Plasma Chamber Edge Ring Fastening to Prevent Arcing Shift
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Solution Overview
Problem
Existing edge rings in plasma chambers are not securely fixed during high-temperature processing, leading to potential displacement and undesirable processing of substrates due to adhesive degradation, which can result in arcing and uneven processing.
Innovation Solution
The edge ring is coupled to a support ring using screws and pull-down structures, with curved edges and slots for fasteners, and is secured by hold-down rods and pneumatic mechanisms to maintain stability during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesives are used to secure the edge ring to the support ring, then the edge ring can be initially attached, but the adhesive force is reduced due to high temperature cycles and the gel can disintegrate over time, leading to displacement
Solution Approach 1:
The securing mechanism is divided into multiple independent fasteners distributed around the edge ring, rather than relying on a single adhesive bond. Each fastener provides independent mechanical support, and the segmentation allows the system to maintain security even if individual fasteners experience wear or thermal degradation.
Solution Approach 2:
The fasteners are pre-installed in the edge ring before operation, and the pull-down structures are pre-configured to apply downward force. This preliminary mechanical securing occurs before thermal cycling begins, establishing a robust physical connection that prevents displacement from the outset, rather than relying on adhesives that degrade over time.
2Reliability
If the edge ring is secured with multiple fasteners and pull-down structures, then the edge ring remains fixed during processing, but the device complexity increases
Solution Approach 1:
The fasteners and pull-down structures are integrated into a unified securing system where the fasteners attach the edge ring to the support ring and the pull-down structures work in conjunction to maintain downward force. This merging of multiple securing elements into a coordinated system achieves high reliability while managing complexity through functional integration rather than separate independent mechanisms.
Solution Approach 2:
The pull-down structures utilize curved surfaces and rounded geometries that conform to the circular edge ring and support ring. This curvature allows the pull-down structures to apply force evenly around the circumference while maintaining simple, manufacturable shapes that reduce overall device complexity compared to angular or irregular geometries.
3Manufacturing precision
If the edge ring has sharp edges to maintain precision, then the structural integrity is maintained, but arcing occurs during plasma processing
Solution Approach 1:
The edges of the edge ring are rounded or chamfered instead of being sharp, eliminating the geometric features that concentrate electric field and initiate arcing during plasma processing. This curvature modification maintains the structural integrity and dimensional precision of the ring while removing the harmful arcing effect, as the rounded edges distribute electric field more evenly.
4Reliability
If the cover ring width is increased to achieve stand-off voltage, then the electrical safety is improved, but the device complexity and space requirements increase
Solution Approach 1:
The cover ring is designed with varying width at different locations, with the widest portion positioned where the stand-off voltage requirement is most critical. This local quality variation provides the necessary electrical safety margin at key locations while minimizing the overall material usage and device complexity compared to a uniformly wide cover ring.
Data Source
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Figure 3A
AI summary
Systems and methods for securing an edge ring to a support ring are described. The edge ring is secured to the support ring via multiple fasteners that are inserted into a bottom surface of the edge ring. The securing of the edge ring to the support ring provides stability of the edge ring during processing of a substrate within a plasma chamber. In addition, the securing of the edge ring to the support ring secures the edge ring to the plasma chamber because the support ring is secured to an insulator ring, which is connected to an insulator wall of the plasma chamber. Moreover, the support ring and the edge ring are pulled down vertically using one or more clasp mechanisms during the processing of the substrate and are pushed up vertically using the clasp mechanisms to remove the edge ring and the support ring from the plasma chamber.