3D NAND Memory Pillar Structures for Higher Integration
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Solution Overview
Problem
There is a desire to increase the degree of integration in three-dimensional NAND-type nonvolatile semiconductor memory devices where memory cells are stacked on a semiconductor substrate.
Innovation Solution
The semiconductor memory device incorporates a stacked body with pillar structures that include semiconductor layers stacked from the outer peripheral surface toward the inner side, and plate-shaped structures that extend in the Z direction, with a recess portion on their side surfaces conforming to the pillar structures, allowing for enhanced integration by supporting the preliminary stacked body during the replacement process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the degree of integration is increased by stacking more memory cells, then the storage capacity improves, but the manufacturing complexity and difficulty of forming pillar structures increases
Solution Approach 1:
The patent introduces a preliminary stacked body that is formed before the final stacked body. This preliminary structure serves as a support during the manufacturing process, particularly during the replacement process where sacrificial layers are removed. By having this preliminary structure in place beforehand, the device can accommodate higher integration without compromising the pillar structure formation, thus resolving the contradiction between increased storage capacity and manufacturing complexity
Solution Approach 2:
The preliminary stacked body acts as an intermediary structure between the manufacturing process steps. It provides mechanical support and structural guidance during the complex replacement process, enabling the formation of highly integrated three-dimensional NAND structures without direct damage to the pillar structures. This intermediary element facilitates the transition from lower to higher integration without proportionally increasing manufacturing difficulty
2Reliability
If the pillar structures are formed with higher precision to avoid damage, then the reliability improves, but the manufacturing process becomes more complex
Solution Approach 1:
The preliminary stacked body is formed with sacrificial layers before the final stacked body is created. This preliminary structure provides a protective framework during the replacement process, ensuring that pillar structures are not damaged when sacrificial layers are removed. The preliminary action of creating this support structure beforehand maintains pillar integrity without requiring overly complex in-process adjustments
Solution Approach 2:
The preliminary stacked body with its sacrificial layers serves as a cushioning structure that protects the pillar structures during manufacturing. By having this protective framework in place before the critical replacement process, the pillar structures are shielded from potential damage, ensuring reliability without adding excessive process complexity
Data Source
AI summary
According to one embodiment, a semiconductor memory device includes a structural body including a stacked body in which conductive layers are stacked in a first direction, a plate-shaped structure extending in the first and second directions in the structural body, first and second pillar structures extending in the first direction in the stacked and structural body, respectively, and each of which a plurality of layers are stacked from an outer peripheral surface side toward an inner side. The second pillar structure does not function as a NAND string. Materials of the plurality of layers in the first and second pillar structures are respectively same. A part of a side surface of the plate-shaped structure is conformed to a part of a side surface of the second pillar structure.