In this study, the SiO 2 etch characteristics of perfluorocarbon such as C 4 F 8 , C 5 F 8 , and C 7 F 8 were investigated using inductively coupled plasmas (ICPs) to study the effect of a high C/F ratio on the etch characteristics of SiO 2 for the ICP. The SiO 2 rates and etch selectivities over Si 3 N 4 and amorphous carbon layer (ACL) were measured by using the mixtures of C x ( x = 4, 5, 7)F 8 /Ar/O 2 . The higher C/F ratio of perfluorocarbon showed lower SiO 2 etch rate but exhibited higher etch selectivities over Si 3 N 4 and ACL due to the higher C 2 while keeping the similar F in the plasma as observed by optical emission spectroscopy and due to the thicker fluorocarbon layer with more carbon-rich fluorocarbon on the materials surface as observed by X-ray photoelectron spectroscopy. Especially, C 7 F 8 is environmentally benign material because it not only has a relatively low global warming potential but also can be captured easily using a capture system (a liquid state at the room temperature). Therefore, C 7 F 8 could be applicable as one of the next generation perfluorocarbon etching materials.
No takes yet. Share an insight, caveat, or question.
Sung et al. (2020) studied this question.