Virtual Blocks from Partial Good Blocks with Defective WGRs
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Solution Overview
Problem
Conventional memory systems discard entire blocks when both the upper and lower decks have defective word line groups (WGRs), reducing memory efficiency and performance due to unavailable memory space for forming superblocks.
Innovation Solution
A memory controller combines multiple partial good blocks (PGBs) to form virtual blocks (VBs) even when defective WGRs are present, utilizing configuration data to identify PGBs with a minimum percentage of non-defective WGRs and forming VBs across multiple memory components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If entire blocks are discarded when both upper and lower decks have defective word line groups, then reliability is maintained, but memory efficiency and productivity deteriorate
Solution Approach 1:
The patent segments a memory block into multiple independent planes (upper and lower decks), each containing multiple word line groups. Instead of treating the entire block as a single unit that must be discarded when defective, the system identifies and isolates defective word line groups within specific planes, allowing healthy portions to be utilized. This segmentation enables selective usage of functional memory regions while excluding only the defective segments.
Solution Approach 2:
The patent applies local quality by allowing different regions of the memory block to have different operational statuses. Healthy word line groups can be used for normal memory operations while defective word line groups are excluded. The system dynamically determines which specific word line groups within which planes are functional, creating a heterogeneous usage pattern where each region's operational status matches its actual quality.
2Reliability
If memory blocks with defective word line groups are discarded, then data integrity is ensured, but available memory space and system performance deteriorate
Solution Approach 1:
The memory block is divided into multiple planes with multiple word line groups each. When defects are detected in specific word line groups, only those specific segments are marked as unusable while the remainder of the block stays operational. This granular segmentation preserves maximum usable memory space while ensuring data integrity in the functional regions.
Solution Approach 2:
The system changes the operational parameters of memory regions dynamically based on defect detection. Instead of a binary discard-or-use approach, the system adjusts which word line groups are active, modifying the effective capacity and accessibility parameters of the memory block to exclude only defective regions while maintaining optimal data integrity in functional regions.
3Device complexity
If conventional block discard method is used, then simplicity is maintained, but memory utilization and productivity worsen
Solution Approach 1:
The patent introduces segmentation at the word line group level within planes, adding complexity to the management structure but enabling significantly improved memory utilization. The segmented approach allows the system to track and manage defects at a finer granularity, facilitating better utilization of available memory resources while maintaining organized control through plane and word line group identifiers.
Data Source
AI summary
Aspects of the present disclosure configure a system component, such as a memory sub-system controller, to generate virtual or superblocks using multiple partial good blocks. The controller identifies a first partial good block (PGB) in a set of memory components, the first PGB having first subset of word line groups (WGRs) that are categorized as being non-defective. The controller searches for a second PGB in the set of memory components having a second subset of WGRs that are categorized as being non-defective. The controller computes a total quantity of WGRs based on the first quantity of WGRs in the first subset of WGRs and a second quantity of WGRs in the second subset of WGRs and, in response, combines the first PGB and the second PGB to form an individual virtual block.