Flash Memory Copyback Error Detection via Volatile Buffer Analysis
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Solution Overview
Problem
Copyback operations in flash memory devices are 'blind' and do not check data for errors, leading to bit errors being propagated and accumulated during the copying process, as the Error Correction Code (ECC) cannot be evaluated before copying data from the source page to the destination page.
Innovation Solution
A method and system for detecting errors in copyback operations by internally copying data from a non-volatile portion to a volatile portion within the flash memory device, analyzing the data for errors, and modifying or disabling subsequent copyback operations based on detected errors, using a controller to verify and correct data before writing it to a second non-volatile portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If copyback operation is performed without error checking, then data transfer speed is improved, but data integrity deteriorates due to error propagation
Solution Approach 1:
The patent performs preliminary error detection by copying data to a volatile buffer before final programming to destination pages. This intermediate step allows error checking to occur before data is permanently written, preventing error propagation while maintaining the speed benefits of copyback operation.
Solution Approach 2:
The patent introduces a volatile buffer as an intermediary between source and destination pages. Data is first copied to this intermediate buffer where error detection can occur, and only after verification is the data programmed to the final destination. This intermediary structure enables error checking without sacrificing the speed of copyback operations.
2Reliability
If error detection is implemented in copyback operation, then data integrity is improved, but operation complexity increases
Solution Approach 1:
The flash memory device performs error detection autonomously using its own internal resources (volatile buffer and existing read/program circuits). The device serves itself by utilizing its built-in capabilities to detect errors during the copyback process without requiring external intervention or additional complex error correction hardware.
Solution Approach 2:
The patent uses existing flash memory components (read circuits, program circuits, and volatile buffer) for multiple purposes: the volatile buffer serves both as temporary storage during copyback and as a verification buffer for error detection. This multi-functionality approach enables error detection without adding dedicated error checking hardware, thus limiting complexity increase.
3Reliability
If data is copied to volatile buffer for verification, then error detection capability is improved, but memory resource usage increases
Solution Approach 1:
The patent copies data partially to the volatile buffer - only enough data to perform error detection on the current page being transferred. This partial action approach uses minimal volatile buffer resources while still enabling error detection for each page, avoiding the need to allocate entire buffer capacity for verification purposes.
Data Source
AI summary
Methods and systems are disclosed herein for detecting problems related to copyback programming. After the copyback data is read into the internal flash buffer, a part of the copyback data stored in the internal flash buffer (such as spare data) is analyzed to determine whether there are any errors in a part of the copyback data read. The analysis may be used by the flash memory in one or more ways related to the current copyback operation, subsequent copyback operations, subsequent treatment of the data in the current copyback operation, and subsequent treatment of the section in memory associated with the source page.