A Study on the High-Aspect-Ratio Oxide Etching Characteristics Using a Trifluoroiodomethane with a Low Global Warming Potential

In this study, high-aspect-ratio (HAR) oxide etching characteristics in inductively coupled plasma (ICP) was investigated using low frequency (2 MHz) bias power. For HAR oxide etching, a Trifluoroiodomethane (CF3I) with a low global warming potential of 1 was used, as an alternative gas for CF4 gas. An experiment was conducted using X/C4F8/He(X = CF3I, CF4) as the mixed gas. 100 nm (etch area)/500 nm (mask area) line patterns were used, and the etch cross section and etch selectivity of the amorphous carbon layer thin film were derived using a scanning electron microscope (SEM). Ion density was extracted using a double Langmuir probe, and CFx and F neutral species were observed via optical emission spectroscopy. In this work, we extracted the very vertically etched profile of the high aspect ratio oxide patterns using CF3I gas chemistry at the ICP etching system. The etching characteristics of the oxide films was also investigated. Based on these results, the possibility for HAR oxide etching using CF3I gas chemistry was suggested in this work. These results also indicate that the use of CF3I gas can significantly reduce global warming concerns and contribute to the development of next-generation HAR oxide etching process.