Electrostatic Chuck Protrusion Geometry for Thermal Uniformity
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Solution Overview
Problem
In microelectronics production, electrostatic chucks face challenges in controlling temperature uniformity and reducing particulate contamination due to uneven loading of substrates on protrusions, leading to inconsistent heat transfer and manufacturing defects.
Innovation Solution
An electrostatic chuck with equally spaced protrusions across its surface, arranged in a trigonal pattern, that contact the substrate to distribute force evenly, reducing particle deposition and enhancing temperature control through gas heat conduction, while made from low-stress materials to minimize stress-induced particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If protrusions are used to enhance contact heat conduction, then heat transfer efficiency is improved, but substrate deformation and particle entrapment occur
Solution Approach 1:
The patent applies local quality by creating protrusions with specific geometric characteristics (spherical caps with controlled radius of curvature) at localized positions on the chuck surface. These protrusions provide enhanced contact heat conduction only where needed, while the spaces between them allow gas conduction in other regions, achieving spatially differentiated heat transfer modes that prevent substrate deformation.
Solution Approach 2:
The patent changes physical parameters by controlling the radius of curvature of protrusion surfaces to match or exceed the substrate's radius of curvature. This parameter matching ensures uniform contact pressure distribution across the protrusion- substrate interface, preventing localized stress concentrations that would cause substrate bowing or deformation.
2Temperature
If protrusions are used to improve heat transfer, then temperature control is enhanced, but particle contamination increases
Solution Approach 1:
The patent employs a porous-like structure with discrete protrusions separated by gaps, creating a distributed contact architecture. This structure reduces particle entrapment by eliminating large flat contact areas where particles could become trapped, while still providing sufficient contact points for effective heat transfer through a combination of contact conduction and gas conduction pathways.
3Temperature
If contact area between substrate and chuck is increased, then heat transfer is improved, but controlling heat transfer becomes difficult
Solution Approach 1:
The patent introduces dynamic controllability by making the protrusions compliant or adjustable, allowing the contact area and contact pressure to be dynamically modified. This enables real-time adjustment of heat transfer rates to match process requirements, transforming a static heat transfer system into a controllable dynamic system.
4Object-generated harmful factors
If protrusions are used to reduce contact area, then particle entrapment is reduced, but heat transfer efficiency decreases
Solution Approach 1:
The patent introduces gas conduction as an intermediary heat transfer mechanism that operates in the spaces between protrusions. This gas-mediated heat transfer pathway compensates for the reduced direct contact area, maintaining overall heat transfer efficiency while allowing the protrusion structure to minimize particle entrapment risks.
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 design achieves uniform temperature distribution, reduces particulate contamination, and improves manufacturing yield by ensuring consistent heat transfer and reduced substrate bowing, thereby minimizing defects.
Implementation Method 1
the back side of a substrate, such as a semiconductor wafer, is held to the face of the electrostatic chuck by an electrostatic force
Implementation Method 2
Heat delivered to the substrate during processing can be transferred away from the substrate and to the electrostatic chuck by contact heat conduction with the protrusions
Implementation Method 3
or by gas heat conduction with a cooling gas
Data Source
AI summary
In accordance with an embodiment of the invention, there is provided an electrostatic chuck comprising an electrode, and a surface layer activated by a voltage in the electrode to form an electric charge to electrostatically clamp a substrate to the electrostatic chuck. The surface layer includes a plurality of protrusions extending to a height above portions of the surface layer surrounding the protrusions to support the substrate upon the protrusions during electrostatic clamping of the substrate. The protrusions are substantially equally spaced across the surface layer as measured by a center to center distance between pairs of neighboring protrusions.