3D Memory Isolation Trench Fill With Undulating Sidewalls
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Solution Overview
Problem
Existing three-dimensional memory devices face challenges in efficiently isolating memory elements and maintaining structural integrity due to the limitations of traditional lateral isolation trench fill structures.
Innovation Solution
A three-dimensional memory device is designed with a lateral isolation trench fill structure that includes a peripheral spacer and a conductive fill structure, featuring laterally-undulating sidewalls with width modulation along both insulating and conductive layers, enhancing structural integrity and isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional lateral isolation trench fill structures are used, then manufacturing process is simpler, but structural integrity and isolation between memory elements deteriorates
Solution Approach 1:
The lateral isolation trench fill structure is segmented into multiple functional components: a dielectric material portion for electrical isolation, a first spacer portion for dimensional control and isolation, and a second spacer portion for additional structural support. This segmentation allows each component to perform its specific function optimally, improving overall structural integrity and isolation between memory elements while maintaining manufacturability through standardized formation processes.
2Reliability
If lateral isolation trench width is increased to improve isolation, then isolation between memory elements improves, but device area increases
Solution Approach 1:
The isolation structure employs local quality by creating width modulation in the lateral isolation trench fill structure. The dielectric material portion and spacer portions have varying widths at different vertical levels, with the structure being wider at certain levels to provide enhanced isolation where needed and narrower at other levels to minimize device area. This localized variation in dimensions optimizes isolation effectiveness while controlling overall device footprint.
3Strength
If conventional isolation trench fill is used, then manufacturing process is simpler, but structural support for alternating stacks deteriorates
Solution Approach 1:
The lateral isolation trench fill structure uses a composite construction combining dielectric material portions with spacer portions formed from different materials. This composite structure provides enhanced mechanical support for the alternating stacks of insulating and conductive layers while maintaining electrical isolation. The different materials in the composite structure contribute different properties - the dielectric provides electrical isolation and the spacers provide structural support and dimensional control - achieving both strength and manufacturability.
Data Source
AI summary
A three-dimensional memory device includes: a pair of alternating stacks of insulating layers and electrically conductive layers, the pair of alternating stacks being laterally spaced from each other by a lateral isolation trench that generally extends along a first horizontal direction; memory openings vertically extending through a respective one of the pair of alternating stacks; memory opening fill structures located in a respective one of the memory openings; and a lateral isolation trench fill structure including a peripheral spacer and a conductive fill structure, wherein a first vertical cross-sectional view of the lateral isolation trench fill structure in a first vertical plane includes: an outer periphery of the peripheral spacer which includes a horizontal top surface segment located in a first horizontal plane; and an inner periphery of the peripheral spacer that is vertically spaced from, and located entirely below, the first horizontal plane.