3D NAND Source Seal Structure Against Etch-Induced Block Collapse

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Solution Overview

Problem

The etch chemistry used in the replacement gate process for 3D NAND memory devices can damage polysilicon materials and other components, leading to block collapse during fabrication.

Innovation Solution

A source seal is introduced between the source contact and tiers of alternating dielectric and conductive materials, formed using a bottom-up conformal deposition process, which protects the source contact from subsequent process damage and allows for the removal of the tier sidewall liner without damaging the source contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If etch chemistry is used in the replacement gate process to remove nitride material, then the nitride material is successfully removed, but polysilicon materials and other components are damaged leading to block collapse

Engineering Contradiction:

Improvenitride material removal precisionVSAvoidblock collapse prevention

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

A seal structure is introduced as an intermediary protective layer between the etch chemistry process and the polysilicon materials. This seal structure selectively protects the polysilicon materials from damage by the etch chemistry while allowing the nitride material removal process to proceed, thereby preventing block collapse without compromising manufacturing precision

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The device structure is segmented into protected regions (polysilicon materials) and unprotected regions (nitride material) through the selective application of the seal structure. This segmentation allows differential treatment during the etch process, enabling precise removal of nitride material while preserving the polysilicon components

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If conventional fabrication processes are used without protective measures, then the fabrication process is simple, but the source contact and other materials suffer damage

Engineering Contradiction:

Improvefabrication process simplicityVSAvoidsource contact damage

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The seal structure is formed in advance before the damaging etch chemistry process. This preliminary protective action ensures that when the etch chemistry is subsequently applied, the source contact and other sensitive materials are already protected, eliminating the need for complex in-process protective measures while preventing damage

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The source seal reduces or eliminates damage to the source contact and other materials, preventing block collapse and enhancing the reliability of the 3D NAND memory device.

Implementation Method 1

formed using a bottom-up conformal deposition process

Methodology Applied

Scientific EffectConformal deposition: Deposition (physical)

Data Source

PatentUS20250359057A1Electronic devices including a source seal adjacent to a source contact

Publication Date: 2025.11.20 MICRON TECHNOLOGY INC

AI summary

An electronic device comprises a source stack comprising one or more conductive materials. A source contact is adjacent to the source stack and a source seal is on a portion of the source contact. Tiers of alternating conductive materials and dielectric materials are adjacent to the source contact. Pillars extend through the tiers and the source contact and into the source stack. Additional electronic devices, electronic systems, and methods of forming the electronic devices are disclosed.