Memory Device Word Line Voltage Equalization
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Solution Overview
Problem
Existing memory devices, such as NAND flash memory, face challenges in ensuring uniform negative boosting during erase operations, leading to uneven electric fields and potential data reliability issues due to differences in plug critical dimension (CD) sizes among word lines.
Innovation Solution
The memory device employs a peripheral circuit to provide different word line voltages to distinct word line groups based on their plug CD characteristics during erase operations and applies an equalizing voltage during the erase voltage discharging section to ensure uniform negative boosting across all groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If different word line groups are provided with different voltages during erase operation, then erase performance is improved, but voltage uniformity deteriorates
Solution Approach 1:
The word lines are divided into multiple groups (first word line group and second word line group), and each group is provided with different voltages during the erase operation. This segmentation allows optimized erase performance for different word line groups while managing the complexity of voltage distribution.
Solution Approach 2:
An equalizing voltage is applied to all word line groups during the equalizing section to eliminate voltage differences between groups. This ensures uniform voltage distribution and prevents harmful effects caused by voltage non-uniformity, such as uneven negative boosting.
2Stability of the object's composition
If equalizing voltage is applied during erase voltage discharging section, then voltage uniformity is improved, but operation complexity increases
Solution Approach 1:
The equalizing section is combined with the erase voltage discharging section, allowing the equalizing voltage to be applied during the same time period when erase voltage is being discharged. This merging of operations achieves voltage uniformity without requiring additional separate equalizing steps, thereby reducing overall operation complexity.
3Adaptability or versatility
If multiple word line groups have different plug CD sizes, then manufacturing flexibility is improved, but negative boosting uniformity deteriorates
Solution Approach 1:
Different voltage levels are applied to different word line groups based on their specific plug CD characteristics. This local quality approach allows each group to receive optimized voltage treatment, improving erase performance for each group while the equalizing voltage ensures overall uniformity.
Solution Approach 2:
The voltage parameter is dynamically adjusted during the erase operation - different voltages are applied to different word line groups during the erasing section, and then an equalizing voltage is applied during the equalizing section. This parameter change strategy ensures both manufacturing flexibility and negative boosting uniformity.
Data Source
AI summary
A memory device includes a memory block and a peripheral circuit. The memory block includes a first word line group of word lines included in the memory block and a second word line group of the word lines included in the memory block. The word lines of the first word line group are different from the word lines of the second word line group. The peripheral circuit provides the first word line group and the second word line group with an equalizing voltage during an equalizing section overlapping an erase voltage discharging section for the memory block to constantly keep voltages of the first word line group and the second word line group to the equalizing voltage.