Improved plasma charging immunity in ultra-thin gate oxide with fluorine and nitrogen implantation

The effects of fluorine and nitrogen incorporation on ultra-thin gate oxide integrity (GOI) were investigated by implanting fluorine and nitrogen into poly gate or Si substrate. It is observed that fluorine and nitrogen implantation into Si substrate prior to oxidation can be used to obtain multiple oxide thickness, albeit its effectiveness is drastically reduced for N₂O-nitrided oxide. Gate leakage measurements performed on antenna devices show that charging damage can be significantly reduced for fluorine- or nitrogen-implanted devices with O₂ oxide. On the other hand, fluorine-alone implant is useful to reduce the gate leakage of antenna devices with N₂O oxide. Finally, improved CMOS GOI, even for p-channel devices, is actually achieved for the first time with medium-dose fluorine implantation, without causing noticeably worsened boron penetration.