High‐aspect‐ratio oxide etching using CF4/C6F12O plasma in an inductively coupled plasma etching system with low‐frequency bias power

Abstract

AbstractHigh‐aspect‐ratio (HAR) etch of SiO2 films was attempted using a low‐frequency (2 MHz) bias power in an inductively coupled plasma (ICP) system using heptafluoroisopropyl pentafluoroethyl ketone (C6F12O) gas, which has a lower global warming potential (GWP). Etching characteristics of the oxide film according to changes such as the CF4/C6F12O mixing ratio, source power (13.56 MHz), and bias power were derived. To understand the etching characteristics and mechanism, optical emission spectroscopy (OES), double Langmuir probe (DLP) measurement, and X‐ray photoelectron spectroscopy (XPS) analysis were performed. We observed the vertically etched profile of the 100 nm etched line pattern with a scanning electron microscope (SEM) and at first suggested that the HAR oxide etching process is feasible using the ICP system.