| AVS 65th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Tuesday Sessions |
| Session PS+EM+SE-TuM |
| Session: | Plasma Processing of Challenging Materials - I |
| Presenter: | Takayoshi Tsutsumi, Nagoya University, Japan |
| Authors: | T. Tsutsumi, Nagoya University, Japan T. Ueyama, Nagoya University, Japan K. Ishikawa, Nagoya University, Japan H. Kondo, Nagoya University, Japan M. Sekine, Nagoya University, Japan Y. Ohya, Tokyo Electron Miyagi Limited M. Hori, Nagoya University, Japan |
| Correspondent: | Click to Email |
Dual frequency pulsed capacitively coupled plasma with a synchronous negative DC-bias to a top electrode is developed for the improvement of high-aspect-ratio contact hole (HARC) fabrications. It enables to suppress the distorted etched profiles such as twisting. These distortions are due to the distortions of ion trajectories inside the deep contact holes, which are charged up positively. It is expected that charged species presented in early afterglow were neutralized on the surfaces in the holes. we focus on the behavior of charged species in the afterglow period of the synchronous negative DC-bias imposition to the top electrode in the pulsed dual frequency CCP.
For temporal change of electron density in the afterglow, the synchronous negative DC-bias resulted in lower decay rate of electron density in afterglow1. The result indicate that higher DC-bias imposition causes more electron generation. Moreover, the decay rate near the bottom electrode is lower than that of near the top electrode. The possible explanation is electron generation or sustaining mechanism in the afterglow of DC synchronized pulsed plasma. We measured OES to confirm the electron generation or plasma sustainment in the afterglow. The intensities of Ar emission (at a wavelength of 750.38 nm) in afterglow decreased at the beginning of RF off period and increased after several μs. This phenomenon was not observed in the constant DC-bias condition.
The synchronous DC-bias voltage seems to accelerate the positive ions to the top electrode. And ion bombardment to the top electrode surface enhance the generation of the secondary electron in the afterglow. We consider that this influence the generation of negative ions and the neutralization of the charged surface of the hole in afterglow.
1T. Ueyema, Y. Fukuanga, T. Tsutsumi, K. Takeda, H. Kondo, K. Ishikawa, M. Sekine, M. Iwata, Y. Ohya, H. Sugai, and Hori, Jpn. J. Appl. Phys. 56, 06HC03 (2017).