IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Plasma Science Monday Sessions
       Session PS-MoP

Paper PS-MoP10
Atomic-Order Plasma Nitridation of Ultrathin Silicon Dioxide Films

Monday, October 29, 2001, 5:30 pm, Room 134/135

Session: Plasma Diagnostics and Plasma-Surface Interactions Poster Session
Presenter: T. Seino, Tohoku University, Japan
Authors: T. Seino, Tohoku University, Japan
T. Matsuura, Tohoku University, Japan
J. Murota, Tohoku University, Japan
Correspondent: Click to Email
Atomic-order nitridation of SiO@sub 2@ by a nitrogen plasma without substrate heating has been investigated using an ECR plasma apparatus. A 3nm-thick SiO@sub 2@ was thermally grown by wet oxidation of Si(100) at 700@super o@C. The SiO@sub 2@ film was nitrided by the nitrogen plasma for 1-324 min at the N@sub 2@ pressure of 1.3-2.6Pa with the microwave power of 200W. After plasma nitridation, some samples were annealed at 400-800@super o@C for 1hour in nitrogen. The depth profile was obtained by the repetition of etching by a 1%-diluted HF solution and XPS measurements. When the incident ions were exposed directly on the surface, the number of the incident ions (the product of the ion density and the plasma exposure time) was 3x10@super 15@-9x10@super 18@cm@super -2@, and the N1s peaks were observed at 397-398eV and at 402eV. With increasing nitrogen plasma exposure time, the N1s peak at 398eV shifted to 397eV corresponding to Si@sub 3@N@sub 4@. By annealing at 400-800@super o@C after nitridation, the N1s peak at 402eV disappeared. The depth profiles for the N1s peak at 397-398eV were almost the same before and after annealing. By a shutter placed above the wafer, the number of the incident ions was suppressed to 5x10@super 14@-1x10@super 16@cm@super -2@ and the ion energy (below 20eV) became lower than that (below 30eV) without the suppression of the incident ions, and the N1s peak was observed only at 399eV. By annealing at 600-800@super o@C after nitridation, the N atom concentration at 399eV was decreased due to the diffusion of the N atoms. This result is similar to the thermal nitridation of SiO@sub 2@ by NH@sub 3@. It is also found that the N atom concentration was normalized by the number of the incident ions in spite of the ion energy and the radical density. From these results, it is considered that the nitridation is caused mainly by the incident ions. It is suggested that the ion energy changes the binding conditions of N atoms in SiO@sub 2@.