Miniaturized Overlay Measurement System Using Flat Top Beam Shaping
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Solution Overview
Problem
Current optical sensor systems for overlay measurement in lithographic apparatuses face challenges in achieving compactness, scalability, and precise measurement of micro diffraction-based overlay errors due to hardware complexity and process variations.
Innovation Solution
A compact sensor apparatus is developed, comprising a beam shaping system, polarization modulation system, and signal detection system, which shapes an illumination beam into a flat top beam spot over a wide wavelength range, projects it onto a substrate, and collects diffraction order sub-beams to measure overlay characteristics, utilizing photonic crystal fibers and spatial light modulators for miniaturization and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional optical sensor systems are used for overlay measurement, then measurement capability is achieved, but hardware complexity and device size increase
Solution Approach 1:
The optical sensor system is divided into multiple independent miniaturized sensors that can be arranged in arrays. Each sensor performs a specific measurement function, and multiple sensors work in parallel to achieve comprehensive overlay measurement coverage, reducing the complexity of any single sensor while maintaining overall measurement precision
Solution Approach 2:
The patent integrates multiple functional components (illumination source, beam shaping elements, detection elements) into a nested hierarchical structure where smaller components are positioned within larger optical paths. This nesting approach miniaturizes the overall device while preserving the complete optical measurement functionality
2Productivity
If multiple sensors are implemented to measure multiple alignment marks simultaneously, then productivity improves, but device complexity and cost increase
Solution Approach 1:
The patent designs a universal miniaturized sensor platform that can measure multiple alignment marks and different overlay parameters using the same basic sensor structure. By making the sensor design universal and interchangeable, the system can achieve high productivity through parallel operation without proportionally increasing device complexity or cost
Solution Approach 2:
The patent creates simplified copies of the measurement function through multiple identical miniaturized sensors rather than using one complex sensor. Each sensor is a simplified copy that performs the same basic measurement, and multiple copies work in parallel to achieve high throughput while keeping individual sensor complexity low
3Adaptability or versatility
If beam shaping systems are designed for wide wavelength range operation, then adaptability improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs beam shaping elements whose optical properties can be dynamically adjusted to match different wavelength ranges. By changing parameters such as beam waist size, curvature radius, or orientation of the shaped beam, the system adapts to different wavelengths without requiring precision manufacturing for each specific wavelength, thereby maintaining manufacturing feasibility while achieving wide spectral adaptability
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 enables reduced hardware complexity, improved accuracy, and scalability, allowing for simultaneous or real-time measurement of multiple alignment marks, thereby correcting processing errors and enhancing overlay precision in lithographic apparatuses.
Implementation Method 1
a beam shaping system configured to shape an illumination beam generated from an illumination system and generate a flat top beam spot of the illumination beam
Implementation Method 2
a signal detection system configured to collect a signal beam comprising diffraction order sub-beams generated from the target
Data Source
AI summary
A compact sensor apparatus having an illumination beam, a beam shaping system, a polarization modulation system, a beam projection system, and a signal detection system. The beam shaping system is configured to shape an illumination beam generated from the illumination system and generate a flat top beam spot of the illumination beam over a wavelength range from 400 nm to 2000 nm. The polarization modulation system is configured to provide tenability of linear polarization state of the illumination beam. The beam projection system is configured to project the flat top beam spot toward a target, such as an alignment mark on a substrate. The signal detection system is configured to collect a signal beam comprising diffraction order sub-beams generated from the target, and measure a characteristic (e.g., overlay) of the target based on the signal beam.