Perforated Dielectric Moat for 3D Memory Via Stability
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in stabilizing memory stack structures due to the lack of effective interconnection methods that ensure reliable contact between memory elements and underlying metal interconnects, particularly in the presence of alternating insulating and conductive layers.
Innovation Solution
A three-dimensional memory device is designed with a perforated dielectric moat structure that surrounds interconnection via structures, providing lateral openings through insulating layers while maintaining contact with underlying metal interconnects, and is formed by creating a pattern of moat region openings, expanding them to form a moat trench, and filling it with dielectric material, thereby enhancing structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If interconnection via structures are formed to contact underlying metal interconnects, then electrical connection reliability is improved, but structural stability of memory stack structures deteriorates due to lack of lateral support
Solution Approach 1:
The dielectric material is segmented into a moat structure with multiple lateral openings at different levels, creating a perforated configuration that provides both structural support and electrical access. This segmentation allows the dielectric to maintain mechanical integrity while enabling via structures to pass through and contact underlying interconnects.
Solution Approach 2:
The via structures are nested within the perforated dielectric moat structure, with the via structures vertically extending through the alternating stack and being laterally surrounded by the moat structure. This nesting arrangement provides lateral support to the vias while maintaining electrical connection pathways.
2Stability of the object's composition
If solid dielectric material is used to surround interconnection vias, then structural stability is improved, but electrical connection to underlying metal interconnects deteriorates due to blocking of contact paths
Solution Approach 1:
The dielectric material is configured as a perforated moat structure with lateral openings at different levels, creating a porous-like configuration that allows electrical connection while maintaining structural integrity. The openings enable via structures to contact underlying metal interconnects without requiring complete removal of dielectric material.
Solution Approach 2:
The solution transitions from a solid three-dimensional dielectric block to a perforated structure with lateral openings, effectively using dimensional considerations to resolve the contradiction. The moat structure extends laterally with openings at multiple levels, providing both structural support and electrical access pathways.
3Reliability
If perforated dielectric moat structure with lateral openings is formed, then electrical connection reliability is improved, but manufacturing complexity worsens due to multiple processing steps
Solution Approach 1:
The moat structure with lateral openings is formed preliminarily before forming the via structures. By pre-configuring the dielectric material with the perforated moat structure, subsequent via formation becomes simpler, as the openings are already in place to receive and guide the via structures.
Solution Approach 2:
The perforated dielectric moat structure serves multiple functions simultaneously: it provides structural support to memory stack structures, enables electrical connection to underlying interconnects, and guides via structure formation. This multi-functionality reduces the need for separate structures for each purpose.
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 vertically extending through the alternating stack, a perforated dielectric moat structure vertically extending through the alternating stack, and an interconnection via structure laterally surrounded by the perforated dielectric moat structure and vertically extending through each insulating layer within the alternating stack. Each of the memory stack structures includes a vertical semiconductor channel and a vertical stack of memory elements located at levels of the electrically conductive layers. The perforated dielectric moat structure includes a plurality of lateral openings at each level of the insulating layers, and does not include any opening at levels of the electrically conductive layers. An interconnection via structure can be laterally surrounded by the perforated dielectric moat structure, and can vertically extend through each insulating layer within the alternating stack.