AVS 65th International Symposium & Exhibition
    Plasma Science and Technology Division Monday Sessions
       Session PS+AS+EM+SS-MoM

Paper PS+AS+EM+SS-MoM1
Atomic-scale Numerical Simulation of a Nanometer-Scale Hole Etching of SiO2 with a Carbon Mask

Monday, October 22, 2018, 8:20 am, Room 104A

Session: Plasma-Surface Interactions
Presenter: Charisse Marie Cagomoc, Osaka University, Japan
Authors: C.M. Cagomoc, Osaka University, Japan
M. Isobe, Osaka University, Japan
S. Hamaguchi, Osaka University, Japan
Correspondent: Click to Email
The current generation of mass-produced semiconductor devices uses nanometer-scale technologies to fit millions of transistors in a single chip. However, the demand for higher integration density is still increasing. For example, sub-10 nanometer transistors have been already established for experimental devices, and fabrication technologies of such devices for mass production are now being developed. For nanometer-scale fabrication processes, the granularity of the structure reflecting the finiteness of atomic sizes and the stochasticity of atomic motion may play important roles in determining the final structure. In this study, to understand such atomic-scale effects in nano-scale fabrication processes, we performed molecular dynamics (MD) simulations of etching processes for silicon dioxide (SiO2) with a carbon mask having a 4-nm diameter hole by energetic fluorocarbon ions. The incident ion energy was typically in the range from 200eV to 1000eV. For example, in the case of CF3+ ion injections, we observed that the depth of the etched out SiO2 increased with increasing incident ion energy while the channel width became narrower as the etching of SiO2 went deeper. Tapering of the carbon mask was also observed when the incident ions hit and deform the mask instead of going straight towards the SiO2. Furthermore, if the incident energy was too high (e.g., 1000 eV in this case), closing of the carbon mask hole occurred due to the formation of long carbon chains that moved across the hole and were bonded to the opposite side. Deposition of carbon atoms from the mask onto the sidewalls of the etched SiO2 was also observed, which caused the formation of silicon carbide and may have impeded horizontal etching of SiO2.