3D NAND String Layout With Shared Select Gates
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Solution Overview
Problem
Current semiconductor devices face limitations in increasing data storage capacity and integration density, particularly in three-dimensional memory cell arrangements.
Innovation Solution
The semiconductor device incorporates a novel structure with parallel separation structures, bit lines, and memory cell strings, featuring shared select gate electrodes and multiple threshold voltage transistors connected in series, allowing for enhanced integration and efficient data storage operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cells are arranged three-dimensionally instead of two-dimensionally, then data storage capacity is improved, but device complexity increases
Solution Approach 1:
The three-dimensional memory structure is divided into multiple blocks separated by separation structures, with each block containing multiple strings. This segmentation allows independent formation and control of different memory regions, reducing overall fabrication complexity while maintaining high storage capacity
Solution Approach 2:
The patent transitions from two-dimensional to three-dimensional memory cell arrangement by forming vertical strings extending through multiple levels with bit lines positioned at different heights. This dimensional change increases storage capacity without proportionally increasing fabrication complexity through shared gate structures
2Ease of manufacture
If shared select gate electrodes are used between adjacent strings, then manufacturing complexity is reduced, but electrical connection complexity increases
Solution Approach 1:
Adjacent strings share common select gate electrodes (first upper select gate, second upper select gate, etc.) that extend across multiple string regions. This merging reduces the total number of gate structures needed during fabrication while the bit line structure provides clear electrical separation and control for each shared gate
Solution Approach 2:
The shared select gate electrodes serve multiple functions: they act as selection gates for multiple adjacent strings simultaneously, and their potential distribution controls access to different string groups. This multi-functionality reduces manufacturing steps while maintaining manageable electrical control through standardized potential application
Data Source
AI summary
Provided are semiconductor devices and data storage systems including the same. The semiconductor devices may include first and second separation structures parallel to each other, a block between the first and second separation structures, and bit lines on the block. The block includes strings, the bit lines include a first bit line electrically connected to first and second strings, each of the strings includes a lower select transistor, memory cell transistors, and upper select transistors connected in series, the upper select transistors in each of the strings include a first upper select transistor and a second upper select transistor below the first upper select transistor. The first upper select transistors of the first and second strings may share a single first upper select gate electrode. Gate electrodes of the lower select transistors of the first and second strings may include surfaces coplanar with each other.