Atomic layer etching of SiO2 using trifluoroiodomethane

[Display omitted] •Atomic layer etching (ALE) of SiO2 using a non-global warming gas, CF3I, is studied.•Based on XPS results, a model is proposed to explain the changes that occurred on the SiO2 surface.•Self-limiting characteristic was observed in the SiO2 ALE process.•The SiO2 ALE process using CF3I results in formation of remanent iodine compounds. 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 O2 plasma. By optimizing various process variables, an etch rate per cycle of 9.3 Å 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 O2 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.