Three-Dimensional Finite Element Analysis of Phase Change Memory Cell with Thin TiO₂ Film

A thin TiO₂ layer inserted in a phase change memory (PCM) cell to form a deep sub-micro bottom electrode (DBE) is proposed and its electro-thermal characteristics are investigated with the three-dimensional finite element analysis. Compared with the conventional PCM cell with a SiN stop layer, the reset threshold current of the PCM cell with the TiO₂ layer is reduced from 1.8 mA to 1.2 mA and the ratio of the amorphous resistance and crystalline resistive increases from 65 to 100. The optimum thickness of the TiO₂ layer and the optimum height of DBE are 10nm and 200nm, respectively. Therefore, the PCM cell with the TiO₂ layer can decrease the programming power consumption and increase heating efficiency. The TiO₂ film is a better candidate for the SiN film in the PCM cell structure to prepare DBE and to reduce programming power in the reset operation.