Ceramic Shaft Geometry for Low-Shading Wafer Rotation
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Solution Overview
Problem
Existing semiconductor processing systems face challenges in providing a cost-effective and structurally robust shaft member for rotating substrates during material layer deposition, as materials transparent to radiant energy are brittle and add complexity.
Innovation Solution
A shaft member is designed with a cylindrical body made from ceramic materials like quartz or sapphire, featuring a drive segment, frustoconical segment, and end key segment, which are strategically arranged to facilitate rotation and fixation, reducing thermal shading and material brittleness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If materials transparent to radiant energy are used for the shaft member, then thermal shading of the substrate is minimized, but the shaft member becomes brittle and fabrication complexity increases
Solution Approach 1:
The shaft member is divided into multiple segments (first shaft segment, second shaft segment, third shaft segment) with distinct functions. The first segment is transparent to radiant energy to minimize thermal shading, while the second and third segments provide anti-rotation features and structural support. This segmentation allows each part to be optimized for its specific function, reducing overall fabrication complexity while maintaining thermal transparency where needed.
Solution Approach 2:
Different portions of the shaft member have different material properties and geometries tailored to local requirements. The first shaft segment uses transparent material for thermal reasons, while the second and third segments use opaque materials with specific geometric features (facets, keyways) for mechanical coupling and anti-rotation. This local differentiation resolves the contradiction by applying material transparency only where thermally critical, not throughout the entire shaft.
2Reliability
If anti-rotation features are added to fix the shaft relative to the substrate support, then rotational stability is improved, but fabrication cost and complexity increase
Solution Approach 1:
Anti-rotation functionality is segmented into specific features on the second and third shaft segments rather than requiring complex features on the entire shaft. The second segment has a first anti-rotation feature with circumferential facets, and the third segment has a second anti-rotation feature with keyway geometry. This segmentation simplifies fabrication by limiting complex features to specific locations.
Solution Approach 2:
Instead of adding complex anti-rotation features to a simple shaft, the invention inverts the approach by making the shaft itself geometrically complex in specific segments while keeping the overall structure relatively simple. The circumferential facets and keyway features are integrated into the shaft segments rather than being separate components, reducing assembly complexity while maintaining rotational stability.
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 enhances the structural integrity and cost-effectiveness of the shaft member, ensuring uniform material layer deposition while minimizing thermal variations and fabrication complexities.
Implementation Method 1
The shaft member may also be formed from a material transparent to the radiant energy communicated to the substrate support to limit temperature variation across the substrate due to the tendency of the shaft to shade the substrate from the external heating elements
Data Source
AI summary
A shaft member includes a cylindrical body formed from a ceramic material and having a drive segment, a frustoconical segment, and an end key segment. The drive segment extends about a rotation axis, the frustoconical segment is offset from the drive segment along the rotation axis, and the end key segment extends axially from the frustoconical segment and is axially separated from the drive segment by the frustoconical segment of the shaft member. The end key segment has a first circumferential facet and a second circumferential facet circumferentially opposite the first circumferential facet to fix the shaft member in rotation about the rotation axis relative to a support member seated when the end key segment is slidably received within an end key socket defined within the support member. Process kits, semiconductor processing systems, and methods of making semiconductor processing systems are also described.