Segmented Gas Distribution Plate for High-Power Plasma Processes
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Solution Overview
Problem
Substrate processing systems face challenges with window breakage due to high thermal gradients and the limited material options that are RF-transparent, non-eroding, and cost-effective, particularly in transformer coupled plasma (TCP) processes where materials like oxide ceramics and quartz are prone to failure.
Innovation Solution
A radially and circumferentially segmented gas distribution plate made of RF-transparent materials like alumina or aluminum nitride, with interlocking ring segments and expansion gaps to manage thermal stress, providing a durable and cost-effective solution for high-temperature and high-power applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If oxide ceramics are used for the window, then thermal insulation properties are improved, but thermal shock resistance deteriorates due to high coefficients of thermal expansion
Solution Approach 1:
The gas distribution plate is divided into multiple radially arranged segments that can expand and contract independently. This segmentation allows each segment to accommodate thermal expansion without generating excessive stress, thereby maintaining thermal insulation properties while improving thermal shock resistance.
Solution Approach 2:
The gas distribution plate utilizes composite material construction combining oxide ceramics with metallic components or different ceramic materials. This composite structure leverages the thermal insulation properties of ceramics while incorporating materials with lower thermal expansion coefficients to reduce thermal stress and prevent catastrophic breakage.
2Stability of the object's composition
If quartz is used for the window, then dimensional stability is improved due to low coefficient of thermal expansion, but erosion resistance deteriorates in halogen-based etch chemistries
Solution Approach 1:
The gas distribution plate employs composite material construction where quartz or quartz-like materials are combined with erosion-resistant coatings or paired with halogen-resistant materials such as tungsten or molybdenum. This composite approach preserves the low thermal expansion and dimensional stability of quartz while adding protection against halogen-based etch chemistry erosion.
3Reliability
If aluminum nitride is used for the window, then thermal conductivity and thermal shock resistance are improved, but cost increases significantly and large diameter blanks are difficult to obtain
Solution Approach 1:
The gas distribution plate is segmented into multiple smaller components that can be manufactured individually using more cost-effective materials and processes. These segments are then assembled into a complete plate, achieving the thermal management performance of aluminum nitride without requiring expensive large-diameter single-crystal blanks.
Solution Approach 2:
Aluminum nitride or high-performance thermal conductive materials are applied locally only in regions requiring superior thermal shock resistance, such as areas near the plasma source or high-heat zones. Other regions use more cost-effective materials, optimizing the balance between performance and manufacturing cost.
4Device complexity
If a monolithic gas distribution plate is used, then structural simplicity is improved, but stress concentration increases under thermal gradients leading to breakage
Solution Approach 1:
The gas distribution plate is divided into multiple radially arranged segments that are mechanically connected but thermally independent. This segmentation allows each segment to expand and contract independently under thermal gradients, eliminating stress concentration points and preventing catastrophic breakage while maintaining a relatively simple overall structure.
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 segmented gas distribution plate effectively reduces stress and prevents breakage by diverting thermal energy, offering improved durability and cost-effectiveness compared to traditional materials, while maintaining RF transparency and preventing erosion.
Implementation Method 1
A radially and circumferentially segmented gas distribution plate made of RF-transparent materials like alumina or aluminum nitride, with interlocking ring segments and expansion gaps to manage thermal stress
Implementation Method 2
The window should be made of an inert, RF-transparent material having low dielectric loss properties
Data Source
AI summary
A gas distribution plate for a substrate processing system includes an outer ring including a stepped interface on a radially inner surface thereof and N inner rings, where N is an integer greater than zero. At least one of the N inner rings is circumferentially segmented and includes an inner stepped interface and an outer stepped interface. An outer stepped interface of a radially outer one of the N inner rings is configured to rest on and mate with the inner stepped interface of the outer ring. A center portion includes an outer stepped interface on a radially outer surface thereof that is configured to rest on and mate with an inner stepped interface of a radially inner one of the N inner rings.