Vertical Memory Source Connection Shielding Against Stack Collapse
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Solution Overview
Problem
The existing fabrication technologies for vertical memory devices face a risk of collapse during the replacement of source sacrificial layers, as the stack of layers may destabilize before the epitaxial layer is fully formed, leading to potential structural instability and failure in forming vertical memory cell strings.
Innovation Solution
The formation of a shield structure that encloses a portion of the source sacrificial layers to protect them from removal, ensuring the stack remains stable and supports the vertical memory device structure, thereby reducing the risk of collapse and facilitating the formation of source connections through sidewall selective epitaxial growth (SEG).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If source sacrificial layers are completely removed to form source connections, then electrical connectivity is achieved, but structural stability is compromised causing stack collapse
Solution Approach 1:
The shield structure is selectively formed in specific regions (staircase regions and between gate line cut structures) rather than uniformly across the entire device. This local application provides structural support where needed while allowing source sacrificial layer removal in other regions to proceed, achieving both stability and manufacturability
Solution Approach 2:
The shield structure acts as an intermediary element that temporarily supports the stack during the source sacrificial layer removal process. It mediates between the conflicting requirements by providing mechanical support to prevent collapse while allowing the necessary etching and replacement processes to occur
2Reliability
If shield structure is formed to enclose source sacrificial layers, then structural stability is improved, but device complexity increases
Solution Approach 1:
The shield structure is segmented into discrete regions rather than forming a continuous enclosure. It is formed in specific staircase regions and between gate line cut structures, providing support only where structurally necessary while simplifying the overall fabrication process by avoiding universal application
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The shield structure effectively prevents the complete removal of source sacrificial layers in critical regions, maintaining structural integrity and enabling successful formation of vertical memory cell strings by supporting the stack and allowing for the formation of stable source connections.
Implementation Method 1
a shield structure formed in the first stack of layers. The shied structure encloses a stack of layers without the source connection layer
Implementation Method 2
forming channel structures that extend in the first direction into the first layers. The channel structure includes a channel layer surrounded by one or more insulating layers
Data Source
AI summary
A semiconductor device includes a first stack of layers stacked on a substrate. The first stack of layers includes a source connection layer that is formed by replacing source sacrificial layers. The semiconductor device includes a channel structure that extends in the first stack of layers. The channel structure includes a channel layer that is in contact with the source connection layer in the first stack of layers. Further, the semiconductor device includes a shield structure formed in the first stack of layers. The shied structure encloses a stack of layers without the source connection layer.