Fundamentals of topographic substrate leveling.

The leveling of 100 - 500micron wide, 1 micron deep isolated holes and trenches by 1 - 3micron thick silicon oil films was observed by measuring film thickness changes at the centers of the features using a non-contact, interferometric technique. The dependence of the leveling time t on feature width w, film viscosity eta and the initial film thickness h sub o was investigated and compared to theoretical predictions. Experimental data were obtained for various values of w, eta and h sub o. Except when the film thickness was about 1micron the data for each different type of geometry fall on a single curve when the degree of leveling or planarization is plotted against T = tgamma h sub o sup 3 /eta w sup 4 where gamma is the surface tension of the film. At the same value of T, the degree of planarization of isolated holes was about twice that of isolated trenches.