Gasket Positioning for Clamped Monolithic Showerhead Electrode
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing showerhead electrode assemblies in plasma processing chambers face challenges in securely clamping monolithic stepped electrodes to backing plates without adhesive bonding, which can lead to contamination and particle generation during semiconductor fabrication, and require precise alignment and gas distribution for optimal plasma confinement.
Innovation Solution
A gasket with alignment pin recesses and circumferentially spaced pockets is used to receive locking pins and alignment features, cooperating with cam locks to clamp the stepped electrode to the backing plate, ensuring secure attachment and alignment while allowing for thermal and electrical conductivity without adhesive bonding, and providing a gas seal for uniform process gas distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive bonding is used to attach the electrode to the backing plate, then attachment strength is improved, but contamination and particle generation occur during semiconductor fabrication
Solution Approach 1:
The patent replaces adhesive bonding (chemical system) with a mechanical clamping system consisting of cam locks and locking pins that physically secure the electrode to the backing plate through friction and geometric interlocking, eliminating contamination from adhesives while maintaining attachment strength
Solution Approach 2:
The gasket acts as a flexible sealing element that conforms to the mating surfaces of the electrode and backing plate, providing both sealing and mechanical support while allowing the clamping mechanism to apply distributed pressure without point loads that could cause contamination
2Manufacturing precision
If precise alignment features are added to ensure proper electrode positioning, then alignment precision is improved, but device complexity increases
Solution Approach 1:
Alignment pins are pre-installed in the backing plate and alignment features are pre-formed on the electrode and gasket, enabling self-alignment during assembly without requiring complex adjustment procedures or high-precision machining of all mating surfaces
Solution Approach 2:
The gasket serves as an intermediary component that incorporates alignment features and sealing elements, mediating between the electrode and backing plate to provide alignment and sealing functions without requiring direct precision mating between the electrode and backing plate surfaces
3Reliability
If multiple gas supply holes and outlets are created for uniform gas distribution, then plasma confinement is improved, but particle generation risk increases
Solution Approach 1:
The gas distribution system is segmented into multiple discrete supply holes and outlets arranged in specific patterns, allowing uniform gas distribution across the plasma region while each individual hole/outlet can be precisely manufactured to minimize particle generation from machining operations
Data Source
AI summary
An electrode assembly for a plasma reaction chamber used in semiconductor substrate processing. The assembly includes an upper showerhead electrode which is mechanically attached to a backing plate by a series of spaced apart cam locks. A thermally and electrically conductive gasket with projections thereon is compressed between the showerhead electrode and the backing plate at a location three to four inches from the center of the showerhead electrode. A guard ring surrounds the backing plate and is movable to positions at which openings in the guard ring align with openings in the backing plate so that the cam locks can be rotated with a tool to release locking pins extending from the upper face of the electrode.