substrate bias. These results are compared with plasma diagnostics to gain a better understanding of the process requirements and windows for threshold etching of SiN. This work is partially supported by the Naval Research Laboratory base program.