| AVS 62nd International Symposium & Exhibition | |
| Plasma Science and Technology | Friday Sessions |
| Session PS+SS+TF-FrM |
| Session: | Atomic Layer Etching (ALE) and Low-Damage Processes II |
| Presenter: | Masatoshi Kawakami, Hitachi High-Technologies, Japan |
| Authors: | M. Kawakami, Hitachi High-Technologies, Japan D. Metzler, University of Maryland, College Park C. Li, University of Maryland, College Park G.S. Oehrlein, University of Maryland, College Park |
| Correspondent: | Click to Email |
The requirement for atomic scale etching is becoming more important with increasing miniaturization of semiconductor devices. A novel approach for oxide etching has been developed by Metzler et al [1]. Controlled etching of SiO2 at the angstrom-level is based on steady-state Ar plasma and deposition of a thin reactive fluorocarbon layer enabled by precise, periodic C4F8 injection. High process stability is necessary for the success of this method and its use in mass production. Chamber wall interactions are crucial to the stability of this process. In this research, we studied the influence of chamber wall temperature and chamber wall chemical state on ALE process performance. The experiments were conducted in an inductively coupled plasma system excited at 13.56 MHz. The temperature of the quartz coupling window was measured with an infrared temperature sensor. In situ real time ellipsometry allows for film thickness measurements during the process. Plasma gas-phase chemistry was characterized by optical emission spectroscopy. We conducted the cyclic Ar/C4F8 SiO2 ALE process using different initial chamber temperature, and chamber wall polymer coverage condition. It was found that although the polymer film thickness deposited in each cycle is constant, the etching behavior changed, likely related to a change in depositing species. Chamber wall temperature shows a clear effect on the CO and SiF emission and their relative ratio. When the surface of the quartz coupling window started to be covered by a fluorocarbon film, the overall CO and SiF intensity decreased while the CO/SiF emission peak ratio did not change. The relationship to observed etching behavior will be discussed.
The authors gratefully acknowledge financial support of this work from National Science Foundation (CBET-1134273) and US Department of Energy (DE-SC0001939).
References:
[1]D. Metzler, R. Bruce, S. Engelmann, E.A. Joseph, and G.S. Oehrlein, J Vac Sci Technol A 32, 020603 (2014)