Signal Integrity and Coupling Electric Field Analysis of a Novel Double-Layer RRAM Crossbar Array in Neuromorphic Chips

The 3-D stacking technology of crossbar arrays in neuromorphic chips offers significant potential for future storage and computing advancements. To reduce RC delay and increase interconnect density, this article proposes a novel double-layer resistive random access memory (RRAM) crossbar array structure with monolithic vias (MIVs), comprising two identical RRAM crossbar arrays on the top and bottom layers, vertically connected by four parallel MIVs. First, we extracted the equivalent circuit of the structure in ANSYS Q3D software, including resistance, parasitic inductance, and coupling capacitance. Subsequently, the spiking signal is added to the RRAM crossbar array to analyze the signal integrity problem from three perspectives: array size, coupling capacitance, and the presence or absence of parasitic inductance. The findings reveal that the increase in array size and coupling capacitance, and the presence of parasitic inductance can lead to signal integrity issues such as IR drop, crosstalk, and ripple. Furthermore, an electromagnetic coupling analysis is conducted to explore interactions between parallel and vertical interconnects during signal transmission. The findings highlight that adjusting the structure-to-ground distance significantly suppresses the coupling electric field, reducing its intensity from 10^6 to 10^4, thus improving system stability.