Stairless 3D Memory Word Line Via Structure Over Support Features
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Solution Overview
Problem
Existing three-dimensional memory devices face challenges in efficiently forming stairless structures with word line contact via structures over support features, which can lead to structural integrity and performance issues.
Innovation Solution
The formation of a three-dimensional memory device involves creating an alternating stack of insulating and electrically conductive layers, with memory openings and contact via structures, and includes the use of annular insulating fins and dielectric support pillars to stabilize the structure, using methods that involve etching, filling, and replacing sacrificial materials with conductive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If word line contact via structures are formed over support features in existing three-dimensional memory devices, then contact and support for word line structures are ensured, but structural integrity and performance issues arise
Solution Approach 1:
The contact via structure is segmented into multiple functional components: an upper contact portion for electrical contact, a lower contact portion for structural support, and intermediate annular insulating fins that provide both electrical isolation and mechanical reinforcement. This segmentation allows each component to optimize its function while collectively maintaining structural integrity.
Solution Approach 2:
The contact via structure employs composite construction with different materials for different functions: conductive material for electrical contact, annular insulating fins for electrical isolation and structural support, and fill material for mechanical stabilization. This composite approach resolves the contradiction by combining materials with complementary properties.
2Device complexity
If stairless structures are formed in three-dimensional memory devices, then device complexity is reduced, but manufacturing precision challenges increase
Solution Approach 1:
The annular insulating fins are formed in advance within the contact via structure before final fill material deposition. This preliminary action establishes precise geometric constraints and alignment references that guide subsequent manufacturing steps, enabling accurate formation of the stairless structure without requiring high precision in each individual step.
Solution Approach 2:
The annular insulating fins serve as intermediary structures that mediate between the upper and lower contact portions. These fins provide a stable intermediate framework that simplifies the overall structure formation process while ensuring precise positioning and alignment of the contact via elements.
3Strength
If annular insulating fins are added to contact via structures, then structural integrity is improved, but device complexity increases
Solution Approach 1:
The annular insulating fins perform multiple functions simultaneously: they provide electrical isolation between conductive layers, offer mechanical support to the contact via structure, and serve as alignment references for subsequent processing steps. This multi-functionality justifies the added structural elements by delivering multiple benefits from a single feature.
Data Source
AI summary
A three-dimensional memory device includes an alternating stack of insulating layers and electrically conductive layers, a memory opening vertically extending through the alternating stack, a memory opening fill structure located in memory opening and including a vertical stack of memory elements located at levels of the electrically conductive layers and a vertical semiconductor channel, and a layer contact via structure contacting a first electrically conductive layer. The layer contact via structure overlies one or more support features.