String Selection Line Repair in 3D Non-Volatile Memory
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Solution Overview
Problem
Three-dimensional semiconductor memory devices face challenges in efficiently managing and repairing defective memory cells due to their unique structural characteristics, which differ from conventional two-dimensional devices, leading to operational inefficiencies and reduced memory capacity when using traditional block-based repair methods.
Innovation Solution
A method and system for repairing defective strings in non-volatile memory devices by replacing defective string selection lines with replacement lines from a repair memory block, allowing the controller to access the replacement lines instead, thereby efficiently utilizing limited repair memory blocks and maintaining device functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional block-based repair methods are used in three-dimensional semiconductor memory devices, then the repair process is simple to implement, but the memory capacity and operational efficiency are reduced due to the need to replace entire blocks rather than individual defective strings
Solution Approach 1:
The patent segments the repair process from the block level to the string level. Instead of replacing entire memory blocks containing defective strings, the invention identifies and replaces only the specific defective string selection lines. This segmentation allows the majority of functional strings within a block to remain operational, thereby preserving memory capacity while maintaining manageable repair complexity through systematic string-level identification and replacement procedures
Solution Approach 2:
The patent applies local quality by treating each string selection line as an independent repairable unit with its own replacement line. Rather than applying a uniform block-level repair approach, the invention allows different string selection lines within the same memory block to have different repair statuses - some may be defective and replaced, while others remain functional. This localized repair strategy optimizes memory capacity retention by preserving functional strings while addressing only the defective portions
2Reliability
If string-level repair is implemented instead of block-based repair, then memory capacity is preserved by keeping functional strings operational, but the repair management and control complexity increases
Solution Approach 1:
The patent implements preliminary action by pre-establishing replacement string selection lines for each string selection line in the memory block before defects occur. During the manufacturing or initialization phase, redundant string selection lines are prepared and designated as replacements for potential future defects. This preliminary preparation simplifies subsequent repair operations, as the control logic only needs to activate pre-configured replacement lines rather than managing complex real-time repair decisions, thereby maintaining device functionality while controlling repair management complexity
Solution Approach 2:
The patent uses copying by creating duplicate string selection lines that serve as replacements for defective ones. Each string selection line has a corresponding replacement line that is an exact functional copy, capable of assuming the same control functions. This copying approach simplifies repair management because the replacement lines are designed to be interchangeable with the original lines, requiring minimal changes to the control logic and maintaining system reliability through functional duplication
Data Source
AI summary
A non-volatile memory device may replace a defective string selection line connected to a defective string of a defective memory block among a plurality of memory blocks with a replacement string selection line of a repair memory block; and access the replacement string selection line of the repair memory block instead of the defective string selection line of the defective memory block. The non-volatile memory device performs a repair operation in units of string selection lines and may efficiently use repair resources.