| AVS 64th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Tuesday Sessions |
| Session PS-TuP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | Isao Yoshida, National Institute of Advanced Industrial Science and Technology (AIST), Japan |
| Authors: | S. Nunomura, National Institute of Advanced Industrial Science and Technology (AIST), Japan K. Katayama, National Institute of Advanced Industrial Science and Technology (AIST), Japan Y. Yoshida, National Institute of Advanced Industrial Science and Technology (AIST), Japan |
| Correspondent: | Click to Email |
In plasma processing, a hydrogen (H) atom is a key species (a radial) that strongly influences the gas-phase reactions and surface reasons. So, the investigation on H atom reaction kinetics is beneficial for controlling the gas-phase species and the material surface property. Here, we study the H atom generation and loss kinetics in low-pressure capacitively coupled plasmas (CCP).
We performed the H density measurement in CCP in two different configurations of electrodes: direct and remote configurations. In direct configuration, the processing material was exposed into the plasma, whereas in the remote configuration, the processing material was separated from the plasma by the metal mesh to reduce the ion bombardment and charging. The H atom density was quantitatively determined from vacuum ultra violet absorption spectroscopy (VUVAS) [1]. We found that the H atom density was strongly reduced across the mesh electrode in the remote configuration. For example, the H atom density was varied from ~1x1010 cm-3 in the discharge region to ~1x1012 cm-3 in the processing region for our mesh geometry of 0.2 mm thickness and 36% aperture ratio [2].
The fluid model simulations for CCP discharges have been performed to study the details of the H atom generation, diffusion and recombination kinetics [2]. The simulation yielded the H atom density of~1.0 x 1012 cm-3, which was in good agreement with that measured by VUVAS. The H atoms are generated mainly in the discharge region, via two processes: the electron impact dissociation (e + H2 => e + 2H) and the ion-molecule reaction (H2+ + H2 => H3+ + H). For the loss of H atoms, it is dominated by the surface recombination on the electrode. In the presentation, more details of experimental and simulation results are presented.
The authors are grateful to Dr. Y. Abe (Tokyo Tech.), Prof. N. Ezumi (U. Tsukuba), and Prof. N. Ohno (Nagoya U.) for valuable discussions. This work was supported in part by New Energy and Industrial Technology Development Organization (NEDO) and JSPS KAKENHI (Grant Number 24540546 and 15K04717)
References :
[1] S. Takashima, M. Hori, T. Goto and K. Yoneda, J. Appl. Phys. 89 (2001) 4727.
[2] S. Nunomura, H. Katayama, and I. Yoshida, Plasma Sources Sci. Technol. 26 (2017) 055018.