Electrostatic Chuck with Carbon Nanotube Clamping Surface
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Solution Overview
Problem
Electrostatic chucks used in integrated circuit fabrication often contaminate and warp substrates due to hard clamping surfaces and erode with soft surfaces, leading to electrostatic discharges and damage, while conventional materials used in clamping surfaces acquire charges and discharge, causing further issues.
Innovation Solution
An electrostatic chuck with a clamping surface made of a hard polymeric material filled with carbon nanotubes, which provides resiliency and reduces erosion and contamination, along with electrodes for inducing localized charges and a dielectric layer for electrical isolation, maintaining the substrate at a desired potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hard clamping surface is used, then the chuck can retain the substrate effectively, but the substrate becomes contaminated and warped
Solution Approach 1:
The clamping surface uses a composite structure combining a hard underlying layer for structural support and a soft compliant coating layer for substrate contact. This composite material approach allows the hard surface to provide retention force while the soft coating prevents contamination and warping by conforming to the substrate topography.
2Object-affected harmful factors
If a soft clamping surface is used, then the substrate is protected from warping, but the clamping surface erodes through repeated use
Solution Approach 1:
The composite structure with a hard underlying layer and soft compliant coating allows the hard layer to bear the mechanical stress and erosion from repeated use, while the soft coating protects the substrate. This division of functional roles resolves the contradiction between substrate protection and surface durability.
3Ease of manufacture
If conventional polymeric materials are used in the clamping surface, then the chuck can be manufactured easily, but electrostatic discharges occur causing contamination and damage
Solution Approach 1:
The polymer material is modified by changing its electrical conductivity parameter through the addition of conductive fillers such as carbon black or metal particles. This parameter change allows the material to dissipate electrostatic charges effectively while maintaining the manufacturing advantages of polymeric materials.
Solution Approach 2:
The polymer is combined with conductive fillers to create a composite material that maintains the ease of manufacture and structural properties of the polymer while adding charge dissipation capability. This composite approach resolves the contradiction between manufacturability and electrostatic discharge prevention.
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 carbon nanotube-filled clamping surface reduces substrate damage, minimizes particulate generation, and allows for effective charge dissipation, maintaining surface quality and integrity, suitable for high vacuum environments and sensitive substrates.
Implementation Method 1
The carbon nanotubes provide a resiliency to the clamping surface that reduces erosion of the clamping surface and damage to the backside of the substrate
Implementation Method 2
Electrodes are disposed beneath the clamping surface, for inducing localized electrostatic charges in the substrate and thereby retaining the substrate against the clamping surface
Implementation Method 3
the carbon nanotubes provide an electrically conductive path from a face of the clamping surface that receives the substrate to an opposing face of the clamping surface
Data Source
AI summary
An electrostatic chuck for retaining a substrate. The chuck has a clamping surface for receiving the substrate, where the clamping surface is formed of a hard polymeric material filled with carbon nanotubes. Electrodes are disposed beneath the clamping surface, for inducing localized electrostatic charges in the substrate and thereby retaining the substrate against the clamping surface. A base supports the clamping surface and the electrodes.