Compressive Stress MTJ Barrier for Low Switching Current
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Solution Overview
Problem
Existing magnetic memory devices face high switching current issues due to high electrical resistance, leading to high power consumption and reliability concerns, which hinder the development of functional magnetic memory cells.
Innovation Solution
A magnetic storage memory device with a magnetic tunneling junction (MTJ) structure that includes a fixed layer, a barrier layer under compressive stress, and a free layer, where the barrier layer's resistivity is reduced by applying compressive stress using a compressive stress-inducing layer (CSIL) or inert gas sputtering, thereby reducing switching current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the barrier layer resistivity is reduced to decrease switching current, then power consumption decreases, but the TMR ratio may be reduced
Solution Approach 1:
The patent applies compressive stress to the barrier layer through a CSIL layer, which changes the physical state of the barrier layer and reduces its resistivity. This parameter change allows the barrier layer to maintain lower resistance while preserving the TMR effect, thereby reducing power consumption without sacrificing reliability
Solution Approach 2:
The compressive stress inducing layer (CSIL) acts as an intermediary between the top electrode and the barrier layer. The CSIL transfers compressive stress to the barrier layer, modifying its electrical properties and enabling reduced switching current while maintaining the necessary TMR ratio for reliable operation
2Speed
If the barrier layer resistivity is reduced to accelerate switching, then switching speed increases, but dielectric breakdown risk increases
Solution Approach 1:
By applying compressive stress through the CSIL layer, the barrier layer's resistivity is optimized to a specific range that enables fast switching while maintaining sufficient dielectric strength. The stress-induced parameter change allows the barrier to be more conductive for switching purposes but remains structurally intact to prevent breakdown
Solution Approach 2:
The CSIL layer provides beforehand cushioning by pre-applying compressive stress to the barrier layer before operation. This pre-stressing protects the barrier layer from excessive electric field stress during switching operations, preventing dielectric breakdown while enabling accelerated switching
3Use of energy by moving object
If anti-ferromagnetic layers are added to reduce resistance, then switching current decreases, but device complexity increases
Solution Approach 1:
The patent extracts the stress-inducing function from the traditional multi-layer magnetic structure and places it in a separate CSIL layer. This extraction simplifies the overall device architecture by using a single barrier layer instead of multiple anti-ferromagnetic layers, reducing device complexity while achieving the same switching current reduction
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
The reduction in barrier layer resistivity accelerates switching and decreases power consumption, enhancing the scalability and reliability of magnetic memory devices with lower switching currents.
Implementation Method 1
the barrier layer's resistivity is reduced by applying compressive stress using a compressive stress-inducing layer (CSIL) or inert gas sputtering
Implementation Method 2
the barrier layer's resistivity is reduced by applying compressive stress using a compressive stress-inducing layer (CSIL) or inert gas sputtering
Data Source
AI summary
A non-volatile magnetic memory element includes a fixed layer, a barrier layer formed on top of the fixed layer, and a free layer formed on top of the barrier layer, wherein the electrical resistivity of the barrier layer is reduced by placing said barrier layer under compressive stress. Compressive stress is induced by either using a compressive stress inducing layer, or by using inert gases at low pressure during the sputtering process as the barrier layer is deposited, or by introducing compressive stress inducing molecules into the molecular lattice of the barrier layer.