A novel phase change material, Si2Sb2Te3 has been reported to show good phase change abilities. Etching of this material is a critical step in the fabrication of phase change memory devices. In this paper, the characteristics of Si2Sb2Te3 etched in CF4/Ar atmosphere are investigated. The influence of the etching rate and surface roughness with different CF4/Ar ratio, pressure, and power are systematically studied. Furthermore, our X-ray photoelectron spectroscopy test results show that Te is the bottleneck to accelerating the etching rate.
A phase change memory cell based on Ge0.5Sb2Te3/Ti0.6Sb2Te3 double-layer structure is proposed for 3-level storage. The fabricated cell can realize 3-level storage ability by both current and voltage operation. Cycling ability has been proved better than 2×103. Thermal simulation shows that the resistivity difference between the two materials can greatly affect the temperature distribution in the cell. More heat will be generated in the amorphous Ge Ge0.5Sb2Te3/ film when the current flow through due to the higher resistivity. And the lower crystallization temperature of Ge0.5Sb2Te3/compared to that of Ti0.6Sb2Te3 ensures its priority of crystallization, which makes the 3-level storage feasible.