Orthogonal Polarization Sensor for Lithography Substrate Inspection
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Solution Overview
Problem
Current lithographic systems face challenges in accurately measuring substrate properties due to the reduced accuracy of radiation polarization orientation, which affects measurement precision and limits the ability to illuminate targets with a wide range of incident angles, especially when using rotating polarizers.
Innovation Solution
A sensor system with a radiation projector capable of projecting linearly polarized radiation in two orthogonal directions, allowing for improved polarization accuracy and the ability to inspect substrates in-line without occupying excessive space within the lithographic apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rotating polarizer is used to illuminate targets with linearly polarized radiation, then the ability to provide polarized radiation is achieved, but the accuracy of polarization orientation is reduced
Solution Approach 1:
The radiation projector is divided into two separate parts: a first part that projects linearly polarized radiation in a first direction, and a second part that projects linearly polarized radiation in a second direction orthogonal to the first. This segmentation eliminates the need for a rotating polarizer and maintains fixed, accurate polarization orientations for both directions simultaneously.
2Adaptability or versatility
If a rotating polarizer is used to adjust polarization orientation, then adaptability to different target orientations is improved, but the accuracy and reliability of measurement are reduced
Solution Approach 1:
The system segments the polarization function into two independent radiation projectors, each providing fixed orthogonal polarization directions. This eliminates the mechanical rotation mechanism that introduces error, thereby improving reliability while maintaining adaptability through the fixed orthogonal configuration.
3Adaptability or versatility
If a rotating polarizer is used to illuminate targets, then the system can handle various incident angles, but the device complexity and space requirements increase
Solution Approach 1:
Instead of using a single rotating polarizer that requires space for mechanical rotation, the system uses two separate radiation projectors with fixed polarization orientations. This segmentation reduces device complexity and space requirements while maintaining the ability to handle various incident angles through the orthogonal polarization configuration.
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 measurement accuracy by ensuring precise polarization orientation and enabling the illumination of targets with orthogonal polarized radiation, reducing errors and increasing the efficiency of in-line inspection processes.
Implementation Method 1
a first part configured such that the radiation projector can project onto the substrate linearly polarized radiation oriented in a first direction and a second part configured such that the radiation projector can project onto the substrate linearly polarized radiation oriented in a second direction, orthogonal to the first direction
Implementation Method 2
a detector configured to detect the radiation reflected from the substrate
Data Source
AI summary
A sensor measuring properties of a substrate in which radiation is projected onto the substrate by a radiation projector that has a first part configured such that the radiation projection can project onto the substrate linearly polarized radiation oriented in a first direction and a second part configured such that the radiation projector can project onto the substrate linearly polarized radiation oriented in a second direction orthogonal to the first direction.