Memory Wordline Corrective Reads Using Dynamic Voltage References
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Solution Overview
Problem
Conventional corrective read techniques in memory sub-systems fail to consider the duration of data retention and program/erase cycles, leading to over-compensation or under-compensation of read voltage offsets, resulting in reduced performance and reliability due to lateral charge migration and cross-pillar variation.
Innovation Solution
Implementing a dynamic reference corrective read technique that determines corrective read offsets dynamically by measuring distribution voltage on wordlines, using delta voltage values to mitigate lateral charge migration and improve read accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional corrective read techniques are used, then read operations can be performed, but read errors increase due to over-compensation or under-compensation of read voltage offsets
Solution Approach 1:
The patent applies dynamics by transitioning from static, predetermined corrective read offsets to dynamic offsets that are determined at the time of the read operation. The controller measures distribution voltages on adjacent wordlines and calculates corrective read offsets based on real-time voltage differences, allowing the system to adapt to changing conditions such as lateral charge migration and cross-pillar variation.
Solution Approach 2:
The patent implements feedback by measuring the actual distribution voltages on wordlines and using these measurements to determine corrective read offsets. The system continuously monitors voltage levels and adjusts the read offsets based on the measured voltage differences, creating a closed-loop control system that compensates for drift and variation in real-time.
2Device complexity
If fixed read voltage offsets are used, then device complexity is reduced, but performance deteriorates due to lateral charge migration and cross-pillar variation
Solution Approach 1:
The patent applies self-service by enabling the memory device to determine its own corrective read offsets without requiring external calibration or complex pre-programming. The controller performs distribution voltage measurements and calculates the necessary offsets autonomously based on the measured voltage differences between adjacent wordlines, allowing the system to self-correct for drift and variation.
3Manufacturing precision
If predetermined corrective read offsets are used, then manufacturing precision is improved, but reliability decreases due to inability to account for data retention duration and program/erase cycles
Solution Approach 1:
The patent applies parameter changes by transitioning from fixed corrective read offsets to dynamically adjusted offsets that change based on measured distribution voltages. The system modifies the read voltage parameters in real-time based on the actual voltage conditions, accounting for factors such as data retention duration, program/erase cycles, and environmental variations that affect memory cell characteristics.
Data Source
AI summary
A system includes a memory device and a processing device, operatively coupled with the memory device, to perform operations including: receiving a request to perform a read operation on a segment of the memory device; performing a distribution voltage measurement on at least two wordlines of the segment to obtain at least one delta voltage value; determining a corrective read offset based on the at least one delta voltage value; and performing a corrective read operation on the segment using the corrective read offset.