Integrated Gas Diffuser Support Structure for PECVD Particle Reduction
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Solution Overview
Problem
Thermal cycling in plasma enhanced chemical vapor deposition (PECVD) chambers causes differential expansion of parts, leading to particle contamination due to rubbing between adjacent components, which reduces yield by entraining particles into the processing gas flow.
Innovation Solution
A gas diffuser support structure with a backing plate and integrated cross structure, featuring a central bore and a gas deflector coupled by a single fastener, which reduces stress and deformation, minimizing particle formation by allowing greater lateral and vertical expansion without rubbing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional gas diffuser support structures are used, then the structure provides adequate support, but thermal cycling causes differential expansion between adjacent parts leading to particle generation
Solution Approach 1:
The gas diffuser is merged with the support structure into a single integrated component, eliminating the interface between the gas diffuser and support structure where differential expansion and rubbing occurred. This integration ensures that thermal expansion occurs uniformly without relative motion between parts, thereby preventing particle generation while maintaining structural support functionality.
2Stability of the object's composition
If multiple fasteners are used to couple the gas deflector, then the structure is more stable, but stress concentration increases leading to greater particle formation
Solution Approach 1:
The multiple fasteners coupling the gas deflector to the support structure are removed entirely. The integrated design allows the gas deflector to be formed as part of the single piece structure, eliminating the need for fasteners and the associated stress concentration points that generated particles during thermal cycling.
3Strength
If rigid support structures are used, then lateral and vertical expansion is constrained, but rubbing between parts increases during thermal cycling
Solution Approach 1:
By merging the gas diffuser and support structure into one integrated component, the design allows uniform thermal expansion in both lateral and vertical directions without creating relative motion between adjacent parts. The integrated structure maintains sufficient strength while accommodating thermal expansion freely, eliminating rubbing and particle generation.
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 significantly reduces particle formation, stress, and reaction forces, decreasing contamination and improving chamber cleanliness by over 99% and stress reduction by about 80%, thereby enhancing the yield of the PECVD process.
Implementation Method 1
the thermal cycling causes portions of the gas path to expand or contract at different rates. The differential expansion between adjacent parts causes the parts to rub against each other
Implementation Method 2
a gas deflector coupled to the cross structure by a single fastener
Data Source
AI summary
Embodiments of the present disclosure generally provide apparatus and methods for gas diffuser support structure for a vacuum chamber. The gas diffuser support structure comprises a backing plate having a central bore formed therethrough, an integrated cross structure formed in the central bore, and a gas deflector coupled to the cross structure by a single fastener.