3D Memory Read Voltage Zoning for Word-Line Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing memory systems face challenges in providing optimal read reference voltages for memory cells, leading to read errors due to significant differences between actual and applied read level offsets, especially in three-dimensional memory structures.
Innovation Solution
Implementing zoned read parameters that assign memory cells into zones based on target read voltage rankings, using representative read voltages for each zone to minimize voltage gaps and improve read accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single read reference voltage is used for all memory cells in a block, then the device complexity is reduced, but the read accuracy deteriorates due to significant voltage offsets in three-dimensional memory structures
Solution Approach 1:
The memory block is divided into multiple zones based on word line groups, with each zone having its own read reference voltage. This segmentation allows different voltage offsets to be applied to different physical regions of the 3D memory structure, compensating for location-dependent variations while maintaining manageable complexity through organized zoning.
Solution Approach 2:
Different read reference voltages are applied to different zones within the memory block, matching the local electrical characteristics of each region. This local quality approach ensures that each zone receives the optimal voltage for its specific physical location, improving overall read accuracy in three-dimensional memory structures.
2Measurement precision
If location-dependent read reference voltages are applied to each word line, then the read accuracy is improved, but the device complexity increases significantly
Solution Approach 1:
Adjacent word lines with similar voltage offset characteristics are merged into the same zone, sharing a common read reference voltage. This merging reduces the total number of distinct voltage levels required while maintaining adequate read accuracy, as the voltage offset variations within each zone are sufficiently small.
Solution Approach 2:
Each zone's read reference voltage serves multiple word lines simultaneously, making the voltage configuration multi-functional. This universality approach allows a single voltage level to be applied to multiple word lines within a zone, reducing the overall complexity of the voltage configuration system.
3Measurement precision
If more zones are created to reduce voltage gaps, then the read accuracy is improved, but the device complexity increases
Solution Approach 1:
Instead of creating a separate zone for every single word line (excessive action), the patent applies partial zoning where multiple word lines are grouped into zones. This partial action approach achieves sufficient read accuracy improvement without the excessive complexity of fine-grained zoning, finding an optimal middle ground.
Data Source
AI summary
Technology for zoned read parameters. The read parameters may include read reference levels and/or offsets applied to base read reference levels. The memory system may assign memory cells located in a region (e.g., block) into zones based on a ranking of a target read level for each set of memory cells in the region. The memory system may assign word lines in a block into zones based on a ranking of a target read voltage and/or target read voltage offset for each word line. The memory system may read each particular set of memory cells (e.g., word line in the block) using a representative read voltage for the zone into which the particular word line is assigned.