Thermal Stability of HfOx-Based Resistive Memory Array: A Temperature Coefficient Study

In HfO
_x
-based RRAM array, the temperature dependent shift of resistance at the low resistance state is statistically distributed. The differences in temperature dependent shifts among cells bring challenge to the reliability of analog or multilevel resistive switching behavior, namely thermal instability, which is characterized by the temperature coefficient (Tα) of RRAM. Its effect on RRAM performances was studied by pulse programming and retention measurement. Through atomistic simulation, this letter showed that thermal instability of cells with a positive Tα was related to the arrangement of oxygen vacancy inside the switching layer. Based on this model, the probability of cells with a positive Tα was found to be effectively reduced by introducing a baking process which led to an overall improvement of retention for the 1 k bit array.