3D Memory Source Select Gate Contact Via Structure
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in efficiently forming source select gate contacts without electrical shorts, particularly due to misalignment issues between support pillar structures and contact via structures, which affects the reliability and yield of the memory devices.
Innovation Solution
A three-dimensional memory device structure is developed with a retro-stepped dielectric material portion and support pillar structures, where the source select level contact via structure has a greater minimum lateral separation distance from the support pillars than the word line level contact via structures, and the support pillars are omitted from the area centered at the geometrical center of the source select level contact via structure to prevent electrical shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If support pillar structures are formed in the alternating stack, then mechanical support and structural stability are improved, but the risk of electrical shorts between contact via structures and support pillars increases
Solution Approach 1:
The patent applies local quality by creating a source select level contact via structure with a larger minimum lateral separation distance from support pillars compared to word line level contact via structures. This localized differentiation in separation distances optimizes each contact type's specific requirements while maintaining overall device reliability and preventing electrical shorts.
2Reliability
If the minimum lateral separation distance between source select level contact via structure and support pillars is increased, then electrical short prevention is improved, but device complexity increases
Solution Approach 1:
The patent segments the contact via structures into two distinct types: source select level contact via structures with larger minimum lateral separation distances from support pillars, and word line level contact via structures with smaller separation distances. This segmentation allows each contact type to have optimized spacing tailored to its specific electrical isolation requirements, improving reliability without uniformly increasing device complexity.
Data Source
AI summary
Electrical short caused by misalignment of source select level contact via structure and support pillar structures can be prevented by modifying the pattern of the support pillar structures such that the support pillar structures are omitted from the area in which source select gate contact via structures are formed. The insulating layer at the level overlying the source select level electrically conductive layer can have a sufficient thickness to prevent deformation during formation of the backside recesses. A minimum lateral separation distance between the source select level contact via structure and the support pillar structures is greater than any minimum lateral separation distance between the word line level contact via structures and the support pillar structures.