Improvement of fabrication accuracy of vertically curved silicon waveguide optical coupler using hard mask shielded ion implantation bending

Abstract

Abstract To obtain high device fabrication uniformity and reproducibility for vertically curved silicon waveguide optical coupler, we developed the high accuracy ion implantation bending (IIB) method by incorporating a tungsten mask that can partially shield the ion implantation. The developed IIB method improved the positional accuracy of the origin of vertically curved Si wire bending from a wet etching-level of 1 μm order to a dry etching-level of several 100 nm order, and we obtained a fabrication accuracy of about less than ±0.4 μm of the tip position of the Si-wire vertically curved structures.