Magnetic Memory Device Anisotropic Field Optimization
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Solution Overview
Problem
Magnetic memory devices face a challenge in maintaining high retention characteristics while restricting the increase in write current, as larger anisotropic magnetic fields required for better retention lead to increased write currents.
Innovation Solution
A magnetic memory device is designed with a stacked structure including a storage layer and a reference layer separated by a tunnel barrier layer, with an anisotropic magnetic field within the range of −1 kOe to +1 kOe, using materials like FeCoB and MgO, to achieve high retention characteristics while controlling write current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the anisotropic magnetic field is increased to maintain high retention characteristics, then the retention characteristics are improved, but the write current increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the anisotropic magnetic field parameter within a specific range (−1 kOe to +1 kOe) and adjusting the thickness of the storage layer to 3 nm or less. These parameter optimizations enable achieving high retention characteristics while preventing excessive increase in write current, directly resolving the technical contradiction between retention and write current.
2Quantity of substance
If the element size is reduced to increase storage density, then the storage capacity is improved, but the retention characteristics deteriorate
Solution Approach 1:
The patent employs parameter changes by reducing the storage layer thickness to 3 nm or less and controlling the anisotropic magnetic field within −1 kOe to +1 kOe. These parameter adjustments allow miniaturization of the magnetoresistive element while maintaining adequate retention characteristics, thereby enabling increased storage density without sacrificing reliability.
3Use of energy by moving object
If the anisotropic magnetic field is decreased to reduce write current, then the write current is reduced, but the retention characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the anisotropic magnetic field to fall within the specific range of −1 kOe to +1 kOe and controlling the storage layer thickness at 3 nm or less. This precise parameter control achieves the optimal balance point where write current is sufficiently reduced while retention characteristics remain high, resolving the contradiction between these two parameters.
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 configuration enables a magnetic memory device with high retention characteristics while minimizing the increase in write current, by optimizing the anisotropic magnetic field and material composition to maintain efficient data storage.
Implementation Method 1
a tunnel barrier layer (nonmagnetic layer) 30 provided between the storage layer 10 and the reference layer 20
Implementation Method 2
A magnetic memory device (semiconductor integrated circuit device) including a magnetoresistive element
Data Source
AI summary
According to one embodiment, a magnetic memory device includes a stacked structure that includes a first magnetic layer having a variable magnetization direction, a second magnetic layer having a fixed magnetization direction, and a nonmagnetic layer provided between the first magnetic layer and the second magnetic layer, wherein the entire first magnetic layer exhibits a parallel or antiparallel magnetization direction to the second magnetic layer, and has an anisotropic magnetic field Hk_film within a range from −1 kOe to +1 kOe.