Evaluation of silicon oxide cleaning using F2∕Ar remote plasma processing

Abstract

In this study, chamber cleaning experiments using a F2∕Ar remote plasma generated from a toroidal-type remote plasma source were carried out in a plasma enhanced chemical vapor deposition (PECVD) system. The cleaning processes for the various silicon oxide layers, including PE-oxide (deposited by PECVD using SiH4 and N2O), O3-TEOS oxide (deposited by thermal CVD using ozone and TEOS precursor), and BPSG (borophosphosilicate glass), were investigated by varying the various process parameters, such as the F2 gas flow rate, the F2∕(F2+Ar) flow ratio, and the cleaning temperature. The species emitted during cleaning were monitored by Fourier transformed infrared spectroscopy and residual gas analysis. Under the current experimental conditions, the cleaning rate of the BPSG was 4.1–5.0 and 3.9–7.3 times higher than that those of the PE-oxide and O3-TEOS oxide layers, respectively, at room temperature and an F2∕(F2+Ar) flow ratio of 28.5%–83%. As the cleaning temperature increased from 100 to 350 °C, the cleaning rates of the PE-oxide, O3-TEOS oxide, and BPSG layers were increased by factors of 2.0–3.0, 1.5–2.2, and 3.0–3.4, respectively, at an F2∕(F2+Ar) flow ratio of 28%–68%. The F2∕(F2+Ar) flow ratio and cleaning temperature were found to be the most critical parameters involved in determining the cleaning rate of the various oxide layers.