ISSN:
1077-3118
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Simulations of charging and profile evolution during etching of high aspect ratio polysilicon gates in typical high-density plasmas containing heavy ions (e.g., BCl3+, Cl2+), predict a reduction in charging and notching when lighter ions (e.g., He+) are added. The reduction occurs because of the influence of the ion mass on the ratio R of the ion sheath transit time to the rf period, which determines the spread in the ion energy distribution at the wafer. The effect is most pronounced when R≤0.1–0.2 for light ions and, simultaneously, R≥0.6 for heavy ions; then, more light ions arrive at the patterned structure with low energies, where they help decrease localized charging. When the rf bias frequency is reduced so that R≤0.3 for all ions, the effect disappears. © 1997 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.119988
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