EUV Exposure Apparatus Wavelength-Specific Light Detection
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Solution Overview
Problem
Existing exposure apparatuses for Extreme UltraViolet Lithography (EUVL) face challenges in accurately monitoring and adjusting for fluctuations in the optical system characteristics due to the unique properties of EUV light sources and multilayer film reflecting mirrors, which complicates the estimation of light fluctuations.
Innovation Solution
The exposure apparatus includes detectors for both exposure and non-exposure wavelength components of light, allowing for independent measurement and adjustment of the projection optical system, including mirror positions and attitudes, to accurately account for irradiation heat effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor-based adjustment system is applied to EUVL exposure apparatus, then the system can monitor light fluctuations, but it cannot accurately estimate the amount of fluctuation in projection optical system characteristics due to the unique properties of EUV light sources and multilayer film reflecting mirrors
Solution Approach 1:
The patent introduces a model-based estimation system that acts as an intermediary between the sensor measurements and the actual optical system characteristics. The model calculates the relationship between light quantity fluctuations and optical system characteristic changes, enabling accurate estimation of mirror deformation and other characteristic variations that cannot be directly measured by sensors alone.
Solution Approach 2:
The patent changes the approach from direct measurement to model-based parameter estimation. By using a computational model that relates light quantity fluctuations to optical system characteristic changes, the system can estimate parameters like mirror deformation amounts that are difficult to measure directly, thereby resolving the information loss problem.
2Measurement precision
If multiple detectors are used to independently detect exposure and non-exposure wavelength components, then the measurement capability is improved, but the device complexity increases
Solution Approach 1:
The patent segments the detection function by using separate detectors for exposure wavelength and non-exposure wavelength components. This segmentation allows each detector to be optimized for its specific wavelength range, improving measurement precision while keeping the overall system manageable through functional division.
Solution Approach 2:
The patent makes the detector system multi-functional by having detectors that can serve dual purposes: monitoring both exposure and non-exposure wavelength components, and providing data for both direct measurement and model-based estimation of optical system characteristics. This universality reduces the need for entirely separate detection systems.
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 enables precise adjustment of the projection optical system, ensuring accurate image formation characteristics and maintaining system performance despite fluctuations in light quantities and heat absorption, thereby improving the operational reliability of EUVL exposure apparatuses.
Implementation Method 1
a detector that detects the quantity of light of the non-exposure wavelength component of the light
Implementation Method 2
a special mirror for reflecting EUV light (multilayer film reflecting mirror) is used
Implementation Method 3
fluctuations in the characteristics of the optical system resulting from the irradiation heat of light
Data Source
AI summary
An exposure apparatus that exposes an object to be exposed with light from an EUV light source. The light has an exposure wavelength component and a non-exposure wavelength component. The exposure apparatus has a detector that independently detects the quantity of light of the exposure wavelength component and the quantity of light of the non-exposure wavelength component of the light. Therefore, for example, even if the quantity of light of the exposure wavelength component and the quantity of light of the non-exposure wavelength component individually fluctuate, it is possible to accurately ascertain fluctuations in the characteristics of the optical system resulting from irradiation heat. As a result, it is also possible to achieve a high performance mirror adjustment system.