Memory System Program Operations for Threshold Voltage Distribution
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Solution Overview
Problem
Existing memory systems face challenges in improving threshold voltage distribution of memory cells after programming, which can lead to read failures and reduced data reliability.
Innovation Solution
A memory system and method that includes a memory block with multiple string groups connected to select lines, where a control logic controls the performance of first and second program operations, as well as dummy program operations across different word lines to optimize threshold voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single program operation is performed on memory cells, then the programming speed is maintained, but the threshold voltage distribution deteriorates leading to read failures
Solution Approach 1:
The patent divides the memory block into multiple string groups (first string group and second string group) that can be programmed independently and simultaneously. This segmentation allows multiple program operations to proceed in parallel, improving overall programming speed while maintaining proper threshold voltage distribution through coordinated control of different string groups
Solution Approach 2:
The patent performs a first program operation on a first physical page before performing a second program operation on a second physical page. This preliminary action ensures that threshold voltage distribution is established correctly in the first page before proceeding to the second page, preventing read failures while maintaining efficient programming throughput
2Productivity
If program operations are performed sequentially on all string groups, then threshold voltage distribution is maintained, but the overall programming time increases
Solution Approach 1:
The patent segments the programming process into independent string groups that can operate in parallel. The first string group and second string group are programmed simultaneously through coordinated control, which maintains reliability while improving productivity by utilizing multiple channels concurrently
Solution Approach 2:
The patent implements a periodic programming sequence where first program operations and second program operations are alternately executed on different string groups. This periodic action pattern ensures that threshold voltage distribution is maintained while achieving high throughput through systematic parallel processing
Data Source
AI summary
A memory device includes a memory block, a peripheral circuit, and a control logic. The memory block includes a plurality of string groups respectively connected to a corresponding select line, among a plurality of select lines. The peripheral circuit performs a program operation of data on the memory block. The control logic controls the program operation of the peripheral circuit. The memory block is connected to first to n-th word lines. The control logic is configured to control the peripheral circuit to perform a first program operation on a physical page, among physical pages that are included in a first string group, connected to an i-th word line, performs a second program operation on a physical page that is connected to an (i−1)-th word line, and perform a dummy program operation on a physical page that is connected to an (i+1)-th word line. Here, n is a natural number equal to or greater than 3, and i is a natural number greater than 0 and less than n−1.