EUV Radiation Source Alignment Detector for Lithography
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Solution Overview
Problem
Current lithographic apparatuses face challenges in accurately determining the relative alignment between the fuel and the focus of radiation in EUV radiation sources, leading to inefficiencies and potential damage to sensors due to the indirect measurement methods and time-varying properties of the radiation output.
Innovation Solution
A radiation source with a nozzle to direct fuel droplets and an alignment detector featuring dual sensor arrangements to measure properties of the radiation, allowing for direct measurement of the focus position and fuel droplet position, enabling precise control of the radiation alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If indirect measurement methods are used to determine alignment between fuel and radiation focus, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent introduces an intermediary alignment detector with sensor arrangements that directly measure the positions of both the fuel droplet and radiation focus. This mediator device translates the alignment information into measurable signals without requiring complex indirect inference methods, thereby improving measurement precision while maintaining reasonable device complexity.
Solution Approach 2:
The patent replaces indirect mechanical measurement methods with optical detection using sensor arrangements that directly detect the alignment between fuel and radiation focus. This substitution enables precise real-time measurement without the complexity of mechanical alignment systems.
2Productivity
If radiation is directed at fuel to generate plasma, then productivity is improved through EUV radiation output, but sensors may be damaged by excessive radiation intensity
Solution Approach 1:
The patent implements a feedback control system where sensor arrangements continuously monitor the alignment between fuel and radiation focus, and the controller adjusts the radiation parameters accordingly. This feedback mechanism maintains optimal EUV radiation output while preventing excessive intensity that could damage sensors, thus resolving the contradiction between productivity and sensor protection.
Solution Approach 2:
The patent dynamically adjusts radiation parameters such as intensity and focus position based on real-time alignment measurements. By changing these parameters adaptively, the system maximizes EUV radiation productivity while keeping sensor exposure within safe limits, preventing sensor degradation.
3Ease of operation
If alignment between fuel and radiation focus is not precisely controlled, then ease of operation is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent implements a self-aligning system where the alignment detector and controller automatically adjust the radiation focus to match the fuel droplet position. This self-service mechanism eliminates the need for manual alignment adjustments, maintaining ease of operation while achieving high manufacturing precision through automatic feedback control.
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 enhances the accuracy of radiation alignment control, reduces start-up and recovery times, and minimizes sensor degradation, thereby improving the efficiency and reliability of the lithographic process.
Implementation Method 1
a first sensor arrangement configured to measure a property of a third amount of radiation that is indicative of a focus position of the first amount of radiation
Implementation Method 2
a second sensor arrangement configured to measure a property of a fourth amount of radiation, the fourth amount of radiation being a portion of the first amount of radiation that is reflected by the fuel droplet
Implementation Method 3
the radiation source being configured to receive a first amount of radiation such that, in use, the first amount of radiation is incident on a fuel droplet at the plasma formation location and such that the first amount of radiation transfers energy to the fuel droplet so as to generate a plasma that emits a second amount of radiation
Data Source
AI summary
A radiation source (SO) suitable for providing a beam of radiation to an illuminator of a lithographic apparatus. The radiation source comprises a nozzle (128) configured to direct a stream of fuel droplets along a trajectory (140) towards a plasma formation location (212). The radiation source is configured to receive a first amount of radiation (205) such that, in use, the first amount of radiation is incident on a fuel droplet at the plasma formation location. The first amount of radiation transfers energy to the fuel droplet to generate a radiation generating plasma that emits a second amount of radiation (132). The radiation source further comprises an alignment detector having a first sensor arrangement (122) and a second sensor arrangement (134). The first sensor arrangement is configured to measure a property of a third amount of radiation (205a) that is indicative of a focus position of the first amount of radiation. The second sensor arrangement is configured to measure a property of a fourth amount of radiation (138), the fourth amount of radiation being a portion of the first amount of radiation that is reflected by the fuel droplet upon which the first amount of radiation is incident.