Investigation of Reverse Filament Formation in ITO/HfO2-based RRAM

To overcome the large discrepancy in speed between computational devices and that of contemporary large capacity non-volatile memory (NVM) technologies, resistive random access memory (RRAM) technologies are seen as promising candidates, offering speed/energy improvements in several orders of magnitude while being 3D integration compatible [1]. Indium-Tin-Oxide (ITO) has several unique properties for RRAM operation, perhaps most prominently the self-compliance and an ultra-low switching voltage (±200 mV) [2]. We report on considerations for ITO electrical bottom electrode (BE) RRAM where we vary the ALD oxide deposition parameters in order to improve the reverse filament formation (RFF) occurring at large reset voltages. RFF is when the conducting filament is reformed. One of the key parameters of RRAM is the endurance, how many times it can switch before failure. The RFF is one of the limitations in the number of switches until a device reaches failure and it is thus of high importance to ensure a sufficient margin between the highest applied reset voltage and the RFF voltage not to compromise the endurance. We optimized the oxide to improve the RFF properties.