Memory Page Grouping by Program Time for Error Detection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In memory systems, data retention characteristics deteriorate over time, leading to read errors and reduced reliability, especially in semiconductor memory devices with 3D stack structures, due to the inherent characteristics of NAND flash memory, which affects the utilization efficiency and reliability of the memory system.

Innovation Solution

The memory system manages data by grouping pages based on program time information, performing test reads on pages with longer program lapse times, detecting errors, and reprogramming selected pages to maintain data integrity and reduce read errors, thereby improving retention characteristics and system reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If data is stored in NAND flash memory devices with 3D stack structures, then storage capacity and integration density are improved, but data retention characteristics deteriorate over time leading to read errors

Engineering Contradiction:

Improvestorage capacityVSAvoiddata retention characteristics

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The system performs preliminary classification of pages based on program time information before read operations. Pages are divided into first pages (programmed within a first time period) and second pages (programmed outside the first time period), allowing differential handling to prevent read errors in advance

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Different read operations are applied to different groups of pages based on their program time characteristics. First pages undergo a first read operation while second pages undergo a second read operation, tailoring the read process to the specific retention characteristics of each group

Inventive Principle:

Principle #3Local quality

2Reliability

If test reads are performed on all pages, then read errors are detected, but system operation time and complexity increase

Engineering Contradiction:

Improveerror detection capabilityVSAvoidsystem operation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The page set is segmented into first pages and second pages based on program time information. This segmentation allows the system to apply different read operations to different segments, avoiding the need to perform exhaustive test reads on all pages while maintaining error detection capability for pages that require it

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs read operations selectively on specific page groups rather than all pages. By identifying pages that require attention based on program time characteristics, the system applies read operations only where necessary, reducing overall operation time while maintaining sufficient error detection

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS9983916B2Memory system and operating method thereof

Publication Date: 2018.05.29 SK HYNIX INC

AI summary

An operating method of a memory system including a plurality of memory blocks may include grouping the pages of a selected memory block among the plurality of memory blocks based on a program time, sequentially performing a test read on the groups of the pages, detecting an error in the pages of the test-read groups, and reprogramming a page selected based on a result of the error detection.