Thermally induced stress relaxation and densification of spin-on-glass thin films

Abstract

The stress–temperature relationship of silica spin-on-glass thin films on silicon wafers was studied. Upon heating, the stress–temperature curves showed a dramatically increasing slope when the temperature of the film was greater than 340 °C. At 450 °C, a significant, irreversible change in the stress of the film was observed. This change in stress was correlated with an increase in film electron density and a decrease in film thickness. The observed thermally activated stress–relaxation behavior was interpreted in terms of reflow of the glassy hydrogen–silsesquioxane-based material.