Effect of oxygen concentration on the spike formation during reactive ion etching of SiC using the mixed gas plasma of NF{sub 3} and O{sub 2}
- Department of Applied Chemistry, Graduate School of Engineering, Doshisha University, 1-3 Miyako-dani, Tadara, Kyotanabe, Kyoto 610-0321 (Japan) and Department of Molecular Science and Technology, Faculty of Engineering, Doshisha University, 1-3 Miyako-dani, Tadara, Kyotanabe, Kyoto 610-0321 (Japan)
Reactive ion etching (RIE) of poly-{beta}-SiC was investigated in the NF{sub 3}/O{sub 2} mixture gas plasma. The addition of 10% oxygen concentration to the NF{sub 3} plasma increased the etching rate to {approx}80 nm/min at a total pressure of 10 Pa and 997 nm/min at a total pressure of 20 Pa. The ratio of increase in etching rate against that in the pure NF{sub 3} plasma was {approx}43%. RIE for longer than 30 min in the 90% NF{sub 3} and 10% O{sub 2} mixture gas plasma gave a much smoother surface than that etched in the pure NF{sub 3} plasma. However, the further addition of O{sub 2} decreased the etching rate. Optical-emission spectra indicated the presence of an oxygen radical, in addition to fluorine radical and molecular nitrogen cations, in the NF{sub 3}/O{sub 2} mixture gas plasma. X-ray photoemission spectroscopy analysis of the etched samples revealed that the SiO{sub 2} layer was formed on the surface at the higher O{sub 2} concentration. The role of oxygen in the NF{sub 3}/O{sub 2} mixture gas plasma was elucidated. Scanning electron microscopy observation revealed that many thornlike substances, i.e., spikes, were formed on the SiC surface during RIE at the total pressure of 10 Pa. Images of the cross section of spike formed during RIE at the total pressure of 2 Pa also indicated that the sputtered aluminum particle from a mask may be preferentially deposited on the top of carbon-rich island formed on the SiC surface and act as a micromask together with carbon on the carbon-rich island to form a thornlike spike. An etching model of the SiC surface and the mechanism on formation and growth of the spike on the SiC surface in the NF{sub 3}/O{sub 2} mixture gas plasma are proposed.
- OSTI ID:
- 20979399
- Journal Information:
- Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films, Vol. 25, Issue 2; Other Information: DOI: 10.1116/1.2699473; (c) 2007 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1553-1813
- Country of Publication:
- United States
- Language:
- English
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