[20p-438-1~21] 8.2 Plasma deposition of thin film, plasma etching and surface treatment

▼ [20p-438-11] Molecular dynamics simulation of hole etching in SiO₂ by energetic fluorocarbon ion injection

〇(M1)Charisse Cagomoc¹, Michiro Isobe¹, Kazuhiro Karahashi¹, Takuya Hirohashi², Junichi Hashimoto², Mitsuhiro Omura², Hisataka Hayashi², Satoshi Hamaguchi¹ (1.Osaka University, 2.Toshiba Memory Corp.)

Keywords:molecular dynamics, etching

As the semiconductor devices have continued to shrink and their sizes have reached nanometer scales, the control of fabrication processes for such devices has become extremely challenging. For example, the granularity of the structure reflecting the finiteness of atomic sizes and the stochasticity of atomic motion may affect the topography of etched structures. In this study, to understand such atomic-scale effects in nano-scale fabrication processes, we have performed molecular dynamics (MD) simulations of SiO₂etching by energetic fluorocarbon ions. In the etching process, a carbon (diamond or amorphous carbon) film having a 4-nm diameter hole was used as a mask. In our study, the incident ion energy was typically set in the range from 200eV to 1000eV. For example, in the case of CF₃⁺ion injections, it has been observed that the etched depth increases with the incident ion energy and the bottom of the etched hole becomes narrower (i.e., the etched hole becomes tapered at the bottom) as the etched depth increases. This is because sputtered Si and O atoms from the inner wall of the etched hole tend to be redeposited on the opposite side of the inner wall. Furthermore, it has been observed that the inner wall is highly fluorinated, especially near the opening (i.e., top) of the hole. The fluorination of the inner wall increases its sputtering by energetic ion impact.