| AVS 55th International Symposium & Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS1-WeM |
| Session: | Plasma-Surface Interactions in Materials Processing I |
| Presenter: | T. Kitajima, National Defense Academy of Japan |
| Authors: | T. Kitajima, National Defense Academy of Japan T. Nakano, National Defense Academy of Japan T. Makabe, Keio University, Japan |
| Correspondent: | Click to Email |
The nitridation of high-k HfSiO film surface by nitrogen plasma is an important process for enabling amorphous homogeneous film without phase separation at high temperatures.1 The relation of plasma generated species fluxes toward the film surface and the nitrogen incorporation degree of HfSiON is not well characterized. The authors have previously shown that the improved film quality of plasma grown SiO2 due to rare-gas dilution of O2 plasmas and its relation with the increased metastable O(1D) atom flux.2 Here we diagnose the ground and metastable N atom densities in rare-gas diluted N2 plasmas and relate the flux components with the N incorporation to the Hf Silicates. The ground N(4S) and metastable N(2D) density in the Ar diluted N2 ICP (70 MHz) is measured by the VUV absorption spectroscopy using 120 nm and 149.3 nm emissions from the discharge light source ( N(4P) -> N(4S) , N(2P) -> N(2D)). For the gas pressure of 100 mTorr and the ICP power of 100 W, N(2D) density is 2 x 1010 cm-3 in pure N2 and decreases to 1 x 1010 cm-3 at N2/(N2+Ar) ratio of 0.5 while N(4S) density stays at 7-8 x 1010 cm-3. N(2D) density increases to 3.5 x 1010 cm-3 of maximum with the decrease of N2/(N2+Ar) ratio to 0.1. The trend is also found for the case of He diluted N2 plasma. The decrease of N(2D) for N2 fraction of 100 to 50 % is due to the reduced dissociative excitation of N2 while the EEDF is kept stable. The increase of N(2D) for N2 fraction of 10 % is caused by the increase of high energy electrons due to the reduced energy loss by vibrational excitation of N2. Since the N(2D) / N(4S) ratio reaches 0.5, we expect collisional excitation of N(4S) is important source for N(2D). The nitrided HfSiO films are examined by XPS and the N incorporation is correlated to the expected N atom flux to the surface. Detailed growth results are shown in the presentation.
Authors thank the Suzuki Foundation for the partial support of conducting this study.
1M.A.Quevedo-Lopez, J.J.Chambers, M.R.Visokay, A.Shanware, and L.Colombo, Appl.Phys.Lett., 87, 012902 (2005).
2T.Kitajima, T.Nakano, and T.Makabe, JVST A. (to be published).