Electrostatic Substrate Holder Void Pressure Cleaning in EUV Lithography
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Solution Overview
Problem
In ultraviolet and extreme ultraviolet lithography, substrate holders face challenges in preventing contaminant accumulation, which can adversely affect the quality of the exposure process and patterning of semiconductor substrates, due to the complexity of maintaining a clean environment and the high precision required in substrate handling.
Innovation Solution
The substrate holder incorporates a self-cleaning feature with a plurality of burls and fluid passages that are in communication with a source of variable gas pressure, allowing for the removal of non-gaseous contaminants by adjusting pressure within the void between the substrate and the holder, thereby preventing contamination and ensuring consistent exposure performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a substrate holder is used in ultraviolet and extreme ultraviolet lithography, then the substrate can be held and moved for exposure processing, but contaminants accumulate on the substrate holder surface affecting exposure quality
Solution Approach 1:
The patent applies preliminary action by implementing a self-cleaning mechanism that proactively removes contaminants before they can adversely affect the substrate or exposure process. The cleaning system uses gas pressure to blow contaminants off the substrate holder surface into a vacuum environment, preventing contamination rather than addressing it after the fact.
Solution Approach 2:
The substrate holder incorporates a self-service cleaning capability where the holder itself generates the cleaning action through integrated gas passages and openings. By applying gas pressure through these passages, the system automatically cleans its own surface without requiring external manual intervention, thus maintaining exposure quality continuously.
2Reliability
If the substrate holder surface is kept clean to maintain exposure quality, then the complexity of the cleaning system increases
Solution Approach 1:
The substrate holder integrates multiple functions into a single component: it holds the substrate, positions it for exposure, and simultaneously performs self-cleaning through integrated gas passages and openings. This multi-functionality reduces the need for separate cleaning devices and simplifies the overall system architecture while maintaining exposure quality.
Solution Approach 2:
The patent employs pneumatic principles by using gas pressure to achieve the cleaning function. Gas is delivered through passages and openings in the substrate holder to blow contaminants away, providing an efficient and relatively simple mechanism for surface cleaning without requiring complex mechanical or chemical cleaning systems.
3Ease of operation
If gas pressure is applied to remove contaminants, then the substrate holder can be cleaned effectively, but the system requires additional components for gas delivery
Solution Approach 1:
The patent merges the gas delivery system with the substrate holder structure itself. The gas passages and openings are integrated directly into the holder, combining the cleaning function with the substrate positioning function. This integration reduces the number of separate components and simplifies the overall gas delivery system while maintaining effective cleaning capability.
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 solution effectively reduces contaminant accumulation on the substrate holder, maintaining the quality of the exposure process and ensuring consistent overlay performance by actively removing contaminants through controlled pressure adjustments, thus enhancing the reliability of the lithography system.
Implementation Method 1
adjusting pressure within the void between the substrate and the substrate holder surface causes non-gaseous materials within the void to be removed from the void by drawing them through the openings in the substrate holder
Data Source
AI summary
An electrostatic substrate holder for use in an extreme ultraviolet radiation lithography system includes a substrate receiving surface having a plurality of gas passages in fluid communication with a variable gas pressure pump. Varying the pressure in a void space between the backside of the substrate and the substrate receiving surface of the substrate holder promotes removal of non-gaseous materials within the void space between the backside of the substrate and the substrate receiving surface of the substrate holder.