Backside Trench Bridges in 3D Memory for Stack Stability

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Three-dimensional memory devices face challenges in maintaining structural integrity during replacement processes, leading to potential stack collapse.

Innovation Solution

The introduction of bridge structures spanning backside trenches, composed of alternating insulating and conductive layers, provides enhanced structural support by replacing sacrificial material layers with electrically conductive layers, ensuring stability during the replacement process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sacrificial material layers are replaced with electrically conductive layers, then electrical functionality is improved, but structural stability deteriorates during the replacement process

Engineering Contradiction:

Improveelectrical functionalityVSAvoidstructural stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

Bridge structures are formed in advance within the backside trenches to provide structural support before the sacrificial material removal process begins. This preliminary structural reinforcement prevents stack collapse during the subsequent replacement of sacrificial material with electrically conductive layers.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The bridge structures act as intermediary support elements between the alternating stacks. These bridges span the backside trenches and provide mechanical support to the alternating stacks during the sacrificial material replacement process, enabling the transition from sacrificial to conductive material without structural failure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If bridge structures are introduced to prevent stack collapse, then structural integrity is improved, but device complexity increases

Engineering Contradiction:

Improvestructural integrityVSAvoiddevice complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The bridge structures serve multiple functions: they provide structural support to prevent stack collapse, maintain spacing between alternating stacks, and potentially serve as electrical interconnects. This multi-functionality justifies the added structural elements without proportionally increasing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The memory device employs composite structures combining alternating insulating and electrically conductive layers within the stacks, with bridge structures spanning the trenches. This composite architecture integrates structural support and electrical functionality in a unified design.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS12457743B2Three-dimensional memory device including trench bridges and methods of forming the same

Publication Date: 2025.10.28 SANDISK TECHNOLOGIES LLC

AI summary

A three-dimensional memory device includes layer stacks each of which includes a first-tier alternating stack of first insulating layers and first electrically conductive layers and a second-tier alternating stack of second insulating layers and second electrically conductive layers separated by a backside trench. Memory opening fill structures vertically extend through a respective layer stack, and includes a respective vertical stack of memory elements and a respective vertical semiconductor channel. In one embodiment, a bridge structure spans an entire width of the backside trench such that a top surface of the bridge structure is located below a top surface of the second-tier alternating stack, and a bottom surface of the bridge structure is located above a bottom surface of the first-tier alternating stack. In another embodiment, a perforated bridge structure includes a plurality of vertically-extending openings.