Electrostatic Clamp Trench Layout to Suppress Field Emission
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Solution Overview
Problem
Electrostatic clamps in lithographic apparatuses experience non-uniform charge distribution leading to potential deformation of components and substrates due to field emission from conductive elements, which is difficult to address without disrupting the vacuum environment.
Innovation Solution
The electrostatic clamp design incorporates conductive elements recessed within trenches on a dielectric member, preventing field amplification at triple-point junctions and reducing electron emission by embedding these elements with dielectric or insulating material, ensuring stable clamping forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive elements are exposed on the surface of the dielectric member, then electrical connectivity between burls is achieved, but field emission occurs causing non-uniform charge distribution and component deformation
Solution Approach 1:
The harmful triple-point junctions are extracted and removed from the system by recessing conductive elements into trenches, eliminating the source of field emission while preserving the electrical connectivity function between burls
Solution Approach 2:
The conductive element is nested within the trench structure, with the trench walls providing dielectric containment around the conductive element, effectively shielding the triple-point junctions from the vacuum environment and preventing electron emission
2Object-affected harmful factors
If the clamp is removed from vacuum for cleaning to remove accumulated charge, then static charge is removed, but production time is lost and vacuum integrity is disrupted
Solution Approach 1:
The design converts the potential harm of charge accumulation into a beneficial self-discharging mechanism by allowing controlled electron emission through the recessed structure, eliminating the need for external cleaning operations and maintaining continuous production
Solution Approach 2:
The clamp structure performs self-discharging of accumulated static charge through the trench geometry, which allows controlled electron emission to neutralize charge buildup without requiring external intervention or removal from the vacuum environment
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 effectively mitigates cycle-induced charging and field emission, maintaining clamping stability and precision without the need for disruptive in-line discharging or surface treatment, enhancing production efficiency and component integrity.
Implementation Method 1
an electrostatic clamp for holding an object by electrostatic force
Implementation Method 2
Such non-uniformly distributed accumulated charge may have detrimental effects on the general operation of the lithographic apparatus
Data Source
AI summary
An electrostatic clamp for holding an object by electrostatic force is disclosed. The electrostatic clamp comprises a dielectric member having a plurality of conductive burls extending from a surface to define a plane in which the object is held, and a conductive element extending between and connecting the plurality of burls. The conductive element is disposed within one or more trenches formed on the surface of the dielectric member. Also disclosed is a method of manufacturing the electrostatic clamp.