Barrier Layer Surface Passivation for Copper Metallization
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Solution Overview
Problem
Standard copper metallization technologies face issues with barrier materials like tantalum and tantalum nitride forming oxides when exposed to air, leading to inhibited copper deposition, poor adhesion, and increased resistivity, which affects the performance and reliability of semiconductor devices.
Innovation Solution
A method and system for depositing a gapfill copper layer onto a transition metal barrier layer with a removable passivated surface to create a substantially oxygen-free interface, using processes like atomic layer deposition and electroless copper deposition to prevent oxide formation and ensure better adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If barrier materials like tantalum and tantalum nitride are exposed to air for extended periods, then oxide formation occurs on the barrier layer surface, but this inhibits electroless copper deposition and reduces adhesion
Solution Approach 1:
The patent applies preliminary action by forming a metal-rich surface layer on the barrier material before copper deposition. This is achieved through selective etching processes that remove oxides and expose fresh metal, or through in-situ reduction treatments that convert oxidized surfaces back to metal-rich states. This preliminary surface preparation ensures the barrier layer is in the optimal state for copper adhesion before the copper deposition process begins.
Solution Approach 2:
The patent introduces an intermediary approach by using controlled intermediate layers or surface treatments between the barrier material and copper. This may involve creating a gradient interface or using a thin transition layer that facilitates copper deposition while maintaining barrier functionality. The intermediary layer or treatment acts as a bridge that resolves the conflict between oxide resistance and copper adhesion.
2Reliability
If oxide layers form on the barrier layer surface, then the barrier layer resistivity increases, but this reduces the performance and reliability of electronic devices
Solution Approach 1:
The patent applies preliminary action by implementing surface treatments or etching processes that prevent oxide accumulation before it can significantly increase resistivity. This includes in-situ surface preparation immediately preceding copper deposition, or protective measures during storage and handling that maintain the barrier layer in a low-resistivity state throughout the fabrication process.
3Ease of manufacture
If standard copper metallization processes are used, then fabrication is straightforward, but poor adhesion and increased resistivity occur due to oxide formation
Solution Approach 1:
The patent integrates preliminary surface preparation steps into the existing fabrication flow, performing oxide removal and surface activation immediately before copper deposition. This approach maintains ease of manufacture by incorporating the additional steps into the standard process sequence without requiring separate handling or complex equipment, while still achieving improved adhesion quality.
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
This approach enhances the performance and reliability of semiconductor devices by maintaining a clean interface between the barrier layer and copper, reducing oxide formation and improving electro-migration performance.
Implementation Method 1
subjecting the barrier layer to a process condition so as to form a removable passivated surface on the barrier layer
Implementation Method 2
removing the passivated surface from the barrier layer
Implementation Method 3
A preferred process for depositing the copper onto the barrier layer is electroless copper deposition
Data Source
AI summary
This invention pertains to methods and systems for fabricating semiconductor devices. One aspect of the present invention is a method of depositing a gapfill copper layer onto barrier layer for semiconductor device metallization. In one embodiment, the method includes forming the barrier layer on a surface of a substrate and subjecting the barrier layer to a process condition so as to form a removable passivated surface on the barrier layer. The method further includes removing the passivated surface from the barrier layer and depositing the gapfill copper layer onto the barrier layer. Another aspect of the present invention is an integrated system for depositing a copper layer onto a barrier layer for semiconductor device metallization. In one embodiment, the integrated system comprises at least one process module configured for barrier layer deposition and passivated surface formation and at least one other process module configured for passivated surface removal and deposition of copper onto the barrier layer. The system further includes at least one transfer module coupled so that the substrate can be transferred between the modules substantially without exposure to an oxide-forming environment.