3D Memory Isolation Trenches With Undulating Sidewalls
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Solution Overview
Problem
Existing three-dimensional memory devices face challenges in achieving enhanced structural support and efficient manufacturing processes, particularly in the formation of lateral isolation trenches that provide adequate isolation and support for memory elements.
Innovation Solution
A three-dimensional memory device is designed with laterally undulating isolation trenches that include neck portions with straight sidewalls and laterally bulging portions with convex sidewalls, interlaced along a horizontal direction. This configuration is achieved through a method involving the formation of alternating stacks of insulating and sacrificial layers, followed by the creation of memory openings, and the subsequent filling and isolation trench formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional lateral isolation trenches with uniform width are used, then the manufacturing process is simple, but the structural support and isolation effectiveness are insufficient
Solution Approach 1:
The lateral isolation trench is designed with laterally undulating sidewalls featuring convex portions that protrude toward adjacent alternating stacks. This curved/undulating geometry provides enhanced structural support and improved isolation effectiveness compared to conventional straight-sided trenches, while maintaining manufacturability through standard etching and filling processes.
2Reliability
If lateral isolation trenches with enhanced isolation are implemented, then isolation effectiveness improves, but manufacturing complexity increases
Solution Approach 1:
The undulating sidewall profile with convex portions is formed using conventional semiconductor manufacturing techniques including patterned etching and conformal filling, avoiding the need for complex specialized processes while achieving superior isolation effectiveness between adjacent memory stacks.
3Strength
If uniform width isolation trenches are used, then manufacturing is easier, but structural support for memory elements is reduced
Solution Approach 1:
The convex portions of the undulating sidewalls are formed with controlled radii of curvature using standard photolithography and etching processes, achieving the desired structural support enhancement without requiring extreme manufacturing precision or specialized equipment.
Data Source
AI summary
A three-dimensional memory device includes a pair of alternating stacks of insulating layers and electrically conductive layers that are laterally spaced from each other by a lateral isolation trench that laterally extend 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 located in the lateral isolation trench and including a plurality of neck portions having a first width, and a plurality of laterally bulging portions having a second width along the second horizontal direction that is greater than the first width, and interlaced with the plurality of neck portions along the first horizontal direction.