Silicon dioxide dry etching by a consumable solid source and He plasma

The semiconductor and photonics industries rely heavily on gases, such as fluorocarbons, hydrofluorocarbons, perfluorinated compounds, and chlorofluorocarbons, for plasma-based processing. However, those gases have a high global warming potential. In the context of increasing sustainability demands and regulatory constraints, alternative etching approaches are urgently needed. This work presents a proof-of-concept method for the dry etching of silicon dioxide (SiO2) using a solid fluorocarbon source activated by helium plasma. The etching species are generated in situ from fluorocarbon solid material, which is gradually consumed during processing. This eliminates the need for continuous gas flow and significantly reduces emissions associated with both gas supply and abatement systems. The process achieves uniform SiO2 etching at rates exceeding 50 nm/min and enables the fabrication of nanostructures with lateral dimensions below 300 nm and aspect ratios greater than 5. The solid-source approach offers a promising pathway toward more sustainable and long-lasting plasma etching solutions, with potential to reduce the environmental footprint of micro- and nanofabrication processes.