Comparison of novel punch-through diode (NPN) selector with MIM selector for bipolar RRAM

Recently, we have experimentally demonstrated a bipolar RRAM selector based on punch-through diode using an NPN stack by Si epitaxy (NPN selector). Historically, Metal-Insulator-Metal (MIM) selector has been a promising candidate as a bipolar RRAM selector due to low processing temperature which may enable back-end compatible stacked RRAM. In this report, we present an electrical performance comparison of the two technologies. NPN selector performance is obtained from experimentally calibrated TCAD simulations. A simple Fowler Nordheim (FN) and Direct Tunneling (DT) based model of MIM selector is chosen to evaluate performance (on-current, on-voltage and on/off current ratio). We show that MIM requires excess voltage for same on-off current ratio compared to NPN which undesirably increases RRAM array power consumption. Conversely, for the same operational voltage MIM selector has poorer on/off current ratio. Lower off-current capability enables NPN selectors to serve larger array sizes for comparable array leakage and consequently power loss.