Silicon V grooves fabricated using Ta2O5 etch mask prepared by room-temperature magnetron sputtering

Abstract

A tantalum pentoxide (Ta2O5) etch mask process has been developed in the fabrication of silicon V grooves for precision positioning of optical fibers. The relationship between the Ta2O5 etch mask undercutting and the etching temperature of a mixture of ethylenediamine, pyrocatechol, and water (EDP) was studied. The Ta2O5 etch mask with a thickness of 500 nm was deposited by radio-frequency magnetron sputtering at room temperature on both sides of a 4 in. (100) Si substrate. Desired patterns were formed on the substrate using a dielectric lift-off technique. Etching temperatures of EDP ranging from 90 to 120 °C have been tested for the process. The undercut was found to decrease with the increasing etching temperature of EDP. At the etching temperature of 120 °C, an undercut of 1.61±0.13 μm using the Ta2O5 etch mask was achieved.