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Surface dependent electron and negative ion density in inductively coupled discharges

1999; American Institute of Physics; Volume: 17; Issue: 6 Linguagem: Inglês

10.1116/1.582040

1520-8559

G. A. Hebner, Matthew G. Blain, T. W. Hamilton, C. A. Nichols, Robert Jarecki,

Semiconductor materials and devices

Electron and negative ion density have been measured in a modified Applied Materials decoupled plasma source commercial metal etch chamber using gas mixtures of BCl3, Cl2 and Ar. Measurements were performed for four different substrate types to examine the influence of surface material on the bulk plasma properties: aluminum, alumina, photoresist, and 50% patterned aluminum/photoresist. Electron densities in the Cl2/BCl3 mixtures varied from 0.25 to 4×1011 cm−3. Photodetachment measurements of the negative ion density indicate that the negative ion density was smaller than the electron density and that the electron to negative ion density ratio varied between 1 and 6. The presence of photoresist had a dominant influence on the electron and negative ion density compared to alumina and aluminum surfaces. In most cases, the electron density above wafers covered with photoresist was a factor of 2 lower, while the negative ion density was a factor of 2 higher than the aluminum or alumina surfaces.