Flash Memory Pre-Programming for Over-Programming Control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Flash memory devices experience over-programming issues due to excessive charges trapped in the storage layer and degradation of the insulating oxide layer after multiple program-erase cycles, leading to reliability problems such as read failures and disturbances in adjacent memory cells.

Innovation Solution

Before erasing data, memory cells are programmed to a pre-programmed state, and verify operations are performed to identify the threshold voltage. Based on this, the program voltage is adjusted to mitigate over-programming by using lower voltages or shorter pulse lengths for subsequent operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If memory cells are programmed using standard program pulses after multiple program-erase cycles, then programming speed is maintained, but over-programming occurs leading to read failures and reliability degradation

Engineering Contradiction:

Improvememory device reliabilityVSAvoidprogramming speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies preliminary action by performing a pre-program operation before the main programming operation. This pre-program step prepares the memory cells by partially programming them to a specific threshold voltage range, which prevents over-programming during subsequent operations while maintaining overall programming efficiency. The pre-program phase sets up the conditions needed for reliable main programming without excessive charges.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamics by adjusting program pulse parameters (voltage level, pulse width, or number of pulses) based on the program-erase cycle count and the specific memory block characteristics. The control logic dynamically modifies programming conditions to prevent over-programming in aged memory cells while maintaining speed in newer cells, creating an adaptive programming system that resolves the reliability-speed tradeoff.

Inventive Principle:

Principle #15Dynamics

2Productivity

If higher program voltages are used to maintain programming speed, then productivity is improved, but over-programming and harmful effects on memory cells increase

Engineering Contradiction:

Improveprogramming speedVSAvoidover-programming effects

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent segments the programming operation into two distinct phases: a pre-program phase with controlled, lower voltage pulses to establish baseline threshold voltages, and a main programming phase with higher voltage pulses for rapid data programming. This segmentation allows each phase to use optimized voltage levels, preventing over-programming while maintaining overall speed through the efficiency of both stages.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies parameter changes by modifying program pulse characteristics (voltage amplitude, pulse duration, or pulse count) based on the program-erase cycle history of memory blocks. The control logic adjusts these parameters dynamically, using lower voltages for blocks that have undergone many cycles and standard voltages for newer blocks, thereby preventing over-programming effects while maintaining productivity.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If standard programming operations are performed without pre-programming, then device complexity is reduced, but manufacturing precision and threshold voltage control deteriorate

Engineering Contradiction:

Improvethreshold voltage controlVSAvoidprogramming operation complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by using verify operations after programming to detect over-programmed cells and adjusting subsequent programming pulses accordingly. The control logic monitors threshold voltage distribution and modifies programming parameters in real-time based on verify results, ensuring precise threshold voltage control while managing the complexity through automated feedback loops.

Inventive Principle:

Principle #23Feedback

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 approach prevents over-programming, maintaining the reliability of memory devices by ensuring memory cells are programmed to the intended threshold level, thereby reducing read failures and maintaining data integrity.

Implementation Method 1

program (write) and erase operations, to change the threshold voltage of each memory cell to a respective level

Methodology Applied

Scientific EffectThreshold voltage change:

Implementation Method 2

performing a verify operation to identify the threshold voltage

Methodology Applied

Scientific EffectThreshold voltage detection:

Data Source

PatentUS20250285683A1Methods and apparatuses for operating a memory device

Publication Date: 2025.09.11 YANGTZE MEMORY TECH CO LTD

AI summary

Example memory devices, memory systems, and methods for managing over-programming in flash memory are disclosed. In one example, a method of operating a memory device includes, before erasing data in a memory block of the memory device, programing memory cells in the memory block to a pre-programmed state, and identifying a threshold voltage of the memory cells in the pre-programmed state. The method further includes, after erasing the data in the memory block, programing memory cells in the memory block using at least one program pulse determined based on the threshold voltage.