Ta2O5 Interfacial Layer between GST and W Plug enabling Low Power Operation of Phase Change Memories

A novel memory cell for phase-change memories (PCMs) that enables low-power operation has been developed. Power (i.e., current and voltage) for the cell is significantly reduced by inserting a very thin Ta
₂
O
₅
film between GeSbTe (GST) and a W plug. The Ta
₂
O
₅
interfacial layer works not only as a heat insulator enabling effective heat generation in GST but also as an adhesion layer between GST and SiO
₂
underneath. Nonetheless, sufficient current flows through the interfacial layer due to direct tunneling. A low programming power of 1.5 V/100 muA can therefore be obtained even on a W plug with a diameter of 180 nm fabricated using standard 0.13-mum CMOS technology. In addition, the uniformity and repeatability of cell resistance are excellent because of the inherently stable Ta
₂
O
₅
film properties