Arc Suppression Plate With Isolation Lip For Plasma Chamber
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Solution Overview
Problem
Current plasma processing chambers face issues with current arcing near semiconductor substrates due to loose fits of screw covers made from materials like quartz, leading to prolonged downtime and increased maintenance costs, as well as non-uniform etching resulting from alternate paths to ground.
Innovation Solution
A plasma processing chamber design featuring a substrate support assembly with a plate having countersunk regions and a surrounding isolation plate with nipples, which securely fits over the plate's lip to prevent arcing by isolating fasteners and maintaining a consistent path to ground, while being designed to prevent displacement during cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If screw covers made from quartz or ceramics are used to isolate fasteners, then arcing near the substrate is suppressed, but the screw covers become unserviceable or require breaking to access fasteners for maintenance
Solution Approach 1:
The isolation plate is segmented into a main body portion and a separate lip portion. The lip fits into the countersink to secure the isolation plate in position, while the main body provides electrical isolation. This segmentation allows the fastener to remain accessible through the lip opening while maintaining arc suppression functionality.
Solution Approach 2:
The lip acts as an intermediary element between the isolation plate and the countersink. It provides a mechanical connection point that allows maintenance access while the main body of the isolation plate maintains the electrical isolation function. The lip mediates between the need for secure positioning and fastener accessibility.
2Ease of operation
If small diameter screw covers are used to prevent wedging, then access to fasteners is maintained, but the loose fit causes displacement during cleaning operations
Solution Approach 1:
The solution moves from a two-dimensional fit (screw cover diameter matching countersink) to a three-dimensional engagement by adding the lip that fits into the countersink cavity. This dimensional change provides secure retention while maintaining fastener accessibility through the lip opening.
3Ease of manufacture
If aluminum and aluminum alloys are used for chamber components, then manufacturing and assembly are simplified, but stray arcing near the substrate occurs due to conductive properties
Solution Approach 1:
The isolation plate applies local quality by using ceramic material specifically at the location where electrical isolation is needed (around the fastener in the countersink), while the rest of the chamber can continue to use aluminum components. This localized application of different material properties solves the arcing problem without requiring complete chamber redesign.
Solution Approach 2:
The solution employs composite material strategy by combining ceramic (for electrical isolation) with metal fasteners and aluminum chamber components. The ceramic isolation plate with integrated lip creates a composite structure that leverages the electrical insulation properties of ceramic while maintaining mechanical fastening capabilities.
Data Source
AI summary
A plasma processing chamber configured to generate a plasma is provided. The plasma processing chamber includes a substrate support assembly which includes a substrate support that is capable of supporting a substrate. The plasma processing chamber further includes a plate having a bottom surface and a top surface, and the plate is coupled to the plasma processing chamber. The plate further includes a plurality of countersunk regions for receiving a corresponding plurality of fasteners that enable coupling of the plate to the plasma processing chamber, and the plate has a lip that surrounds an outer region of the plate near the top surface of the plate. The substrate support is configured to be connected to the top surface of the plate. The plasma processing chamber further includes an isolation plate that surrounds the outer region of the plate, and the isolation plate includes a plurality of nipples and each of the plurality of nipples is configured to mate with the plurality of countersunk regions in the plate. The isolation plate is configured to fit in the lip of the plate that surrounds the outer region of the plate.