Papers by Keyword: PRAM

Abstract: Risk management is the key factor to projects success, while the integrated risk management based on the life cycle of engineering project is an inevitable trend. With project lifecycle management and integrated thought as theoretical basis, this paper has introduced some related concepts about the integrated risk management based on the life cycle of engineering project, constructed the risk management model based on the PRAM (project risk analysis and management) method, and has discussed integrated management of project risk, combined with the characteristics of modern engineering projects.

Abstract: This paper describes structure evaluation of GexSbyTez (GST) film fabricated by chemical vapor deposition (CVD). We successfully established composition controlled GST CVD with smooth surface by applying appropriate deposition conditions. By increasing Ge flow rate or reducing substrate temperature, the average grain size was reduced and the film flatness was improved. As the results, we succeeded to obtain the extremely smooth surface, and also to fill a finite hole with conformal film deposition. All GexSbyTez films showed FCC or amorphous crystalline structures, both are utilized in the proposed phase change random access memory (PRAM), in spite of the wide range of composition control. We believe these CVD-GST films are useful for PRAM applications.

Abstract: Thermal stress model considering the effect of phase transformation is proposed for Phase-Change Random Access Memory (PRAM). The results of simulation show that the high level of stress is generated on the junction where Ge2Sb2Te5(GST), TiN and SiO2 meet together. The high level of stress can also be observed in the interface between TiN and SiO2. From simulation results, it can be predictable that delamination between GST and TiN can occur during operation of PRAM. It is expected that the simulation model, which has been developed in this research, is very useful tool for PRAM device design.

Abstract: Ge2Sb2Te5 (GST) has been widely studied for PRAM as reversible phase change material. GST is expected to reduce RESET (crystalline → amorphous) operation power, which is one of important issues for PRAM technology. In order to investigate the effect of nitrogen doping on electrical switching characteristics, we fabricated two kinds of PRAM cells with nitrogen-doped (N-doped) and un-doped GST, which were different bottom electrode contact size (0.80~1.00
). N-doped GST PRAM cells have higher dynamic resistance with small sized bottom electrode contact and lower RESET voltage (about 1.2 V, 50 ns) than un-doped GST PRAM cells (about 1.6 V, 50 ns). The resistance switching ratio (RRESET to RSET) was about 100. The results of this study indicate that nitrogen doping into GST film and smaller size of bottom electrode contact reduce RESET power for PRAM operation.