Flash Memory Kink Compensation via Seeding Voltage

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Solution Overview

Problem

Flash memory devices experience kink effects due to capacitive coupling between memory cell components during programming, leading to over-programming and operational errors, especially in NAND array architectures where all bit lines are programmed simultaneously, resulting in unintended voltage shifts and incorrect programming states.

Innovation Solution

Implementing a method for memory kink compensation by applying sequentially incrementing programming pulses with a seeding voltage followed by a reduced programming pulse step voltage magnitude to mitigate the effects of kink, adjusting the programming pulse step voltage based on the number of affected memory cells and the type of kink encountered, and using a kink check mechanism to determine the necessary compensation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If all bit lines are programmed simultaneously in NAND array architecture, then programming speed is improved, but capacitive coupling between memory cell components causes kink effects leading to over-programming

Engineering Contradiction:

Improveprogramming speedVSAvoidprogramming accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent segments the programming process into multiple phases with different pulse characteristics. Initial programming pulses are applied with one set of parameters, followed by verification, and then additional pulses are applied only to cells that require further programming. This segmentation allows simultaneous programming of all bit lines while preventing over-programming through staged verification and conditional re-programming.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements a feedback mechanism where programming verification is performed between initial and additional programming pulses. The verification step detects which cells have reached the desired programmed state and which require additional programming. This feedback loop prevents over-programming by applying additional pulses only to cells that need them, while leaving already-programmed cells unchanged.

Inventive Principle:

Principle #23Feedback

2Reliability

If programming pulse voltage is increased to ensure complete programming, then programming reliability is improved, but kink effects cause unintended voltage shifts and over-programming

Engineering Contradiction:

Improveprogramming reliabilityVSAvoidkink effects

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary programming pulses to all memory cells before verification. This preliminary action ensures that cells receive the necessary programming voltage to reach the desired state. Following this, verification is performed to identify cells that have been adequately programmed versus those requiring additional pulses, preventing over-programming of cells that already reached the target state.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent initially applies programming pulses that may be excessive for some cells (causing kink effects and potential over-programming), but then uses verification to identify which cells actually need the full voltage. Additional pulses are applied partially only to cells that require them, rather than applying excessive voltage to all cells continuously.

Inventive Principle:

Principle #16Partial or excessive action

3Manufacturing precision

If programming pulses are applied in multiple stages with verification, then programming accuracy is improved, but programming time is increased

Engineering Contradiction:

Improveprogramming accuracyVSAvoidprogramming time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent uses periodic programming action where programming pulses are applied in cycles separated by verification steps. The pattern involves applying pulses, verifying results, and then deciding whether to apply additional pulses. This periodic approach balances accuracy and time by using the minimum necessary verification cycles to achieve correct programming without unnecessary delays.

Inventive Principle:

Principle #19Periodic action

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 effectively reduces the risk of over-programming and improves programming accuracy by compensating for the kink effects, ensuring that memory cells are programmed to the correct states without exceeding intended voltage thresholds, thereby enhancing the reliability of flash memory devices.

Implementation Method 1

Flash memory devices experience kink effects due to capacitive coupling between memory cell components during programming

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentUS9025388B2Method for kink compensation in a memory

Publication Date: 2015.05.05 MICRON TECHNOLOGY INC

AI summary

This disclosure concerns memory kink compensation. One method embodiment includes applying a number of sequentially incrementing programming pulses to a memory cell, with the sequential programming pulses incrementing by a first programming pulse step voltage magnitude. A seeding voltage is applied after applying the number of sequentially incrementing programming pulses. A next programming pulse is applied after applying the seeding voltage, with the next programming pulse being adjusted relative to a preceding one of the sequentially incrementing programming pulses by a second programming pulse step voltage magnitude. The second programming pulse step voltage magnitude can be less than the first programming pulse step voltage magnitude.