Electrostatic Chuck CTE Matching for Thermal Deflection
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Solution Overview
Problem
The mismatch of coefficients of thermal expansion between the dielectric layer and the backing plate in electrostatic chucks causes significant deformation during temperature changes, leading to potential leakage of backside gas and reduced wafer handling reliability in semiconductor processing.
Innovation Solution
Selecting materials for the electrostatic clamp with closely matched coefficients of thermal expansion between the ceramic and metal components, such as titanium and aluminum nitride, to minimize deflection across a predetermined temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If materials with different coefficients of thermal expansion are used for the dielectric layer and backing plate, then structural support and rigidity are provided, but significant deformation occurs during temperature changes
Solution Approach 1:
The patent applies parameter changes by carefully selecting materials with matched coefficients of thermal expansion. Specifically, the dielectric layer and backing plate are chosen to have similar CTE values, which minimizes differential thermal expansion and resulting surface deformation during temperature changes while maintaining the required structural support and rigidity.
Solution Approach 2:
The patent employs composite materials by bonding a dielectric layer to a backing plate to create an electrostatic chuck assembly. The composite structure combines the electrical insulation properties of the dielectric layer with the mechanical strength of the backing plate, while the materials are selected to have matched thermal expansion coefficients to prevent deformation.
2Force
If the electrostatic chuck surface deforms due to thermal expansion mismatch, then clamping capability is maintained, but leakage of backside gas occurs and wafer handling reliability reduces
Solution Approach 1:
The patent resolves this contradiction by changing the material selection parameters to match the coefficients of thermal expansion between the dielectric layer and backing plate. This parameter matching prevents surface deformation during temperature changes, thereby maintaining both clamping capability and preventing gas leakage, thus ensuring reliable wafer handling.
3Shape
If materials with closely matched coefficients of thermal expansion are selected, then thermal deformation is minimized, but material selection becomes more restrictive
Solution Approach 1:
The patent addresses this contradiction by establishing specific parameter ranges for material selection. By defining acceptable CTE matching criteria and selecting materials that fall within these ranges, the patent achieves minimal thermal deformation while maintaining reasonable material selection flexibility for manufacturing.
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 approach reduces thermal deformation and enhances the reliability of the electrostatic chuck by maintaining a flat surface, ensuring proper clamping and handling of semiconductor wafers during ion implantation and other semiconductor processes.
Implementation Method 1
the backing plate having a first coefficient of thermal expansion associated therewith... the clamping plate having a second coefficient of thermal expansion associated therewith... the first coefficient of thermal expansion and second coefficient of thermal expansion are substantially similar
Data Source
AI summary
An apparatus and method are provided for selecting materials for forming an electrostatic clamp. The electrostatic clamp has a backing plate having a first coefficient of thermal expansion, wherein the backing plate provides structural support and rigidity to the electrostatic clamp. The electrostatic clamp further has a clamping plate having a clamping surface associated with contact with a workpiece, wherein the clamping plate has a second coefficient of thermal expansion associated therewith. The clamping plate is bonded, attached or grown to the backing plate, wherein minimal deflection of the clamping plate is evident across a predetermined temperature range. The first coefficient of thermal expansion and second coefficient of thermal expansion, for example, are substantially similar, and vary by no greater than a factor of three.