Semiconductor Read Disturb Detection via Dummy Word Line Voltage

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Solution Overview

Problem

In nonvolatile memory devices, read disturb phenomena cause unintended charge storage due to repeated read operations, leading to delayed detection of data restoration issues and increased processing time, especially when the voltage of adjacent word lines rises during data retrieval.

Innovation Solution

A semiconductor device with a transmission and reception circuit and a control circuit that applies a second voltage higher than the adjacent word line voltage to a dummy word line to detect read disturb by acquiring threshold voltage distribution information and determining the influence of read disturb based on this information, allowing for early detection and data restoration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If read operations are repeated to retrieve data, then data access is enabled, but unintended charge is stored in memory cells due to read disturb phenomenon

Engineering Contradiction:

Improvedata access capabilityVSAvoiddata integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies a second voltage higher than the first voltage to a dummy word line before performing read operations on adjacent word lines. This preliminary action creates a protective voltage environment that prevents charge from being accidentally stored in memory cells during subsequent read operations, thereby preventing read disturb effects before they occur.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces a dummy word line as an intermediary element between the read target word line and other word lines. This dummy word line acts as a mediator that absorbs or redirects the voltage effects during read operations, preventing direct harmful effects on memory cells connected to adjacent word lines while still enabling normal data access.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If detection of read disturb influence is delayed, then normal read operations continue, but data restoration fails or processing time increases

Engineering Contradiction:

Improveread operation continuityVSAvoiddata restoration time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent measures threshold voltage distribution of memory cells connected to the dummy word line and uses this measurement as feedback to detect read disturb effects. By continuously monitoring the threshold voltage distribution and comparing it against reference values, the system can detect read disturb influence in real-time and trigger data restoration operations before failures occur, reducing processing time.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces physical inspection methods with electrical measurement methods to detect read disturb effects. By measuring threshold voltage distribution electrically rather than physically examining memory cell states, the system achieves rapid, non-intrusive detection that maintains read operation continuity while enabling timely data restoration.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a dummy word line with higher voltage is applied for read disturb detection, then early detection is enabled, but device complexity increases

Engineering Contradiction:

Improveread disturb detection accuracyVSAvoidcontrol circuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the dummy word line serve multiple functions: it acts as both a protective element during read operations and as a sensing element for detecting read disturb effects. By measuring threshold voltage distribution on the same dummy word line used for protection, the system eliminates the need for separate detection circuits, thereby reducing overall device complexity while maintaining high detection accuracy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the voltage parameter applied to the dummy word line dynamically - applying a second voltage higher than the first voltage during specific detection periods. This parameter change enables the dummy word line to operate in different modes (protection mode and detection mode) using the same hardware structure, avoiding the need for additional complex circuitry while achieving accurate read disturb detection.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20230170032A1Semiconductor device, memory system and semiconductor memory device

Publication Date: 2023.06.01 KIOXIA CORP

AI summary

A semiconductor device includes a transmission and reception circuit and a control circuit. The transmission and reception circuit transmits and receives a signal to and from a semiconductor memory device. The control circuit acquires threshold voltage distribution information of a memory element connected to a word line for read disturb detection to which a second voltage higher than a first voltage applied to an adjacent word line adjacent to a read target word line during a read operation is applied and determines an influence of read disturb based on the threshold voltage distribution information.