Seok-Pyo Song

Requirements of bipolar switching ReRAM for 1T1R type high density memory array

ReRAM has been researched as a promising candidate for diverse NVM application [1]. Still switching mechanism and classification are not clear, there are simply two kinds of switching polarity: unipolar and bipolar. Considering distribution, operation margin and so on, bipolar switching looks much attractive than unipolar. Along with a selective device, polarity of switching could make the architecture of cell array different. The Crossbar array structure has been considered an attractive solution for unipolar switching with diode. To make the crossbar array with bipolar switching devices, research on a new selective device such as MIEC [2] is much necessary to meet the requirements of current drivability and on/off properties. In addition, self-rectifying device [3–4] could be an alternative for a high density crossbar array. Recently, several research groups have shown very fast and high reliable device. It could be a good signal that ReRAM could have speed and endurance for DRAM or embedded applications. In case of those applications, 1T1R structure could be an effective and it could be used to check the feasibility by changing ReRAM cell with capacitor or MTJ. From now on, transistor has been mainly considered as a controller for the compliance current in set process. But the bipolar 1T1R structure for a high density array, there are several things to be considered, because a transistor would be acting as a changeable resistance at a set and reset process and its resistance goes up as the technology shrinks. So in this paper, we tried to figure out the requirements of bipolar ReRAM switching for the high density 1T1R memory array by changing reset current and symmetry of ReRAM devices.