The effects of HfO2 crystallinity depending on the crystallintiy of the underlying electrode material on the device characteristics and reliability for resistance random access memory are investigated. HfO2 film on TiN electrode as a gap fill material for the bottom electrode contact, which has a polycrystalline structure, shows the degradation of the resistive switching characteristics possibly due to the local crystallization of HfO2 film on the crystallized TiN electrode. On the contrary, HfO2 film on TiAlN electrode, which has an amorphous structure, shows the excellent switching and endurance characteristics owing to controlling the crystallization of HfO2 film. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3591439] All rights reserved.