Lateral resolution in laser-patterned thermal processing of GaAs

Time-dependent two-dimensional calculations are employed to estimate the limits placed, by thermal diffusion, on the lateral resolution of thermally-activated excimer-laser-induced patterned processing of GaAs. Sinusoidal and rectangular fluence profiles are used for holographic or projection exposure. Despite thermal diffusion, holographic exposure can result in feature sizes well into the nanostructure regime, except for low activation energy processes conducted at low peak temperatures. In projection patterning, pattern fidelity is severely affected by thermal diffusion. In this case, reasonably rectangular process profiles can only be obtained for feature sizes as large as several microns, unless hard process thresholds and/or stopping layers are involved.