Flash Memory Cell Dual Erase Node Wear Distribution
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Solution Overview
Problem
Integrated circuit memory cells, particularly flash memory cells, have a limited lifespan due to degradation from repeated program/erase cycling, with erase performance degrading faster than program performance, limiting their effective lifespan.
Innovation Solution
Implementing dual erase modes by using a pair of program/erase nodes, such as an erase gate and a word line, which are selectively switched or alternated for erase functions to reduce wear on individual nodes, thereby increasing the lifespan of the memory cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single program/erase node is used for flash memory cell erase operations, then the device structure remains simple, but the cell lifespan is limited due to rapid erase performance degradation
Solution Approach 1:
The single program/erase node is segmented into two separate nodes (first program/erase node and second program/erase node). Each node is assigned to handle erase operations alternately, dividing the wear and degradation burden. This segmentation allows the memory cell to endure more erase cycles by distributing stress across multiple nodes rather than concentrating it on one node.
Solution Approach 2:
The system dynamically switches between the first and second program/erase nodes based on usage patterns. The erase control circuitry monitors and alternates which node performs erase operations, creating a dynamic load-balancing mechanism. This dynamic allocation optimizes node utilization and prevents any single node from degrading too rapidly.
2Reliability
If erase operations are performed frequently to maintain data integrity, then data reliability is improved, but the erase node degrades faster reducing overall cell endurance
Solution Approach 1:
The system implements periodic switching between the first and second program/erase nodes for erase operations. Instead of continuously using one node, the erase control circuitry alternates usage in a periodic manner, allowing each node to rest and recover between usage cycles. This periodic action distributes the cumulative stress from frequent erase operations across multiple nodes, extending overall system endurance.
3Duration of action of stationary object
If the memory cell structure is kept simple with minimal components, then manufacturing cost is reduced, but the cell cannot sustain repeated erase cycling
Solution Approach 1:
The first and second program/erase nodes are merged into a unified dual-node architecture that functions as an integrated system. The erase control circuitry coordinates both nodes to work together, managing erase operations and switching between nodes. This merging creates a synergistic system where the combined capacity of two nodes provides extended endurance while maintaining a cohesive structural design.
Data Source
AI summary
An integrated circuit device may at least one memory cell configured for dual erase modes. Each memory cell may be configured to be erased via two different nodes, which may be selectively used (e.g., in any switched or alternating manner) to reduce the erase cycling at each individual node and thereby increase (e.g., double) the lifespan of the cell. For example, the device may include flash memory cells having a pair of program/erase nodes (e.g., an erase gate and a word line) formed over each respective floating gate, wherein the program/erase nodes are selectively used (e.g., in any switched or alternating manner) for the cell erase function.