Surface Dependent Electron and Negative Ion Density in Inductively Coupled Discharges;Journal Vacuum Science Technology

摘要

Electron and negative ion density have been measured in a modfied Applied Materials DPS metal etch chamber using gas mixtures of BCl(sub 3), Cl(sub 2) 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 percent patterned aluminum / photoresist. Electron densities in the Cl(sub 2) / BCl(sub 3) mixtures varied from 0.25 to 4 x 10(sup 11) cm(sup -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 intluence 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 two lower while the negative ion density was a factor of two higher than the aluminum or alumina surfaces.