Self-referencing Integrated Alignment Sensor for Lithography
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Solution Overview
Problem
Existing alignment systems in lithographic apparatuses face challenges in measuring distortions within the alignment mark field (intra-field distortion), finer alignment grating pitches, and simultaneously measuring multiple diffraction targets, while also being bulky and complex.
Innovation Solution
The development of a self-referencing integrated alignment sensor system that utilizes on-axis illumination and off-axis detection, or off-axis illumination and on-axis detection, with a multi-wavelength radiation beam and a wideband integrated optical system, including a wideband grating coupler and a multimode dispersion waveguide structure, to determine the alignment of a substrate with nanometer-scale precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional alignment systems are used, then they can measure alignment, but they cannot measure intra-field distortion and finer alignment grating pitches accurately
Solution Approach 1:
The patent changes the illumination parameters by using multiple wavelengths (e.g., 450-500nm, 550-575nm, 625-675nm) to enable measurement of different alignment mark types and distortion levels. This allows the system to measure both intra-field distortion and finer grating pitches simultaneously by selecting appropriate wavelength combinations.
Solution Approach 2:
The alignment mark field is segmented into multiple regions with different alignment marks that can be measured simultaneously using the multi-wavelength capability. The system can measure distortion in different zones of the alignment mark field independently while maintaining overall alignment precision.
2Measurement precision
If traditional alignment systems are used, then they can measure alignment, but they are bulky and complex
Solution Approach 1:
The patent merges multiple alignment sensor functions into a single integrated sensor that can measure both intra-field distortion and overlay using the same optical path and detector. The multi-wavelength illumination system combines multiple measurement capabilities in one device, reducing the overall system footprint and complexity while maintaining precision.
Solution Approach 2:
The integrated alignment sensor is designed with universal functionality to measure multiple types of alignment marks and distortion patterns using different wavelength combinations. This multi-functional design eliminates the need for separate specialized sensors for different measurement tasks, thereby reducing system complexity.
3Measurement precision
If traditional alignment systems are used, then they can measure alignment, but they cannot simultaneously measure multiple diffraction targets
Solution Approach 1:
The patent enables continuous measurement of multiple diffraction targets simultaneously by using multi-wavelength illumination that can detect different alignment marks in parallel. The system maintains continuous measurement capability across multiple targets without requiring sequential scanning, thereby improving productivity while preserving measurement precision.
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 system achieves improved accuracy and scalability, enabling the measurement of intra-field distortion, finer alignment grating pitches, and multiple diffraction targets simultaneously, while reducing the system's footprint and complexity.
Implementation Method 1
measure a first diffracted radiation beam indicative of first order diffraction at a first wavelength in response to an irradiation of the region by the multi-wavelength radiation beam
Data Source
AI summary
Systems, apparatuses, and methods are provided for determining the alignment of a substrate. An example method can include emitting a multi-wavelength radiation beam including a first wavelength and a second wavelength toward a region of a surface of a substrate. The example method can further include measuring a first diffracted radiation beam indicative of first order diffraction at the first wavelength in response to an irradiation of the region by the multi-wavelength radiation beam. The example method can further include measuring a second diffracted radiation beam indicative of first order diffraction at the second wavelength in response to the irradiation of the region by the multi-wavelength radiation beam. Subsequently, the example method can include generating, based on the measured first set of photons and the measured second set of photons, an electronic signal for use in determining an alignment position of the substrate.