Lower Electrode Edge Seal for Plasma Chamber Leakage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lower electrode assemblies in plasma processing chambers face issues with trapped air and leakage of reactive chemical species, leading to vacuum leaks and degradation of bond layers, which can cause operational failures.
Innovation Solution
A lower electrode assembly design that includes a gas passage to maintain inert gas at a positive pressure in an annular space between the ring and the groove walls, preventing chemical species ingress and using a TEFLON-encapsulated O-ring with a dovetail feature and backing seal to enhance sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lower electrode assembly is used without additional sealing features, then the structure is simple, but trapped air and leakage of reactive chemical species occur leading to vacuum leaks and bond layer degradation
Solution Approach 1:
The patent implements a multi-layer nested sealing structure where an inner seal (O-ring) is positioned within a groove, surrounded by an intermediate seal layer, and further protected by an outer seal structure. Each sealing layer is nested within the previous one, creating redundant sealing barriers that prevent chemical species ingress and trapped air formation while maintaining a relatively compact assembly geometry.
Solution Approach 2:
The sealing system is divided into multiple independent sealing segments: an inner O-ring seal, an intermediate seal layer, and an outer seal structure. Each segment performs a specific sealing function and can be independently selected, installed, and replaced. This segmentation allows optimization of each sealing layer for its specific function while maintaining overall system reliability.
2Reliability
If inert gas is supplied at high pressure to the annular space, then chemical species ingress is prevented, but gas consumption increases and may affect plasma process stability
Solution Approach 1:
The patent utilizes pneumatic pressure by supplying inert gas through a gas passage into the annular space between the lower electrode assembly and the showerhead. This creates a positive pressure barrier that prevents reactive chemical species from migrating into the annular space and degrading the bond layer. The gas flow rate and pressure are controlled to provide adequate protection while minimizing gas consumption and plasma process interference.
Solution Approach 2:
The patent creates an inert atmosphere in the annular space by continuously supplying inert gas (such as nitrogen or argon) to displace and prevent the ingress of reactive chemical species from the plasma chamber. This inert environment protects the bond layer and other sensitive components from chemical degradation while maintaining a controlled environment that minimizes interference with the plasma process.
3Reliability
If multiple sealing layers are implemented, then protection against chemical species ingress is improved, but device complexity increases
Solution Approach 1:
The patent implements a multi-layer nested sealing structure where an inner seal (O-ring) is positioned within a groove, surrounded by an intermediate seal layer, and further protected by an outer seal structure. Each sealing layer is nested within the previous one, creating redundant sealing barriers that prevent chemical species ingress and trapped air formation while maintaining a relatively compact assembly geometry.
Solution Approach 2:
The sealing system is divided into multiple independent sealing segments: an inner O-ring seal, an intermediate seal layer, and an outer seal structure. Each segment performs a specific sealing function and can be independently selected, installed, and replaced. This segmentation allows optimization of each sealing layer for its specific function while maintaining overall system reliability.
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 effectively prevents chemical species leakage and maintains seal integrity under vacuum conditions, reducing the risk of operational failures and ensuring consistent temperature uniformity.
Implementation Method 1
maintain the inert gas at a pressure of 100 mTorr to 100 Torr in an annular space between walls of the groove and the ring
Implementation Method 2
an edge seal comprising a ring compressed in the groove
Data Source
AI summary
A lower electrode assembly configured to support a semiconductor substrate in a plasma processing chamber includes a base plate, an upper plate above the base plate, and a mounting groove surrounding a bond layer located between the base plate and the upper plate. An edge seal including a compressible ring is mounted in the mounting groove such that the compressible ring is axially compressed between the upper plate and the base plate. At least one gas passage is in fluid communication with an annular space between the compressible ring and an inner wall of the mounting groove. The at least gas one passage extends through the base plate and includes a plurality of outlets in fluid communication with the annular space. In some examples, a backing seal may be located between the edge seal and an inner wall of the mounting groove.