Electrostatic Clamp Burl Stack for Selective Refurbishment
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Solution Overview
Problem
Existing electrostatic clamps in EUV lithographic apparatuses face issues with protrusions becoming smooth over time, leading to wafer sticking and damage, necessitating costly and time-consuming refurbishment through etching and redeposition of metallic structures.
Innovation Solution
A clamp design featuring a stack of alternating layers of etch-resistant material and conductive material for burls, allowing selective removal and refurbishment of only the top parts, reducing the need for complete structure replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clamp uses conventional electrostatic design with metallic lines connecting burls, then the clamp can hold the substrate, but the protrusions become sticky over time requiring full refurbishment
Solution Approach 1:
The clamp structure is segmented into distinct functional layers: a dielectric member, conductive elements (Manhattan lines), burls (protrusions), and an etch-resistant layer. This segmentation allows selective refurbishment of only the burl components without affecting the underlying conductive elements or dielectric member, reducing refurbishment time and complexity
Solution Approach 2:
An etch-resistant layer is applied in advance to the conductive elements and Manhattan lines before the burls are subjected to wear. This preliminary protective action ensures that during subsequent refurbishment processes, only the burls need to be removed and redeposited, while the underlying structure remains intact and protected
2Measurement precision
If the clamp operates under near vacuum conditions for EUV lithography, then precise positioning is achieved, but the metallic conductive material wears down requiring costly refurbishment
Solution Approach 1:
The burls are designed as consumable components that can be easily removed and redeposited during refurbishment. By making the burls replaceable rather than permanent, the system allows for cost-effective maintenance where only the worn protrusions are replaced, not the entire expensive conductive structure
Solution Approach 2:
The clamp employs a composite structure combining different materials with specific properties: dielectric material for insulation, conductive material for electrical connection, and etch-resistant material for protection. This composite design allows each layer to perform its specific function while protecting the more valuable underlying layers
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
Facilitates faster and cheaper refurbishment of electrostatic clamps by enabling selective removal and redeposition of damaged surfaces, maintaining the clamp's functionality without extensive reassembly.
Implementation Method 1
Electrostatic clamps may be particularly suited to operating at EUV wavelengths
Data Source
AI summary
The disclosure provides a clamp comprising a dielectric member; a conductive element disposed on the dielectric member and comprised of a first conductive material; and a number of burls arranged on the conductive element for supporting the object, each burl comprising a second conductive material, wherein the clamp comprises a stack of alternating layers of etch resistant material and a third conductive material arranged between the conductive element and the number of burls.