Magnetic random access memory array with thin conduction electrical read and write lines
AssigneesHeadway Technologies, Inc., Applied Spintronics, Inc.
InventorsTai Min, Pokang Wang, Xizeng Shi, Yimin Guo
Life of this patent
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Abstract
An MTJ MRAM cell is formed between ultra-thin orthogonal word and bit lines of high conductivity material whose thickness is less than 100 nm. Lines of this thickness produce switching magnetic fields at the cell free layer that are enhanced by a factor of approximately two for a given current. The fabrication of a cell with such thin lines is actually simplified as a result of the thinner depositions because the fabrication process eliminates the necessity of removing material by CMP during patterning and polishing, thereby producing uniform spacing between the lines and the cell free layer.
Claims10
A method of forming an MTJ MRAM cell between the intersection of ultra-thin word and bit lines comprising:
- providing a substrate having a substantially planar upper surface;
- forming on said substrate an ultra-thin horizontal bit line of high conductivity material, extending in a first direction and having a width between approximately 300 nm and 500 nm and a thickness that is less than 100 nm, wherein said formation further comprises:
- forming a first layer of high conductivity material on said substrate, said layer having a thickness that is less than 100 nm;
- forming a layer of photoresist on said first conducting layer;
- patterning said photoresist layer to leave a strip of width between approximately 300 nm and 500 nm;
- using said strip as an etch mask to remove portions of said first high conductivity material layer peripheral to said strip;
- depositing a layer of insulating material to refill said removed first conducting layer portions;
- removing a photoresist strip, leaving thereby a bit line and surrounding insulating layer having a common and substantially planar upper surface;
- forming a multilayered magnetic tunnel junction (MTJ) element on the substantially planar upper surface of said bit line, a lower surface of said MTJ element electrically contacting said bit line;
- forming a layer of insulation surrounding said MTJ element, an upper surface of said layer being co-planar with an upper surface of said MTJ element and with a planar substrate surface.
A method of forming an MTJ MRAM cell between the intersection of ultra-thin word and bit lines comprising:
- providing a substrate having a substantially planar upper surface, said substantially planar upper surface including an upper surface of an MTJ MRAM cell;
- forming on said substantially planar substrate upper surface an ultra-thin horizontal bit line of high conductivity material, extending in a first direction and having a width between approximately 300 nm and 500 nm and a thickness that is less than 100 nm, wherein said formation further comprises:
- forming a first layer of high conductivity material on said substrate, said layer contacting the planar upper surface of said MTJ MRAM cell and said layer having a thickness that is less than 100 nm;
- forming a layer of photoresist on said first high conductivity material layer;
- patterning said photoresist layer to leave a strip of width between approximately 300 nm and 500 nm;
- using said strip as an etch mask to remove portions of said first conducting layer peripheral to said strip;
- removing said photoresist strip to expose the remaining portion of said first conducting layer, said portion being a horizontal ultra-thin bit line;
- forming a first layer of insulating material over said ultra-thin horizontal bit line, said insulating layer covering said remaining portion and said layer having a substantially planar upper surface;
- forming a multilayered magnetic tunnel junction (MTJ) element on the upper surface of said ultra-thin horizontal bit line, a lower surface of said MTJ element electrically contacting said ultra-thin horizontal bit line;
- forming a conducting electrode on said MTJ element;
- forming a substantially planar second layer of insulation over said conducting electrode.
Dependencies are inferred from the claim text.