Suppression of Poly Depletion Effect by Optimizing Ion Implantation and Rapid Thermal Annealing Process in 55nm Nor Flash Technology

Poly depletion effect (PDE) results in unstable PMOS device performance in 55nm nor flash technology. Optimized boron ion implantation and rapid thermal annealing process are proposed to suppress poly depletion effect by increasing the concentration of dopants at poly-gate oxide interface. It is experimentally revealed that the variation of PMOS devices can be significantly improved by 60%~95% through these optimizations. Among them, returning spike RTA, advanced process typically adopted at 55nm node, to soak RTA has great potential for completely suppressing PDE and improving device performance.