EUV Optical Element Stage Load Cancellation Under Pressure Differential
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Solution Overview
Problem
Existing EUV light generation systems face challenges in maintaining accurate stage mechanism operation under hydrogen atmosphere, leading to high manufacturing costs and potential damage due to pressure differentials between atmospheric and reduced pressure environments.
Innovation Solution
Incorporation of a cancellation mechanism that balances loads applied to the stage mechanism due to pressure differences by using a movable cover member and opposing load transmission, allowing for the use of less expensive and compact stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a stage mechanism is placed inside the chamber to operate optical elements under reduced pressure, then the optical elements can be precisely positioned and oriented, but the stage mechanism is exposed to harmful pressure differentials that cause potential damage and require expensive protective designs
Solution Approach 1:
The system is divided into two separate chambers: a first chamber maintaining reduced pressure for EUV light generation, and a second chamber at atmospheric pressure for housing the stage mechanism. The optical element is transferred between these chambers via a transfer chamber, allowing precise positioning to occur in a protected atmospheric environment while maintaining the vacuum environment needed for EUV operations.
Solution Approach 2:
A transfer chamber acts as an intermediary between the reduced pressure chamber and atmospheric pressure chamber. This intermediate space allows the optical element to be moved from the vacuum environment to the atmospheric environment where the stage mechanism operates, protecting the stage from pressure differentials while maintaining access to the EUV light source.
2Reliability
If a robust protection mechanism is added to protect the stage mechanism from pressure differentials, then the stage can operate reliably under reduced pressure, but the device complexity and manufacturing cost increase significantly
Solution Approach 1:
Instead of protecting a single stage mechanism with complex seals and pressure equalization systems, the system segments the environment entirely - placing the stage mechanism in a separate atmospheric pressure chamber. This eliminates the need for complex pressure protection mechanisms while maintaining reliability through environmental separation.
Solution Approach 2:
The stage mechanism is extracted from the reduced pressure chamber and placed in a separate atmospheric pressure chamber. This extraction removes the stage mechanism from the harmful pressure differential environment, eliminating the need for complex protective measures while maintaining the integrity of both systems.
3Ease of manufacture
If a compact and cost-effective stage mechanism is used, then manufacturing costs are reduced, but the stage cannot withstand the pressure differentials present in reduced pressure environments
Solution Approach 1:
The system separates the stage mechanism from the reduced pressure environment, allowing the use of simple, cost-effective stage designs that would be vulnerable to pressure differentials. By operating the stage in an atmospheric pressure chamber, standard manufacturing techniques can be used without requiring specialized pressure-resistant materials or designs.
Solution Approach 2:
The transfer chamber serves as an intermediary that enables the optical element to move between the reduced pressure chamber and atmospheric pressure chamber. This allows a simple, cost-effective stage mechanism to be used in the atmospheric chamber while still enabling access to the EUV light source in the vacuum chamber through the transfer mechanism.
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
Enables the use of cost-effective and compact stage mechanisms by canceling out loads from pressure differentials, maintaining operational accuracy and reducing potential damage.
Implementation Method 1
a cancellation mechanism which is arranged at a position facing the first cover member via the holder, connected to the holder to be movable in accordance with change of at least either the position or the angle of the optical element, and transmits, to the holder, a second load in a direction opposite to a direction of a first load applied to the first cover member due to pressure difference between atmospheric pressure and pressure inside the chamber
Data Source
AI summary
An EUV light generation apparatus includes a chamber having internal pressure maintained below atmospheric pressure; a first bellows pipe having one end connected to the chamber; a first cover member which seals the other end under atmospheric pressure; a holder connected to the first cover member and arranged inside the chamber in a state of holding an optical element; a stage mechanism connected to the first cover member outside the chamber and configured to change at least either a position or an angle of the optical element with respect to the EUV light; a fixing member which fixes the stage mechanism to the chamber; and a cancellation mechanism which is connected to the holder to be movable in accordance with change of at least either the position or the angle, and transmits, to the holder, a second load opposite to a first load applied to the first cover member.