[11a-PA2-1~17] 3.2 Equipment optics and materials

[11a-PA2-7] Antireflective surface with a step in the taper: Numerical optimization and large-area fabrication

〇Kotaro Dai¹, Lingfeng Shen¹, Kei Shinotsuka¹ (1.Oji Holdings Corp.)

Keywords:Antireflection, Micro- and nano- fabrication

In this study, we developed a practical method to improve the optical performance of subwavelength antireflective two-dimensional (2D) gratings. A numerical simulation of both convex and concave paraboloids suggested that surface reflectivity drastically decreases when a step is introduced in the taper. The optimum height and depth of a step provided average reflectance of 0.040% for concave protrusions in the visible range. Furthermore, a stepped paraboloid was experimentally fabricated by colloidal lithography and dry etching. A cyclo-olefin polymer (COP) reverse replica (concave) imprinted by the Si mold exhibited a measured reflectance of 0.077% on average in the visible range. It was also demonstrated that the antireflective structure was fabricated on the whole surface of a 6 inch Si wafer, which is a sufficient size for industrial utilization.