Memory Program Refresh Using GIDL to Tighten Read Windows

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Solution Overview

Problem

Existing memory devices face challenges in storing additional bits per cell due to narrow threshold voltage distributions and reduced read window budgets, making it difficult to increase bit storage without compromising reliability.

Innovation Solution

Implementing program refresh with gate-induced drain leakage (GIDL) to tighten threshold voltage distributions and recover read window budgets by applying controlled bias voltages to generate positive charge carriers to neutralize negative charge carriers, thereby enhancing memory cell programming efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If traditional programming methods are used to increase bits per cell, then storage capacity increases, but threshold voltage distributions become narrow and read window budgets decrease

Engineering Contradiction:

Improvebits per cellVSAvoidread window budget

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies parameter changes by modifying the voltage distribution characteristics through GIDL operations. By controlling the voltage applied to the control gate and drain, the method adjusts the threshold voltage distribution width, thereby expanding the read window budget while maintaining increased bits per cell storage capacity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the typically harmful GIDL effect, which causes leakage current and threshold voltage shifts, into a beneficial operation for refreshing and redistributing charge carriers. By deliberately inducing GIDL under controlled conditions, the method tightens threshold voltage distributions and recovers read window budgets, transforming a detrimental phenomenon into a useful mechanism for maintaining reliability in high-density storage.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Quantity of substance

If more bits are stored per cell, then storage density increases, but threshold voltage distributions narrow making differentiation difficult

Engineering Contradiction:

Improvebits per cellVSAvoidthreshold voltage distribution width

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent uses parameter changes by adjusting the voltage conditions during GIDL operations to control the spread and width of threshold voltage distributions. This allows differentiated voltage levels for multiple bits per cell while maintaining sufficient separation between distribution edges for reliable reading.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback through iterative GIDL refresh operations that monitor and adjust charge carrier distributions. By repeatedly applying controlled GIDL and measuring the resulting threshold voltage distributions, the system optimizes the separation between voltage levels representing different bit states, thereby improving measurement precision for multi-bit cells.

Inventive Principle:

Principle #23Feedback

3Reliability

If program refresh operations are performed to maintain data integrity, then reliability improves, but disturb effects such as erase and program disturb increase

Engineering Contradiction:

Improvedata integrityVSAvoiddisturb effects

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by performing GIDL refresh operations selectively on specific word lines or memory regions that require refreshing, rather than uniformly across the entire memory array. This localized approach maintains data integrity in affected regions while minimizing disturb effects on neighboring cells that do not require refreshing.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses partial action by applying GIDL operations with controlled voltage magnitudes and durations that are sufficient to refresh charge carriers but not excessive enough to cause significant disturb effects. By optimizing the refresh parameters to the minimum necessary level, the method maintains reliability while reducing harmful side effects.

Inventive Principle:

Principle #16Partial or excessive 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 increases read margin and reliability, allowing for more bits to be stored per cell while minimizing disturb effects such as erase and program disturb.

Implementation Method 1

program refresh with gate-induced drain leakage (GIDL) to tighten threshold voltage distributions and recover read window budgets by applying controlled bias voltages to generate positive charge carriers to neutralize negative charge carriers

Methodology Applied

Scientific EffectGate-induced drain leakage (GIDL): Avalanche Breakdown

Data Source

PatentUS20260080962A1Program refresh with gate-induced drain leakage

Publication Date: 2026.03.19 MICRON TECHNOLOGY INC

AI summary

A memory device includes a memory array and control logic, operatively coupled to the memory array, to perform operations including causing gate-induced drain leakage (GIDL) to be generated during a seeding operation of a program refresh operation, and causing, during the seeding operation, positive charge carriers generated by the GIDL to be transported to neutralize negative charge carriers generated by the program refresh operation.