Sidewall coating for non-uniform spin momentum-transfer magnetic tunnel junction current flow

摘要

A magnetic tunnel junction device comprises a substrate including a patterned wiring layer. A magnetic tunnel junction (MTJ) stack is formed over the wiring layer. A low-conductivity layer is formed over the MTJ stack and a conductive hard mask is formed thereon. A spacer material is then deposited that includes a different electrical conductivity than the low conductivity layer. The spacer material is etched from horizontal surfaces so that the spacer material remains only on sidewalls of the hard mask and a stud. A further etch process leaves behind the sidewall-spacer material as a conductive link between a free magnetic layer and the conductive hard mask, around the low-conductivity layer. A difference in electrical conductivity between the stud and the spacer material enhances current flow along the edges of the free layer within the MTJ stack and through the spacer material formed on the sidewalls.