Non-volatile Memory Suspend-Resume Verify Logic
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Solution Overview
Problem
Non-volatile memory devices experience degradation in program threshold voltage distribution and reliability due to time intervals caused by suspend-resume operations during program operations.
Innovation Solution
A non-volatile memory device with a control logic unit that performs initial and normal program verify operations using different verify conditions, applying distinct program voltages and develop times in response to suspend and resume commands to mitigate degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If suspend-resume operation is performed during program operation, then read operation can be executed during programming, but program threshold voltage distribution degrades
Solution Approach 1:
The patent applies preliminary action by performing a first program verify operation immediately when a suspend command is received, before the actual suspend occurs. This preliminary verification captures the programming state at the moment of suspension, and the stored first verify result is later compared with a second verify result obtained after resume, enabling accurate determination of whether programming was successfully completed despite the interruption.
Solution Approach 2:
The patent implements feedback by comparing the first verify result (obtained at suspend) with the second verify result (obtained after resume) to determine the final programming outcome. This feedback mechanism allows the system to correctly identify programming completion status even when suspend-resume operations occur, preventing misjudgment of programming results and maintaining threshold voltage distribution accuracy.
2Device complexity
If normal program verify operation is used during suspend-resume, then verify process is simple, but reliability of programming decreases
Solution Approach 1:
The patent segments the program verify operation into two distinct parts: a first program verify operation performed at the moment of suspend command reception, and a second program verify operation performed after resume. Each verify operation uses the same normal verify condition, but their results are compared to account for the suspend-resume interruption. This segmentation maintains operational simplicity while improving reliability through result comparison.
Solution Approach 2:
The first program verify operation serves as a preliminary action that captures the programming state before the suspend-resume cycle completes. By storing this preliminary verify result and comparing it with the post-resume verify result, the system ensures reliable programming determination without complicating the individual verify operations themselves.
Data Source
AI summary
A non-volatile memory device includes a memory cell array including memory cells respectively connected to bit lines; and a control logic unit configured to control a program operation with respect to the memory cells. The control logic unit is configured to perform a normal program verify operation with respect to the memory cells by using a normal program verify condition, during the program operation, and, based on a suspend command that is received during the program operation, perform an initial program verify operation with respect to the memory cells by using an initial program verify condition that is different from the normal program verify condition.