Characterization of high rate deposited PECVD silicon dioxide films for MCM applications

Silicon dioxide has recently received considerable attention as an interlayer dielectric for use in multichip modules (MCMs) because of its excellent properties. A high deposition rate at relatively low temperatures is desirable for process compatibility and high throughput. PECVD silicon dioxide films up to 7 μm thick were deposited at 1000 angstrom/min in a showerhead type system using SiH4, N2O, and N2. Substrate temperature was varied from 250-350°C. The deposited films were annealed at various temperatures (up to 500°C). Uniformity, etch rate, film stress, refractive index, Si 2p and O 1s binding energies, and Si-H and OH bonding configurations were studied. C-V and I-V characterizations of the films were performed to investigate their electrical quality. All the as-deposited films exhibited moderate compressive stress. A considerable change in stress was observed after annealing the films in the above noted temperature range. OH content in the films was found to decrease and the hydrogen content in the films was found to increase with increasing deposition temperature. A good correlation between silanol (Si-OH) and hydrogen content and silicon richness of the films with film stress was observed. The refractive index was found to decrease with increasing anneal temperature for all the films. Etching rates were lower for films deposited at higher temperatures. All films exhibited excellent breakdown characteristics.