RF Sputtered MgO Spin Current Coupling Layer for MRAM
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Solution Overview
Problem
Existing magnetic random access memory (MRAM) technologies face challenges in optimizing the spin current coupling layer for efficient switching in magnetic tunnel junction (MTJ) elements, particularly in maintaining low Resistance Area product (RA) while ensuring effective spin current coupling and crystallinity, which affects switching efficiency and resistance states.
Innovation Solution
The use of an MgO spin current coupling layer deposited by RF sputtering method, allowing for adjustable thickness without significant changes in overall RA, combined with a magnetic spin current layer and exchange coupling layers, enhances spin current coupling and switching efficiency by maintaining low RA and improving spin polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the spin current coupling layer is increased to improve spin current coupling, then the coupling efficiency improves, but the Resistance Area product (RA) increases
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness of the MgO spin current coupling layer to a specific range (0.5-2.0 nm) and controlling the RA product to be no greater than 5 Ωμm². By precisely adjusting these parameters, the patent achieves optimal spin current coupling efficiency while maintaining low resistance, resolving the contradiction between coupling efficiency and resistance.
2Ease of manufacture
If a conventional DC sputtering method is used to deposit the spin current coupling layer, then the manufacturing process is simpler, but the layer crystallinity and spin current coupling are insufficient
Solution Approach 1:
The patent replaces the conventional DC sputtering method with RF sputtering methodology. This substitution changes the deposition mechanism, allowing for better control of layer crystallinity and spin current coupling properties while maintaining manufacturing feasibility. The RF sputtering process enables the formation of highly crystalline MgO layers with optimal spin current coupling characteristics.
3Object-affected harmful factors
If the spin current coupling layer is made thinner to reduce RA, then the resistance decreases, but the spin current coupling efficiency deteriorates
Solution Approach 1:
The patent employs composite material strategy by creating a multi-layer structure consisting of MgO spin current coupling layer, magnetic spin current layer, and exchange coupling layers. This composite structure allows the thin MgO layer (0.5-2.0 nm) to maintain low RA while the combined system achieves effective spin current coupling through the synergistic interaction of multiple layers with complementary functions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in improved switching efficiency and reduced switching voltage, with higher spin polarization and better control over the manufacturing process, leading to more robust and efficient magnetic memory elements.
Implementation Method 1
a spin current coupling layer formed on the magnetic free layer structure, wherein the spin current coupling layer is constructed of MgO deposited in a sputter deposition chamber using a radio frequency (RF) power source
Implementation Method 2
the spin current coupling layer is constructed of MgO deposited in a sputter deposition chamber using a radio frequency (RF) power source
Implementation Method 3
The switching of the MTJ element between high and low resistance states results from electron spin transfer
Implementation Method 4
Magnetic Random Access Memory (MRAM) is a non-volatile data memory technology that stores data magnetoresistive cells, such as Magnetoresistive Tunnel Junction (MTJ) elements
Data Source
AI summary
A method for manufacturing a magnetic memory element for use in a magnetic random access memory device to form a MgO spin current coupling layer with improved spin current coupling and reduced device area resistance (RA). The method involves depositing a magnetic free layer structure, and then depositing a MgO spin current coupling layer over the magnetic free layer. The magnetic spin current coupling layer is deposited in a sputter deposition chamber using radio frequency (RF) power. The sputter deposition of the spin current coupling layer can be performed using a MgO target without intervening oxidation steps to form a continuous layer of MgO that is not a multilayer structure of Mg and intermittent oxidation layers. Because the MgO spin transport layer deposited by this RF sputtering does not affect RA of the device, the thickness of the MgO spin transport layer can be adjusted to optimize spin transport performance.