Illumination Module for Metrology Diffracted Radiation Detection
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Solution Overview
Problem
Existing metrology systems face challenges in accurately detecting diffracted radiation at different wavelengths due to wavelength-dependent variations, which complicates the detection of diffracted radiation and affects measurement precision in metrology applications.
Innovation Solution
An illumination module with a configurable range of illumination angles and a grating light valve module that controls the spectral configuration of measurement illumination, allowing for variation in spectral configuration based on illumination angles to optimize detection conditions for diffracted radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple different wavelengths are used to measure diffracted radiation, then measurement precision is improved, but detection complexity increases due to wavelength-dependent angle variations
Solution Approach 1:
The system dynamically adjusts the illumination angle based on the selected wavelength. The controller varies the illumination angle in dependence on the wavelength to maintain optimal detection conditions, transforming a static single-wavelength system into a dynamic multi-wavelength system that adapts to each wavelength's diffraction characteristics
Solution Approach 2:
The system changes the illumination angle parameter in response to wavelength selection. By varying the illumination angle according to the wavelength-dependent diffraction pattern, the system compensates for the increased complexity and maintains precise detection across multiple wavelengths
2Measurement precision
If the illumination angle is varied to optimize detection, then detection accuracy is improved, but the system complexity increases due to the need to coordinate multiple parameters
Solution Approach 1:
The controller implements feedback control by monitoring the selected wavelength and automatically adjusting the illumination angle to the optimal value. This closed-loop approach coordinates multiple parameters (wavelength, illumination angle, detector positioning) without requiring complex manual intervention, thereby improving detection accuracy while managing system complexity through automated control
Solution Approach 2:
The controller serves multiple functions: it selects wavelengths, determines optimal illumination angles, coordinates the illumination source, and positions the detector. This multi-functional approach consolidates control logic into a single unit, improving detection accuracy across varying conditions while avoiding the complexity of multiple independent control systems
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
Enhances the detection of diffracted radiation by ensuring that wanted diffraction orders are captured across multiple wavelengths, improving measurement accuracy and precision in metrology devices.
Implementation Method 1
a grating light valve module for controllably configuring a spectral configuration of said measurement illumination
Implementation Method 2
a configurable illumination module operable to provide measurement illumination over a configurable range of illumination angles
Implementation Method 3
detection of diffracted radiation from a diffractive structure resultant from a measurement of the diffractive structure using said measurement illumination
Data Source
AI summary
Disclosed is an illumination module for a metrology device. The illumination module comprises a configurable illumination module operable to provide measurement illumination over a configurable range of illumination angles, a grating light valve module for controllably configuring a spectral configuration of the measurement illumination; and a controller operable to control the configurable illumination module and the grating light valve module such that the spectral configuration of the measurement illumination is varied in dependence with illumination angle within the range of illumination angles so as to obtain a desired detection condition for detection of diffracted radiation from a diffractive structure resultant from a measurement of the diffractive structure using the measurement illumination.