Cogged Susceptor Shaft Coupling for CVD Wobble Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing substrate support systems experience wobble and tilt during semiconductor processing, leading to non-uniform film deposition and increased maintenance challenges.
Innovation Solution
A substrate support assembly featuring a susceptor and shaft coupled via a cogged interface, which distributes stress and reduces wobble by providing a secure and stress-distributed connection, using materials like graphite and quartz for thermal conductivity and optical transparency to minimize shadowing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional substrate support assembly is used, then the structure is simple, but wobble and tilt occur during rotation leading to non-uniform film deposition
Solution Approach 1:
The substrate support assembly is divided into multiple functional components: a shaft with first and second ends, a susceptor with distinct regions, and a coupling mechanism with cogged features. This segmentation allows each component to be optimized independently - the shaft provides rotational support, the susceptor holds the substrate, and the coupling features eliminate wobble - while working together to achieve uniform film deposition without excessive complexity
Solution Approach 2:
A coupling mechanism acts as an intermediary between the shaft and susceptor, featuring cogged indentations and protrusions that engage to eliminate wobble and tilt. This intermediary component transfers rotational motion from the shaft to the susceptor while maintaining precise alignment and preventing unwanted movements, thereby ensuring uniform film deposition without requiring direct rigid connection
2Manufacturing precision
If the susceptor rotates during deposition, then film coverage is improved, but wobble and tilt increase making maintenance difficult
Solution Approach 1:
The system employs dynamic coupling features - cogged indentations and protrusions - that maintain precise engagement during rotation. These features allow the susceptor to rotate freely for uniform film coverage while simultaneously constraining wobble and tilt through the interlocking geometry, and the modular design enables easy disengagement for maintenance
3Manufacturing precision
If a secure coupling is used to reduce wobble, then deposition uniformity improves, but the risk of deformation or damage increases
Solution Approach 1:
The coupling force is segmented and distributed across multiple cogged contact points between the shaft and susceptor. This distribution of mechanical stress across several engagement points prevents concentration of force that could cause deformation or damage, while still providing sufficient securing force to eliminate wobble and ensure deposition uniformity
Solution Approach 2:
The cogged coupling features are designed with specific geometric parameters - tooth profile, contact surface area, and engagement depth - that optimize the balance between securing force and stress distribution. By carefully controlling these parameters, the coupling provides enough force to eliminate wobble while maintaining structural integrity of the susceptor
Data Source
AI summary
An apparatus for rotating a substrate within a deposition chamber is described. The substrate is rotated using a substrate support assembly with a shaft and a susceptor coupled to a top of the shaft. The susceptor and the shaft are coupled together using a cogged feature. The cogged feature includes a plurality of teeth or projections on a coupling portion of the shaft which interlock with an indent disposed on the bottom of the susceptor. A lift pin assembly is further coupled to the shaft and configured to raise and lower a substrate from the susceptor.