Non-Volatile Memory Word Line Allocation by Reliability
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Solution Overview
Problem
Existing non-volatile memory technologies face challenges in increasing capacity without significantly increasing cost, primarily due to the high engineering effort required to store multiple bits per memory cell.
Innovation Solution
Determine the reliability of word lines by testing actual memories and designate word lines with higher reliability to store more bits per memory cell, customizing memory cells based on reliability testing results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple bits per memory cell are implemented to increase capacity, then memory capacity is improved, but engineering effort and cost increase significantly
Solution Approach 1:
The patent applies local quality by differentiating word lines into multiple reliability groups (first group, second group, third group) based on their individual reliability characteristics. Each group is assigned a different number of bits per memory cell (first number, second number, third number) according to its reliability level. This allows high-reliability word lines to store more bits while low-reliability word lines store fewer bits, optimizing overall capacity without requiring uniform high-complexity engineering across all word lines.
2Quantity of substance
If reliability testing is performed on all word lines to optimize bit storage, then memory capacity is improved, but testing time and complexity increase
Solution Approach 1:
The patent implements preliminary action by performing reliability testing on word lines during the manufacturing process before the memory device is deployed. This advance testing allows the system to identify and categorize word lines into different reliability groups beforehand, so that when the memory is in use, the optimized bit-per-cell configuration is already in place without requiring additional testing time during operation.
Data Source
AI summary
Multiple non-volatile memory dies are tested to identify word lines that have a first reliability and word lines that have a second reliability. Word lines that have the first reliability are designated to store data at a first number of bits per memory cell. Word lines that have the second reliability are designated to store data at a second number of bits per memory cell. The second number of bits per memory cell include more bits per memory cell than the first number of bits per memory cell.