Recovery of silicon surface after reactive ion etching of SiO₂ using CHF₃/C₂F₆ plasma

The effects of SF₆ or NF₃ gas plasma and subsequent rapid thermal anneal (RTA) treatment for the recovery of modified silicon surfaces after reactive ion etching (RIE) with CHF₃/C₂F₆ plasma were investigated using X-ray photoelectron spectroscopy and secondary ion mass spectrometry. NF₃ or SF₃ plasma treatment effectively removed the residue layer and impurities in the silicon substrate were removed by the subsequent RTA treatment at 700°C. The effects of NF₃ or SF₆ plasma and the additional RTA treatment in recovering the reactive ion etched silicon surface were also studied by measuring the leakage current densities and the barrier heights of posttreated PtSi/n-type Si Schottky barrier diodes. The minimum leakage current and the maximum barrier height were obtained after NF₃ plasma and subsequent RTA treatment, which constitute the most probable recovery process for silicon surfaces contaminated by RIE.