Analyzer Plate Polarization Measurement in Lithography
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Solution Overview
Problem
Conventional lithographic apparatuses face challenges in accurately measuring the polarization of radiation due to polarization-dependent transmission through slits, leading to measurement errors and the need for complex and heavy detector systems, which increase weight and space requirements on the x-y-z positioning stage.
Innovation Solution
A lithographic apparatus with an analyzer plate having regions that preferentially let through radiation polarized in specific directions, allowing for accurate measurement using a single radiation sensor domain, while maintaining a compact and lightweight design, and enabling in-line measurements without altering the patterning device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a moving slit is used to gather position dependent information on the image, then measurement precision is improved, but device complexity and weight increase due to the need for heavy detector systems
Solution Approach 1:
The analyzer plate is divided into multiple regions (first region, second region, etc.) with different transmission characteristics for different polarization directions. Each region can be independently illuminated and measured, allowing the system to gather polarization information without requiring a moving slit and heavy detector system.
Solution Approach 2:
The analyzer plate acts as an intermediary element that converts polarization state information into intensity variations. By placing the analyzer plate in the beam path, the system can measure polarization effects through a single stationary radiation sensor without needing complex moving slit mechanisms.
2Measurement precision
If multiple regions with different transmission characteristics are used in the analyzer plate, then measurement precision for polarization is improved, but device complexity increases
Solution Approach 1:
Different regions of the analyzer plate are assigned different transmission characteristics tailored to specific polarization directions. The first region is arranged to preferentially let through radiation polarized in a first direction, while the second region is arranged to preferentially let through radiation polarized in a second direction. This local differentiation enables precise polarization measurement without requiring complex system architecture.
3Measurement precision
If the slit width is made smaller to provide higher resolution, then measurement precision is improved, but the signal-to-noise ratio deteriorates
Solution Approach 1:
Instead of using a single narrow slit that may be difficult to align and has poor signal-to-noise ratio, the analyzer plate creates multiple effective measurement paths through its multi-region structure. Each region can be illuminated and measured independently, providing redundant information that improves the signal-to-noise ratio while maintaining resolution.
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 solution provides accurate polarization measurements with improved signal-to-noise ratio and reduced complexity, minimizing the impact on production output and allowing for precise analysis of projection system performance without the need for extensive recalibration.
Implementation Method 1
an analyzer plate having a first region arranged to preferentially let through radiation polarized in a first direction and a second region arranged to preferentially let through radiation polarized in a second direction
Data Source
AI summary
An analyzer plate positioned between a projection system and a radiation sensor is illuminated by a projected beam of radiation. The analyzer plate includes two crossing regions, each of which transmits radiation with a different polarization direction. The beam of projection radiation is patterned without influencing the polarization of the beam. By patterning the beam of projection radiation so that one region receives more radiation than the other region, the radiation sensor is given polarization selectivity.