Flash Memory Charge Loss Compensation via Refill Program

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Flash memory cells experience reduced reliability and charge retention capability due to high program and erase cycle (PE cycle) stress, leading to charge loss and reduced data retention over time.

Innovation Solution

A memory device and compensation method that perform a reading operation on programmed memory cells to detect charge loss, and then execute a refill program operation to recharge the affected memory cells, thereby maintaining data retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If flash memory cells undergo high program and erase cycles, then storage capacity and usage flexibility are improved, but charge retention capability deteriorates

Engineering Contradiction:

Improveusage flexibilityVSAvoidcharge retention capability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system performs a reading operation before data is actually lost to detect charge loss phenomena in advance. By identifying memory cells with charge loss before the data becomes completely unreliable, the system can proactively initiate refill program operations to restore the charges, thereby maintaining charge retention capability while allowing high program and erase cycle usage.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If refill program operation is performed on charge loss memory cells, then data retention is improved, but additional program operations increase wear

Engineering Contradiction:

Improvedata retentionVSAvoidprogram operation count

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system implements a feedback mechanism where reading operations continuously monitor the charge status of memory cells. When charge loss is detected, the system triggers refill program operations specifically on the affected cells. This targeted approach ensures data retention is maintained while minimizing unnecessary program operations, as only cells with actual charge loss undergo refilling.

Inventive Principle:

Principle #23Feedback

3Reliability

If reading operation is performed to detect charge loss, then data reliability is maintained, but additional read operations increase power consumption

Engineering Contradiction:

Improvedata reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system performs reading operations on memory cells to detect charge loss, applying partial action only where needed. Rather than continuously reading all memory cells, the system targets specific cells that exhibit charge loss phenomena, thereby maintaining data reliability while minimizing unnecessary read operations and associated power consumption.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS12254934B2Memory device and compensation method of data retention thereof

Publication Date: 2025.03.18 MACRONIX INTERNATIONAL CO LTD

AI summary

A memory device, such as a 3D AND type flash memory, and a compensation method of data retention thereof are provided. The compensation method includes the following. A reading operation is performed on each of a plurality of programmed memory cells of the memory device. Whether a charge loss phenomenon occurs in the programmed memory cells is determined through the reading operation to set the programmed memory cells to be charge loss memory cells. A refill program operation is performed on the charge loss memory cells.