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

The stress-temperature relationship of silica spin-on-glass thin films on s ilicon wafers was studied. Upon heating, the stress-temperature curves show ed a dramatically increasing slope when the temperature of the film was gre ater than 340 degrees C. At 450 degrees C, a significant, irreversible chan ge in the stress of the film was observed. This change in stress was correl ated with an increase in film electron density and a decrease in film thick ness. The observed thermally activated stress-relaxation behavior was inter preted in terms of reflow of the glassy hydrogen-silsesquioxane-based mater ial. (C) 2000 American Institute of Physics. [S0003-6951(00)02704-2].