Hydrocarbon Getter for EUV Lithography Tools
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Solution Overview
Problem
EUV lithography exposure tools face contamination issues due to residual gases, leading to carbon deposition and oxidation of reflective optical elements, which reduces reflectivity and requires frequent cleaning, thereby decreasing manufacturing throughput.
Innovation Solution
Incorporating a hydrocarbon getter with a high-energy source, such as an electron gun, to crack hydrocarbons and control their partial pressure within a specific range, preventing oxidation and carbon deposition on reflective optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If EUV lithography exposure tools operate with reflective optical elements in vacuum atmosphere, then high manufacturing throughput and precision can be achieved, but carbon deposition and oxidation occur on the optical elements due to residual gases
Solution Approach 1:
The patent extracts and removes hydrocarbon molecules from the vacuum atmosphere using a gettering system with ion pump and cryogenic traps, preventing them from depositing on optical elements. This extraction approach eliminates the harmful carbon deposition while maintaining the vacuum environment necessary for high-precision EUV lithography.
Solution Approach 2:
The patent introduces a gettering system as an intermediary between the residual gases and the optical elements. This intermediary system captures hydrocarbon molecules through ion pumping and cryogenic trapping, preventing direct contact between contaminants and the optical surfaces, thus protecting reflectivity without compromising the vacuum atmosphere.
2Reliability
If hydrocarbon levels are reduced to prevent carbon deposition, then optical element reflectivity is maintained, but oxidation protection is compromised
Solution Approach 1:
The patent carefully controls and adjusts the partial pressure of hydrocarbons to an optimal range (10^-9 to 10^-7 mbar). This parameter optimization ensures sufficient hydrocarbons for oxidation protection while preventing excessive carbon deposition, achieving a balance between protecting optical elements from both oxidation and carbon contamination.
Solution Approach 2:
The patent maintains a controlled inert vacuum atmosphere with specific hydrocarbon partial pressures. This controlled inert environment provides just enough hydrocarbon molecules to protect against oxidation while preventing the formation of excessive carbon deposits, creating a protective atmosphere that balances both harmful effects.
3Reliability
If cleaning operations are performed frequently to remove carbon deposits, then optical element performance is restored, but manufacturing downtime increases
Solution Approach 1:
The patent implements preliminary gettering action during idle periods and between production runs. The ion pump and cryogenic traps continuously or periodically remove hydrocarbons before they can deposit on optical elements, preventing carbon buildup that would require cleaning operations and resulting downtime.
Solution Approach 2:
The patent maintains continuous gettering operation through the ion pump and cryogenic trapping system, constantly removing hydrocarbon molecules from the vacuum atmosphere. This continuous protective action prevents carbon deposition throughout production, eliminating the need for intermittent cleaning operations and maintaining uninterrupted manufacturing throughput.
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 approach significantly reduces downtime and increases manufacturing throughput by maintaining the reflectivity of optical elements and extending their lifespan by minimizing carbon contamination.
Implementation Method 1
a high energy source positioned to impinge a beam having an energy sufficient to crack hydrocarbons
Implementation Method 2
crack hydrocarbons and form a carbon film thereon
Data Source
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AI summary
Carbon contamination of optical elements in an exposure tool is minimized by incorporating a hydrocarbon getter. Embodiments include EUV lithography tools provided with at least one hydrocarbon getter comprising a substrate (10,11) and a high energy source, such as an electron gun or separate EUV source, positioned to direct an energy beam, having sufficient energy to crack heavy hydrocarbons and form carbon, on the substrate (10,11). Embodiments also include exposure tools equipped with a hydrocarbon getter comprising an energy source positioned to impinge a beam of energy on a quartz crystal thickness monitor (10,11), a residual gas analyzer, and a controller to control the electron-current and maintain the amount of hydrocarbons in the system at a predetermined low level.