Fluorinated silicon nitride: Properties and device applications.

The deposition chemistry and properties of Class I p-SiN:F films have been explored in more detail. NH sub 3 acts an effective nitrogen source when added to p-SiN:F feed mixtures, but the resulting films have more N-H bonding than those prepared from SiH sub 4 - NF sub 3 - N sub 2. Plasma deposited p-SiN:F and p-SiN:H films have comparable step coverage. In accelerated aging tests the degradation times for CMOS devices capped with Class I p-SiN:F were comparable to those of uncoated controls. By contrast, degradation was accelerated about 20-fold by p-SiN:H caps deposited in a production line. The chemical stabilization and electrical properties of unstable Class II films have been studied. Highly unstable Class II films show a current hysteresis (slow traps) which may be caused by ionic transport. Films that form only a thin surface oxide exhibit excellent properties. New data show high frequency-deposited p-SiN:F has fewer trap centers and a lower dielectric constant than low frequency-deposited films. The dielectric strength of good Class I, high frequency-deposited films was constant to 500 MHz with a negligible loss term.