Beam Homogenizer Radial Absorption Filter Optical Mixing
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Solution Overview
Problem
Current metrology systems in lithographic processes lack a means to adjust and ensure beam homogeneity, which is crucial for accurate measurements and process control, particularly in scatterometry applications.
Innovation Solution
A beam homogenizer comprising a controllable radial absorption filter system and an optical mixing element, such as one utilizing chaotic billiard theory, is introduced to homogenize the radiation beam, addressing both radial and angular intensity profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional beam source is used in scatterometry, then the device complexity is low, but the beam homogeneity is insufficient for accurate measurements
Solution Approach 1:
The beam homogenizer is segmented into distinct functional modules: a filter system with multiple filter elements (including radial absorption filters and azimuthal absorption filters) and a separate mixing element. This segmentation allows each component to address specific aspects of beam homogeneity independently, improving measurement precision while keeping the overall device complexity manageable through modular design.
Solution Approach 2:
The filter system implements local quality by applying different absorption characteristics to different regions of the beam profile. Radial absorption filters address intensity variations in the radial direction, while azimuthal absorption filters address variations in the azimuthal direction. This localized filtering approach ensures uniform beam homogeneity across the entire beam cross-section without requiring a complete redesign of the beam source.
2Measurement precision
If beam homogeneity is improved using traditional methods, then measurement accuracy increases, but the ability to control both radial and angular intensity profiles is limited
Solution Approach 1:
The filter system is designed with multi-functionality to address both radial and angular intensity profile control. By incorporating both radial absorption filters and azimuthal absorption filters in combination with a mixing element, the system can simultaneously control intensity distribution in multiple directions and adapt to different measurement requirements, enhancing both beam homogeneity and versatility.
Solution Approach 2:
The filter elements are configured to be movable or adjustable, enabling dynamic control of the beam intensity profile. This allows the system to adapt to different measurement scenarios by adjusting the filter positions or configurations, providing both homogeneous beams for general measurements and tailored intensity profiles for specific applications.
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 achieves full spatial and azimuthal homogenization of the radiation beam, enhancing measurement accuracy and process control in lithographic metrology systems.
Implementation Method 1
a filter system comprising a controllable radial absorption profile
Implementation Method 2
an optical mixing element configured to homogenize the filtered beam
Data Source
AI summary
A beam homogenizer for homogenizing a beam of radiation and an illumination system and metrology apparatus comprising such a beam homogenizer as provided. The beam homogenizer comprises a filter system having a controllable radial absorption profile and configured to output a filtered beam and an optical mixing element configured to homogenize the filtered beam. The filter system may be configured to homogenize the angular beam profile radially and said optical mixing element may be configured to homogenize the angular beam profile azimuthally.