Electrostatic Chuck with Peripheral Leads and Composite Structure
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Solution Overview
Problem
Conventional electrostatic chucks (ESCs) face issues with mechanical integrity due to thermal expansion mismatch between ceramic and metal components, leading to cracking and contamination, and the need for frequent replacements, especially when exposed to high-temperature plasma processes.
Innovation Solution
The design incorporates a substantially rigid support layer with interleaved electrodes and a dielectric layer, eliminating the need for holes by forming leads on the peripheral surface, reducing stress initiation points and improving thermal conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic ESC is used to improve corrosion resistance and maintain structural integrity at high temperatures, then resistance to corrosive species and thermal stability is improved, but thermal expansion mismatch between ceramic and metal pedestal causes mechanical stress and cracking
Solution Approach 1:
The patent employs a composite structure consisting of a ceramic ESC layer bonded to a metal pedestal. The ceramic layer provides corrosion resistance and thermal stability, while the metal pedestal provides mechanical strength and thermal conductivity. This composite approach allows each material to contribute its advantageous properties while mitigating the weaknesses of individual materials.
Solution Approach 2:
The patent addresses thermal expansion mismatch by designing the ceramic-metal interface to accommodate differential expansion. The bonding structure and geometry are configured to manage the thermal stresses that arise during heating and cooling cycles, preventing crack initiation and propagation at the interface.
2Reliability
If multiple holes are formed through ceramic ESC for electrode coupling, then electrical connectivity is improved, but mechanical integrity deteriorates due to stress concentration and cracking at hole locations
Solution Approach 1:
The patent transitions from forming holes through the ceramic ESC to a planar electrode configuration where electrodes are deposited on the surface of the ceramic. This dimensional change eliminates through-holes that create stress concentration points, while still achieving the necessary electrical connectivity through surface-mounted electrode structures.
Solution Approach 2:
The patent extracts the electrode structure from the bulk ceramic material and places it on the surface. Instead of creating holes through the ceramic to pass electrodes, the electrodes are applied as surface layers, removing the problematic holes that compromise mechanical integrity while maintaining electrical functionality.
3Reliability
If conventional supports with integrated ESC are used, then substrate holding capability is improved, but frequent replacement is needed due to cracking and particle generation
Solution Approach 1:
The composite ceramic-metal structure provides both the electrostatic holding capability and the mechanical robustness needed for long service life. The ceramic layer maintains electrostatic properties for substrate holding, while the metal pedestal provides structural support and resistance to thermal-mechanical stress, reducing cracking and particle generation.
Solution Approach 2:
The patent converts the potential harm of thermal expansion mismatch into a benefit by designing the interface to accommodate the differential expansion. The metal pedestal's high thermal conductivity benefits the ceramic ESC by providing efficient heat dissipation, preventing thermal runaway and extending service life.
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
This configuration enhances the mechanical integrity and reduces the likelihood of cracking, while maintaining effective electrostatic coupling and heat transfer, thereby minimizing substrate contamination and the need for frequent replacements.
Implementation Method 1
The support can include an ESC that has an electrode capable of being electrically biased to hold the substrate on the support
Implementation Method 2
a dielectric layer having a top surface defining a top of the electrostatic chuck. The first electrode may be disposed between the top surface of the dielectric layer and the support layer
Implementation Method 3
a substantially rigid support layer having a bottom surface defining a bottom of the electrostatic chuck
Data Source
AI summary
Embodiments provided herein generally relate to an electrostatic chuck (ESC). The ESC may comprise a reduced number of stress initiation points, such as holes through the ESC, which may improve the mechanical integrity of the ESC. Electrodes disposed within the ESC may be connected to electrical contacts and a power source via conductive leads, which may be coupled or formed along a peripheral edge of the ESC. Thus, the need for holes formed in the ESC may be reduced or eliminated. In addition, gas channels may be formed on a top surface, a bottom surface, or both. The gas channels may reduce or eliminate the need for a gas channel formed through the ESC and may facilitate heat transfer between a substrate support, the ESC, and a substrate coupled to the ESC.