Characterization and thermal stability of fluorosilicate glass films deposited by high density plasma chemical vapor deposition with different bias power

High-density plasma chemical vapor deposition (HDP-CVD) fluorosilicate glass (FSG) films were evaluated for the application of inter-metal dielectric (IMD) materials in current devices. Film characteristics were examined as a function of deposition/sputter etch (D/S) ratio, which was controlled by the bias power in HDP-CVD. FTIR spectra show that the positions of Si-O and Si-F peaks are independent of the bias power, but the Si-O shifted to a higher wave number and Si-F₂ appeared upon annealing for the films deposited at lower bias power. Stress hysteresis of the FSG films after the first thermal cycle shows a nonequilibrium nature of the microstructure related to impurity content, especially for the film deposited with lower bias power. Thermal desorption of H₂O, F, O₂ and Ar were examined, while most of the desorption behaviour can be related to the physical pore structure and pore quantity.