Hexagonal Lattice Support Pillars for 3D Memory Structural Integrity
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Solution Overview
Problem
Conventional three-dimensional memory devices face challenges with cylindrical support pillars leading to deflection and deformation due to size and shape variations, which affect the accuracy and density of memory structures.
Innovation Solution
The use of a hexagonal lattice configuration for support pillar structures and contact via structures with consistent size and shape, formed through a method involving alternating stacks of insulating and sacrificial layers, to prevent deflection and enhance structural integrity and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cylindrical support pillars are used in conventional three-dimensional memory devices, then the manufacturing process is simpler, but the support pillars suffer from deflection and deformation due to size and shape variations
Solution Approach 1:
The patent replaces cylindrical support pillars with polygonal (hexagonal, octagonal, or square) support pillars. This geometric transformation from curved cylindrical shapes to polygonal shapes with flat sides and corners eliminates the size and shape variations inherent in cylindrical structures, providing more consistent mechanical properties and preventing deflection and deformation while maintaining manufacturing feasibility through standard photolithography patterning processes.
2Reliability
If a hexagonal lattice configuration is used for support pillar structures, then structural support and accuracy are improved, but the device complexity increases
Solution Approach 1:
The patent divides the memory device into distinct regions: a memory array region containing memory stack structures and a staircase region containing the hexagonal lattice of support pillar structures and contact via structures. This segmentation allows the complex hexagonal lattice configuration to be localized to specific areas where structural support is needed, rather than throughout the entire device, thereby reducing overall device complexity while maintaining improved structural support where required.
Solution Approach 2:
The patent employs a hexagonal lattice configuration with asymmetric arrangement of support pillar structures and contact via structures. The hexagonal geometry provides asymmetric positioning that optimizes structural support and electrical connectivity while maintaining manufacturing feasibility through standard photolithography processes, balancing improved reliability with acceptable device complexity.
3Quantity of substance
If support pillar structures and contact via structures are arranged in a hexagonal periodic array, then the density of structures is increased, but the manufacturing precision requirements become more stringent
Solution Approach 1:
The patent combines the formation of support pillar structures and contact via structures into a single hexagonal lattice configuration formed through integrated processing steps. By merging these two distinct structure types into one unified lattice pattern, the patent achieves higher density while using the same photolithography and etching processes for both, thereby maintaining manufacturing precision requirements at a manageable level rather than requiring separate high-precision processes for each structure type.
Data Source
AI summary
A vertically alternating sequence of continuous insulating layers and continuous sacrificial material layers is formed over a substrate, and is patterned to form stepped surfaces. Memory stack structures are formed in a memory array region of the alternating stack. Support pillar structures are formed through the vertically alternating sequence within a staircase region. The support pillar structures are formed at lattice sites of a hexagonal lattice structure that includes unoccupied lattice sites. Portions of the continuous sacrificial material layers are replaced with electrically conductive layers. Contact via structures are formed on a respective one of the electrically conductive layers at the unoccupied lattice sites. Geometrical centers of the support pillar structures are arranged at vertices of a polygon having more than four vertices having a respective contact via structure located at a geometric center of the polygon in a plan view.