Nonvolatile Memory Word Line Defect Detection via Segmented Voltage Response
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Solution Overview
Problem
As semiconductor memory devices become more densely integrated, the risk of defective word lines in memory cell arrays increases, necessitating better methods to determine whether a word line is defective.
Innovation Solution
A nonvolatile memory device with a voltage generator, memory cell array segmented by distance from the voltage generator, and control logic to assess word line voltage responses during program and erase operations, enabling detection of defective word lines by comparing the responses of first and second segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If memory devices are densely integrated to increase storage capacity, then productivity and storage density are improved, but the risk of defective word lines increases, worsening reliability
Solution Approach 1:
The memory cell array is divided into multiple segments along the word line direction, with each segment containing memory cells connected to different portions of the word line. This segmentation allows defective word lines to be isolated to specific segments, preventing them from affecting the entire memory array and enabling continued operation of healthy segments.
Solution Approach 2:
A dedicated defective word line detection circuit is introduced as an intermediary component between the word lines and the memory control logic. This detection circuit monitors word line voltage responses and identifies defective lines, enabling the system to adaptively manage memory resources and maintain reliability despite high integration density.
2Device complexity
If traditional uniform word line monitoring is used, then device complexity is kept low, but measurement precision of word line defects deteriorates
Solution Approach 1:
The monitoring approach is segmented by dividing the memory cell array into multiple segments along the word line direction. Each segment is monitored independently, allowing defects to be precisely localized to specific segments. This segmented monitoring provides higher measurement precision compared to uniform monitoring while maintaining manageable device complexity through modular architecture.
Solution Approach 2:
Different monitoring characteristics are applied to different segments of the memory cell array. Each segment can have its own detection parameters and thresholds optimized for local conditions, improving overall defect detection accuracy without requiring a completely complex unified monitoring system.
Data Source
AI summary
The inventive concept relates to a nonvolatile memory device and a method of detecting a defective word line. The method includes executing a defective word line detection operation using a program/erase voltage applied to a selected word line, wherein the defective word line detection operation determines whether or not the selected word line is defective in relation to respective word line voltage responses for the first and second segments during execution of the program/erase operation.