SOT Memory Device with Magnetic Source Line
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing architecture of SOT magneto resistive memory devices faces challenges in achieving compactness, low power consumption, and easy fabrication while ensuring reliable deterministic switching of magnetic junctions, particularly in maintaining the amplitude and homogeneity of the magnetic bias field across memory cells.
Innovation Solution
The proposed memory device design incorporates a substrate with SOT current layers and magnetic tunnel junctions, where a source line made of conductive magnetic material provides a magnetic bias field, and enhancing patterns of conductive magnetic material are used to assist in switching the cell state, with a configuration that includes parallel strips and vias to reduce resistance and enhance current density, allowing for a compact and efficient memory device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic source external to the memory cell is provided for generating a magnetic bias field, then deterministic switching of the cell is enabled, but device complexity and fabrication difficulty increase
Solution Approach 1:
The magnetic bias field generation function is merged with the source line by using conductive magnetic material. This integration eliminates the need for separate external magnetic sources, reducing device complexity while maintaining deterministic switching capability through the in-plane magnetic anisotropy field generated by the magnetized source line.
Solution Approach 2:
The source line serves dual functions: providing electrical current to the memory cell and generating the magnetic bias field through its magnetized conductive material. This self-service approach eliminates the need for separate bias field generation components, simplifying the overall device architecture.
2Reliability
If the magnetic bias field amplitude and homogeneity are controlled, then reliable state storage is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The invention changes the magnetic field generation approach by using in-plane magnetized conductive material in the source line rather than external perpendicular fields. This parameter change in magnetization orientation and material properties enables more robust and homogeneous field distribution, reducing sensitivity to manufacturing variations.
Solution Approach 2:
The source line uses composite material properties combining electrical conductivity and magnetic characteristics. This composite approach allows the same component to provide both electrical current and magnetic bias field with inherent homogeneity, reducing the need for precise manufacturing tolerances.
3Area of stationary object
If a compact memory device is designed, then integration density improves, but magnetic bias field homogeneity across memory cells deteriorates
Solution Approach 1:
Each source line segment is locally magnetized to provide the bias field for adjacent memory cells. This local quality approach ensures that each memory cell receives a homogeneous magnetic field from its nearest source line segment, maintaining field uniformity even in compact high-density configurations.
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 design achieves reliable deterministic switching with a large amplitude and homogeneous magnetic bias field, reducing power consumption and improving the speed of operations while maintaining device compactness, as the magnetic bias field is uniformly extended across the memory cells, ensuring reliable storage and retrieval of data.
Implementation Method 1
The current flowing in the SOT current layer generates a spin-orbit torque originating from a spin Hall effect and/or a Rashba effect that aim at changing the magnetization orientation of the free layer 2b
Implementation Method 2
The current flowing in the SOT current layer generates a spin-orbit torque originating from a spin Hall effect and/or a Rashba effect that aim at changing the magnetization orientation of the free layer 2b
Implementation Method 3
the source line comprises a conductive magnetic material providing a magnetic bias field extending to the magnetic tunnel junction of the selected memory cell for assisting the switching of the cell state
Data Source
Figure 1~2a
Figure 2b~3
Figure 4~5
AI summary
The invention concerns a memory device comprising a substrate defining a main plane; a plurality of memory cells each comprising a SOT current layer (3) disposed in the main plane of the substrate and a magnetic tunnel junction (2) residing on the SOT current layer (3); and a bit line and a source line to flow a write current in a write path including the SOT current layer (3) of a selected memory cell. The source line comprises a conductive magnetic material providing a magnetic bias field extending to the magnetic tunnel junction (2) of the selected memory cell for assisting the switching of the cell state when the write current is flowing.