Uncovering Phase Change Memory Energy Limits by Sub-Nanosecond Probing of Power Dissipation Dynamics

Phase change memory (PCM) is one of the leading candidates for neuromorphic hardware and has recently matured as a storage class memory. Yet, energy and power consumption remain key challenges for this technology because part of the PCM device must be self-heated to its melting temperature during reset. Here, it is shown that this reset energy can be reduced by nearly two orders of magnitude by minimizing the pulse width. A high-speed measurement setup is utilized to probe the energy consumption in PCM cells with varying pulse width (0.3–40 nanoseconds) and uncover the power dissipation dynamics. A key finding is that the switching power (P) remains unchanged for pulses wider than a short thermal time constant of the PCM (τ_th < 1 ns in 50 nm diameter device), resulting in a decrease of energy (E = P × τ) as the pulse width τ is reduced in that range. Thermal confinement during short pulses is achieved by limiting the heat diffusion time. The improved programming scheme reduces reset energy density below 0.1 nJ µm⁻², over an order of magnitude lower than state-of-the-art PCM, potentially changing the roadmap of future data storage technology and paving the way toward energy-efficient neuromorphic hardware.