Paper PS1-ThM9
Ground and Metastable Atom Densities in Rare-Gas Diluted O₂ and N₂ Plasmas and Silicon Oxynitride Growth

Thursday, October 18, 2007, 10:40 am, Room 606

The application of rare gas diluted O₂ plasmas for oxide growth have gained interests due to the improved growth rate and film property. Metastable O atoms produced by rare gas metastables may contribute to the enhanced diffusion or reaction of the oxygen atoms at the interface of the film and the substrate. We have shown the increase of the metastable O(¹D) atoms produced in the rare gas diluted O₂ plasma by VUV absorption spectroscopy.¹ The kinetics of the increased O(¹D) atoms and the film growth can be explained by the deduced atom flux using diffusion model. In the study, we extend the scheme to the nitridation of silicon and finally to the oxynitride growth. The ground state N(⁴ S) density in the rare gas diluted N₂ CCP is measured by the VUV absorption spectroscopy using 120 nm emission from the discharge light source ( N(⁴ P) -> N(⁴ S) ). N(⁴ S) density is 8 x 10¹⁰ cm^-3 for 0.5 Torr and 30 W in pure N₂ CCP and stays 5 x 10¹⁰ cm^-3 even for 1 % of N₂ fraction in Ar diluted N₂ plasma. The trend is also found for the case of He diluted N₂ plasma and should be due to the reduced energy loss of electrons by vibrational excitation. The grown nitrides are examined by the depth profiles of XPS and the growth rate corresponds to the trend of N(⁴ S) density. Detailed results and the case of oxynitrides are shown in the presentation.

¹T.Kitajima, T.Nakano, and T.Makabe, Appl. Phys. Lett. 88, 091501 (2006).