NAND Memory Charge-Blocking Segments for Data Retention

Solution Overview

Problem

Conventional NAND memory architectures face data retention issues due to charge migration between memory cells caused by charge-trapping material extending across multiple cells, leading to inefficiencies in charge storage and retrieval.

Innovation Solution

Incorporating breaks in the charge-trapping material between memory cells and employing a vertical stack configuration with alternating insulative and conductive levels, including high-k dielectric materials and charge-blocking layers to impede charge migration and enhance data retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If charge-trapping material is used to store charge in NAND memory cells, then charge storage capability is improved, but charge migration between adjacent memory cells occurs causing data retention issues

Engineering Contradiction:

Improvecharge storage capabilityVSAvoiddata retention

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The charge-blocking material is divided into multiple vertically-spaced segments rather than forming a continuous layer. These segmented blocks are positioned at different vertical levels to interrupt charge migration pathways while preserving charge storage in the charge-trapping material layers between segments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Charge-blocking material segments are introduced as intermediary structures between adjacent memory cells. These segments act as barriers that mediate the interaction between neighboring cells, preventing charge migration while allowing each cell to maintain its charge storage functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If charge-blocking material is introduced to prevent charge migration, then data retention is improved, but device structure becomes more complex

Engineering Contradiction:

Improvedata retentionVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The charge-blocking material is divided into multiple vertically-spaced segments rather than forming a continuous layer. These segmented blocks are positioned at different vertical levels to interrupt charge migration pathways while preserving charge storage in the charge-trapping material layers between segments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solution introduces vertical segmentation of charge-blocking material at different height levels within the memory stack. By utilizing the vertical dimension strategically, the patent creates multiple barriers against charge migration without requiring additional lateral space or complex planar structures.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If vertical stack configuration with alternating insulative and conductive levels is implemented, then charge migration is reduced, but manufacturing process complexity increases

Engineering Contradiction:

Improvecharge migration reductionVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The charge-blocking material is divided into multiple vertically-spaced segments rather than forming a continuous layer. These segmented blocks are positioned at different vertical levels to interrupt charge migration pathways while preserving charge storage in the charge-trapping material layers between segments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The memory structure employs periodic alternating layers of insulative and conductive materials in a vertical stack configuration. This periodic arrangement creates regular intervals for charge blocking and storage functions, enabling systematic manufacturing through repeated deposition cycles.

Inventive Principle:

Principle #19Periodic 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 solution effectively reduces charge migration, improving data retention and string current performance by creating vertically-spaced segments of charge-blocking and charge-storage materials, thereby enhancing the reliability and efficiency of NAND memory cells.

Implementation Method 1

high-k dielectric materials

Methodology Applied

Scientific EffectDielectric: Dielectric

Implementation Method 2

charge-blocking layers to impede charge migration

Methodology Applied

Scientific EffectElectrical resistance: Electrical Resistance

Data Source

PatentUS11563031B2Integrated assemblies having vertically-spaced channel material segments, and methods of forming integrated assemblies

Publication Date: 2023.01.24 MICRON TECHNOLOGY INC

AI summary

Some embodiments include a NAND memory array having a vertical stack of alternating insulative levels and conductive levels. The conductive levels include control gate regions and distal regions proximate the control gate regions. The control gate regions have front surfaces, top surfaces and bottom surfaces. The top and bottoms surfaces extend back from the front surfaces. High-k dielectric material is along the control gate regions. The high-k dielectric material has first regions along the top and bottom surfaces, and has second regions along the front surfaces. The first regions are thicker than the second regions. Charge-blocking material is adjacent to the second regions of the high-k dielectric material. Charge-storage material is adjacent to the charge-blocking material. Gate-dielectric material is adjacent to the charge-storage material. Channel material is adjacent to the gate-dielectric material. Some embodiments include integrated assemblies. Some embodiments include methods of forming integrated assemblies.