Magnetic Tunnel Junction Free-Layer Layout for Fast Stable Switching
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Solution Overview
Problem
Semiconductor devices face challenges in achieving high-speed and low-power operation while maintaining thermal stability due to the difficulty in switching the magnetization direction of the free layer in magnetic tunnel junction structures, particularly because the thickness of the free layer affects both perpendicular magnetic anisotropy and thermal stability.
Innovation Solution
The semiconductor device employs a combination of Spin Orbit Torque (SOT) and Spin Transfer Torque (STT) methods by varying the thickness of the free layer in different portions of the magnetic tunnel junction structure, using a thicker free layer where SOT is applied and a thinner layer where STT is applied, to facilitate simultaneous switching and ensure thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the thickness of the free layer is increased to improve thermal stability, then thermal stability is improved, but the switching speed decreases and power consumption increases
Solution Approach 1:
The free layer is segmented into two distinct portions with different thicknesses: a first portion with greater thickness for thermal stability and a second portion with lesser thickness for fast switching. This segmentation allows each portion to optimize for its specific function, resolving the contradiction between thermal stability and switching speed.
Solution Approach 2:
Different regions of the free layer are assigned different thicknesses to perform different functions. The first portion (thicker) is optimized for thermal stability while the second portion (thinner) is optimized for switching performance. This local differentiation of properties resolves the global contradiction.
2Speed
If the thickness of the free layer is decreased to improve switching speed, then switching speed is improved, but thermal stability deteriorates
Solution Approach 1:
The free layer is divided into two portions where the second portion has reduced thickness to enable fast switching, while the first portion maintains greater thickness for thermal stability. This segmentation allows the system to achieve both fast switching and thermal stability simultaneously.
Solution Approach 2:
The thinner second portion of the free layer is specifically designed for rapid magnetization switching, while the thicker first portion provides thermal stability. This local optimization of thickness in different regions resolves the contradiction between switching speed and thermal stability.
3Ease of manufacture
If a constant thickness free layer is used, then manufacturing is simplified, but both high-speed operation and thermal stability cannot be achieved simultaneously
Solution Approach 1:
The free layer employs local quality variation with different thicknesses in different portions, allowing simultaneous achievement of high-speed operation and thermal stability. The manufacturing process incorporates this thickness variation through selective deposition or etching techniques.
Solution Approach 2:
The free layer transitions from a static uniform thickness design to a dynamic gradient thickness design, where the thickness varies spatially to optimize both switching speed and thermal stability. This dynamic structural approach enables superior operational performance.
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 enables high-speed and low-power operation of the semiconductor device while maintaining thermal stability by effectively switching the magnetization direction using both SOT and STT methods, addressing the limitations of constant free layer thickness.
Implementation Method 1
The semiconductor device employs a combination of Spin Orbit Torque (SOT) and Spin Transfer Torque (STT) methods
Implementation Method 2
The semiconductor device employs a combination of Spin Orbit Torque (SOT) and Spin Transfer Torque (STT) methods
Implementation Method 3
one or more magnetic tunnel junction structures, each magnetic tunnel junction structure interposed between a corresponding first conductive line and a corresponding electrode layer
Data Source
AI summary
In an embodiment, a semiconductor device includes a spin orbit torque (SOT) line extending in a first direction; an electrode layer spaced apart from the SOT line in a third direction; and a magnetic tunnel junction structure interposed between the SOT line and the electrode layer, and including a free layer adjacent to the SOT line in the third direction, a pinned layer adjacent to the electrode layer in the third direction, and a tunnel barrier layer interposed between the free layer and the pinned layer, wherein the magnetic tunnel junction structure includes a first portion overlapping the SOT line and a second portion not overlapping the SOT line in a second direction, the electrode layer overlaps at least a portion of the second portion, and a thickness of the free layer in the first portion is greater than a thickness of the free layer in the second portion.