3D Memory Source-Line Segmentation for Word-Line Isolation

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Solution Overview

Problem

Existing three-dimensional memory devices face challenges in efficiently isolating and connecting word lines and source layers, leading to potential electrical interference and reduced performance.

Innovation Solution

The implementation of laterally separated source lines is achieved by forming a sequence of source layer segments and source isolation dielectric structures, followed by alternating sequences of insulating and sacrificial material layers, which are then replaced with electrically conductive layers to create isolated and connected word lines.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If source lines are continuously connected in three-dimensional memory devices, then electrical connectivity is improved, but electrical interference between adjacent word lines increases

Engineering Contradiction:

Improveelectrical connectivityVSAvoidelectrical interference

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The source layer is divided into multiple discrete source layer segments separated by source isolation dielectric structures. This segmentation allows adjacent source line segments to be electrically isolated while maintaining connectivity within each segment, thereby reducing electrical interference between adjacent word lines while preserving necessary electrical connectivity.

Inventive Principle:

Principle #1Segmentation

2Reliability

If source layer segments are laterally separated by source isolation dielectric structures, then electrical isolation is improved, but device complexity increases

Engineering Contradiction:

Improveelectrical isolationVSAvoidstructural complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Source isolation dielectric structures are introduced as intermediary elements between adjacent source layer segments. These dielectric structures serve as mediators that provide electrical isolation while allowing the overall device architecture to maintain a relatively simple and scalable configuration, avoiding excessive complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If alternating sequences of insulating and sacrificial material layers are formed, then word line connectivity control is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveconnectivity controlVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Alternating sequences of insulating material layers and sacrificial material layers are formed in advance before final word line connectivity establishment. This preliminary action allows for controlled replacement of sacrificial materials with conductive materials, enabling precise connectivity control while organizing the manufacturing process into manageable sequential steps.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12456499B2Three-dimensional memory device including laterally separated source lines and method of making the same

Publication Date: 2025.10.28 SANDISK TECHNOLOGIES LLC

AI summary

A memory device includes a first memory block containing first word lines and a first source layer segment, and a second memory block containing second word lines and a second source layer segment which is electrically isolated from the first source layer segment. The first word lines in the first memory block are electrically connected to the respective second word lines in the second memory block.