3D Memory Lateral Block Isolation for Stairless Word Line Contacts
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in efficiently forming inter-block word line lateral isolation structures for stairless layer contact via structures, which affects the performance and reliability of memory arrays.
Innovation Solution
The solution involves forming an alternating stack of insulating and sacrificial material layers over a substrate, creating memory openings and support openings, and replacing sacrificial material layers with electrically conductive strips, while using dielectric isolation structures and backside trenches to achieve lateral isolation and electrical isolation between memory blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional three-dimensional memory devices are used, then manufacturing processes are simpler, but electrical isolation between memory blocks is insufficient and performance is degraded
Solution Approach 1:
The isolation structure is segmented into multiple functional components: dielectric isolation structures that vertically extend through alternating stacks, backside trenches that laterally extend between memory blocks, and trench fill structures that fill the trenches. This segmentation allows each component to perform its specific isolation function independently, achieving comprehensive electrical isolation while maintaining manageable manufacturing complexity
Solution Approach 2:
The patent introduces lateral isolation through backside trenches that extend in the horizontal direction, complementing the vertical isolation provided by dielectric isolation structures. This multi-dimensional approach to isolation ensures complete electrical separation between memory blocks in both vertical and lateral directions, significantly improving reliability
2Reliability
If stairless layer contact via structures are formed, then device performance is improved, but manufacturing precision requirements increase
Solution Approach 1:
Backside trenches are formed in advance before contact via formation, creating pre-defined isolation boundaries and structural guides. This preliminary action establishes a robust framework that simplifies subsequent via formation processes and reduces alignment precision requirements by providing physical reference structures
Solution Approach 2:
Trench fill structures serve as intermediary elements that fill the backside trenches and provide mechanical support and electrical isolation during the contact via formation process. These intermediary structures act as sacrificial or permanent elements that facilitate precise via formation while maintaining the stairless layer architecture
Data Source
AI summary
A memory device includes an alternating stack of insulating layers and composite layers that alternate along a vertical direction, where each of the composite layers includes a combination of a dielectric connection plate and a plurality of electrically conductive strips that are laterally spaced apart by backside trench isolation structures, arrays of memory openings vertically extending through the alternating stack, memory opening fill structures located in the memory openings, and dielectric isolation structures adjoined to an end portion of a respective one of the backside trench fill structures.