Simulation And Analysis On Resistance Performance Of Phase Change Memory Element

Phase change memory(PCM)is the most promising candidate for the next generation of non-volatile memory due to its low power,re-writable,high durability and small size.PCM can be reversibly switched between the amorphous phase(highly resistive)and the crystalline phase(less resitive),the difference between high resistance and low resistance determines the storage capacity.In order to improve the storage performance,it is of great significance to study the resistance performance of the PCM cell.Based on the storage principle of the PCM cell and the finite element method,the physical model of bottom-up structure and the mathematical model of the PCM cell are established to simulate the phase change process.The incremental amplitude pulses and the equal amplitude pulses are designed to be applied on the PCM cell for RESET operation,the pulse parameters and the geometrical size of the PCM cell are studied.First,the pulse parameters will affect the phase distribution and the resistance of PCM cell,comparing the incremental amplitude pulse with single pulse,the larger the pulse width is,the smaller difference of the PCM cell resistance between the two types of pulse,when the pulse width is larger than 60 ns and the pulse amplitude is larger than 0.95 V,the difference between the two types of pulse is significantly reduced.Comparing the incremental amplitude pulse with the incremental amplitude,the heating rate of the equal amplitude pulses is faster than the incremental amplitude pulses,but it is easier to achieve partial amorphous by the work of incremental amplitude pulse than the equal amplitude pulses,so the PCM cell's resistance can be controlled to get different resistance levels and achieve multi-value storage.Second,changing the geometrical size of the PCM cell,the thickness of the phase change layer will affect the heating rate,the minimum pulse width required for the RESET process will increase with the thickness of the phase change layer.Under the same pulses applied,the larger the heating electrode height is,the greater the crystallization ratio of the PCM cell is.As the contact area between the heating electrode and the phase change layer is getting smaller,the reset current of the PCM cell will decrease due to the current crowding effect,and the speed of resistance growth will increase.Changing the contact area and the heating electrode ratio,the impact of contact area size on the storage performance isgreater than the heating electrode.When the size of the PCM cell changes,the optimal size can reach a certain resistance in the shortest time and speed up the programming rate,then reduce power consumption.Under the work of the different types of pulse,the resistance can be changed by adjusting the pulse parameters and the geometrical size of PCM cell.