Conductive Nanodots in Memory Cells for Data Retention

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Solution Overview

Problem

As memory densities increase, issues with data retention, program saturation, and trap-up worsen in flash memory devices, particularly due to the impracticality of thin polysilicon charge storage nodes, necessitating alternative memory device architectures.

Innovation Solution

The implementation of memory cells with a charge storage node between a tunnel dielectric and an intergate dielectric, utilizing conductive nanodots capable of storing charge, which provides a distinct interface compared to prior structures with nanodots embedded within the charge storage material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If polysilicon charge storage nodes are used to increase memory density, then memory density is improved, but data retention and program saturation issues worsen

Engineering Contradiction:

Improvememory densityVSAvoiddata retention

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the material composition and structural parameters of the charge storage node by introducing conductive nanodots (metal or metal alloy) within the polysilicon charge storage material. This composite structure modifies the electrical and storage properties to improve data retention while maintaining high memory density.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite charge storage node structure consisting of conductive nanodots (metal or metal alloy) embedded within polysilicon charge storage material. This composite approach combines the high density capability of polysilicon with the superior charge retention properties of metal nanodots, resolving the contradiction between density and reliability.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If polysilicon charge storage nodes are used to increase memory density, then memory density is improved, but program saturation issues worsen

Engineering Contradiction:

Improvememory densityVSAvoidprogram saturation

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent modifies the charge storage mechanism by introducing conductive nanodots that provide additional charge trapping sites with different energy levels. This changes the programming characteristics and reduces saturation effects, allowing continued improvement in memory density without the harmful program saturation effect.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The composite structure of metal nanodots within polysilicon creates multiple charge storage mechanisms with different characteristics, preventing the uniform saturation that occurs in pure polysilicon nodes. This allows the system to maintain programming capability at high memory densities.

Inventive Principle:

Principle #40Composite materials

3Quantity of substance

If polysilicon charge storage nodes are used to increase memory density, then memory density is improved, but trap-up issues worsen

Engineering Contradiction:

Improvememory densityVSAvoidtrap-up

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent changes the energy level distribution and charge trapping characteristics by incorporating metal nanodots with different work functions and electronic properties. This modifies the trap-up behavior by providing alternative charge paths and reducing the formation of harmful trapped charges that limit memory density scaling.

Inventive Principle:

Principle #35Parameter changes

4Reliability

If nanodots are embedded within charge storage material, then charge storage capability is improved, but interface distinctness worsens

Engineering Contradiction:

Improvecharge storage capabilityVSAvoidinterface distinctness

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The patent applies local quality by creating distinct regions: conductive nanodots embedded within polysilicon charge storage material, which is itself positioned between tunnel dielectric and intergate dielectric layers. This localized structuring provides both excellent charge storage capability and distinct interfaces for controlled charge injection and storage.

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 solution enhances data storage capabilities by improving data retention and reducing program saturation issues, offering a more effective charge storage mechanism for high-density memory devices.

Implementation Method 1

memory cells having a charge storage node between a tunnel dielectric and an intergate dielectric

Methodology Applied

Scientific EffectElectrical charge storage: Capacitance

Implementation Method 2

tunnel dielectric

Methodology Applied

Scientific EffectQuantum tunneling:

Data Source

PatentUS11527631B2Memory cells having electrically conductive nanodots and apparatus having such memory cells

Publication Date: 2022.12.13 MICRON TECHNOLOGY INC

AI summary

Memory cells having a first dielectric between a charge storage material and a semiconductor, conductive nanodots between the charge storage material and a control gate, and a second dielectric between the control gate and the conductive nanodots.