Effects of fluorine incorporation on ultrathin (4 nm) gate oxide integrity were investigated by fluorine co-implantation into p(+) polysilicon gate. In contrast to previous reports that fluorine incorporation worsens boron penetration and degrades oxide reliability, it was observed that with a medium F+ dose (similar to 1 x 10(14) cm(-2)), charge-to-breakdown characteristics can be improved without noticeable enhancement of boron penetration. It was also observed that fluorinated oxide depicts improved immunity to plasma damage as is evidenced by suppressed gate leakage current of antenna devices after plasma processing.