RELIABILITY IMPROVEMENT OF THIN OXIDE BY DOUBLE DEPOSITION PROCESS OF SILICON USING CHEMICAL-VAPOR-DEPOSITION

The degradation of thin oxide by polysilicon-diffused POCl3 and the reliability improvement of thin oxide by the silicon deposition method were studied. Phosphorus in polysilicon-doped POCl3 degraded the thin oxide qualities. Oxide degradation is increased with the decrement of sheet resistance and polysilicon thickness. In situ double deposition (IDD) of amorphous silicon and polysilicon at 540-degrees-C/30 nm and 625-degrees-C/220 nm, respectively, created a mismatched structure of the grain boundary at the interface. This structure suppresses the segregation of excess phosphorus on the oxide surface, thus maintaining the oxide property.