Variable Resistance Memory Element Oxygen Deficiency Gradient

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Solution Overview

Problem

Existing non-volatile memory elements face challenges in achieving easy breakdown and reducing non-uniformity of resistance values in high-resistance states, particularly due to limitations in the miniaturization and speed of resistance changes in variable resistance memory elements.

Innovation Solution

A non-volatile memory element is manufactured with a stacked-layer structure comprising a third metal oxide layer, a second metal oxide layer, and a first metal oxide layer, where the third metal oxide is oxygen-deficient and has a higher oxygen content than the second and first metal oxides, and the layers are deposited separately, allowing for reversible resistance changes in response to electric signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a variable resistance layer with simple stacked-layer structure is used, then miniaturization and speed are improved, but breakdown occurrence becomes difficult and resistance value non-uniformity increases

Engineering Contradiction:

Improveminiaturization speedVSAvoidbreakdown occurrence ease

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The variable resistance layer is segmented into multiple metal oxide layers (first, second, and third metal oxide layers) with different oxygen contents. This segmentation allows each layer to contribute differently to the overall resistance change mechanism, facilitating easier breakdown while maintaining miniaturization benefits.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the variable resistance layer are given different oxygen contents to create local quality variations. The first metal oxide layer has higher oxygen content than the third metal oxide layer, creating localized regions with different electrical properties that promote controlled breakdown and reduce resistance non-uniformity.

Inventive Principle:

Principle #3Local quality

2Productivity

If a variable resistance layer with simple stacked-layer structure is used, then miniaturization is achieved, but resistance value non-uniformity increases

Engineering Contradiction:

Improveminiaturization capabilityVSAvoidresistance value uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The variable resistance layer is constructed as a composite material system with multiple metal oxide layers having different compositions and oxygen contents. This composite structure combines the advantages of different metal oxides to achieve both miniaturization and uniform resistance characteristics.

Inventive Principle:

Principle #40Composite materials

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 easier occurrence of breakdown and reduces non-uniformity of resistance values, improving the performance and reliability of the memory element by optimizing the density and oxygen deficiency of the metal oxide layers.

Implementation Method 1

When an electric pulse having a positive voltage on the basis of the lower electrode is applied to the upper electrode in this non-volatile memory element, oxygen atoms migrate from the first tantalum oxide layer to an interface between the second tantalum oxide layer and the upper electrode

Methodology Applied

Scientific EffectOxygen ion migration: Ion Repulsion/Attraction

Implementation Method 2

oxygen atoms staying at the interface between the second tantalum oxide layer and the upper electrode migrate to the first tantalum oxide layer, which allows the variable resistance layer to be easily changed to the low-resistance state

Methodology Applied

Scientific EffectElectrochemical redox reaction: Redox Reactions

Implementation Method 3

the second metal oxide layer and the first metal oxide layer are deposited separately

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentUS9142765B2Manufacturing method of non-volatile memory element, non-volatile memory element, and non-volatile memory device

Publication Date: 2015.09.22 PANASONIC SEMICON SOLUTIONS CO LTD

AI summary

A method of manufacturing a non-volatile memory element includes forming a first electrode; forming a variable resistance layer; and forming a second electrode. Forming the variable resistance layer includes forming a third metal oxide layer having a third metal oxide, forming a second metal oxide layer having a second metal oxide, and forming a first metal oxide layer e having a first metal oxide; wherein the variable resistance layer reversibly changes its resistance value in response to an electric signal applied between the first electrode and the second electrode; the first metal oxide is lower in degree of oxygen deficiency than the third metal oxide; the second metal oxide is lower in degree of oxygen deficiency than the third metal oxide; the third metal oxide is an oxygen-deficient metal oxide; and the first metal oxide layer is different in density from the second metal oxide layer.