Electrostatic Chuck Pins for Irregular Glass Flatness
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Solution Overview
Problem
Conventional electrostatic chucks struggle to effectively clamp two-dimensional and three-dimensional glass substrates with localized surface flatness variations beyond 10 µm, as they require a flat substrate surface for optimal contact and clamping, which is not suitable for substrates with irregularities up to 25 µm or more.
Innovation Solution
An electrostatic chuck apparatus featuring a matrix of small, adjustable pogo-like elements with bipolar electrostatic chucks that can individually move to conform to the surface contours of the glass substrate, providing a robust clamping force despite surface irregularities, and is designed to withstand high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional electrostatic chucks are used to clamp glass substrates, then clamping force is provided, but substrates with localized surface flatness variations beyond 10 µm cannot be effectively clamped
Solution Approach 1:
The electrostatic chuck is segmented into multiple independently movable segments or elements that can individually adjust to local surface variations. Each segment can move vertically to conform to the specific flatness characteristics of different regions on the substrate surface, enabling effective clamping of substrates with localized irregularities up to 25 µm or more while maintaining reliable electrostatic contact across the entire substrate area.
Solution Approach 2:
The electrostatic chuck employs dynamically adjustable elements that can change their position in response to detected surface variations. The chucking elements are designed to move vertically along guide surfaces, allowing the system to adapt its configuration in real-time to match the substrate's local flatness profile, thereby maintaining effective clamping force across irregular surfaces.
2Adaptability or versatility
If a rigid electrostatic chuck surface is used, then manufacturing precision is maintained, but contact with irregular substrate surfaces is lost
Solution Approach 1:
The chuck surface is divided into multiple discrete, independently movable elements rather than a single rigid surface. Each element can adjust its height to make contact with irregular substrate surfaces while the overall chuck structure remains relatively simple and manufacturable. This segmentation allows the system to gain adaptability without proportionally increasing overall device complexity.
Solution Approach 2:
The electrostatic chuck incorporates flexible or compliant elements that can deform or move to conform to irregular substrate surfaces. These flexible chucking elements maintain electrical contact through elastic deformation or vertical movement, providing surface adaptability while using simple, manufacturable components rather than complex rigid mechanisms.
3Force
If high voltage is applied to create electrostatic field, then clamping force is generated, but substrates with surface irregularities experience poor field distribution
Solution Approach 1:
The electrostatic field generation is segmented into multiple independent electrode elements corresponding to the movable chuck segments. Each electrode element generates a localized electrostatic field that acts on the substrate area directly above it. This segmentation ensures that even if the substrate surface is irregular, each local electrostatic field maintains proper distribution and strength at its specific location, providing uniform clamping force across the entire substrate despite surface variations.
Solution Approach 2:
The electrostatic chuck system provides locally optimized field distribution by having each electrode element independently generate fields tailored to its local substrate conditions. The movable segments ensure that each local electrostatic field is positioned at the optimal distance from the substrate surface, maintaining field uniformity and effective clamping force across regions with different local flatness characteristics.
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 apparatus securely clamps glass substrates with localized surface flatness variations up to 100 µm, maintaining contact and providing a sufficient clamping force, even at elevated temperatures, thus enabling efficient coating processes for both 2D and 3D substrates.
Implementation Method 1
ESC is a technology in which a static electric field with planar field lines (produced from a high voltage potential) is applied to parallel electrodes separated by a dielectric and induces molecular dipoles in a substrate. These molecular dipoles align themselves with the externally-applied electric field and are thus attracted cumulatively to the field lines from the electrodes.
Implementation Method 2
When a substrate, such as a glass sheet, is placed on the chuck the field lines between the electrodes also pass through the glass causing charge separation in the glass and attraction of the glass to the electrodes embedded in the chuck.
Implementation Method 3
A plurality of electrostatic chuck pins extend through at least a portion of the plurality of the apertures and are resiliently mounted to the chassis such that the extent to which the electrostatic chuck pins extend through the chassis is individually variable
Data Source
Figure 1
Figure 2A~3A
Figure 3
AI summary
An electrostatic chuck apparatus for chucking glass includes a substantially rigid chassis with a plurality of apertures extending from one side of the chassis to another side of the chassis. A plurality of electrostatic chuck pins extend through the openings and are resiliently mounted to the chassis such that the extent to which the electrostatic chuck pins extend through the chassis is individually variable. With this construction, the electrostatic chuck pins maintaining contact with the surface of the glass despite the presence of some variation in the localized surface flatness of the glass.