Integration of 28nm MJT for 8∼16Gb level MRAM with full investigation of thermal stability

28nm MTJ for 8∼16Gb MRAM device has been successfully integrated with special patterning & etch technique. Resistance (R) separation between high and low R states was 15.2σ, comparable to that for 80nm MTJ cells. Thermal stability factor (Δ) followed prediction fairly well, and MTJ with free layer (FL) of 25A and aspect ratio (AR) of 3 showed Δ of 56. In order to realize sub-30nm MRAM device, a novel FL with substantially low critical current density (J c ) or revolutionary MTJ scheme needs to be developed.