A study has been undertaken to determine the effect of ion‐implanted fluorine on the properties of SiO2for use as a gate dielectric in MOS devices.C‐Vmeasurements and bias‐temperature stressing showed that mobile‐ion drift can be compensated for by the implanted ions. Further tests showed that it is the implant damage and not the ion itself which was responsible for the compensation. uv excitation of the samples was used in an attempt to identify the nature of the compensation effect, but the results are not definitive.