The dependence of Q(BD) on the combined post annealing conditions of RTA and FA in the tungsten polycide gate technology has been experimentally investigated. In the case of RTA to be processed after FA, Q(BD) is controlled by the amount of fluorine diffused into the oxide, and then it is decreasing as increasing RTA temperature and time. However, in the vice-versa case, Q(BD) shows the poor characteristics because of the effect of lightly activated polysilicon. Based on these experimental results, the combined post annealing with FA/RTA sequence is useful to obtain the high Q(BD) performance.