Paper MS-ThP7
Fabrication of Deeply Striped Pattern Structures by ICP-RIE Technique on the Lithium Niobate Substrate

Thursday, November 13, 2014, 6:00 pm, Room Hall D

In this study, striped pattern structures with linewidth of 5 μm and 10 μm on lithium niobate (LiNbO₃) substrate were fabricated by the inductively coupled plasma reactive ion etching (ICP-RIE) technique for the waveguide applications. Pure nickel (Ni) thin film of 300 nm in thickness used as the etching mask and was deposited by sputtering technique on the LiNbO₃ substrate with a 20 nm adhesion layer of nickel-chrome (Ni-Cr) alloy with a composition ratio of 80/ 20. The LiNbO₃ substrates with the Ni etching mask was etched in the boron trichloride (BCl₃)/ Argon (Ar) mixed etching gas which flow ratio was controlled at 30/ 5 SCCM and the working pressures controlled at 30 mTorr, 40 mTorr, 50 mTorr, and 60 mTorr, respectively. The ICP powers were controlled from 100 W to 600 W and the RF powers were controlled from 100 W to 500 W during 45 minutes of each ICP-RIE process.

From the experimental results, it can be found that the DC bias (-V) decreases with the working pressure, and increases with the ICP powers and the RF powers. Under suitable ICP-RIE etching parameters, the structure with 6 μm in depth and the sidewall angle of 80° was successfully prepared on the the surface of LiNbO₃ substrate, which the etch selectivity ratio was 10 and the etching rate was 70 nm/ min.