3D Memory Device Modulated Insulating Layers
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in efficiently forming vertical NAND strings with alternating stacks of insulating and conductive layers, particularly in achieving the necessary thickness variations and structural integrity across different regions.
Innovation Solution
The method involves forming an alternating stack of insulating layers with varying thicknesses and spacer material layers over a substrate, creating support and memory openings, and subsequently forming support pillar and memory stack structures, including electrically conductive layers, to construct a three-dimensional memory device with enhanced structural support and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform thickness insulating layers are used across the entire alternating stack, then the manufacturing process is simpler, but the structural integrity and electrical performance in different functional regions deteriorate
Solution Approach 1:
The patent applies local quality by varying the insulating layer thickness according to the functional requirements of different regions. The first region (memory region) has insulating layers with a first thickness optimized for memory cell formation, while the second region (support region) has insulating layers with a second thickness optimized for mechanical support. This regional differentiation resolves the contradiction by achieving both structural integrity in the support region and proper memory functionality in the memory region, rather than using a uniform thickness that would compromise one or the other.
2Strength
If thicker insulating layers are used in the second region for support, then structural strength is improved, but the manufacturing precision required to maintain alternating stack integrity increases
Solution Approach 1:
The patent segments the alternating stack into distinct regions with different insulating layer thicknesses. The first region contains insulating layers with a first thickness suitable for memory operations, while the second region contains insulating layers with a greater second thickness for mechanical support. This segmentation allows each region to be optimized independently for its specific function, achieving the required mechanical strength in the support region without compromising the overall alternating stack structure, as each segment is designed and formed with appropriate process parameters.
3Adaptability or versatility
If varying thickness insulating layers are formed, then regional functional requirements are met, but the complexity of the deposition and etching processes increases
Solution Approach 1:
The patent employs preliminary action by forming a thickness modulation layer in the second region before forming the alternating stack. This thickness modulation layer serves as a template or guide that pre-establishes the regions where thicker insulating layers are needed. Subsequent conformal deposition of insulating material and selective removal processes then naturally produce the desired varying thickness profile. This preliminary structuring simplifies the overall process complexity compared to attempting to directly deposit varying thicknesses, as it uses standard conformal deposition techniques combined with selective etching based on the pre-formed thickness modulation layer.
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 approach enables the fabrication of robust three-dimensional memory devices with modulated insulating and conductive layers, ensuring improved electrical conductivity and mechanical strength, thereby addressing the challenges of layer thickness variations and structural integrity.
Implementation Method 1
performing an anneal in an oxidizing ambient after forming the support openings
Data Source
AI summary
A three-dimensional memory device includes an alternating stack of insulating layers and electrically conductive layers located over a substrate, memory stack structures including a memory film and a vertical semiconductor channel and extending through a first region of the alternating stack, and support pillar structures extending through a second region of the alternating stack that is laterally offset from the first region. Each insulating layer includes a respective first insulating material portion having a respective first insulator thickness in the first region of the alternating stack and a respective second insulating material portion having a respective second insulator thickness that is greater than the respective first insulator thickness in the second region.