STT-MRAM Storage Layer Composition for Low-Current Fast Writing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional nonvolatile memory elements face challenges in achieving high-speed operation with a small current, particularly in replacing SRAM, where the write speed and current requirements are not adequately addressed, and the configuration of the storage layer is complex.

Innovation Solution

A nonvolatile memory element with a simple structure comprising a stack of a magnetization fixed layer, an intermediate layer, and a storage layer, where a nonmagnetic material is dispersed in at least one of these layers, achieved through alternate stacking and heat treatment, allowing for efficient magnetization reversal with reduced current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a conventional MTJ element uses current induced magnetic field for magnetization reversal, then data can be written, but write current increases with miniaturization

Engineering Contradiction:

Improvewrite speedVSAvoidwrite current

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent introduces a nonmagnetic material into the storage layer to change the magnetic parameters (coercive force, magnetization reversal characteristics) of the storage layer, enabling magnetization reversal at lower current values and achieving high-speed operation with reduced current requirements

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The storage layer is formed as a composite structure containing both magnetic material and nonmagnetic material, where the nonmagnetic material modifies the magnetic properties of the storage layer to achieve lower current thresholds for magnetization reversal while maintaining high-speed performance

Inventive Principle:

Principle #40Composite materials

2Device complexity

If the storage layer configuration is simplified to reduce device complexity, then manufacturing becomes easier, but write speed and current control may be compromised

Engineering Contradiction:

Improvestorage layer configurationVSAvoidwrite speed

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

By changing the compositional parameters of the storage layer (adding nonmagnetic material), the patent achieves both simplified structure and high performance, resolving the contradiction between device complexity and write speed

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The nonmagnetic material is selectively introduced into the storage layer to locally modify magnetic properties where needed, maintaining overall structural simplicity while achieving the desired write characteristics

Inventive Principle:

Principle #3Local quality

3Use of energy by moving object

If the nonmagnetic material content in the storage layer is increased to reduce write current, then magnetization reversal becomes easier, but saturation magnetization decreases

Engineering Contradiction:

Improvewrite currentVSAvoidsaturation magnetization

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent optimizes the concentration parameter of the nonmagnetic material in the storage layer to achieve the right balance: enough nonmagnetic material to reduce write current but not so much that saturation magnetization becomes insufficient for reliable operation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes part of the magnetic material with nonmagnetic material to change the magnetic field generation mechanism, using spin transfer torque more efficiently to achieve magnetization reversal with lower current

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 proposed solution enables high-speed operation with a small current, reducing the write error rate and simplifying the memory element configuration, making it suitable for replacing SRAM and DRAM with improved write speed and reduced current requirements.

Implementation Method 1

subjecting the stack to heat treatment to disperse the nonmagnetic material in the storage layer

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Implementation Method 2

a spin transfer torque based magnetic random access memory (STT-MRAM) to which magnetization reversal by spin injection is applied

Methodology Applied

Scientific EffectSpin transfer torque:

Implementation Method 3

magnetization reversal by spin injection is applied has attracted attention

Methodology Applied

Scientific EffectSpin injection:

Implementation Method 4

a magnetic tunnel junction (MTJ) element having a tunnel magneto resistance (TMR) effect

Methodology Applied

Scientific EffectTunnel magneto resistance (TMR) effect:

Data Source

PatentUS12588424B2Nonvolatile memory element and method for manufacturing the same

Publication Date: 2026.03.24 SONY SEMICON SOLUTIONS CORP

AI summary

A variable-resistance nonvolatile memory element 11 of the present disclosure has a stack 30 including at least a magnetization fixed layer 31, an intermediate layer 32, and a storage layer 33, and a nonmagnetic material36 is dispersed in at least one of the magnetization fixed layer 31 and the storage layer 33.