Wavelength Selector for Lithography Detection Accuracy
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Solution Overview
Problem
Existing detection systems in lithography apparatuses face challenges in achieving both high detection accuracy and throughput, particularly when dealing with asymmetrical marks on substrates, as adjusting the output of semiconductor lasers to reduce detection errors requires significant time for stabilization, impacting productivity.
Innovation Solution
A detection apparatus that uses a wavelength selector with two-dimensionally arrayed elements to selectively guide diffracted light of specific wavelengths to a detector, allowing for quick switching of wavelengths based on the position of the detection target, thereby reducing detection errors and improving throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the output of each of a plurality of light sources is adjusted to reduce detection error, then detection accuracy is improved, but the time required for stabilization increases, reducing productivity
Solution Approach 1:
The patent pre-calculates and stores optimal wavelength selection information for different positions on the substrate before actual detection begins. This preliminary preparation eliminates the need for time-consuming real-time adjustments of light source outputs, allowing the system to quickly switch between pre-determined wavelength configurations based on mark position, thereby maintaining high detection accuracy while improving throughput
Solution Approach 2:
Instead of adjusting the output intensity of multiple light sources (which causes stabilization time issues), the patent changes the wavelength parameter of the illumination light by selecting different wavelengths from a broadband light source based on the detected mark position. This parameter change approach achieves detection error reduction without the stability problems associated with intensity adjustment
2Measurement precision
If the wavelength of light is changed in accordance with the position on the substrate to reduce detection error, then detection accuracy is improved, but the complexity of the detection system increases
Solution Approach 1:
The patent employs a single broadband light source that can emit multiple wavelengths rather than requiring multiple separate monochromatic light sources. This universal light source approach simplifies the system structure while still enabling wavelength selection based on mark position, reducing detection error without proportionally increasing system complexity
Solution Approach 2:
The patent introduces a wavelength selection mechanism (such as a diffraction grating or prism combined with a spatial filter) that acts as an intermediary between the broadband light source and the detection target. This intermediary component enables efficient wavelength selection without requiring direct control of multiple light sources, thereby managing system complexity while achieving position-dependent wavelength adjustment
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 enables accurate detection of mark positions with reduced errors and faster stabilization times, enhancing the productivity of lithography processes by quickly determining the optimal wavelength for each position on the substrate.
Implementation Method 1
diffraction directions of light components of the plurality of wavelengths included in the illumination light on the detection target are different from each other
Implementation Method 2
a wavelength selector including an incident surface on which diffracted light from the detection target illuminated by the illuminator is incident, and configured to select light of a specific wavelength from the diffracted light
Data Source
AI summary
The present invention provides a detection apparatus for detecting a position of a detection target including a diffraction grating pattern, comprising: an illuminator configured to illuminate the detection target with illumination light including a plurality of wavelengths; a wavelength selector including an incident surface on which diffracted light from the detection target is incident, and configured to select light of a specific wavelength from the diffracted light; and a detector configured to receive the light of the specific wavelength selected by the wavelength selector and detect the position of the detection target, wherein positions on the incident surface where light components of the plurality of wavelengths included in the illumination light are incident are different from each other, and wherein the wavelength selector controls each of the plurality of elements in accordance with the position on the incident surface.