Gate oxide integrity improvement by optimising poly deposition process

The gate oxide integrity of oxide thickness 13.5 nm has been studied for different amorphous poly deposition conditions. The poly grain was varied by the poly deposition conditions. The study, which was carried out on BiCMOS devices, showed substantial reliability degradation in the gate oxides when using amorphous poly deposition at temperatures of 550 /spl deg/C versus 530 /spl deg/C and thickness of 60 nm versus 65 nm. A possible mechanism for the drastic reliability degradation is the protrusion of poly grains into the softening oxide at high temperature.