Isolating Defective Memory Planes to Prevent Neighbor Disturb
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Solution Overview
Problem
In multi-plane memory device operations, defective blocks can disturb neighboring good blocks, leading to program or read failures and data loss, especially in Single Level Cell (SLC) devices where early detection is challenging due to limited programmed states and short program or erase loops.
Innovation Solution
The approach involves initiating operations in a multi-plane mode and switching to a single-plane mode for blocks that do not complete programming or erasing within a trigger number of loops, with the option to perform word line leakage detection to identify and isolate faulty blocks, allowing continued operation of non-defective blocks without neighbor plane disturb.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-plane operation is used to improve productivity, then programming speed increases, but defective blocks disturb neighboring good blocks causing program failures
Solution Approach 1:
The patent performs preliminary detection of defective blocks before executing multi-plane programming operations. By detecting blocks with leakage currents or other defects in advance, the system can exclude these blocks from multi-plane operations, preventing them from disturbing neighboring good blocks while still maintaining high productivity through parallel programming of healthy blocks.
Solution Approach 2:
The patent extracts and isolates defective blocks from the multi-plane operation group. By identifying blocks that exhibit abnormal characteristics (such as excessive leakage current) and removing them from the set of blocks participating in parallel programming, the system eliminates the source of disturbance while preserving the productivity benefits of multi-plane operation for the remaining good blocks.
2Loss of time
If multi-plane operation is used to enhance efficiency, then operation time decreases, but neighbor plane disturb causes data loss
Solution Approach 1:
The patent performs preliminary detection and classification of blocks before multi-plane operations. By identifying potentially defective blocks that could cause neighbor plane disturb in advance, the system can exclude them from parallel operations, preventing data loss in neighboring blocks while maintaining the time efficiency of multi-plane programming for the remaining healthy blocks.
Solution Approach 2:
The patent introduces an intermediary detection and classification mechanism between block selection and multi-plane operation execution. This intermediary layer identifies blocks that could cause or suffer from neighbor plane disturb, acting as a filter that prevents harmful interactions while allowing efficient parallel operations to proceed among safe blocks.
3Device complexity
If SLC memory is used to reduce device complexity, then structure simplifies, but early detection of defective blocks becomes difficult
Solution Approach 1:
The patent employs self-service detection methods where the memory device performs its own defect detection using built-in circuitry. By utilizing the existing memory structure and control logic to detect leakage currents and identify defective blocks, the system avoids adding complex external detection equipment while maintaining the ability to identify problems in SLC memory blocks.
Solution Approach 2:
The patent replaces complex physical inspection methods with electrical measurement techniques. Instead of using sophisticated external equipment to detect defects in SLC memory, the system uses electrical measurements of leakage current and threshold voltage shifts, which can be performed using standard memory control circuitry, thereby maintaining simplicity while enabling effective defect detection.
Data Source
AI summary
Apparatuses and techniques are described for detecting and isolating defective blocks of memory cells in a multi-plane operation such as program or erase. In one aspect, a program operation begins in a multi-plane mode, for one block in each plane. If fewer than all blocks complete programming by the time a trigger number of program loops have been performed, one or more unpassed blocks are programmed further, one at a time, in a single plane mode. If the one or more unpassed blocks do not complete programming when a maximum allowable number of program loops have been performed, they are marked as bad blocks and disabled from further operations. In another aspect, when a trigger number of program loops have been performed, one or more unpassed blocks are subject to a word line leakage detection operation.