Supporting Pillars in 3D NAND Stack Structure for Etching Control
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Solution Overview
Problem
The manufacturing process of three-dimensional NAND flash memory devices faces challenges in controlling the etching of sacrificial layers, leading to complexity and potential over-etching issues.
Innovation Solution
The use of supporting pillars in a stack structure design, which penetrate and surround contacts, effectively controls the etching amount of sacrificial layers by limiting the flow of etchant and preventing over-etching, thereby simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sacrificial layers are removed to form horizontal openings for manufacturing gate layers, then the gate layers can be formed, but the sacrificial layers may be over-etched leading to manufacturing complexity
Solution Approach 1:
Supporting pillars are introduced as intermediary structures that physically block the etchant from over-etching the sacrificial layers. The pillars are positioned at specific locations (first and second sides of the contact) to control the etching process, allowing the sacrificial layers to be removed only to the desired extent without requiring complex process control
2Reliability
If supporting pillars are designed with extension portions around the contact, then over-etching is prevented, but the structure becomes more complex
Solution Approach 1:
The supporting pillar structure is segmented into distinct functional portions: a body portion disposed around the first side of the contact and extension portions located on two sides of the body portion, with at least one extension portion disposed around the second side of the contact. This segmentation allows each portion to serve a specific function in controlling the etching process while maintaining manufacturing feasibility
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
This design allows for precise control of sacrificial layer etching, reducing manufacturing complexity and preventing over-etching, thus enhancing the integration and efficiency of the memory device fabrication process.
Implementation Method 1
The use of supporting pillars in a stack structure design, which penetrate and surround contacts, effectively controls the etching amount of sacrificial layers by limiting the flow of etchant and preventing over-etching
Data Source
AI summary
Provided is a memory device including a substrate, a stack structure on the substrate, a contact, and a supporting pillar. The stacked structure includes a plurality of conductive layers and a plurality of insulating layers stacked alternately on each other. The contact is connected to one of the plurality of conductive layers of the stack structure. The supporting pillar penetrates the stack structure and is disposed around the contact. The supporting pillar includes a body portion and a plurality of extension portions. The body portion is arranged around a first side of the contact. The plurality of extension portions are located on two sides of the body portion. A length of each of the extension portions is greater than a width of the contact, and one of the extension portions is disposed around a second side of the contact.