Hybrid Showerhead Ceramic Faceplate Thermal Stress
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Solution Overview
Problem
Conventional showerheads in thermal atomic layer deposition (T-ALD) systems face issues with ceramic faceplate fractures due to thermal stress and temperature gradients, particularly at high temperatures above 590 degrees Celsius, as the ceramic faceplate directly contacts a metallic top plate with a different coefficient of thermal expansion, leading to fractures and defects.
Innovation Solution
A hybrid showerhead design featuring a ceramic faceplate with a smaller diameter and a metal ring surrounding it, which decouples the ceramic faceplate from the top plate and pedestal, providing a thermal break and reducing temperature gradients, thereby preventing fractures and enhancing axial cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the ceramic faceplate directly contacts the metallic top plate, then the structural support is simplified, but thermal stress causes fractures at high temperatures
Solution Approach 1:
A metal ring is introduced as an intermediary component between the ceramic faceplate and the metallic top plate. This metal ring serves as a thermal buffer that decouples the ceramic faceplate from direct thermal contact with the top plate, reducing thermal stress and preventing fractures while maintaining structural support.
Solution Approach 2:
The showerhead structure is segmented into distinct components: the ceramic faceplate, the metal ring, and the metallic top plate. This segmentation allows each component to be optimized for its specific function - the ceramic faceplate for gas distribution, the metal ring for thermal management, and the top plate for structural support - while working together to solve the thermal stress problem.
2Area of stationary object
If the ceramic faceplate is made larger to cover more area, then the gas distribution coverage is improved, but the temperature gradient increases causing more fractures
Solution Approach 1:
The metal ring acts as a thermal intermediary that surrounds the ceramic faceplate and provides a thermal buffer zone. This allows the ceramic faceplate to have a larger diameter for improved gas distribution coverage while the metal ring mitigates the temperature gradient effects, preventing thermal stress fractures.
Solution Approach 2:
The metal ring provides localized thermal management around the perimeter of the ceramic faceplate. By concentrating thermal buffering where it is most needed (at the edges where temperature gradients are highest), the system allows larger ceramic faceplates without proportionally increasing fracture risk.
3Reliability
If the ceramic faceplate is decoupled from the top plate using a metal ring, then thermal stress is reduced, but the device complexity increases
Solution Approach 1:
The metal ring is a relatively simple intermediary component that provides significant thermal buffering. By using a single continuous metal ring rather than complex multi-component assemblies, the design achieves thermal stress reduction while minimizing the increase in device complexity.
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 design effectively reduces thermal stresses and prevents fractures in the ceramic faceplate at high temperatures, ensuring reliable operation up to 650 degrees Celsius by isolating the ceramic faceplate from thermal loads and improving cooling efficiency.
Implementation Method 1
providing a thermal break and reducing temperature gradients
Implementation Method 2
the ceramic faceplate directly contacts a metallic top plate with a different coefficient of thermal expansion
Data Source
AI summary
A showerhead for a processing chamber comprises a metal plate attached to the processing chamber. a ceramic faceplate attached to the metal plate and including a plurality of gas outlets on a substrate-facing surface. and a metal ring surrounding the ceramic faceplate and attached to the processing chamber.