Reliability-Enhanced Reverse Forming Operation Scheme for Analog Resistive Random-Access Memory

This study presents a novel reverse forming (RevF) operation scheme to enhance the multi-bit programming reliability of analog resistive random-access memory (RRAM), which is essential for advancing computing-in-memory (CIM) technology. The proposed RevF method uses a series of progressively intensified RESET operations following the initial forming process. The RevF scheme significantly strengthens the unstable conductive filaments (CF) at the bottom of the HfO2 resistive switching layer (RSL) and reduces excessive oxygen ions in the TaOx thermal enhanced layer (TEL). Array-level experimental evaluations on a fully integrated 128Kb RRAM chip showcase a 3-fold reduction in the post-programming conductance instability (i.e., relaxation effect), as quantified by the relative deviation (RD), and a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{6}}$ </tex-math></inline-formula>-fold enhancement in the retention time. To further verify the effectiveness and advantage of the RevF scheme, a classical denoising diffusion probabilistic model (DDPM) is implemented, yielding significantly enhanced image quality compared to the conventional operation scheme.