Electrostatic Chuck Interface Layer for Thermal Fatigue Resistance
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Solution Overview
Problem
Existing electrostatic chucks experience mechanical fatigue and cracking due to high temperatures and temperature cycling, which is exacerbated by differences in thermal expansion coefficients of materials used in the chuck's components.
Innovation Solution
Incorporating an interface layer formed as a solid solution with the ceramic body, which includes specific metal compounds and additives, to mitigate mechanical fatigue and reduce volumetric expansion, along with methods of forming the chuck that involve sintering and coating heating elements and electrodes with these materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high temperatures and temperature cycling are applied during substrate processing, then substrate processing capability is improved, but mechanical fatigue and cracking of chuck components occur
Solution Approach 1:
An interface layer comprising a ceramic compound (such as magnesium aluminate spinel, MgAl2O4) is introduced between the heating element/electrode and the ceramic body. This intermediary layer acts as a buffer that reduces thermal stress transmission and prevents direct mechanical fatigue between components with different thermal expansion coefficients, thereby maintaining component integrity during high-temperature processing
Solution Approach 2:
The chuck is constructed as a composite structure with multiple materials: the ceramic body (e.g., aluminum nitride, silicon carbide), heating elements (e.g., molybdenum, tungsten), electrodes (e.g., molybdenum with gold or platinum coating), and the interface layer (ceramic compound). This composite design allows each material to be optimized for its specific function while the interface layer coordinates their thermal expansion differences, preventing cracking under temperature cycling
2Adaptability or versatility
If different materials with different coefficients of thermal expansion are used for body, electrodes, and heating elements, then functional performance is improved, but mechanical fatigue and cracking are exacerbated
Solution Approach 1:
The interface layer serves as a mediator between materials with different thermal expansion coefficients. It has intermediate expansion properties that bridge the gap between the ceramic body and metal components (heating elements/electrodes), reducing differential thermal stress and preventing fatigue cracking while allowing each material to maintain its functional properties
Solution Approach 2:
The interface layer's ceramic compound composition is specifically selected to have thermal expansion parameters that fall between those of the ceramic body and metal components. This parameter matching reduces thermal mismatch stress during temperature cycling, allowing the multi-material construction to maintain strength and resist fatigue
3Duration of action of stationary object
If an interface layer is added to mitigate mechanical fatigue, then chuck lifespan is improved, but device complexity increases
Solution Approach 1:
The interface layer can be formed with a porous or microstructured ceramic compound that provides mechanical compliance and stress distribution. This structure absorbs thermal expansion differences through controlled porosity while maintaining structural integrity, extending chuck lifespan without requiring complex multi-layer constructions
Solution Approach 2:
The interface layer is formed as a composite ceramic compound (such as magnesium aluminate spinel MgAl2O4) that combines the beneficial properties of multiple oxides. This single-phase composite material provides both mechanical fatigue resistance and thermal management in one layer, extending lifespan without proportionally increasing structural 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 interface layer reduces the likelihood of cracks and extends the lifespan of the electrostatic chuck by minimizing volumetric expansion, allowing for more reliable operation under high temperature conditions.
Implementation Method 1
an interface layer formed overlying the heating element and/or the one or more electrodes, and/or between the ceramic body and the dielectric layer, wherein the interface layer forms a solid solution with the ceramic body
Implementation Method 2
a heating element or a plurality of heating elements embedded within the body
Implementation Method 3
one or more electrodes (e.g., an electrostatic and an RF electrode) embedded in the body
Data Source
AI summary
Electrostatic chucks and methods of forming electrostatic chucks are disclosed. Exemplary electrostatic chucks include a ceramic body, a device embedded within the ceramic body, and an interface layer formed overlying the device. Exemplary methods include providing ceramic precursor material within a mold, providing a device, coating the device with an interface material to form a coated device, placing the coated device on or within the ceramic precursor material, and sintering the ceramic precursor material to form the electrostatic chuck and an interface layer between the device and ceramic material formed during the step of sintering.