Magnetoresistive Storage Layer Edge Gradient for STT-MRAM
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Solution Overview
Problem
In semiconductor memory devices, particularly STT-MRAM, the writing error rate (WER) is high due to the challenges in controlling magnetization reversal in storage layers with sizes larger than a single magnetic domain size, leading to incoherent magnetization reversal and increased dwell time of magnetic domain walls, which results in writing errors.
Innovation Solution
The solution involves setting a lower saturation magnetization (Ms) at the storage layer edge region compared to the central region, reducing the shape magnetic anisotropy energy and improving the distribution of effective magnetic anisotropy energy, thereby restraining magnetic domain walls from being trapped and reducing the writing error rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the storage layer size is increased to achieve larger memory capacity, then the memory capacity is improved, but the magnetization reversal becomes incoherent and writing error rate increases
Solution Approach 1:
The patent applies local quality by creating a storage layer with spatially varying saturation magnetization: the central region has higher Ms while the edge region has lower Ms. This gradient in magnetic properties ensures that the edge region reverses magnetization first during writing operations, guiding domain wall motion and preventing trapping, thereby maintaining coherent reversal and low writing error rates even in larger storage layers that provide increased memory capacity.
2Stability of the object's composition
If the saturation magnetization is increased to improve magnetic stability, then the magnetic stability is improved, but the shape magnetic anisotropy energy increases and magnetization reversal becomes difficult
Solution Approach 1:
The patent implements local quality by establishing a saturation magnetization gradient within the storage layer: the edge region has reduced Ms compared to the central region. This local reduction at the edges decreases the shape magnetic anisotropy energy barrier at critical locations, facilitating easier initiation of magnetization reversal and domain wall motion, while the central region maintains higher Ms to preserve overall magnetic stability and data retention.
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 enhances the reliability of semiconductor memory devices by reducing the dwell time of magnetic domain walls and improving the writing error rate, ensuring coherent magnetization reversal and accurate data storage.
Implementation Method 1
a magnetoresistive element includes a first magnetic layer, a nonmagnetic layer, and a second magnetic layer. The magnetoresistive element is capable of storing data according to a direction of magnetization in the first magnetic layer
Data Source
AI summary
According to one embodiment, a semiconductor memory device includes a magnetoresistive element and an insulating layer. The magnetoresistive element includes a first magnetic layer, a nonmagnetic layer, and a second magnetic layer and. The magnetoresistive element is capable of storing data according to a direction of magnetization in the first magnetic layer. The insulating layer covers a side surface of the magnetoresistive element. The first magnetic layer includes a first region and a second region. Each of the first and second regions includes a magnetic material and a nonmagnetic material. A concentration ratio of the nonmagnetic material to the magnetic material is higher in the second region than in the first region.