Stacked Magnetic Memory Cells With Uniform Coercive Force

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Solution Overview

Problem

Existing magnetic memory devices face challenges in optimizing the stacked magnetoresistive elements, leading to performance issues due to differences in annealing time and layer thickness across memory cells, resulting in non-uniform magnetic characteristics and coercive forces.

Innovation Solution

The solution involves varying the thickness of specific layers in stacked structures of memory cells, such as the storage layer, under layer, sub-magnetic layers, and shift canceling layers, to ensure uniform magnetic characteristics and coercive forces across multiple memory cells stacked at different heights, by adjusting the annealing time and layer thicknesses in a controlled manner.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If memory cells are disposed at different height positions to increase integration density, then the degree of integration is improved, but non-uniform magnetic characteristics and coercive forces occur due to differences in annealing time and layer thickness

Engineering Contradiction:

Improveintegration densityVSAvoidmagnetic characteristic uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by making different layers have different thicknesses at different height positions. Specifically, the first layer thickness varies for memory cells at different heights, while the second layer thickness is adjusted to compensate for annealing time differences. This localized variation in layer thickness ensures that each memory cell achieves uniform magnetic characteristics despite being at different heights, resolving the contradiction between integration density and magnetic uniformity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes physical parameters (layer thickness) to resolve the contradiction. By varying the thickness of magnetic layers based on height position and annealing time, the patent optimizes magnetic characteristics. The thickness parameters are specifically adjusted so that memory cells at different heights achieve consistent coercive forces and magnetoresistive properties, enabling high integration while maintaining manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If annealing time is extended to improve magnetic characteristics, then magnetic properties are improved, but production time and energy consumption increase

Engineering Contradiction:

Improvemagnetic property qualityVSAvoidannealing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-calculating and pre-setting the optimal layer thicknesses before the annealing process. The thickness of each layer is determined in advance based on the expected annealing time and desired magnetic characteristics. This preliminary design allows the annealing process to be completed in optimal time without trial and error, improving magnetic property quality while minimizing production time and energy consumption.

Inventive Principle:

Principle #10Preliminary action

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 results in uniform magnetoresistive properties and coercive forces across memory cells, enhancing the performance and reliability of the magnetic memory device by minimizing characteristic differences and optimizing performance.

Implementation Method 1

a magnetoresistive element which includes a storage layer having a magnetization direction switchable by spin transfer torque

Methodology Applied

Scientific EffectSpin transfer torque:

Implementation Method 2

a magnetoresistive element which includes a storage layer having a magnetization direction switchable by spin transfer torque and a resistance value variable according to a relative direction between the magnetization direction and a reference layer magnetization direction fixed in a predetermined direction

Methodology Applied

Scientific EffectTunnel magnetoresistance: Magnetoresistance

Data Source

PatentUS11758739B2Magnetic memory device

Publication Date: 2023.09.12 KIOXIA CORP

AI summary

A magnetic memory device including a first memory cell which includes a first stacked structure including a magnetic layer and a second memory cell which is provided on the first memory cell and includes a second stacked structure including a magnetic layer. Each of the first stacked structure and the second stacked structure 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. A concentration of iron (Fe) contained in the first magnetic layer included in the first stacked structure and a concentration of iron (Fe) contained in the first magnetic layer included in the second stacked structure are different from each other.