Non-volatile Memory Copy-back Voltage Control

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Solution Overview

Problem

In non-volatile memory devices, the copy-back operation often applies unnecessary high program voltage to memory cells with repaired columns, leading to interference and deterioration of device characteristics, as the existing Incremental Step Pulse Program method sets a maximum program voltage regardless of cell state.

Innovation Solution

A method and device for measuring and recording the maximum program voltage used during copy-back operations, allowing for controlled application of program voltage based on the state of individual memory cells to prevent excessive voltage application and minimize interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the Incremental Step Pulse Program method sets a maximum program voltage for copy-back operations, then the programming speed is improved, but unnecessary high voltage is applied to memory cells with repaired columns causing interference and deterioration

Engineering Contradiction:

Improveprogramming speedVSAvoidinterference and deterioration of memory cells

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies different program voltage levels to different memory cells based on their individual states. Memory cells with repaired columns are identified and assigned lower voltage levels, while normal memory cells receive higher voltage levels. This localized differentiation resolves the contradiction by allowing high voltage application only where needed for speed, while protecting vulnerable cells from harmful interference.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent dynamically adjusts the program voltage parameter based on the state of each memory cell. By measuring whether a memory cell has a repaired column and changing the voltage parameter accordingly, the system achieves both fast programming for normal cells and protection for repaired cells, resolving the speed versus harm contradiction.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If high program voltage is applied to all memory cells during copy-back operation, then programming efficiency is improved, but memory cell reliability deteriorates due to unnecessary voltage stress on repaired columns

Engineering Contradiction:

Improveprogramming efficiencyVSAvoidmemory cell reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements local quality by treating memory cells with repaired columns differently from normal memory cells. It identifies cells with repaired columns and applies a lower program voltage specifically to those cells, while maintaining high voltage for normal cells. This selective approach preserves programming efficiency for the majority of cells while protecting the reliability of vulnerable cells.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies partial action by providing high program voltage only to the extent needed - specifically to memory cells without repaired columns. For cells with repaired columns, the voltage is reduced to the minimum necessary level. This partial application of high voltage maintains overall programming efficiency while avoiding excessive voltage stress that would harm reliability.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS7944758B2Non-volatile memory device and method for copy-back thereof

Publication Date: 2011.05.17 SK HYNIX INC

AI summary

A method for performing a copy-back operation in a non-volatile memory device includes: measuring and recording a maximum program voltage used to program a part of target data to copy-back when a copy-back command is inputted; and performing a copy-back operation using the recorded maximum program voltage.