Concave Edge Seal Geometry for Plasma Electrode Assemblies
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Solution Overview
Problem
Existing edge seals for lower electrode assemblies in plasma processing chambers face issues with radial expansion, leading to potential contact with surrounding edge rings and cracking when exposed to reactive plasmas, which can result in particle generation and contamination.
Innovation Solution
An elastomeric band with a concave outer surface is used, designed to be axially compressed within a mounting groove, minimizing outward bulging and preventing contact with surrounding components, thereby protecting the bond layers and maintaining a secure seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an elastomeric band is axially compressed to seal the bond layer, then the sealing effectiveness is improved, but the band bulges outward and may contact surrounding parts causing cracking and particle generation
Solution Approach 1:
The elastomeric band is designed with a concave outer surface instead of a flat or convex shape. This curvature allows the band to accommodate axial compression without bulging outward, as the concave geometry directs the compression stress inward rather than allowing outward expansion. The concave surface maintains the seal's effectiveness while preventing contact with surrounding parts that would cause cracking and particle generation.
2Ease of operation
If the elastomeric band is made more compliant to reduce bulging, then the serviceability is improved, but the sealing force may be insufficient
Solution Approach 1:
The concave outer surface geometry provides a mechanical advantage by distributing compression forces more evenly across the band's structure. This allows the elastomeric material to maintain its sealing force while being more compliant and resistant to bulging. The curved geometry essentially amplifies the sealing effect of the compression force while reducing the tendency to deform outward.
3Reliability
If the band is compressed to protect bond layers from reactive chamber conditions, then the protection is improved, but the band may bind with surrounding parts reducing operational lifespan
Solution Approach 1:
The concave outer surface design prevents the band from expanding outward during compression, thereby eliminating contact with surrounding parts that would cause binding and premature failure. This geometric feature allows the band to maintain its protective sealing function throughout the operational lifespan without degradation from mechanical binding or cracking.
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 elastomeric band effectively reduces the risk of cracking and particle generation, ensuring a reliable and contamination-free seal during plasma processing, enhancing the operational lifetime of the electrode assembly.
Implementation Method 1
an edge seal comprising an elastomeric band having an outer concave surface in an uncompressed state, the band mounted in the groove such that upper and lower ends of the band are axially compressed
Data Source
AI summary
An edge seal for sealing an outer surface of a lower electrode assembly configured to support a semiconductor substrate in a plasma processing chamber, the lower electrode assembly including an annular groove defined between a lower member and an upper member of the lower electrode assembly. The edge seal includes an elastomeric band configured to be arranged within the groove, the elastomeric band having an annular upper surface, an annular lower surface, an inner surface, and an outer surface. When the elastomeric band is in an uncompressed state, the outer surface of the elastomeric band is concave. When the upper and lower surfaces are axially compressed at least 1% such that the elastomeric band is in a compressed state, an outward bulging of the outer surface is not greater than a predetermined distance. The predetermined distance corresponds to a maximum outer diameter of the elastomeric band in the uncompressed state.