Metal Silicide Source Contact Protection in 3D NAND Etching
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Solution Overview
Problem
Conventional 3D NAND Flash memory devices face reliability and durability issues due to etch chemistries and conditions used in the replacement gate process, which can damage the laterally-oriented source contact in vertical memory arrays.
Innovation Solution
Incorporating a metal silicide material over the source contact, which exhibits a low etch rate and protects the source contact from the etch chemistries and conditions, thereby preventing damage during the replacement gate process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional wet etch process is used in replacement gate process, then conductive materials can be formed, but source contact is damaged and reliability decreases
Solution Approach 1:
A metal silicide layer is introduced as an intermediary protective layer between the source contact and the etch chemistry. This layer acts as a barrier that prevents direct contact between the aggressive etch chemicals and the source contact, thereby protecting the source contact from damage while still allowing the replacement gate process to proceed
Solution Approach 2:
The metal silicide layer is formed on the source contact before the replacement gate process begins. This preliminary protective coating is deposited in advance to prevent etch damage before the harmful etch chemistry is introduced, ensuring the source contact is already protected when the replacement gate process starts
2Device complexity
If conventional source contact structure is used, then device structure is simple, but source contact is etched and performance degrades
Solution Approach 1:
The source contact structure is transformed from a single-material structure to a composite structure by adding a metal silicide layer on top of the polysilicon source contact. This composite structure combines the electrical properties of polysilicon with the protective properties of metal silicide, preventing etch damage while maintaining electrical functionality
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 metal silicide material enhances the performance, reliability, and durability of the source contact by preventing degradation during the replacement gate process, improving the overall integrity of the vertical memory array.
Implementation Method 1
the metal silicide material may exhibit a low etch rate when exposed to the etch chemistries and conditions used in the replacement gate process
Data Source
AI summary
An electronic device includes a source contact adjacent to a source stack, the source stack including one or more conductive materials, tiers of alternating conductive material and dielectric materials adjacent to the source contact, pillars extending vertically through the tiers and the source contact and at least partially into the source contact, a fill material extending vertically through the tiers to the source contact, and a metal silicide material between the fill material and an upper surface of the source contact. Related devices, systems, and methods are also disclosed.