Effects of moisture and electrode material on AlN-based resistive random access memory

Resistive random access memory (RRAM) has been developed as a next-generation nonvolatile memory because of its fast operation speed, low power consumption, high density, and simple structure. Non-oxide materials such as AlN-based RRAM also exhibit low operation energy and large on/off ratios. However, AlN-based RRAM may deteriorate upon oxidation when exposed to air/moisture. In addition, chemical reactivity between the electrode and the switching layer material affects device stability. In this study, four kinds of top electrode materials (Al, Ti, TiN, and Pt) were used in an AlN/TiN stack and a water-resistant encapsulation layer was used to prevent the degradation of AlN-based RRAM. The electrical properties of the device were measured at weekly intervals for 7 weeks. The devices containing Al and Ti top electrodes showed degradation of resistance states despite being encapsulated in a thin Al2O3 layer. In contrast, the devices with TiN and Pt electrodes maintained their resistance states and switching properties regardless of the encapsulation layer. These trends in degradation can be explained by the electrode and AlN reactivity with moisture based on fundamental thermodynamics.