Magnetoresistive element having a sidewall-current-channel structure

A method of manufacturing a perpendicular magnetic tunnel junction (put) element having a sidewall-current-channel (SCC) structure for being used in a magnetic memory device, the method comprising the steps of:

• providing a bottom electrode;
• depositing an MTJ stack over the bottom electrode, wherein the MTJ stack comprises at least a magnetic reference layer, a tunnel barrier layer provided on a top surface of the magnetic reference layer and a magnetic recording layer provided on a top surface of the tunnel barrier layer;
• depositing an insulating medium layer over the MTJ stack;
• depositing a protective cap layer over the insulating medium layer;
• depositing a hard mask layer over the protective cap layer;
• conducting a photolithographic process to form a patterned hard mask having an opening exposed area on the protective cap layer;
• first etching the protective cap layer and the insulating medium layer not covered by the patterned hard mask;
• forming a conductive encapsulation layer on the top surface of the patterned hard mask, on the top surface of the etched insulating medium layer and on sidewalls of the insulating medium layer, the protective cap layer and the hard mask, wherein the conductive encapsulation layer is a conformal layer made of an electrically conductive material;
• second etching away the conductive encapsulation layer on horizontal surfaces, leaving the conductive encapsulation layer on vertical sidewalls of the insulating medium layer, the protective cap layer and the hard mask, wherein sidewalls of the insulating medium layer are covered by the conductive encapsulation layer forming a conductive medium electrically connecting the magnetic recording layer and the protective cap layer;
• third etching the MTJ stack to form a plurality of MTJ cells;
• and
• forming a dielectric encapsulation layer on the top surface of the patterned hard mask and on sidewalls of the MTJ stack and the conductive encapsulation layer, wherein the dielectric encapsulation layer is made of an electrically insulating material.

A magnetoresistive element comprising:

• a magnetic reference layer having a perpendicular magnetic anisotropy and having an invariable magnetization direction;
• a tunnel barrier layer provided on the magnetic reference layer;
• a magnetic recording layer provided on the tunnel barrier layer and having a perpendicular magnetic anisotropy and a variable magnetization direction;
• a nonmagnetic nano-current-crowding channel (NCC) structure provided on the magnetic recording layer;
• a protective cap layer provided on the NCC structure;
• and
• a hard mask layer provided on the protective cap layer;
• wherein said tunnel barrier layer has a first resistance-area product, said NCC structure comprises an insulating medium throughout said NCC thickness, and a conductive medium throughout said NCC thickness, the insulating medium comprising an insulating oxide or nitride material and having a second resistance-area product, the second resistance-area product being larger than the first resistance-area product, the conductive medium comprising a metal or metal alloy or metal nitride material and being an electrically conductive path between the magnetic recording layer and the protective cap layer, said magnetic recording layer has a sufficiently small sheet resistance so that an electric current crowding occurs in said magnetic recording layer while the current density across said tunnel barrier layer is substantially uniform when a voltage is applied to said magnetoresistive element.

A magnetoresistive element comprising:

• a bottom electrode provided on a substrate;
• a sidewall-current-channel (SCC) structure provided on the bottom electrode, wherein the SCC structure comprises an insulating medium in a central region of the SCC structure, and a conductive medium being a vertical sidewall of the SCC structure and surrounding the insulating medium;
• a perpendicular anisotropy enhancement layer provided on the insulating medium;
• a magnetic recording layer provided on the perpendicular anisotropy enhancement layer and having a perpendicular magnetic anisotropy and a variable magnetization direction;
• a tunnel barrier layer provided on the magnetic recording layer;
• a magnetic reference layer provided on the tunnel barrier layer and having a perpendicular magnetic anisotropy and having an invariable magnetization direction;
• a protective cap layer provided on the insulating medium;
• and
• a hard mask layer provided on the protective cap layer;
• wherein the tunnel barrier layer has a first resistance-area product (RA1), the insulating medium comprises an insulating oxide or nitride material and has a second resistance-area product (RA2), the second resistance-area product (RA2) is higher than the first resistance-area product (RA1), the conductive medium comprises a conductive material making electrical connection between the magnetic recording layer and the bottom electrode layer.