3D Memory Contact-Support Assembly for Defect-Free Layer Replacement

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Solution Overview

Problem

Current three-dimensional memory devices face challenges in efficiently integrating contact and support structures, leading to defects and pattern collapse during the replacement of sacrificial material layers with electrically conductive layers.

Innovation Solution

The integration of a first and second support and contact assembly, comprising a contact via structure and a dielectric pillar structure with an air gap, which provides structural support and prevents sidewall contact with the dielectric pillar structures, allowing for the replacement of sacrificial material layers with electrically conductive layers without defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sacrificial material layers are replaced with electrically conductive layers in conventional three-dimensional memory devices, then electrical connectivity is achieved, but defects and pattern collapse occur during the replacement process

Engineering Contradiction:

Improvedefect-free manufacturingVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The support structure is segmented into discrete dielectric pillars positioned at specific locations rather than a continuous support layer. This segmentation allows selective structural support where needed during the sacrificial material replacement process, preventing pattern collapse in critical areas while maintaining manufacturing feasibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Dielectric pillar structures serve as intermediary support elements between the substrate and the memory stack layers. These pillars provide temporary mechanical support during the replacement of sacrificial material with electrically conductive material, preventing defects and pattern collapse, and are later removed or integrated into the final device structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Quantity of substance

If contact and support structures are integrated in three-dimensional memory devices, then device density is improved, but structural stability during manufacturing deteriorates

Engineering Contradiction:

Improvedevice densityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

Dielectric pillar structures are formed in advance before the replacement of sacrificial material layers with electrically conductive layers. This preliminary action establishes structural support frameworks that prevent pattern collapse during subsequent manufacturing steps, ensuring structural stability is maintained throughout the process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The dielectric pillar structures provide localized structural support at specific critical locations within the memory device rather than uniform support throughout. This local quality approach maintains structural stability where needed while allowing the integrated contact and support structure design to achieve high device density elsewhere.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If dielectric pillar structures are used to prevent pattern collapse, then manufacturing reliability is improved, but device complexity increases

Engineering Contradiction:

Improvepattern accuracyVSAvoidstructure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The support function is extracted and isolated into discrete dielectric pillar structures rather than being distributed throughout the entire device structure. This extraction simplifies the overall device complexity by concentrating the support function in specific, manageable elements that can be easily integrated into the manufacturing process.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS20240274191A1Three-dimensional memory device with integrated contact and support structure and method of making the same

Publication Date: 2024.08.15 SANDISK TECHNOLOGIES LLC

AI summary

A memory device includes a first-tier alternating stack of first insulating layers and electrically conductive layers located over a substrate, a second-tier alternating stack of second insulating layers and second electrically conductive layers overlying the first-tier alternating stack, a memory stack structure vertically extending through the first-tier alternating stack and the second-tier alternating stack, and a first support and contact assembly vertically extending through the first-tier alternating stack and the second-tier alternating stack. The first support and contact assembly includes a first contact via structure contacting an annular top surface of an electrically conductive layer, a first dielectric pillar structure underlying the reference-level electrically conductive layer, and a first-tier dielectric spacer that laterally surrounds the first contact via structure.