3D Memory Isolation Structure With Meandering Dielectric Layout
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in efficiently integrating support circuitry for vertical NAND strings, particularly in forming effective dielectric isolation structures that enable stable and efficient operation of memory elements.
Innovation Solution
A semiconductor structure is developed with a meandering dielectric isolation structure, comprising an alternating stack of insulating and electrically conductive layers, memory openings, and dielectric barrier structures, along with conductive via portions to facilitate electrical contact and isolation, allowing for the formation of vertical stacks of memory elements and semiconductor channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dielectric isolation structures are used in three-dimensional memory devices, then manufacturing processes are simpler, but electrical isolation efficiency and operational stability are insufficient
Solution Approach 1:
The dielectric isolation structure is segmented into multiple portions arranged in a meandering pattern, creating multiple isolation regions that collectively provide enhanced electrical isolation. This segmentation allows the isolation function to be distributed across multiple smaller elements rather than relying on a single continuous structure.
Solution Approach 2:
The dielectric isolation structure employs a meandering (curved) geometry instead of straight lines, creating a serpentine pattern that increases the isolation path length within a compact area. This curved configuration enhances electrical isolation efficiency by extending the isolation distance without proportionally increasing the footprint area.
2Reliability
If dielectric material plates are placed at levels of electrically conductive layers, then electrical isolation is improved, but manufacturing complexity increases due to precise alignment requirements
Solution Approach 1:
A dielectric barrier structure is introduced as an intermediary element positioned between the dielectric material plates and the electrically conductive layers. This barrier structure facilitates precise alignment and positioning of the dielectric material plates relative to the conductive layers, reducing the direct alignment precision requirements while maintaining effective electrical isolation.
3Productivity
If vertical contact via structures are formed through dielectric material plates, then electrical contact efficiency is improved, but device complexity increases due to additional structure layers
Solution Approach 1:
The vertical contact via structures serve multiple functions: they provide electrical contact through the dielectric material plates, maintain structural integrity across different layers, and enable interconnection between various functional elements. This multi-functionality reduces the need for separate specialized structures, effectively managing complexity while maintaining high contact efficiency.
Data Source
AI summary
A method includes forming an in-process alternating stack of insulating layers and sacrificial material layers, forming a meandering dielectric isolation structure through the in-process alternating stack, forming memory stack structures through the alternating stack, where each of the memory stack structures includes a respective vertical stack of memory elements and a vertical semiconductor channel, forming sacrificial via fill structures on the respective sacrificial material layers, replacing first portions of the sacrificial material layers with electrically conductive layers, and forming layer contact via structures contacting a respective one of the electrically conductive layers by replacing at least the sacrificial via fill structures with a conductive material portion.