A novel edge contact type cell for phase change RAM using N-doped GeSbTe films

A novel 2D nanometer edge contact type cell for phase change RAM is manufactured, in which the active area can be controlled mainly by the thickness of both bottom electrode film and the GST film. The high resistive GST is indispensable to minimize the writing current and threshold voltage of PCRAM. The GST resistivity can be increased effectively by doping nitrogen and the nitrogen-doped film is first used in the novel 2D nanometer structure successfully for reducing the threshold voltage application. It is found the phase change from FCC to hexagonal structure is suppressed by nitrogen doping, while 3 stable resistance states is first found in the resistivity-annealling temperature curve for the film by sputtering method, which might be used in multilevel PCRAM.