Materials and Processes for Emerging Memories

Resistive memories such as STT-MRAM, RERAM and PCRAM use many elements, alloys and compounds that are not used in traditional semiconductor memory and even logic devices. Even newer FERAM materials based on doped HfOx, require optimizing crystal structure to get ferro-electric properties, that are not typically preferred for logic devices. For all these materials, requirements such as precise thickness in sub Angstrom values, precise composition control, surface smoothness and texture control become very critical. In addition, etching of these materials provide new challenges because halogens used in traditional RIE are in many cases too aggressive for some of these materials. The focus of this paper is on status of deposition (PVD and ALD) and etching approaches used for resistive memories. Blanket film data as well as some typical electrical behavior obtained from metalinsulator-metal (MIM) pillar structures is presented.