Electrostatic Chuck Step Surface Adsorption Force
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Solution Overview
Problem
Conventional electrostatic chucks with protruding surface parts for supporting objects, such as wafers or glass substrates, often have electrode and Johnson-Rahbek force components that are too far apart, leading to a deterioration in adsorption force and increased contamination due to particles.
Innovation Solution
An electrostatic chuck design featuring a base body with a protruding surface part having a step surface between the top and bottom surfaces, which enhances adsorption force while maintaining a small contact area to reduce contamination, utilizing a conductive film to manage particle fall and electric charge distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the protruding surface part is disposed to reduce contact area with the object, then contamination of the object due to particles is reduced, but the adsorption force of the electrostatic chuck deteriorates
Solution Approach 1:
The protruding surface part is divided into multiple functional surfaces: a first top surface for supporting the object with minimal contact area, and a second top surface positioned at a lower level to generate adsorption force. This segmentation allows the support function and adsorption function to be separated spatialally, resolving the contradiction between reducing contamination and maintaining adsorption force.
Solution Approach 2:
The invention introduces a vertical dimension hierarchy with the first top surface at a higher level and the second top surface at a lower level. This multi-level arrangement enables the object to be supported by the elevated first top surface while the lower second top surface provides adsorption force, effectively decoupling the two functions in the vertical dimension.
2Object-affected harmful factors
If the electrode and bottom surface are disposed far from the object to reduce contamination, then particle attachment is reduced, but the adsorption force becomes weaker
Solution Approach 1:
The base body surface is segmented into multiple levels: the first top surface elevated for minimal contact and the second top surface lowered for strong adsorption. This segmentation allows the electrode to be positioned closer to the object through the second top surface, maintaining strong adsorption force while the elevated first top surface minimizes particle attachment risk.
Solution Approach 2:
The second top surface acts as an intermediary structure that enables the electrode to generate strong adsorption force near the object without requiring the entire base body surface to be close to the object. This intermediary allows localized proximity for adsorption while maintaining overall distance for contamination reduction.
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 electrostatic chuck achieves a strong adsorption force with reduced contamination and improved processing accuracy by leveraging the step surface's proximity to the object, minimizing particle contact and allowing precise temperature control.
Implementation Method 1
an electrode (6) that generates a Coulomb's force
Implementation Method 2
the bottom surface of the first surface on which a Johnson-Rahbek force occurs
Data Source
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AI summary
An electrostatic chuck according to an embodiment is an electrostatic chuck for adsorbing an object. The electrostatic chuck includes a base body having a first surface that includes a bottom surface and a protruding surface part protruding from the bottom surface. The protruding surface part has a first top surface and a step surface disposed between the first top surface and the bottom surface.