An 8F/sup 2/ MRAM technology using modified metal lines

Abstract

A novel 8F/sup 2/ cell structure for high density magnetic random access memory (MRAM) and its operating characteristics are proposed. In this new scheme, we formed bottom electrode contact (BEC) through twin metal lines (MLs) and a magnetic tunnel junction (MTJ) was located just on the BEC for the reduction of cell size. From the results of simulation and experiment, we have confirmed that the generated magnetic field in the new scheme is more uniform than that in the conventional scheme with a negligible reduction of writing field strength. We adopted a self-aligned BEC process to prevent electrical shorting between ML and BEC. To avoid electrical shorting and improve the magnetic properties of MTJs, a chemical mechanical polishing (CMP) process was adopted before MTJ deposition. As a result, we confirmed the feasibility of high-density 1T1MTJ MRAM, composed of 8F/sup 2/ cells with optimal MTJ characteristics.