Atomic layer etching of SiO₂ using trifluoroiodomethane

Herein, atomic layer etching (ALE) of silicon dioxide (SiO2) was performed using trifluoroiodomethane (CF3I) in a capacitively coupled plasma reactor. First, a fluorocarbon polymer was deposited using CF3I plasma to fluorinate the SiO2 surface. Second, the deposited polymer and fluorinated SiO2 were removed using O-2 plasma. By optimizing various process variables, an etch rate per cycle of 9.3 angstrom was obtained with a controlled source power of 300 W. In addition, a self-limiting characteristic was confirmed during the CF3I exposure for the polymer deposition in the first step, as well as during the O-2 exposure for polymer removal in the second step. Finally, the remnant iodine on the etched substrate was analyzed because CF3I contains iodine. Iodine compounds were generated during the SiO2 ALE process.