Lower Electrode Edge Seal Geometry to Limit Compression Bulging
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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 parts 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 minimize outward bulging when axially compressed, ensuring it fits within the mounting groove without exceeding the maximum outer diameter in an uncompressed state, thereby preventing contact with surrounding edges and reducing the risk of cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an elastomeric edge seal is used to protect bond layers from reactive gases, then sealing effectiveness is improved, but radial expansion under compression causes the seal to contact surrounding parts and crack
Solution Approach 1:
The elastomeric band is designed with a concave outer surface instead of a convex or flat surface. This concave geometry allows the band to be axially compressed while the material conforms to the groove walls without radially expanding outward. The concave shape distributes the compression stress along the groove boundaries rather than concentrating it as outward bulging, preventing contact with surrounding parts and eliminating the cracking issue while maintaining effective sealing of the bond layers.
2Reliability
If the elastomeric band is compressed axially to seal the bond layer, then sealing performance is improved, but outward bulging exceeds the groove boundaries and causes contact with surrounding edges
Solution Approach 1:
The concave outer surface geometry is specifically designed to control the deformation behavior of the elastomeric band during axial compression. When compressed, the band material flows inward and conforms to the concave profile, with the outer surface curving inward rather than bulging outward. This geometric design ensures that the band remains contained within the groove boundaries while maintaining intimate contact with the groove walls for effective sealing.
3Object-affected harmful factors
If the elastomeric band is designed to minimize outward bulging, then contact with surrounding parts is reduced, but sealing effectiveness may be compromised
Solution Approach 1:
The concave outer surface design simultaneously achieves both objectives: it minimizes outward bulging to prevent contact with surrounding parts while maintaining sealing effectiveness. The concave geometry directs the compressed elastomeric material to conform precisely to the groove walls, ensuring intimate contact for sealing. The inward-curving profile creates a geometric constraint that prevents radial expansion while allowing axial compression to generate sufficient contact pressure against the groove boundaries for effective sealing.
Solution Approach 2:
The elastomeric band is designed with different surface geometries for different functions: the concave outer surface minimizes outward bulging and prevents contact with surrounding parts, while the inner surface maintains contact with the groove walls to provide sealing. This local differentiation of surface geometry allows the same component to simultaneously prevent harmful contact and ensure sealing effectiveness.
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 protects the bond layers from reactive gases, reduces the likelihood of particle generation, and enhances the serviceability of the lower electrode assembly by minimizing contact with surrounding parts, thus maintaining a clean and functional plasma processing environment.
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 and a maximum outward bulging of the band is no greater than a predetermined distance
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.