EUV Lithography Temperature Control Device for Substrate Stability
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Solution Overview
Problem
In lithographic apparatuses, uncontrolled substrate temperature changes due to purge gas heat load cause thermal deformations, affecting pattern accuracy during EUV lithography.
Innovation Solution
A temperature control device with both heating and cooling means is integrated between the projection system and substrate table, allowing for net cooling of the gas flow to maintain stable substrate temperature, comprising resistive heating elements and heat-pipe cooling systems, with a control system adjusting operations based on metrology and infrared reflectivity measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If purge gas is used to prevent contamination, then substrate protection from contaminants is improved, but substrate temperature stability deteriorates due to net positive heat load
Solution Approach 1:
A temperature control device is introduced as an intermediary between the purge gas flow and the substrate. This device actively controls the gas temperature to prevent excessive heating of the substrate while maintaining the purge gas flow for contamination protection. The intermediary device balances the conflicting requirements of contamination prevention and temperature stability.
Solution Approach 2:
The temperature of the purge gas is actively controlled and adjusted as a parameter. By changing the gas temperature parameter through heating or cooling means in the temperature control device, the system prevents the gas from introducing excessive heat to the substrate while maintaining flow for contamination protection.
2Object-affected harmful factors
If gas flow is increased to improve contamination prevention, then substrate protection is improved, but thermal deformation increases due to greater heat load
Solution Approach 1:
The temperature control device serves as an intermediary that decouples the relationship between gas flow rate and substrate heating. It allows high gas flow rates for contamination protection while actively controlling the gas temperature to prevent thermal deformation and maintain pattern accuracy.
Solution Approach 2:
The system independently controls both gas flow rate and gas temperature as separate parameters. This allows optimization of gas flow for contamination protection while simultaneously adjusting gas temperature to prevent thermal deformation, resolving the contradiction between contamination protection and manufacturing precision.
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 controls substrate temperature, reducing thermal deformations and enhancing pattern overlay accuracy by providing a net cooling effect that compensates for heat loads from purge gases and radiation, thereby improving the precision of EUV lithography.
Implementation Method 1
comprising both heating and cooling means, such as resistive heating elements and heat-pipe cooling systems
Implementation Method 2
heat-pipe cooling systems
Implementation Method 3
resistive heating elements
Implementation Method 4
a purge gas that is used to prevent contaminants, originating from the exposed resist and/or wafer stage compartment
Data Source
AI summary
A lithographic apparatus includes a substrate table constructed to hold a substrate, a projection system configured to project a patterned radiation beam through an opening and onto a target portion of the substrate, and a conduit having an outlet in the opening. The conduit is configured to deliver gas to the opening. The lithographic apparatus includes a temperature control apparatus disposed in a space between the projection system and the substrate table. The temperature control device is configured to control the temperature of the gas in the space after the gas passes through the opening.