Flash Memory Adaptive Read Voltage Adjustment for ECC Extension
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Solution Overview
Problem
The increasing capacity of flash memory devices requires an extension of the Error Correction Code (ECC) correction capability beyond the current limitations, which is not effectively addressed by existing technologies.
Innovation Solution
A flash memory system that includes a controller and a register to adjust read voltage and read pass voltage parameters based on the presence of specific types of errors in memory cells, allowing for adaptive correction without increasing the number of ECC bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the capacity of flash memory is increased, then data storage capability is improved, but the ECC correction capability becomes insufficient
Solution Approach 1:
The patent adjusts read voltage and read pass voltage parameters dynamically based on error detection results. When errors are detected in memory cells, the system modifies voltage levels to improve sensing accuracy for subsequent read operations, enabling correction of errors that would otherwise exceed ECC capabilities.
Solution Approach 2:
The system implements a feedback mechanism where read operations detect errors in memory cells, and this information is used to update read parameters for future operations. The controller monitors error patterns and adjusts voltage parameters accordingly, creating a closed-loop system that continuously improves data integrity.
2Reliability
If more redundant bits are added to extend ECC correction capability, then error correction capability is improved, but die size cost increases
Solution Approach 1:
Instead of adding more redundant ECC bits, the patent changes operational parameters (voltage levels) to improve the effectiveness of existing ECC circuits. By adjusting read voltage and read pass voltage, the system enhances sensing accuracy and extends correction capability without increasing the number of stored bits.
Solution Approach 2:
The patent creates multiple copies of data in the form of redundant bits that are already present in the flash memory structure, but utilizes voltage adjustment to effectively generate additional correction information from existing data, rather than storing separate correction data.
3Measurement precision
If read voltage is increased to improve sensing accuracy, then measurement precision is improved, but memory cell errors increase due to over-stress
Solution Approach 1:
The patent dynamically adjusts voltage parameters based on detected error patterns. When errors are detected, read voltage is decreased and read pass voltage is increased, creating a balanced voltage configuration that improves sensing without causing additional cell stress or errors.
Solution Approach 2:
The system transitions from static voltage parameters to dynamic voltage adjustment. Read parameters are modified based on real-time error detection results, allowing the system to adapt voltage levels to specific memory cell conditions and avoid uniform over-stress.
4Reliability
If read pass voltage is increased to correct coupling errors, then reliability is improved, but interference with adjacent memory cells increases
Solution Approach 1:
The patent adjusts read pass voltage specifically when coupling errors are detected in adjacent memory cells. By increasing read pass voltage selectively, the system compensates for coupling effects without continuously applying high voltage that would cause interference.
Solution Approach 2:
The system applies preliminary voltage adjustments based on predicted coupling effects. When errors indicating coupling interference are detected, read pass voltage is increased in advance to counteract the harmful interference in subsequent operations.
Data Source
AI summary
Provided are a flash memory and an operation method thereof. The flash memory includes a memory cell array, a controller and a register. The register stores read parameters that include a read voltage value and a read pass voltage value. The controller is configured to perform the read operation on a selected page according to the read parameters to read out the raw data stored in the selected page, determine whether the raw data includes an error bit, and in response to determining that the raw data includes the error bit, update the read parameters by decreasing the read voltage value and/or increasing the read pass voltage value.