Partial Page Programming of Multi-Level Cell Segments
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Solution Overview
Problem
Existing flash memory systems face inefficiencies in data storage and retrieval due to the need for complex programming and reading operations across multiple segments of a word line, leading to potential data disturbance and errors, especially when handling multi-level cell (MLC) NAND blocks with varying memory states.
Innovation Solution
Implementing a method where memory cells along a word line are programmed in segments, allowing all logical states of a segment to be set in a single pass, enabling simultaneous programming of lower and upper page data, and using error correction codes to ensure data integrity, with flags indicating programmed segments to facilitate efficient reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If entire word lines are programmed together in traditional flash memory systems, then programming throughput is maximized, but memory space utilization efficiency deteriorates when storing small portions of data
Solution Approach 1:
The patent divides a word line into multiple independently programmable segments, allowing selective programming of only the portions of memory that need to be updated. This segmentation enables efficient use of memory space when storing small data portions while maintaining the ability to program multiple segments in parallel for high throughput operations.
2Loss of substance
If multiple segments of a word line are programmed at different times, then memory space utilization is improved, but data disturbance and reading complexity increase
Solution Approach 1:
The patent introduces status flags that are set in advance to indicate which segments of a word line have been programmed. During read operations, these flags guide the reading process to appropriately handle mixed-programmed states, preventing data disturbance and ensuring correct data retrieval without requiring complex real-time analysis.
3Adaptability or versatility
If partial word line programming is implemented, then granularity of data storage is improved, but reading operations become more complex
Solution Approach 1:
The patent employs status flags that provide feedback information about the programming state of each word line segment. This feedback mechanism simplifies read operations by automatically indicating which segments contain valid data and which are unprogrammed, allowing the read circuitry to adapt its operation based on the current state without requiring complex external control logic.
Data Source
AI summary
Multiple bits of data are programmed together to each cell of a segment of a word line while other segments of the same word line are unprogrammed. Subsequently, additional segments are similarly programmed. Data is read from a partially programmed word line (with a mix of programmed and unprogrammed segments) using a single reading scheme.