Non-Volatile Memory Word Line Layout for Interference Reduction
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Solution Overview
Problem
Interference from neighboring word lines in non-volatile memory systems causes widening of threshold voltage distributions or memory cell current distributions, compromising the reliability of data storage.
Innovation Solution
Storing data on non-consecutive word lines with intervening word lines in an unprogrammed condition to minimize neighbor word line interference, and performing in-memory vector-matrix multiplication using weight information stored in memory cells connected to these word lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data is stored on consecutive word lines to maximize storage capacity, then storage density is improved, but neighbor word line interference causes threshold voltage distribution widening which deteriorates data reliability
Solution Approach 1:
The patent segments the word line array into multiple independent groups (first group, second group, third group, etc.), where each group contains non-consecutive word lines. This segmentation allows data to be distributed across separated word lines within each group, reducing neighbor word line interference while maintaining storage capacity through parallel group operations.
Solution Approach 2:
The patent introduces unprogrammed word lines as intermediary elements between programmed word lines within the same group. These unprogrammed word lines act as buffers that prevent interference propagation between adjacent programmed word lines, thereby maintaining threshold voltage distribution narrowness while enabling higher storage density.
2Reliability
If data is stored on non-consecutive word lines to reduce neighbor word line interference, then threshold voltage distribution narrowness is improved, but storage capacity is reduced due to unprogrammed intervening word lines
Solution Approach 1:
The patent divides the word line array into multiple groups where each group contains non-consecutive word lines with unprogrammed interveners. By having multiple such groups operating in parallel, the system achieves narrow threshold voltage distributions within each group while the aggregate storage capacity across all groups approaches that of a fully utilized array.
Solution Approach 2:
The patent enables different groups of word lines to serve different functional purposes: some groups are optimized for high-density data storage, while others can be used for redundancy, error correction, or future expansion. This multi-functionality allows the system to maintain narrow threshold voltage distributions while effectively utilizing the available storage capacity across all groups.
Data Source
AI summary
A non-volatile storage apparatus comprises memory cells, word lines connected to the memory cells and a control circuit connected to the memory cells and the word lines. The control circuit is configured to store weights in memory cells connected to word lines of a first group of the word lines that comprises non-consecutive word lines such that between word lines of the first group are positioned one or more other word lines. The control circuit is configured to maintain in an unprogrammed condition those memory cells connected to the one or more other word lines. Vector-matrix multiplication is performed in-memory using the weight information stored in memory cells connected to word lines of the first group of word lines without using data stored in memory cells connected to the one or more other word lines.