Nonvolatile Memory Element With Fixed Resistance Layer

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Solution Overview

Problem

Conventional nonvolatile memory elements with a stacked structure of high and low oxygen content transition metal oxide layers require high initial breakdown voltage due to the high resistance layer, necessitating a special circuit for electric pulses, which complicates the design and reduces reliability.

Innovation Solution

Incorporating a fixed resistance layer with a predetermined resistance value between 70Ω to 1000Ω, integrated with the variable resistance element, to lower the initial breakdown voltage and reduce resistance variations, thereby simplifying the circuit requirements and enhancing reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a stacked structure of high oxygen content layer and low oxygen content layer is used as variable resistance layer, then stable resistance change is achieved, but initial breakdown voltage becomes excessively high

Engineering Contradiction:

Improvestable resistance changeVSAvoidinitial breakdown voltage

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

A fixed resistance layer is introduced as an intermediary component between the high oxygen content layer and low oxygen content layer. This fixed resistance layer acts as a voltage distribution mediator that prevents excessive voltage concentration on the high oxygen content layer, thereby reducing the initial breakdown voltage while preserving the stable resistance change characteristics of the stacked variable resistance layer structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The fixed resistance layer has a predetermined resistance value within the range of 70Ω to 1000Ω, which is specifically optimized to control voltage distribution. By adjusting this resistance parameter, the system achieves a balance between reducing initial breakdown voltage and maintaining stable resistance change operation of the variable resistance layer.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If high voltage electric pulses are applied for initial breakdown, then resistance change characteristics are obtained, but special circuits are required which complicates design

Engineering Contradiction:

Improveresistance change characteristicsVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The fixed resistance layer is pre-configured in the structure before operation to automatically perform the voltage distribution function during normal operation. This preliminary structural arrangement eliminates the need for special high-voltage generating circuits that would otherwise be required to achieve initial breakdown, thereby reducing device complexity while maintaining resistance change characteristics.

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

The integration of a fixed resistance layer stabilizes the voltage distribution across the high oxygen concentration layer, reducing the initial breakdown voltage and minimizing resistance variations, thus improving the reliability and miniaturization of nonvolatile memory elements.

Implementation Method 1

a fixed resistance layer having a predetermined resistance value, stacked together with the variable resistance element... the predetermined resistance value ranges from 70Ω to 1000Ω inclusive

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

selectively causing the occurrence of oxidation/reduction reaction in an electrode interface which is in contact with a variable resistance layer

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 3

selectively causing the occurrence of oxidation/reduction reaction in an electrode interface which is in contact with a variable resistance layer

Methodology Applied

Scientific EffectReduction: Reduction

Data Source

PatentUS8692222B2Nonvolatile memory element and method of manufacturing the nonvolatile memory element

Publication Date: 2014.04.08 PANASONIC SEMICON SOLUTIONS CO LTD

AI summary

A nonvolatile memory element according to the present disclosure includes: a variable resistance element including a first electrode layer, a second electrode layer, and a variable resistance layer which is located between the first electrode layer and the second electrode layer and has a resistance value that reversibly changes based on an electrical signal applied between the first electrode layer and the second electrode layer; and a fixed resistance layer having a predetermined resistance value and stacked together with the variable resistance element. The variable resistance layer includes (i) a first transition metal oxide layer which is oxygen deficient and (ii) a second transition metal oxide layer which has a higher oxygen content atomic percentage than the first transition metal oxide layer. The predetermined resistance value ranges from 70Ω to 1000Ω inclusive.