Capacitive Synaptor with Overturned Charge Injection for Compute-in-Memory

A capacitive synaptic transistor (synaptor) compatible with the fabrication process of conventional Flash memory is proposed for compute-in-memory (CIM) array cells to support energy-efficient inference operations. This synaptor demonstrates the highly reliable endurance characteristic of program/erase (P/E) due to overturned charge injection occurring between a control gate (CG) and a floating gate (FG) rather than between the FG and a channel. On-and off-state capacitances (Con and Coff) are determined by the area ratio of CG and FG. After optimizing the pulse conditions, we achieved the P/E endurance of at least 10⁷ cycles and retention time of 10⁴ sec.