Double Seal Venting Pathways for Substrate Processing Chamber Virtual Leaks
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Solution Overview
Problem
Conventional vacuum seal arrangements in substrate processing chambers suffer from 'virtual leaks' due to trapped air, which impairs the effectiveness of the vacuum seal and can defeat the purpose of maintaining a vacuum by allowing atmospheric gas into the process volume.
Innovation Solution
A double seal arrangement with venting pathways is implemented, featuring a radially inner barrier seal and a radially outer vacuum seal, along with first, second, and third venting pathways that create a constrictive, long, and tortuous passage to prevent process chemistry radicals from reaching the vacuum seal, thereby reducing the likelihood of virtual leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional single vacuum seal arrangement is used, then the structure is simple, but air becomes trapped in the seal gland toe causing virtual leaks
Solution Approach 1:
The single vacuum seal is segmented into a double seal arrangement with a barrier seal and a vacuum seal, each performing distinct functions. The barrier seal prevents chemistry damage while the vacuum seal maintains vacuum integrity, eliminating the trapped air problem by creating separate sealing zones with dedicated venting pathways.
Solution Approach 2:
The barrier seal acts as an intermediary element between the process chemistry environment and the vacuum seal. It shields the vacuum seal from harmful radicals while the venting pathways provide an escape route for trapped air, preventing virtual leaks without compromising vacuum effectiveness.
2Object-affected harmful factors
If a double seal arrangement with barrier seal is implemented, then protection from process chemistry is improved, but trapped air in seal glands causes virtual leaks
Solution Approach 1:
The sealing function is segmented into two independent seals: the barrier seal exposed to process chemistry and the vacuum seal protected from chemistry. This segmentation allows each seal to optimize its function while venting pathways eliminate trapped air between them, resolving the contradiction between chemistry protection and vacuum integrity.
Solution Approach 2:
The barrier seal serves as a protective intermediary that absorbs chemistry damage while venting pathways provide a controlled escape route for trapped air. This intermediary approach allows the vacuum seal to remain protected from both chemistry and trapped air, maintaining vacuum effectiveness.
3Reliability
If venting pathways are added to the double seal arrangement, then virtual leaks are reduced, but the device complexity increases
Solution Approach 1:
The venting pathways are merged with the existing double seal gland structure, utilizing the same radial and axial spaces. The pathways are integrated into the barrier seal and vacuum seal assemblies, providing venting functionality without adding separate external components, thus minimizing the increase in device complexity.
Solution Approach 2:
The venting pathways utilize both radial and axial dimensions within the seal gland structure. By employing three-dimensional routing of vent channels through the seal assemblies, the design provides effective venting without requiring additional external space or complex external venting components.
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 double seal arrangement effectively reduces the occurrence of virtual leaks by providing a venting system that impedes the passage of harmful radicals back to the vacuum seal, ensuring a consistent vacuum and preventing atmospheric gas intrusion into the processing chamber.
Implementation Method 1
The more collisions the radicals undergo, the more likely they are to recombine. In some examples, the number of collisions through a venting pathway path is proportional to the cross-sectional size, length, and tortuousness of the path.
Implementation Method 2
a vacuum source connected to at least one of the first, second, and third venting pathways
Data Source
AI summary
In some examples, a double seal arrangement for a substrate processing chamber comprises a radially inner barrier seal disposed within a barrier seal gland. The barrier seal gland includes an inner toe and an outer toe. A radially outer vacuum seal is disposed within a vacuum seal gland. The vacuum seal gland includes at least an inner toe. A first venting pathway is provided between the inner toe of the vacuum seal gland and the outer toe of the barrier seal gland, and a second venting pathway is provided between the outer toe of the barrier seal gland and the inner toe of the barrier seal gland. A third venting pathway is in communication at least with the inner toe of the barrier seal gland, and a vacuum source connected to at least one of the first, second, and third venting pathways.