Angular dependence of Si{sub 3}N{sub 4} etch rates and the etch selectivity of SiO{sub 2} to Si{sub 3}N{sub 4} at different bias voltages in a high-density C{sub 4}F{sub 8} plasma
- School of Chemical and Biological Engineering, Seoul National University, San 56-1, Shillim-dong, Kwanak-ku, Seoul 151-744 (Korea, Republic of)
The dependence of Si{sub 3}N{sub 4} etch rates and the etch selectivity of SiO{sub 2} to Si{sub 3}N{sub 4} on ion-incident angles was studied for different bias voltages in a high-density C{sub 4}F{sub 8} plasma. A Faraday cage and specially designed substrate holders were used to accurately control the angles of incident ions on the substrate surface. The normalized etch yield (NEY), defined as the etch yield obtained at a given ion-incident angle normalized to that obtained on a horizontal surface, was unaffected by the bias voltage in Si{sub 3}N{sub 4} etching, but it increased with the bias voltage in SiO{sub 2} etching in the range of -100 to -300 V. The NEY changed showing a maximum with an increase in the ion-incident angle in the etching of both substrates. In the Si{sub 3}N{sub 4} etching, a maximum NEY of 1.7 was obtained at 70 deg. in the above bias voltage range. However, an increase in the NEY at high ion-incident angles was smaller for SiO{sub 2} than for Si{sub 3}N{sub 4} and, consequently, the etch selectivity of SiO{sub 2} to Si{sub 3}N{sub 4} decreased with an increase in the ion-incident angle. The etch selectivity decreased to a smaller extent at high bias voltage because the NEY of SiO{sub 2} had increased. The characteristic changes in the NEY for different substrates could be correlated with the thickness of a steady-state fluorocarbon (CF{sub x}) film formed on the substrates.
- OSTI ID:
- 21020873
- Journal Information:
- Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films, Vol. 25, Issue 5; Other Information: DOI: 10.1116/1.2757180; (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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