Reset current reduction in phase-change memory cell using a thin interfacial oxide layer

Abstract

In this paper, the impact of a thin interfacial oxide layer on the main electrical characteristics of phase-change memory devices is investigated. Lance-type memory cells were fabricated and a thin film of TiO2 or HfO2 was interposed between the Ge2Sb2Te5 (GST) layer and the 300nm diameter tungsten (W) contact plug. Electrical analyses were performed and a large decrease of the reset current is obtained. In particular TiO2 and HfO2 cells yield about 78% and 60% of current reduction respectively compared to GST reference cells. A very good endurance (>10⁶ cycles) and programming window (2 orders of magnitude) were also observed. We confirm that the reset current reduction is mainly due to a decrease of the equivalent contact area and also to a better thermal efficiency.