3D Memory Source Select Layout With Lateral Electrode Separation

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Solution Overview

Problem

Existing three-dimensional semiconductor devices face challenges in efficiently integrating laterally separated source select electrodes, which affect the performance and scalability of memory blocks.

Innovation Solution

A semiconductor structure is designed with an alternating stack of insulating and conductive layers, featuring laterally extending memory openings and fill structures, including vertically separated source select electrodes, which are formed through a method involving sacrificial material replacement with electrically conductive layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If source select electrodes are continuously extended in the second horizontal direction through the entire memory block, then electrical connectivity and signal transmission are improved, but device complexity and manufacturing difficulty increase due to the need for precise lateral separation

Engineering Contradiction:

Improveelectrical connectivityVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The source select electrode is segmented into multiple portions along the second horizontal direction, creating laterally separated regions within the same memory block. This segmentation allows the electrode to provide electrical connectivity in a distributed manner while reducing the complexity of continuous extension across the entire block, as each segment can be independently formed and controlled.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The source select electrode structure transitions from a two-dimensional continuous plane to a three-dimensional laterally separated configuration. By introducing lateral separation while maintaining vertical continuity through the alternating stack, the design achieves electrical connectivity through multiple spatial dimensions, improving reliability without requiring a single continuous path that would increase manufacturing complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If laterally separated source select electrodes are integrated into the memory block, then data storage capabilities and operational efficiency are improved, but manufacturing precision requirements increase due to the need for precise lateral positioning

Engineering Contradiction:

Improveoperational efficiencyVSAvoidlateral positioning precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The alternating stack of insulating and electrically conductive layers is formed first, establishing a pre-defined structural framework before the source select electrodes are introduced. This preliminary formation of the stack with its inherent layer boundaries provides natural reference planes that guide subsequent electrode positioning, reducing the precision burden on later lateral separation steps.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The alternating stack of insulating and electrically conductive layers serves as an intermediary structure that mediates between the substrate and the laterally separated source select electrodes. This intermediate framework provides physical support and electrical isolation, enabling precise lateral positioning of electrodes without requiring direct high-precision alignment procedures.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If primary source side select gate electrodes are laterally separated along the second horizontal direction, then scalability and integration density are improved, but device complexity increases due to the need for additional isolation structures

Engineering Contradiction:

ImprovescalabilityVSAvoidisolation structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The source-side dielectric isolation structure is merged with the alternating stack architecture, combining the isolation function with the existing insulating layers. This merging eliminates the need for separate, additional isolation structures, as the alternating stack's insulating layers inherently provide the necessary dielectric isolation between laterally separated source select electrodes, thereby improving scalability without proportionally increasing device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The alternating stack of insulating and electrically conductive layers performs multiple functions simultaneously: it provides electrical isolation for laterally separated electrodes, serves as a structural framework, and enables vertical signal transmission. This multi-functionality allows the same structure to support scalability through lateral separation while avoiding the need for dedicated isolation components that would increase device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12507414B2Three-dimensional memory device with laterally separated source select electrodes and methods of forming the same

Publication Date: 2025.12.23 SANDISK TECHNOLOGIES LLC

AI summary

A three-dimensional memory device includes primary source side select gate electrodes located between word lines and bottom source side select gate electrodes. The primary source side select gate electrodes are laterally separated in each memory block, while the word lines and the bottom source side select gate electrodes are not laterally separated in each memory block.