Nonvolatile Memory Cell With Intersecting Electrodes

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Solution Overview

Problem

Current memory cell technologies face challenges in achieving smaller and denser integrated circuits with efficient nonvolatile memory cells that can reliably switch between resistive states without the need for frequent refresh, particularly in volatile memory systems.

Innovation Solution

The integration of a nonvolatile memory cell design featuring a pair of current conductive electrodes with an ion conductive material sandwiched between them, where the electrodes are fabricated with specific orientations and materials to ensure precise control over the formation and reversal of conductive paths, allowing for reversible switching between high and low resistance states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If volatile memory is used to achieve fast access speed, then speed is improved, but data is lost without frequent refresh requiring continuous energy consumption

Engineering Contradiction:
Improveaccess speedVSAvoidenergy consumption for refresh
Core Design Contradiction:
SpeedVSLoss of energy

Solution Approach 1:

The memory system is segmented into two distinct memory cell types: volatile memory cells for fast access and nonvolatile memory cells for energy-efficient data retention. This segmentation allows the system to allocate different functions to different memory components, achieving both fast access and low energy consumption for specific use cases.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of attempting to make volatile memory nonvolatile through continuous refresh operations, the invention inverts the approach by using inherently nonvolatile memory cells that naturally retain data without refresh, thereby eliminating the energy consumption associated with refresh operations while maintaining data retention capability.

Inventive Principle:
Principle #13The other way round (Inversion)

2Productivity

If memory cell size is reduced to increase density, then quantity of cells per area is improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improvememory cell densityVSAvoidfabrication precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The memory cell structure utilizes a three-dimensional configuration with electrodes extending in different spatial dimensions and intersecting at specific angles. This dimensional approach allows for compact cell design that achieves high density while maintaining manufacturable feature sizes through the use of angled intersections and vertical electrode arrangements.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The memory cell employs composite material structures including conductive materials, insulating materials, and ion-conductive materials in specific layer configurations. This composite approach enables precise control over electrical properties and facilitates fabrication through standard semiconductor processing techniques, balancing density with manufacturing precision.

Inventive Principle:
Principle #40Composite materials

3Reliability

If nonvolatile memory cells are designed with complex structures to ensure reliable data retention, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improvedata retention reliabilityVSAvoidmemory cell structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and isolates the essential functionality for nonvolatile data storage into a dedicated memory cell structure with specific electrode and ion-conductive material components. By separating this core function from additional complex control mechanisms, the design achieves reliable data retention through a relatively simple two-electrode structure without requiring elaborate refresh control circuits or multiple storage elements.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The nonvolatile memory cell structure utilizes ion-conductive material that automatically forms and maintains conductive filaments through ionic migration under applied voltage, without requiring external control mechanisms or refresh operations. This self-service mechanism inherent in the material physics provides reliable data retention while minimizing the need for complex control circuitry.

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

This design enables the creation of smaller, denser memory cells that can maintain resistive states without refresh, enhancing data storage efficiency and reliability in nonvolatile memory applications.

Implementation Method 1

A suitable voltage applied across the electrodes generates current conductive super-ionic clusters or filaments. Such result from ion transport through the ion conductive material which grows the clusters/filaments from one of the electrodes (the cathode), through the ion conductive material, and toward the other electrode (the anode).

Methodology Applied
Scientific EffectIon transport: Ion Exchange

Implementation Method 2

The clusters or filaments create current conductive paths between the electrodes. An opposite voltage applied across electrodes essentially reverses the process and thus removes the current conductive paths.

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

At least one of the first current conductive electrode and the second current conductive electrode has an electrochemically active surface received directly against the ion conductive material.

Methodology Applied
Scientific EffectElectrochemical reaction: Redox Reactions

Data Source

PatentEP2630659B1Integrated circuitry comprising nonvolatile memory cells and methods of forming a nonvolatile memory cell
Publication Date: 2018.10.24 MICRON TECHNOLOGY INC
  • EP2630659B1 patent drawingFigure 1
  • EP2630659B1 patent drawingFigure 2~3
  • EP2630659B1 patent drawingFigure 4

AI summary

An integrated circuit has a nonvolatile memory cell that includes a first electrode, a second electrode, and an ion conductive material there-between. At least one of the first and second electrodes has an electrochemically active surface received directly against the ion conductive material. The second electrode is elevationally outward of the first electrode. The first electrode extends laterally in a first direction and the ion conductive material extends in a second direction different from and intersecting the first direction. The first electrode is received directly against the ion conductive material only where the first and second directions intersect. Other embodiments, including method embodiments, are disclosed.