In this paper, we will evaluate model assisted rule base SRAF. Model assisted rule base SRAF combines the advantage of both model based SRAF and rule base SRAF to ensure high process margin without the mask making difficulty with stable wafer output. Model will assist in generating a common rule for rule based SRAF. Method to extract the rule from the models will first be discussed. Model assisted rule based SRAF will be applied to 3Xnm DRAM contact. Evaluation and analysis of the simulated and actual wafer result will be discussed. Our wafer result showed that by applying Model assisted rule based SRAF showed nearly equal performance to models based SRAF with clearly better stability and mask fabrication feasibility.