Non-Volatile Memory Error Recovery via Threshold Voltage Monitoring
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Solution Overview
Problem
Non-volatile memory devices face increased bit error rates due to corrupting events such as the infrared reflow process, which can exceed the error correction capability of existing ECC schemes, leading to data errors in preloaded data.
Innovation Solution
A system with a corrupting event recovery engine in a data storage device that detects corrupting events by reading updated threshold voltages and error metrics from storage elements, comparing them to criteria, and initiating a recovery process to correct errors, including reprogramming affected groups of storage elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple bits are stored in each flash memory cell to increase storage density, then storage density is improved, but bit error rate increases
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage estimation and adjusting read threshold voltages before data reading occurs. The system estimates threshold voltages for storage elements and uses these estimates to set appropriate read thresholds, preventing read errors before they happen. This is particularly important for preloaded data that may be subjected to corrupting events like infrared reflow processes.
Solution Approach 2:
The patent implements feedback by continuously monitoring error metrics and using this information to adjust read threshold voltages. The system reads data, evaluates error metrics, and modifies subsequent read operations based on the observed errors. This feedback loop enables the system to adapt to threshold voltage shifts and maintain reliable data reading despite variations in storage conditions.
2Loss of time
If preloaded data is stored in non-volatile memory before coupling to memory controller, then data availability is improved, but data corruption risk increases due to corrupting events
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage estimation and adjusting read threshold voltages before data reading occurs. The system estimates threshold voltages for storage elements and uses these estimates to set appropriate read thresholds, preventing read errors before they happen. This is particularly important for preloaded data that may be subjected to corrupting events like infrared reflow processes.
Solution Approach 2:
The patent implements feedback by continuously monitoring error metrics and using this information to adjust read threshold voltages. The system reads data, evaluates error metrics, and modifies subsequent read operations based on the observed errors. This feedback loop enables the system to adapt to threshold voltage shifts and maintain reliable data reading despite variations in storage conditions.
3Ease of manufacture
If infrared reflow process is used to attach non-volatile memory device, then manufacturing is improved, but threshold voltage shifting occurs causing data errors
Solution Approach 1:
The patent applies the blessing in disguise principle by detecting the harmful effect of infrared reflow (threshold voltage shifting) and converting it into a beneficial process. The system detects changes in threshold voltages caused by reflow and uses this information to adjust read threshold voltages, thereby compensating for the harmful effect. The harmful thermal processing is thus transformed into a trigger for corrective action that restores data integrity.
Solution Approach 2:
The patent implements feedback by continuously monitoring error metrics and using this information to adjust read threshold voltages. The system reads data, evaluates error metrics, and modifies subsequent read operations based on the observed errors. This feedback loop enables the system to adapt to threshold voltage shifts and maintain reliable data reading despite variations in storage conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively detects and corrects errors caused by corrupting events like infrared reflow, ensuring data integrity by reprogramming affected storage elements and reducing bit error rates.
Implementation Method 1
Flash memory devices can enhance data storage density by storing multiple bits in each flash memory cell. For example, Multi-Level Cell (MLC) flash memory devices provide increased storage density by storing 3 bits per cell, 4 bits per cell, or more.
Implementation Method 2
attaching a non-volatile memory device to a printed circuit board or controller die may include heating the non-volatile memory die, such as according to an infrared (IR) reflow process
Implementation Method 3
Heating the non-volatile memory die may cause threshold voltage shifting of storage elements that store the preloaded data, causing errors in the preloaded data
Data Source
AI summary
A method includes determining a read threshold voltage corresponding to a group of storage elements in a non-volatile memory that includes a three-dimensional (3D) memory of a data storage device. The method also includes determining an error metric corresponding to data read from the group of storage elements using the read threshold voltage. The method includes comparing the read threshold voltage and the error metric to one or more criteria corresponding to a corrupting event.