An improvement in the uniformity of resistive switching behaviors by embedding Cu nanodots is observed in Ta2O5 memory cells. In the conventional device structure, the growth of conductive filaments tends to be random and uncontrollable, which is the major obstacle for memory cell fabrication. By using a bottom electrode covered in metal nanodots, the field distribution in the electrolyte layer is modified and the conductive filaments prefer to grow along the direction of the Cu nanodots. Such controlled growth of conductive filaments leads to a reduced variation of switching parameters, as well as the disappearance of an unpredictable multistep resistive switching phenomenon, which is helpful for improving the device stability. Meanwhile, scaling relations are used to reveal the relationship between switching parameters and the microstructure of conductive filaments. By overlapping the scaling relations and electric field simulation, a model is proposed to explain the improvement in resistive switching performance caused by the presence of embedded Cu nanodots.