Process-Induced ReRAM Performance Improvement of Atomic Layer Deposited HfO2 for Analog In-Memory Computing Applications
We evaluated atomic layer deposition (ALD) for the growth of HfO2 for integration in resistive RAM (ReRAM) test structures on 300mm wafers in order to optimize electrical performance for use as synaptic device elements in analog in-memory computing. The effect of ALD oxidant was evaluated and it was shown that H2O outperformed O3 in terms of better uniformity and lower forming voltage. By utilizing H-based plasma after deposition or inserted as an intermediate step during deposition, we were able to further decrease forming voltage for a fixed dielectric thickness. Reducing deposition temperature to 200°C in conjunction with the H-based plasma treatment resulted in additional reduction in forming voltage. Stable high-resistance switching with analog behavior in scaled BEOL devices was obtained using this HfO2-based ReRAM. Additionally, a tight distribution of forming voltage was obtained ensuring that 99.9999% of devices in a 14nm ReRAM module can be formed below the targeted voltage.