Adsorption and Recovery using Vaporization of Liquid Fluorocarbon Precursor

Abstract

PFC gas is primarily used during the etching process in the manufacture of ULSIs and in cleaning after CVD processes. PFC is classified as a greenhouse gas that stays in the atmosphere for a long time and has a high GWP. High capacity and high integration have been achieved in recent years as semiconductor device structures have been replaced by vertical layer structures, and the consumption of PFC gas has exploded due to the increase in high aspect ratio and patterning processes. Therefore, many researchers have been working on methods to decompose, recover, and reuse the gas after the etching process to reduce the emissions of PFC gas. In this study, etching and recovery processes were performed using C5F8 in L-FC which is in liquid phase at room temperature. Among the L-FCs, C5F8 gas has a high C/F ratio, similar to that of the C4F8 gas, which is a conventional PFC gas. In addition, to confirm its reusability, the recovered C5F8 was injected back into the chamber, and the electron temperature, plasma density, and ion energy distribution were analyzed. Based on these experimental data, the reliability of the etch processes performed with recovered C5F8 gas was evaluated, and the possibility of reusing the recovered C5F8 gas was confirmed.