Study of Si-doped Sb2Te3 films for phase change memory

Silicon doped Sb2Te3 films were deposited by three target (Si, Sb and Te) co-sputtering. For comparison, Ge2Sb2Te5 and Sb2Te3 films were also prepared. Memory cells (pore size = 10 mu m x 10 mu m) were fabricated by micro-fabrication to further study their storage performance. Results indicate that silicon doping increases the crystallization temperature. Meanwhile, silicon doping drastically enhances the resistivity ratio (high resistance state/low resistance state) to 10(6) by increasing both amorphous resistivity and crystal resistivity so as to further increasing the ON/OFF ratio of memory cell. Compared with Ge2Sb2Te5 film, 16at%Si-Sb2Te3 film has a higher crystalline resistivity and lower melting temperature, which are helpful to the reduction of RESET current. Memory cell with silicon doped Sb2Te3 film poccesses memory storage characteristics, and it can be reversibly switched between the high resistance state (RESET status) and the low resistance state (SET status). The SET status can be triggered by electrical pulse of 3 V, 500 ns and it comes back to the RESET status when 4 V, 20 ns pulse is applied, while Ge2Sb2Te5 cells, with the same structure can't be switched back to RESET state.