Rotatable Substrate Support with Ferrofluid Seal for CVD Uniformity
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Solution Overview
Problem
The flow pattern of gases in typical CVD or ALD chambers leads to non-uniform metal deposition on substrates due to the design of heated substrate supports and gas ports, resulting in uneven material distribution.
Innovation Solution
A rotatable substrate support with a ferrofluid sealing assembly between the hub and shaft, allowing for improved gas flow paths and seals, which facilitates uniform deposition by preventing gas flow irregularities and ensuring consistent substrate processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a heated substrate support with gas ports is used in a CVD or ALD chamber, then substrate processing capability is provided, but non-uniform metal deposition occurs due to gas flow patterns
Solution Approach 1:
The substrate support is made rotatable to dynamically change the relative positions of different substrate regions with respect to gas ports and pumping ports during deposition. This rotation enables uniform exposure to gas flows and removes deposited material evenly, achieving uniform metal deposition across the substrate surface.
Solution Approach 2:
A ferrofluid sealing assembly is introduced as an intermediary between the rotating substrate support shaft and the stationary hub. This ferrofluid seal allows the shaft to rotate while maintaining vacuum integrity and enabling controlled gas flow paths, resolving the complexity of maintaining seals in a rotating configuration.
2Manufacturing precision
If a rotating substrate support is implemented to improve deposition uniformity, then manufacturing precision improves, but sealing complexity increases
Solution Approach 1:
A ferrofluid sealing assembly is introduced as an intermediary between the rotating substrate support shaft and the stationary hub. This ferrofluid seal allows the shaft to rotate while maintaining vacuum integrity and enabling controlled gas flow paths, resolving the complexity of maintaining seals in a rotating configuration.
Solution Approach 2:
The traditional mechanical contact seal between rotating and stationary components is replaced with a ferrofluid seal that uses magnetic field containment of a ferrofluid barrier. This substitution eliminates mechanical friction and wear while maintaining effective sealing, reducing long-term operational complexity.
3Manufacturing precision
If gas flow paths are modified to achieve uniform deposition, then manufacturing precision improves, but device complexity increases
Solution Approach 1:
The substrate support is made rotatable to dynamically change the relative positions of different substrate regions with respect to gas ports and pumping ports during deposition. This rotation enables uniform exposure to gas flows and removes deposited material evenly, achieving uniform metal deposition across the substrate surface.
Solution Approach 2:
The gas distribution system utilizes a combination of stationary gas ports in the hub and rotating gas ports in the shaft, creating a composite gas flow path system. This allows gas to be introduced from multiple directions and distributed more uniformly across the substrate surface during rotation.
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 solution enhances the uniformity of metal deposition on substrates, reduces unwanted deposition, and improves particle performance by maintaining a controlled environment and consistent gas flow during the deposition process.
Implementation Method 1
a ferrofluid sealing assembly disposed between the hub and the shaft
Data Source
AI summary
Embodiments of substrate processing equipment and rotatable substrate supports incorporating the same are provided herein. In some embodiments, the substrate support may include a pedestal having a substrate receiving surface, a shaft having an upper end, a lower end, and a central opening, where the shaft is coupled to the pedestal at the upper end, a hub circumscribing the shaft, where the shaft is rotatable with respect to the hub, and where the hub includes a first port that extends from an outer surface of the hub to a volume between the hub and the shaft, and a ferrofluid sealing assembly disposed between the hub and the shaft.