Broadband Alignment Measurement for Lithography Precision
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Solution Overview
Problem
Current lithographic apparatus alignment systems face limitations in performance due to accuracy issues related to signal quality and wavelength-dependent interference, which affect the precision of alignment mark detection and position calculation.
Innovation Solution
A broadband source generates radiation beams with multiple wavelengths, an optical system directs and receives alignment radiation from marks, and a processor analyzes signals from a detector to determine signal quality and calculate mark positions, enabling improved alignment accuracy through signal processing and actuator-driven corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a broadband source with multiple wavelengths is used, then alignment precision is improved through constructive interference, but device complexity increases due to the need for broadband sources and multi-wavelength detection systems
Solution Approach 1:
The patent changes the wavelength parameter by using a broadband source that emits multiple wavelengths simultaneously. This allows the alignment system to exploit constructive interference effects across different wavelengths, improving measurement precision while managing the complexity through integrated detection
Solution Approach 2:
The broadband source serves multiple functions: it provides illumination for alignment marks and simultaneously enables interference-based precision measurement through its multi-wavelength nature. The detector system also performs multiple tasks by analyzing both the presence and interference patterns of different wavelengths
2Manufacturing precision
If signal quality indicating parameters are used to establish further alignment signals, then alignment accuracy is improved, but processing complexity increases due to additional signal analysis requirements
Solution Approach 1:
The system implements feedback by using signal quality indicating parameters to evaluate detected alignment signals and establishing further alignment signals based on this evaluation. The processor analyzes signal quality metrics and uses this information to refine and improve alignment accuracy through iterative signal processing
Solution Approach 2:
The system performs preliminary signal quality assessment before final alignment determination. By evaluating signal quality indicating parameters in advance, the system prepares refined alignment signals that improve subsequent measurement accuracy while organizing processing tasks efficiently
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
The solution enhances alignment precision by leveraging broadband radiation to ensure constructive interference across wavelengths, improving signal quality and accuracy in detecting alignment marks, thereby enhancing the overall performance of lithographic apparatuses.
Implementation Method 1
The solution enhances alignment precision by leveraging broadband radiation to ensure constructive interference across wavelengths
Data Source
AI summary
The invention provides an alignment measurement arrangement having a broadband source, an optical system and a detector. The broadband source is arranged to generate a radiation beam with a first and second range of wavelengths. The optical system is arranged to receive the generated radiation beam, produce an alignment beam, direct the alignment beam to a mark located on an object, to receive alignment radiation back from the mark, and to transmit the alignment radiation. The detector is arranged to receive the alignment radiation and to detect an image of the alignment mark located on the object. The detector furthermore produces a first and a second alignment signal, respectively, associated with said first and second range of wavelengths, respectively. The alignment measurement arrangement finally has a processor, which is connected to the detector. The processor is arranged to receive the first and second alignment signal, to determine a first and second signal quality respectively of the first and second alignment signal respectively by using a signal quality indicating parameter, and to calculate a position of the alignment mark based on the first and second signal quality.