Impact of MIM versus NPN selector on dynamic power in bipolar RRAM array

Traditionally, DC power reduction based on half-select based sneak-path leakage reduction has been the primary metric to evaluate the effectiveness of a selector technology in RRAM arrays. In this paper, we show that dynamic power is comparable and even dominant consideration. We compare MIM selector with NPN technology to compare DC and dynamic power. MIM selector has poor non-linearity and high capacitance due to the implementation with thin high-k dielectrics to ensure high on-current density. NPN selector has better non-linearity as well as lower capacitance as p-region can be thick without compromising non-linearity or on-current density. Consequently overall NPN has lower power based on both DC and dynamic power considerations. In NPN technology, dynamic power is comparable to DC power at sub-30nm nodes. It dominates at sub-15nm node at 100MHz while it dominates at sub-50nm nodes at 1GHz. Thus, selector technology needs to be evaluated and even optimized for dynamic power.