Memory Array Mode Switching with Tailored Erase Voltages

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Solution Overview

Problem

Existing memory devices face issues with performance degradation and unrecoverable read errors when switching storage modes due to inappropriate voltage application during mode transitions, leading to under-programmed or over-programmed memory cells.

Innovation Solution

Implementing specific switch erase and program operations with tailored voltage values to maintain threshold voltage distributions within desired ranges, ensuring reliable mode transitions between single-level and multi-level cell configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a memory device operates in a first storage mode with high storage density, then storage capacity is improved, but reliability deteriorates due to performance degradation and unrecoverable read errors when switching modes

Engineering Contradiction:

Improvestorage capacityVSAvoidread error rate

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies parameter changes by implementing different erase operations with distinct voltage parameters for different storage modes. When switching from first storage mode to second storage mode, the system performs a switch erase operation using a second effective erase voltage that is lower than the first effective erase voltage used in the first storage mode. This voltage parameter adjustment prevents over-erasure and ensures reliable mode transitions while maintaining high storage capacity.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the memory device switches from first storage mode to second storage mode, then adaptability is improved, but reliability worsens due to inappropriate voltage application causing under-programmed or over-programmed cells

Engineering Contradiction:

Improvestorage mode flexibilityVSAvoiddata integrity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements preliminary action by performing a switch erase operation before the actual data programming when transitioning to the second storage mode. This preliminary erase action, using a lower effective erase voltage, prepares the memory cells for reliable programming in the second storage mode by removing any residual charges from the first storage mode, thereby preventing under-programmed or over-programmed cells and ensuring data integrity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes voltage parameters during mode switching by using a second effective erase voltage that is lower than the first effective erase voltage. This parameter change is critical for maintaining reliability during adaptability transitions, as it prevents excessive erasure that would occur if the higher first effective erase voltage were used in the second storage mode.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If a higher effective erase voltage is used in the first storage mode, then erase operation effectiveness is improved, but damage to memory cells increases leading to performance degradation

Engineering Contradiction:

Improveerase operation efficiencyVSAvoidmemory cell durability

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent applies parameter changes by differentiating erase voltages based on storage mode. The first effective erase voltage used in the first storage mode is higher and optimized for rapid erase operations, while the second effective erase voltage used in the second storage mode is lower to prevent damage to memory cells. This selective voltage application maintains high productivity in the first storage mode while preserving memory cell durability during transitions to the second storage mode.

Inventive Principle:

Principle #35Parameter changes

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

Improves memory device reliability and extends lifespan by preventing performance deterioration, reducing error rates, and enhancing storage capacity without additional hardware costs.

Implementation Method 1

performing a switch erase operation to switch the portion of the memory array from the first storage mode to a switched second storage mode... after performing the switch erase operation, a threshold voltage of a memory cell of the portion of the memory array is higher than a threshold voltage of the memory cell of the portion of the memory array after performing the first erase operation

Methodology Applied

Scientific EffectVoltage-induced threshold voltage change: Electric Field

Data Source

PatentUS12504887B2Erase and program operations for memory devices having multiple storage modes

Publication Date: 2025.12.23 YANGTZE MEMORY TECH CO LTD

AI summary

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for operating a memory device having multiple storage modes. In one example method, a portion of a memory array is selected, wherein the portion of the memory array is programmable in a first storage mode or a second storage mode. The second storage mode has a lower storage density than the first storage mode, and the first storage mode corresponds to a first erase operation. A switch erase operation is performed to switch the portion of the memory array from the first storage mode to a switched second storage mode, wherein the switched second storage mode has the same storage density as the second storage mode and corresponds to the switch erase operation. The switch erase operation is different from the first erase operation on the memory array in the first storage mode.