Magnetic Storage Element Boron Concentration Optimization

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Solution Overview

Problem

The existing magnetic storage elements, such as STT-MRAM, face challenges in achieving high mass productivity while maintaining stable magnetic characteristics during heat treatment, particularly when using magnetic materials with high boron concentrations or rare earth elements, which result in low film formation rates and deteriorated magnetic properties.

Innovation Solution

A magnetic storage element with a stack structure comprising a fixed layer and a storage layer, where the fixed layer or storage layer contains elements like B, C, N, Al, Mg, and Si at specific concentrations, enhancing magnetic characteristics and productivity by optimizing the film formation process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnetic materials with high boron concentrations or rare earth elements are used, then magnetic characteristics are improved, but film formation rate decreases and mass productivity is reduced

Engineering Contradiction:

Improvemagnetic characteristicsVSAvoidmass productivity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent optimizes the concentration parameters of boron and rare earth elements in the magnetic layer to achieve a balance between magnetic characteristics and film formation rate. By controlling these compositional parameters within specific ranges, the patent resolves the contradiction between improving magnetic properties and maintaining high productivity.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If magnetic materials with high boron concentrations or rare earth elements are used, then magnetic characteristics are improved, but magnetic properties deteriorate during heat treatment

Engineering Contradiction:

Improvemagnetic characteristicsVSAvoidmagnetic properties stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent creates a composite magnetic layer containing both boron and rare earth elements in specific proportions. This composite material approach enhances the thermal stability of magnetic properties during heat treatment while maintaining the desired magnetic characteristics, resolving the contradiction between improving magnetic properties and ensuring their stability under thermal conditions.

Inventive Principle:

Principle #40Composite materials

3Device complexity

If current magnetic field method is used for magnetization reversal, then storage principle is simple, but power consumption is high and capacity is limited

Engineering Contradiction:

Improvestorage principle simplicityVSAvoidpower consumption

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

The patent replaces the conventional current magnetic field method with a spin transfer torque mechanism for magnetization reversal. This substitution eliminates the need for high-current wires and enables lower power consumption and higher storage capacity while maintaining the fundamental magnetic storage principle.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Use of energy by moving object

If MTJ element volume is reduced, then current for magnetization reversal decreases, but manufacturing precision requirements increase

Engineering Contradiction:

Improvecurrent for magnetization reversalVSAvoidMTJ element dimensional precision

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The patent optimizes the dimensional parameters of the MTJ element to achieve minimal volume for low current requirements while maintaining manufacturability. By carefully controlling the thickness and area parameters within practical fabrication limits, the patent balances the reduction of write current with achievable manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

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 allows for high mass productivity while preserving magnetic characteristics, reducing the write current required for magnetization reversal and maintaining thermal stability, thus addressing the limitations of previous technologies.

Implementation Method 1

a spin transfer torque-magnetic random access memory (STT-MRAM) (magnetic storage device), which uses spin torque magnetization reversal to generate the magnetization reversal without using the current magnetic field

Methodology Applied

Scientific EffectSpin transfer torque:

Implementation Method 2

The MTJ element may be referred to as a tunneling magneto resistive (TMR) element

Methodology Applied

Scientific EffectTunneling magneto resistance (TMR):

Data Source

PatentUS11462681B2Magnetic storage element, magnetic head, magnetic storage device, electronic apparatus, and method for manufacturing magnetic storage element

Publication Date: 2022.10.04 SONY SEMICON SOLUTIONS CORP

AI summary

Provided is a magnetic storage element including a stack structure which includes a fixed layer whose magnetization direction is fixed, a storage layer whose magnetization direction is reversible, and a non-magnetic layer sandwiched between the fixed layer and the storage layer. The magnetization direction has a direction along a stack direction of the stack structure, and the fixed layer or the storage layer has a region which contains at least one contained element selected from the element group consisting of B, C, N, Al, Mg, and Si at 30 atm % or more and 80 atm % or less.