Magnetoresistive Memory Underlayer Doping for Resistance Reduction

Solution Overview

Problem

Magnetoresistive memory devices with high series resistance due to the use of underlayers with high resistance, which increases write current and decreases thermal stability and MR ratio.

Innovation Solution

Doping impurities such as Si into the underlayer to reduce its resistance, either uniformly or selectively at the end portions, while maintaining crystallinity and magnetocrystalline anisotropy, thereby reducing series resistance and improving thermal stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an underlayer is used to maintain crystallinity and magnetocrystalline anisotropy, then thermal stability is improved, but series resistance increases

Engineering Contradiction:

Improvethermal stabilityVSAvoidseries resistance

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies local quality by selectively doping impurities only at the end portions of the underlayer rather than uniformly throughout. This creates a gradient where the doped regions have reduced resistance while the bulk underlayer maintains its crystallinity and magnetocrystalline anisotropy properties, thus resolving the contradiction between thermal stability and series resistance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the electrical resistance parameter of the underlayer by introducing impurities (such as Si, Ge, or Sn) at specific locations. This parameter change reduces the series resistance from the high resistance state to a lower resistance state, while the controlled doping level and location preserve the thermal stability characteristics

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If impurities are doped into the underlayer to reduce resistance, then series resistance decreases, but crystallinity and magnetocrystalline anisotropy may be degraded

Engineering Contradiction:

Improveseries resistanceVSAvoidcrystallinity

Core Design Contradiction:

Loss of energyVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by selectively doping impurities only at the end portions of the underlayer rather than uniformly throughout. This creates a gradient where the doped regions have reduced resistance while the bulk underlayer maintains its crystallinity and magnetocrystalline anisotropy properties, thus resolving the contradiction between thermal stability and series resistance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies partial action by doping only a portion (the end portions) of the underlayer with impurities rather than the entire underlayer. This partial doping is sufficient to reduce the overall series resistance while minimizing the impact on the overall crystallinity and magnetic properties of the underlayer structure

Inventive Principle:

Principle #16Partial or excessive action

3Loss of energy

If impurities are doped into the underlayer to reduce resistance, then write current decreases, but manufacturing precision becomes more difficult

Engineering Contradiction:

Improvewrite currentVSAvoiddoping precision

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The patent applies local quality by selectively doping impurities only at the end portions of the underlayer rather than uniformly throughout. This creates a gradient where the doped regions have reduced resistance while the bulk underlayer maintains its crystallinity and magnetocrystalline anisotropy properties, thus resolving the contradiction between thermal stability and series resistance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies segmentation by dividing the underlayer into different regions: doped end portions and undoped central portions. This segmentation allows the doped regions to provide resistance reduction and the undoped regions to maintain structural integrity, making the doping process more manageable and precise

Inventive Principle:

Principle #1Segmentation

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 approach effectively reduces series resistance, decreases write current, and enhances thermal stability, leading to improved element characteristics and MR ratio in magnetoresistive memory devices.

Implementation Method 1

an underlayer formed on the bottom electrode; a storage layer formed on the underlayer

Methodology Applied

Scientific EffectMagnetocrystalline anisotropy: Anisotropy

Implementation Method 2

Doping impurities such as Si into the underlayer to reduce its resistance

Methodology Applied

Scientific EffectDoping: Dopants

Implementation Method 3

magnetoresistive memory device in which a magnetic tunnel junction (MTJ) element is used

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS10128310B2Magnetoresistive memory device and manufacturing method of the same

Publication Date: 2018.11.13 KIOXIA CORP

AI summary

According to one embodiment, a magnetoresistive memory device includes a magnetoresistive element of a stacked layer structure includes a first magnetic layer, a second magnetic layer, and a nonmagnetic layer between the first and second magnetic layers, and an insulating layer of a group III-V compound provided on a side of the first magnetic layer of the magnetoresistive element, the insulating layer including an chemical element of group II, group IV, or group VI.