Analysis of cotton-like silica contaminants induced by oxygen containing plasma stripping of organic structures on silicon wafer

The issue of unwanted cotton-like silica contaminants formed in oxygen containing plasma stripping of organic sacrificial structures on Si substrates is discussed in this paper. The mechanism is developed with specific reference to three common polymer materials in oxygen plasma etching, which is an indispensable process in most MEMS/IC fabrications. The experiments support that exposed silicon, organic structure, plasma bombardment and oxygen containing environment are four essential factors; and the density and shape of the silica residues are mostly determined by the original vertical and planar dimensions of the organic structures. More experiment results manifest that the residues can be avoided or removed with proper methods.