Electron, ion and vacuum ultraviolet photon effects in 193 nm photoresist surface roughening

Low temperature plasma exposure of methacrylate-based 193 nm photoresist (PR) can result in enhanced surface roughening or smoothing, but mechanisms are poorly understood. We present measurements of 193 nm PR surface roughness following exposure to 1 keV electron beams in various combinations with positive ion and vacuum ultraviolet (VUV) photon irradiation. Electron beams will scission or cross-link 193 nm PR under low and high fluence exposure, respectively. When coupled to simultaneous ion/VUV photon irradiation, low fluence (scissioning) electrons amplify surface roughening while high fluence (cross-linking) electrons reduce surface roughness. These results further suggest that enhanced roughening of 193 nm PR is initiated by the synergistic interaction between an ion bombardment-induced carbon-rich surface layer (∼2 nm) and a sicssioned bulk layer (∼100 nm).