Suppression of boron penetration in PMOS by using oxide gettering effect in poly-Si gate

A new stacked poly-Si gate structure with a thin (∼20 A) oxide inserted in-between for p-channel metal-oxide semiconductor feild effect transistor (pMOSFET) application is proposed and demonstrated. Due to the gettering fluorine effect of this thin oxide for BF 2 + -implanted poly-Si gate, the amount of fluorine in the gate oxide, consequently, the boron penetration enhanced by fluorine are reduced. The thicker or the more apart from the gate oxide of this gettering fluorine oxide is, the more effectively it can suppress the boron penetration. Moreover, this new structure improves more the electrical characteristics than the conventional and the stacked layer poly silicon gate structures