Substrate Measurement Using Reflected Radiation for Alignment
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Solution Overview
Problem
Existing lithographic processes face challenges in accurately measuring and aligning radiation with substrates, particularly at low k1 values, where feature reproduction is difficult due to the classical resolution limit, and alignment accuracy affects measurement quality.
Innovation Solution
An apparatus and method using a reflecting element and detector system to measure parameters and alignment of radiation on a substrate, employing source radiation, reflected radiation, and optionally spectrally resolved detectors for precise alignment and parameter determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radiation with smaller wavelength is used to measure smaller features, then measurement resolution is improved, but penetration depth into substrate decreases
Solution Approach 1:
The patent transitions from direct transmission measurement to reflective measurement geometry. By measuring radiation reflected from the substrate surface rather than transmitted through it, the system achieves high spatial resolution with smaller wavelengths while avoiding the penetration depth limitation. The reflecting element captures reflected radiation at grazing angles, enabling surface-sensitive measurements without requiring deep substrate penetration.
2Manufacturing precision
If tight control loops are used to control stability of lithographic apparatus, then pattern reproduction quality is improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where radiation is directed onto the substrate, reflected radiation is captured by the reflecting element, and the detected signal provides feedback about substrate position and alignment. This feedback enables real-time correction of alignment errors and maintains pattern reproduction quality without requiring overly complex control systems. The reflecting element and detector system create a closed-loop measurement system that continuously monitors and adjusts alignment.
3Measurement precision
If alignment accuracy is improved for radiation on substrate, then measurement quality is improved, but device complexity increases
Solution Approach 1:
The patent introduces a reflecting element as an intermediary component between the radiation source and the detector. This reflecting element captures reflected radiation from the substrate and directs it to the detector, enabling precise alignment measurement without requiring direct complex interaction between the radiation beam and substrate positioning system. The reflecting element serves as a mediator that simplifies the alignment measurement geometry while maintaining high accuracy.
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
Enables accurate alignment and measurement of substrate parameters with micrometer precision, enhancing the quality of lithographic processes by improving alignment and measurement accuracy.
Implementation Method 1
at least one reflecting element configured to receive a reflected radiation resulting from reflection of the source radiation from the substrate and further reflect the reflected radiation into a further reflected radiation
Implementation Method 2
at least one detector configured for measurement of the further reflected radiation for determination of at least an alignment of the source radiation and/or the substrate
Data Source
AI summary
Apparatus and method for measuring one or more parameters of a substrate using source radiation emitted from a radiation source and directed onto the substrate. The apparatus comprises at least one reflecting element and at least one detector. The at least one reflecting element is configured to receive a reflected radiation resulting from reflection of the source radiation from the substrate and further reflect the reflected radiation into a further reflected radiation. The at least one detector is configured for measurement of the further reflected radiation for determination of at least an alignment of the source radiation and/or the substrate.