Study Of SiN X -Doped SbTe Phase-Change Materials For Phase-Change Random Access Memory

Recent years, with the rapid development of portable electronic equipment, there is an increasing demand for nonvolatile memory technology. Currently, the most widely used nonvolatile memory is flash memory. However, because of the limit of flash storage mechanism, the scaling of flash memory is a bottleneck for further development. Phase change random access memory (PRAM) has been regarded as the promising candidate for the next-generation nonvolatile memories due to its excellent characteristics such as smaller scale, nonvolatile, long cycle life, low power consumption, fast read/write speed, and compatibility with CMOS technology. The phase change material Ge-Sb-Te (GST) film is most widely used in PRAM devices. However, several critical problems still remain to be improved and resolved. Si element has been added into SbTe film to form Si-Sb-Te phase change film. SST material has better amorphous stability, higher crystalline resistivity and lower melting temperature than GST material. But in SST film, Te was found to separate out concomitant with crystallization process. In order to stabilize the phase structure of the film, SiNx-doped SbTe films were prepared and studied in this letter, we have done mainly the following work:1. SbTe films doped with different SiNx concentrations were prepared. By XRD, TEM and in situ ?lm resistance measurements, we studied the microstructure and the electrical properties. The TEM and XRD analyses indicate that the microstructure of SiNx-doped SbTe films is the rhombohedra Sb2Te3 grains surrounded by amorphous SiNx boundaries, which can also be regard as the SiNx-SbTe nanocomposite. The SiNx amorphous matrix acting as microheaters and the higher crystalline resistivity of the SiNx-SbTe films can reduce the RESET current of PCM by using SiNx-SbTe film. In situ measurements of ?lms have shown that with the increase of SiNx concentration, the crystallization temperature, activation energy of crystallization and amorphous state stability of SiNx- SbTe films increased.2. A memory device based on SiNx-doped SbTe film was fabricated. The device has a memory switching characteristics. The device can be SET at the pulse 2.2V-80ns-50ns (Pulse amplitude - Pulse width - Pulse failing edge) and RESET at the pulse 4.2V-20ns-5ns.