Showerhead Inner Electrode Warping Mitigation
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Solution Overview
Problem
The existing showerhead electrode assemblies in plasma processing chambers face issues with warping of the inner electrode due to thermal heating, leading to non-uniform processing rates and potential contamination from particulate contaminants caused by differential thermal expansion and rubbing between the inner electrode and the backing plate.
Innovation Solution
A showerhead electrode assembly is designed with a plurality of threaded fasteners and a clamp ring to mechanically attach the inner electrode to the backing plate, providing lateral support and improving thermal contact, while gaskets ensure thermal and electrical contact without rubbing, and alignment pins ensure accurate positioning to prevent warping and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the inner electrode is mechanically attached to the backing plate without sufficient support points, then the assembly is simpler to manufacture, but the inner electrode warps during operation due to thermal heating
Solution Approach 1:
The mechanical attachment system is segmented into multiple discrete fasteners (at least three, preferably four or more) distributed around the periphery of the inner electrode, rather than using a single centralized attachment mechanism. This segmentation provides distributed support points that effectively constrain thermal warping across the entire electrode surface.
Solution Approach 2:
The support structure implements local quality by positioning fasteners at specific peripheral locations where thermal expansion forces are most pronounced. The clamp ring applies localized clamping force at these critical points, providing targeted stabilization where it is most needed to prevent warping.
2Temperature
If the inner electrode is securely attached to the backing plate, then thermal contact is improved, but differential thermal expansion causes rubbing contact between the electrode and plate
Solution Approach 1:
A clamp ring is introduced as an intermediary component between the inner electrode and the backing plate. This clamp ring serves as a mediator that applies uniform clamping force to secure the electrode while accommodating differential thermal expansion, thereby preventing direct rubbing contact between the electrode and the backing plate surface.
Solution Approach 2:
The clamp ring functions as a flexible constraint structure that can adapt to thermal expansion differences between the inner electrode and backing plate. This flexible shell design maintains secure thermal contact while allowing for dimensional changes during operation, eliminating rigid rubbing contact.
3Measurement precision
If alignment features are added to the inner electrode, then positioning accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
Alignment features (such as alignment pins or registered holes) are incorporated into the inner electrode design during the manufacturing process. These features perform the alignment function preliminarily, ensuring correct positioning when the electrode is installed, which simplifies the assembly process and reduces the need for complex alignment procedures during installation.
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 reduces warping of the inner electrode, maintains uniform processing rates, and minimizes particulate contamination, thereby enhancing the yield and quality of semiconductor substrates processed in the plasma reaction chamber.
Implementation Method 1
The gaskets provide thermal and electrical contact between the inner electrode and the backing plate
Implementation Method 2
The gaskets provide thermal and electrical contact between the inner electrode and the backing plate
Data Source
AI summary
A thermally and electrically conductive gasket of a gasket set configured to be mounted between a faceplate and backing plate of a showerhead electrode assembly includes an inner gasket configured to be mounted on an inner electrode of a showerhead electrode assembly. The inner gasket includes a plurality of concentric flat rings connected by a plurality of spokes. A first annular gasket surrounds and is concentric with the inner gasket and includes a flat annular ring having a plurality of cutouts. A second annular gasket surrounds and is concentric with the first annular gasket and includes a flat annular ring having a plurality of cutouts. A third annular gasket surrounds and is concentric with the second annular gasket and includes a flat annular ring having a plurality of cutouts. The gasket accommodates gas injection holes, alignment pin holes, an alignment ring groove, and/or threaded holes.