The optimization of sawtooth gratings using RCWA and its fabrication on a slanted silicon substrate by fast atom beam etching

Abstract

This paper presents scalar and vector analyses of sawtooth gratings with a period of 2.0 µm in terms of Fourier transformation and rigorous coupled wave analysis (RCWA) and its fabrication on a slanted silicon substrate by a newly proposed fast atom beam (FAB) etching method. First, the optical and geometrical properties of sawtooth gratings were investigated and optimized under the phase-matching requirement, and the 1st diffraction efficiency for TM polarization and the scalar approximation, 73.0% and 100%, were estimated, respectively. Second, sawtooth gratings optimized by two diffraction analysis methods were successfully fabricated by the FAB etching method. Last, by a hot-embossing process suitable for mass production, 100 µm thick poly-methyl methacrylate (PMMA) material was replicated from a sawtooth-patterned silicon substrate, and its 1st diffraction efficiency for TM polarization, 63.0%, was measured from optical testing.