Ion attachment mass spectrometry of nonequilibrium atmospheric-pressure pulsed remote plasma for SiO{sub 2} etching

An etching process for SiO{sub 2} that employs atmospheric-pressure pulsed remote plasma with a mixture gas (CF{sub 4}/Ar) has been demonstrated. The etch rate increased by increasing the pulse frequency and also increased rapidly with the addition of a small amount of O{sub 2} gas. A SiO{sub 2} etch rate of 400 nm/min was obtained without any bias supplied to the substrate, and more than 8 {mu}m/min was obtained with H{sub 2}O addition. The exhaust gas from the plasma source was investigated using ion attachment mass spectrometry (IAMS). With IAMS, the polymerized species were measured without the generation of fragment ions. The results suggest that HF molecules are generated by H{sub 2}O addition to CF{sub 4} and that the etch rate of SiO{sub 2} depends on the density of HF molecules.