Vertical Semiconductor Device Lower Connection Protrusion
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Solution Overview
Problem
Vertical NAND flash memory devices face reliability issues due to the instability of their lower connection structures, which affect the electrical connections between the channel and the substrate.
Innovation Solution
A vertical semiconductor device with a stacked structure, including insulation layers and gate electrodes alternately stacked, and a lower connection structure that protrudes from the substrate, ensuring stable electrical connections through a channel structure with a charge storage structure and a channel that extends to the substrate surface, using a method that involves forming a mold structure with sacrificial layers and removing them to create a gap for the lower connection structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lower connection structure is used in vertical NAND flash memory devices, then the device can be manufactured with standard processes, but the lower connection structure becomes unstable and reliability deteriorates
Solution Approach 1:
The lower connection structure transitions from a planar configuration to a three-dimensional structure with protrusions extending upward from the substrate. This vertical dimensionality addition creates multiple contact points and increases the effective connection area, thereby improving both stability and reliability of the electrical connection between the channel and substrate.
Solution Approach 2:
The protrusions of the lower connection structure are formed in advance during the manufacturing process, before final assembly. This preliminary formation ensures that the stable connection structure is already in place to support subsequent processing steps and final device operation, preventing connection failures.
2Reliability
If the lower connection structure is designed to fill the gap between substrate and stacked structure, then electrical connection is improved, but the manufacturing process becomes more complex
Solution Approach 1:
A protective pattern is introduced as an intermediary element during the manufacturing process. This protective pattern serves as a mask or template that guides the formation of the lower connection structure's protrusions, enabling precise filling of the gap between substrate and stacked structure while simplifying the overall manufacturing process through controlled material deposition.
Solution Approach 2:
The manufacturing process utilizes changes in material properties and deposition parameters to achieve selective filling. By controlling etching rates, deposition thickness, and material selectivity, the lower connection structure fills the gap precisely without requiring overly complex multi-step processes, balancing manufacturing ease with connection reliability.
3Stability of the object's composition
If the protrusion is positioned at the central portion of the sidewall, then structural stability is improved and seams are prevented from exposure, but the device geometry becomes more complex
Solution Approach 1:
The lower connection structure features an asymmetric design where protrusions are strategically positioned at the central portion of the sidewall rather than being uniformly distributed. This asymmetric configuration specifically targets the prevention of seam exposure at critical locations while maintaining overall structural stability, accepting localized geometric complexity to achieve global reliability improvement.
Data Source
AI summary
A vertical semiconductor device may include a stacked structure, a channel structure and a lower connection structure. The stacked structure may include insulation layers and gate electrodes alternately repeatedly stacked. The stacked structure may be spaced apart from an upper surface of a substrate. The channel structure may include a charge storage structure and a channel. The channel structure may pass through the stacked structure. The lower connection structure may be formed on the substrate. The lower connection structure may be electrically connected with the channel and the substrate. A sidewall of the lower connection structure may include a protrusion disposed at a central portion of the sidewall from the upper surface of the substrate in a vertical direction. The vertical semiconductor device may have a high reliability.