Correlated Electron Memory Using Mott Transition for Low Power

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Solution Overview

Problem

Current non-volatile memory technologies face challenges in achieving low power consumption, high speed, high density, and scalability below 65 nanometers, with existing resistance switching materials being unstable over time and temperature, and requiring high voltage and current for operation.

Innovation Solution

The use of Correlated Electron Materials (CEMs) that exhibit an abrupt conductor/insulator transition due to electron correlations, eliminating the need for forming voltage or current and allowing resistance switching with small voltages, and featuring a homogeneous crystal structure for stable resistance switching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional resistance switching materials are used, then memory can be implemented, but the materials are unstable over time and temperature and require high voltage and current for operation

Engineering Contradiction:

Improvestability of resistance switchingVSAvoidvoltage and current requirement

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the fundamental material parameter from conventional resistance switching materials to correlated electron materials (CEMs), which exhibit a metal-insulator transition driven by electron correlations rather than structural phase changes. This parameter change enables stable resistance switching at low voltages and currents, resolving the contradiction between reliability and energy consumption

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes the metal-insulator phase transition in correlated electron materials as the basis for resistance switching. Unlike conventional materials that require high energy to induce phase changes, CEMs undergo this transition at low energy levels, providing both stability and low power operation simultaneously

Inventive Principle:

Principle #36Phase transitions

2Quantity of substance

If Flash memory is used to achieve high density, then bit density increases, but random access capability is sacrificed for speed

Engineering Contradiction:

Improvebit densityVSAvoidrandom access speed

Core Design Contradiction:

Quantity of substanceVSSpeed

Solution Approach 1:

The patent replaces the mechanical wear-based erasure mechanism of Flash memory with a field-effect-based resistance switching mechanism in CEMs. This substitution eliminates the need for sequential block erasure, enabling true random access while maintaining high density, as each memory cell can be independently and rapidly programmed without affecting neighboring cells

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If EEPROM technology is used, then read/write capability is achieved, but the number of erase/write cycles is limited to slightly over 600,000

Engineering Contradiction:

Improveread/write capabilityVSAvoidendurance of erase/write cycles

Core Design Contradiction:

Ease of operationVSDuration of action of stationary object

Solution Approach 1:

The patent employs correlated electron materials that inherently retain their resistance state without requiring continuous power or periodic refresh, and the material itself provides the switching mechanism without degrading over time. This self-sustaining property enables endurance exceeding 10 billion read/write cycles, dramatically improving upon the 600,000 cycle limit of conventional EEPROMs

Inventive Principle:

Principle #25Self-service

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

CEMs provide a non-volatile memory with high endurance, low voltage operation, and scalability, achieving resistance states that are stable over a wide temperature range and numerous read/write cycles without fatigue, enabling denser memory arrays and faster programming.

Implementation Method 1

Correlated Electron Materials (CEMs) that exhibit an abrupt conductor/insulator transition due to electron correlations

Methodology Applied

Scientific EffectElectron correlations:

Implementation Method 2

the CEM switches resistive states due to a Mott-transition in the majority of the volume of the CEM

Methodology Applied

Scientific EffectMott transition:

Implementation Method 3

featuring a homogeneous crystal structure for stable resistance switching

Methodology Applied

Scientific EffectHomogeneous crystal structure:

Data Source

PatentUS7872900B2Correlated electron memory

Publication Date: 2011.01.18 SYMETRIX MEMORY LLC

AI summary

A non-volatile resistive switching memory that includes a homogeneous material which changes between the insulative and conductive states due to correlations between electrons, particularly via a Mott transition. The material is crystallized into the conductive state and does not require electroforming.