3D Memory Backside Trench Bridges Against Stack Collapse

Solution Overview

Problem

Three-dimensional memory devices face challenges in maintaining structural integrity during replacement processes, particularly in preventing stack collapse due to the absence of adequate structural support in vertical NAND strings.

Innovation Solution

Incorporation of dielectric bridges and backside trench fill structures that provide lateral spacing and support, using a method that involves forming memory openings, filling them with memory elements and semiconductor channels, and creating dielectric bridges to enhance structural stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If vertical NAND strings are used to achieve high density three-dimensional memory, then storage capacity is improved, but structural integrity deteriorates due to absence of adequate structural support causing stack collapse

Engineering Contradiction:

Improvestorage capacityVSAvoidstructural integrity

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The patent divides the continuous backside trench fill structure into segmented portions with lateral spacing, creating discrete support regions that prevent stack collapse while maintaining manufacturing feasibility. The segmented approach allows each portion to independently support adjacent vertical NAND strings without requiring a continuous structure throughout the entire trench.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from two-dimensional planar memory structures to three-dimensional vertical architectures by stacking multiple layers of memory cells vertically. This dimensional change enables significantly increased storage capacity by utilizing the vertical dimension for stacking word lines, bit lines, and memory cells in multiple tiers above the substrate.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Strength

If continuous backside trench fill structures are used to provide structural support, then structural integrity is improved, but manufacturing complexity increases due to difficulty in forming continuous structures

Engineering Contradiction:

Improvestructural supportVSAvoidmanufacturing complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent divides the continuous backside trench fill structure into segmented portions with lateral spacing, creating discrete support regions that prevent stack collapse while maintaining manufacturing feasibility. The segmented approach allows each portion to independently support adjacent vertical NAND strings without requiring a continuous structure throughout the entire trench.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent forms the backside trench fill structures before completing the vertical NAND string formation process. This preliminary action establishes the structural support framework in advance, providing a stable foundation that prevents stack collapse during subsequent processing steps and reduces the complexity of forming support structures later.

Inventive Principle:

Principle #10Preliminary action

3Strength

If lateral spacing is increased to prevent stack collapse, then structural support is improved, but device area increases

Engineering Contradiction:

Improvestructural supportVSAvoiddevice area

Core Design Contradiction:

StrengthVSArea of stationary object

Solution Approach 1:

The patent divides the continuous backside trench fill structure into segmented portions with lateral spacing, creating discrete support regions that prevent stack collapse while maintaining manufacturing feasibility. The segmented approach allows each portion to independently support adjacent vertical NAND strings without requiring a continuous structure throughout the entire trench.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs composite material structures combining dielectric materials for the backside trench fill portions with conductive materials for the word lines and bit lines. This composite approach enables optimized structural support and electrical functionality within the same device architecture, allowing lateral spacing to be minimized while maintaining both mechanical integrity and electrical performance.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS12513902B2Three-dimensional memory device containing bridges for enhanced structural support and methods of forming the same

Publication Date: 2025.12.30 SANDISK TECHNOLOGIES LLC

AI summary

A three-dimensional memory device includes vertical layer stacks that are laterally spaced apart by backside trenches that laterally extend along a first horizontal direction, where each of the vertical layer stacks includes a respective alternating stack of insulating layers and electrically conductive layers, memory openings vertically extending through the alternating stacks, memory opening fill structures located in the memory openings and including a respective vertical stack of memory elements and a respective vertical semiconductor channel, and backside trench fill structures located within a respective one of the backside trenches. Each of the backside trench fill structures includes a plurality of dielectric bridge structures laterally spaced apart along the first horizontal direction and dielectric fin portions located at levels of a plurality of the electrically conductive layers. The dielectric fin portions laterally protrude outward relative to sidewalls of the insulating layers within the respective neighboring pair of alternating stacks.