Weak Word Line Detection in 3D Memory Devices
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Solution Overview
Problem
In nonvolatile memory devices, the varying characteristics of memory cells in a 3D structure lead to inconsistent threshold voltage distributions, affecting the efficiency of data storage and retrieval during program operations.
Innovation Solution
A memory device with a weak word line determiner and program operation controller that performs pre-program operations to identify and adjust for weak word lines, allowing for optimized program modes based on the characteristics of each word line to improve threshold voltage distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a uniform program voltage is applied to all word lines, then the device structure remains simple, but the threshold voltage distribution becomes inconsistent due to varying memory cell characteristics
Solution Approach 1:
The patent segments the program operation into two distinct modes: a first program mode for weak word lines and a second program mode for normal word lines. This segmentation allows different program voltages to be applied based on word line characteristics, improving threshold voltage distribution consistency without requiring complete redesign of the control system.
Solution Approach 2:
The patent performs preliminary classification of word lines into weak and normal categories before executing the program operation. By determining which word lines require special treatment in advance, the system can apply appropriate program voltages selectively, resolving the threshold voltage inconsistency issue while maintaining manageable control complexity.
2Manufacturing precision
If different program voltages are applied to different word lines, then the threshold voltage distribution consistency improves, but the program operation time increases due to mode switching
Solution Approach 1:
The patent performs preliminary classification of word lines into weak and normal categories before the actual program operation. By determining which word lines require special treatment in advance, the system can execute the appropriate program mode without time-consuming switches during the programming process itself, thus improving threshold voltage consistency while minimizing time loss.
Solution Approach 2:
The patent structures the program operation as periodic alternating actions between first program mode and second program mode based on word line characteristics. This periodic structure allows systematic handling of different word line types in an organized sequence, balancing the need for differentiated voltage application with efficient time utilization.
Data Source
AI summary
A memory device, and a method of operating the same, includes a plurality of memory cells coupled to a plurality of word lines, a peripheral circuit configured to perform a program operation of storing data in the plurality of memory cells, a weak word line information storage configured to store information about a weak word line among the plurality of word lines, and a program operation controller configured to control the peripheral circuit such that the program operation is performed in a first program mode or a second program mode depending on a result of determining whether a selected word line corresponding to an address provided from a memory controller is a weak word line by comparing word lines based on the information about the weak word line.