Memory Read Level Threshold Dragging for Error Reduction

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Solution Overview

Problem

In conventional memory sub-systems, read level thresholds associated with the first programming pass are adjusted independently from those of the second programming pass, leading to decreased throughput and increased probability of pre-read bit errors and uncorrectable error correction code errors.

Innovation Solution

The 'drag along' operation adjusts first programming pass read level thresholds based on measured changes in second programming pass read level thresholds, ensuring proportional changes to maintain optimal performance and reduce error probabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If read level thresholds for first programming pass are adjusted independently from second programming pass, then device complexity is reduced, but reliability decreases and productivity decreases

Engineering Contradiction:

Improvethreshold adjustment complexityVSAvoiderror probability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent merges the threshold adjustment processes of the first and second programming passes by making the first pass threshold adjustments dependent on the second pass threshold adjustments. This coupling ensures that both passes use coordinated threshold values, reducing error probabilities while maintaining manageable system complexity through a hierarchical adjustment strategy.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent implements feedback by using the threshold adjustments from the second programming pass to inform and adjust the thresholds for the first programming pass. This feedback mechanism ensures that threshold values are optimized based on actual performance data, improving reliability without requiring completely independent complex adjustment systems for each pass.

Inventive Principle:

Principle #23Feedback

2Ease of operation

If read level thresholds for first programming pass are adjusted independently from second programming pass, then ease of operation is improved, but productivity decreases

Engineering Contradiction:

Improvethreshold adjustment easeVSAvoidmemory operation throughput

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent applies preliminary action by performing the second programming pass threshold adjustments first, then using those results to guide the first programming pass threshold adjustments. This sequencing ensures that the most critical threshold optimizations are established beforehand, improving overall productivity while maintaining operational simplicity through a structured two-stage process.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If read level thresholds are not synchronized across programming passes, then device complexity is reduced, but manufacturing precision decreases

Engineering Contradiction:

Improvethreshold synchronization complexityVSAvoidprogramming distribution alignment

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent merges the threshold calibration processes across programming passes by establishing a dependency relationship where first pass thresholds are adjusted based on second pass threshold performance. This ensures precise alignment of programming distributions across passes while avoiding the complexity of fully independent threshold management systems.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11309020B2Dragging first pass read level thresholds based on changes in second pass read level thresholds

Publication Date: 2022.04.19 MICRON TECHNOLOGY INC

AI summary

A processing device performs a multi-pass programming operation on the memory device resulting in first pass programming distributions and second pass programming distributions. One or more read level thresholds between the second pass programming distributions are changed. Responsive to changing the one or more read level thresholds between the second pass programming distributions, one or more read level thresholds between the first pass programming distributions are adjusted based on the changes to the one or more read level thresholds between the second pass programming distributions.