Metrology Apparatus Parallel Diffraction Order Measurement
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Solution Overview
Problem
Current lithographic processes face challenges in efficiently measuring metrology targets under varying measurement conditions, such as different wavelengths and polarizations, which limits the accuracy and robustness of process control in manufacturing integrated circuits and other devices.
Innovation Solution
An inspection apparatus and method that utilize an objective to receive diffracted radiation from metrology targets, separating it into portions corresponding to different radiation characteristics and diffraction orders, allowing for simultaneous measurement of positive and negative diffraction orders using a dispersive optical element and polarization element, enabling parallel measurement of multiple wavelengths and polarizations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequential measurement of different radiation characteristics is used, then measurement completeness is improved, but measurement time increases
Solution Approach 1:
The patent segments the diffracted radiation into different diffraction orders using a dispersive optical element, allowing simultaneous measurement of multiple radiation characteristics (wavelengths and polarizations) in parallel channels rather than sequentially
Solution Approach 2:
The patent adds a spatial dimension to the measurement by using a detector array that simultaneously captures multiple diffraction orders at different positions, transforming sequential temporal measurement into parallel spatial measurement
2Measurement precision
If multiple measurement conditions are tested separately, then measurement accuracy is improved, but process complexity increases
Solution Approach 1:
The patent merges multiple measurement functions into a single optical path by combining the dispersive optical element with the detection system, allowing simultaneous measurement of multiple wavelengths and polarizations through one integrated apparatus rather than separate measurement systems
Solution Approach 2:
The detection system is designed with universal capability to handle multiple radiation characteristics simultaneously, where a single detector array can capture information about different wavelengths and polarizations through spatial separation of diffraction orders
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 approach enhances measurement accuracy and process robustness by enabling simultaneous measurement of multiple wavelengths and polarizations, improving the precision of overlay and other parameters in lithographic processes, particularly for opaque materials and tight design rules.
Implementation Method 1
an objective configured to receive diffracted radiation from a metrology target having positive and negative diffraction order radiation
Implementation Method 2
an optical element configured to separate the diffracted radiation into portions separately corresponding to each of a plurality of different values or types of one or more radiation characteristics and separately corresponding to the positive and negative diffraction orders
Data Source
AI summary
An inspection apparatus, including: an objective configured to receive diffracted radiation from a metrology target having positive and negative diffraction order radiation; an optical element configured to separate the diffracted radiation into portions separately corresponding to each of a plurality of different values or types of one or more radiation characteristics and separately corresponding to the positive and negative diffraction orders; and a detector system configured to separately and simultaneously measure the portions.