Variable Resistance Memory Read Circuit Multilevel Storage

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Solution Overview

Problem

Current resistance change type memory devices using single switch layers have limited variability in resistance values, restricting their ability to store multilevel data effectively.

Innovation Solution

A memory device configuration featuring a variable resistance element with two switch layers and a barrier layer, where the resistance state is modulated by oxygen vacancies, allowing for three distinct resistance states and increased variability, enabling multilevel data storage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single switch layer is used in the variable resistance element, then the device structure is simpler, but the variability in resistance values is limited

Engineering Contradiction:

Improvestructure complexityVSAvoidresistance value variability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The variable resistance element is segmented into multiple switch layers (first switch layer and second switch layer) instead of using a single switch layer. Each switch layer can independently modulate resistance, enabling multiple distinct resistance states (first, second, and third resistance states) and significantly increasing resistance value variability for multilevel data storage

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The variable resistance element uses a composite structure comprising different switch layers with varying oxygen vacancy characteristics. The first switch layer and second switch layer are composed of different materials or have different oxygen vacancy concentrations, creating a composite system that achieves broader resistance variability while maintaining structural organization

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If two switch layers with different oxygen vacancy characteristics are used, then the range of resistance values increases, but the device structure becomes more complex

Engineering Contradiction:

Improverange of resistance valuesVSAvoidlayer structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The switch region is divided into multiple discrete switch layers, each contributing differently to the overall resistance. This segmentation allows independent control and modulation of resistance by each layer, achieving a wide resistance range while maintaining a systematic and manageable layered structure

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different switch layers are designed with different local qualities, specifically different oxygen vacancy characteristics. The first switch layer has different oxygen vacancy concentration or mobility compared to the second switch layer, allowing each layer to contribute uniquely to resistance modulation and enabling fine-grained control over resistance states

Inventive Principle:

Principle #3Local quality

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 doubles the range of resistance values, facilitating easier allocation of data to variable resistance values and enhancing the capability for multilevel data storage in memory devices.

Implementation Method 1

the resistance state is modulated by oxygen vacancies, allowing for three distinct resistance states and increased variability

Methodology Applied

Scientific EffectOxygen vacancy modulation:

Data Source

PatentUS10446227B2Read circuit for a variable resistance memory device

Publication Date: 2019.10.15 KIOXIA CORP

AI summary

According to one embodiment, a memory device includes: a memory cell including a variable resistance element and connected between a word line and a bit line; and a control circuit configured to control an operation of the memory cell. The variable resistance element includes: a first layer including a first compound including oxygen; a second layer including a second compound including oxygen; and a third layer between the first layer and the second layer.