Etching Characteristics of Low-k Dielectric Using C5H2F10 Liquefied Gas Plasma for Mitigating of Global Warming Potential

Abstract

In this work, we studied the etch characteristics and dielectric constant change of SiOC thin films by plasma etching for the fabrication of nanoscale devices to evaluate the C5H2F10 as alternative etching gas. We performed plasma etching of SiOC films with inductively coupled plasma using the CF4+X+O2 mixed gas, where X = CHF3 and C5H2F10. Plasma diagnosis such as optical emission spectroscopy and double Langmuir probe measurements were carried. We analyzed the chemical compositions of residues on the etched SiOC film surface using X-ray photoelectron spectroscopy. After the process, contact resistance was measured using the transmission line method to analyze the degree of polymer on the surface of the silicon. Ellipsometry were used to evaluate the change in the dielectric constant of the thin film due to plasma exposure. It was confirmed that the etched profile was more vertical than that of the CHF3 gas plasma, and the increase in the dielectric constant of the SiOC thin film by C5H2F10 gas plasma is less than that of CHF3 gas plasma. These results confirmed that C5H2F10 gas was a powerful alternative to CHF3 gas in semiconductor processing for the fabrication of nanoscale devices.