Semiconductor Memory Device With Segmented Drain Select Lines
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Solution Overview
Problem
As semiconductor memory devices approach their physical scaling limits, improving the degree of integration of memory cells while maintaining operational stability becomes a challenge, particularly in three-dimensional structures where the integration of two memory cell strings per hole leads to deteriorated operating characteristics.
Innovation Solution
The semiconductor memory device employs a configuration where multiple memory cell strings are arranged in a zigzag pattern with alternating activation of drain select lines and bit lines, allowing for independent control of memory cell strings to improve integration and stability, and operates two memory cell strings as a single unit when characteristics deteriorate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If two memory cell strings are included in one hole to improve degree of integration, then the degree of integration of memory cells is improved, but the operating characteristics of respective memory cells are deteriorated
Solution Approach 1:
The memory cell strings are divided into first and second groups that are separately controlled by first and second drain select lines, respectively. This segmentation allows independent control of each memory cell string, preventing interference between adjacent strings while maintaining high integration density with two strings per hole.
2Quantity of substance
If memory cell strings are arranged in 3D structure to improve degree of integration, then scaling limit is overcome, but control complexity increases
Solution Approach 1:
The patent implements dynamic control of memory cell strings by selectively activating different drain select lines (first or second) based on which string needs to be accessed. This dynamic switching mechanism simplifies the control logic compared to static multi-dimensional addressing, as only one drain select line needs to be active at a time despite having multiple strings per hole.
Data Source
AI summary
Provided herein may be a semiconductor memory device. The semiconductor memory device may include first holes arranged in a first direction to be spaced apart from each other by a first distance, a first drain select line coupled to first memory cell strings among first and second memory cell strings separated from each of the first holes, and a second drain select line coupled to the second memory cell strings. Identical data may be stored in the first and second memory cells coupled to a selected word line, among memory cells included in each of the first memory cell strings and memory cells included in each of the second memory cell strings.