Reduction of Barrier Resistance X Area (RA) Product and Protection of Perpendicular Magnetic Anisotropy (PMA) for Magnetic Device Applications
First Claim
1. A method of forming a magnetic tunnel junction (MTJ) stack of layers including a tunnel barrier layer between two magnetic layers, comprising:
- (a) providing a bottom magnetic layer with perpendicular magnetic anisotropy (PMA);
(b) depositing a first metal layer that forms a bottom magnetic layer/first metal layer interface;
(c) performing a first passive oxidation process with a maximum oxygen pressure of about 10−
5 torr, the first passive oxidation process oxidizes an upper portion of the first metal layer while a bottom portion of the first metal layer along the bottom magnetic layer/first metal layer interface remains unoxidized;
(d) forming one or more metal or metal oxide layers on the oxidized portion of the first metal layer wherein steps (b)-(d) form a tunnel barrier layer; and
(e) depositing a top magnetic layer on a top surface of the tunnel barrier layer.
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Accused Products
Abstract
A method of forming a MTJ with a tunnel barrier having a high tunneling magnetoresistance ratio, and low resistance x area value is disclosed. The method preserves perpendicular magnetic anisotropy in bottom and top magnetic layers that adjoin bottom and top surfaces of the tunnel barrier. A key feature is a passive oxidation step of a first Mg layer that is deposited on the bottom magnetic layer wherein a maximum oxygen pressure is 10−5 torr. A bottom portion of the first Mg layer remains unoxidized thereby protecting the bottom magnetic layer from substantial oxidation during subsequent oxidation and anneal processes that are employed to complete the fabrication of the tunnel barrier and MTJ. An uppermost Mg layer may be formed as the top layer in the tunnel barrier stack before a top magnetic layer is deposited.
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Citations
39 Claims
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1. A method of forming a magnetic tunnel junction (MTJ) stack of layers including a tunnel barrier layer between two magnetic layers, comprising:
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(a) providing a bottom magnetic layer with perpendicular magnetic anisotropy (PMA); (b) depositing a first metal layer that forms a bottom magnetic layer/first metal layer interface; (c) performing a first passive oxidation process with a maximum oxygen pressure of about 10−
5 torr, the first passive oxidation process oxidizes an upper portion of the first metal layer while a bottom portion of the first metal layer along the bottom magnetic layer/first metal layer interface remains unoxidized;(d) forming one or more metal or metal oxide layers on the oxidized portion of the first metal layer wherein steps (b)-(d) form a tunnel barrier layer; and (e) depositing a top magnetic layer on a top surface of the tunnel barrier layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 18)
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15. A method of forming a magnetic tunnel junction (MTJ) stack of layers including a tunnel barrier layer between two magnetic layers, comprising:
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(a) providing a bottom magnetic layer with perpendicular magnetic anisotropy (PMA); (b) depositing a first metal layer that forms a bottom magnetic layer/first metal layer interface; (c) performing a first passive metal nitride deposition process with a maximum nitrogen pressure of about 10−
5 torr, the first passive metal nitride deposition process deposits a first metal nitride layer on the first metal layer while keeping the bottom magnetic layer/first metal layer interface from reacting with nitrogen;(d) forming one or more metal, metal oxide, metal oxynitride, or metal nitride layers on the first metal nitride layer, steps (b)-(d) form a tunnel barrier layer; and (e) depositing a top magnetic layer on a top surface of the tunnel barrier layer. - View Dependent Claims (16, 17)
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19. A method of forming a spin torque oscillator (STO) device, comprising:
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(a) forming a first metal oxide layer on a substrate that includes the steps of; (1) forming a first metal layer on the substrate and oxidizing an upper portion thereof with a first passive oxidation having a maximum oxygen pressure of about 10−
5 torr; and(2) forming one or more metal or metal oxide layers on the oxidized upper portion of the first metal layer; (b) forming a spin polarization (SP) layer on a top surface of the first metal oxide layer; (c) forming a non-magnetic layer on the SP layer; (d) forming an oscillation layer (OL) on the non-magnetic layer; and (e) forming a second metal oxide layer on the OL with a process comprising; (1) forming a second metal layer on the OL and oxidizing an upper portion thereof with a second passive oxidation process having a maximum oxygen pressure of 10−
5 torr; and(2) forming one or more metal or metal oxide layers on the oxidized upper portion of the second metal layer. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A method of forming an RF signal generation device, comprising:
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(a) forming a spin torque oscillator (STO) with a top surface and having at least one magnetic reference layer (MRL) that contacts a first terminal, a magnetic oscillation layer (MOL), and a first junction layer formed between the MRL and MOL; (b) forming a non-magnetic spacer layer on the MOL, the non-magnetic spacer layer is connected to a second terminal; (c) forming a magnetoresistive (MR) sensor on the non-magnetic spacer, the MR sensor has at least one magnetic sensing layer that is magnetostatically coupled with said MOL, a second magnetic reference layer, and a second junction layer that is a metal oxide formed between the magnetic sensing layer and the second magnetic reference layer, the metal oxide is formed by a process comprising; (1) depositing a first metal layer on the magnetic sensing layer; (2) oxidizing an upper portion of the first metal layer with a passive oxidation process having a maximum oxygen pressure of 10−
5 torr; and(3) forming one or more metal or metal oxide layers on an oxidized upper portion of the first metal layer; and (d) forming a third terminal on the MR sensor, the magnetic sensing layer has an oscillation state with an oscillation frequency that is induced in said MOL when a magnetic field is applied to said STO and MR sensor in a direction perpendicular to the STO top surface concurrently with a first electric current flowing between the first and second terminals, and the magnetostatic coupling generates magnetic oscillation with an RF frequency in the magnetic sensing layer that produces a varying voltage across the MR sensor when a second electric current flows between the second and third terminals. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37)
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38. A method of forming a three terminal device, comprising:
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(a) forming a bottom magnetic layer as a polarizing layer that contacts a first terminal; (b) forming a non-magnetic metal layer or a low RA tunnel barrier on the polarizing layer, where the low RA tunnel barrier is formed by a process comprising; (1) depositing a first metal layer on the bottom magnetic layer; (2) oxidizing an upper portion of the first metal layer with a passive oxidation process having a maximum oxygen pressure of 10−
5 torr; and(3) forming one or more metal or metal oxide layers on the oxidized upper portion of the first metal layer; (c) depositing a middle magnetic layer as a free layer on the non-magnetic metal layer or the low RA tunnel barrier, the free layer contacts a second terminal, a current flowing between the first terminal and second terminal is used during a write operation; (d) forming a tunnel barrier on the free layer where the tunnel barrier formation process comprises; (1) depositing a second metal layer on the free layer; (2) oxidizing an upper portion of the second metal layer with a passive oxidation process having a maximum oxygen pressure of 10−
5 torr; and(3) forming one or more metal or metal oxide layers on an oxidized upper portion of the second metal layer; and (e) depositing a top magnetic layer as a reference layer on the tunnel barrier, the reference layer contacts a third terminal, a current flowing between the second terminal and third terminal is employed during a read operation.
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39. A method of forming a three terminal device, comprising:
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(a) forming a bottom magnetic layer as a reference layer that contacts a first terminal; (b) forming a tunnel barrier on the reference layer where the tunnel barrier formation process comprises; (1) depositing a first metal layer on the reference layer; (2) oxidizing an upper portion of the first metal layer with a passive oxidation process having a maximum oxygen pressure of 10−
5 torr; and(3) forming one or more metal or metal oxide layers on an oxidized upper portion of the first metal layer; (c) depositing a middle magnetic layer as a free layer on the tunnel barrier, the free layer contacts a second terminal, a current flowing between the first terminal and second terminal is used during a read operation; (d) forming a non-magnetic metal layer or a low RA tunnel barrier on the free layer, where the low RA tunnel barrier is formed by a process comprising; (1) depositing a second metal layer on the free magnetic layer; (2) oxidizing an upper portion of the second metal layer with a passive oxidation process having a maximum oxygen pressure of 10−
5 torr; and(3) forming one or more metal or metal oxide layers on the oxidized upper portion of the second metal layer; and (e) depositing a top magnetic layer as a polarizing layer on the non-magnetic metal layer or low RA barrier, the polarizing layer contacts a third terminal, a current flowing between the second terminal and third terminal is employed during a write operation.
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Specification