Acoustic Sensor Apparatus for Lithographic Substrate Topography
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Solution Overview
Problem
Current lithographic technologies face challenges in accurately measuring the topography and position of targets on substrates, particularly when opaque layers obscure alignment marks and internal reflections cause interference, leading to errors in topography measurements.
Innovation Solution
An acoustic sensor apparatus that transmits and receives acoustic signals to determine both the topography and position of targets on substrates using a single device, employing acoustic lenses and transducers to convert signals into electronic data for processing, which can account for substrate warping and differentiate between temporal detection windows for accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radiation-based position sensors are used to detect target position, then position measurement can be performed, but opaque layers between the sensor and target block the radiation and make detection difficult
Solution Approach 1:
The patent replaces radiation-based position sensors with acoustic sensors that use acoustic waves instead of electromagnetic radiation. Acoustic waves can penetrate opaque layers that block light, enabling position detection of targets beneath opaque layers without being affected by the blocking issue. This substitution of the measurement medium (from electromagnetic radiation to acoustic waves) directly resolves the contradiction between position measurement capability and opaque layer interference.
2Measurement precision
If radiation-based topography sensors are used to measure substrate surface, then topography measurement can be performed, but internal reflections between substrate layers cause interference and measurement errors
Solution Approach 1:
The patent replaces radiation-based topography sensors with acoustic sensors that measure substrate topography using acoustic waves. Acoustic waves interact differently with substrate layers compared to electromagnetic radiation, significantly reducing internal reflections and interference patterns. This allows for more accurate topography measurements without the harmful interference effects caused by multiple internal reflections between substrate layers.
3Measurement precision
If separate position sensors and topography sensors are used, then both measurements can be performed, but the apparatus becomes complex and throughput decreases due to multiple scans required
Solution Approach 1:
The patent combines position sensing and topography sensing functions into a single integrated acoustic sensor apparatus. The same acoustic transducer and signal processing system are used to perform both position detection and topography measurement, eliminating the need for separate sensor systems. This merging reduces apparatus complexity and enables both measurements to be completed during a single substrate scan, thereby improving manufacturing throughput while maintaining measurement precision.
Solution Approach 2:
The acoustic sensor apparatus is designed with multi-functionality, where the same hardware system (acoustic transducer, signal processor) can perform multiple measurement functions - both position detection and topography measurement. This universal design allows a single sensor apparatus to replace multiple specialized sensors, simplifying the overall system architecture and enabling simultaneous or sequential execution of different measurement tasks without requiring separate dedicated devices.
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 enables simultaneous and accurate measurement of substrate topography and target position, reducing errors and improving throughput by using acoustic signals that bypass the limitations of radiation-based methods, such as opaque layer interference and internal reflections.
Implementation Method 1
a transducer arranged to convert the at least part of the acoustic signal to an electronic signal
Implementation Method 2
employing acoustic lenses and transducers to convert signals into electronic data for processing
Data Source
AI summary
A sensor apparatus comprising an acoustic assembly arranged to transmit an acoustic signal to a substrate and receive at least part of the acoustic signal after the acoustic signal has interacted with the substrate, a transducer arranged to convert the at least part of the acoustic signal to an electronic signal, and, a processor configured to receive the electronic signal and determine both a topography of at least part of the substrate and a position of a target of the substrate based on the electronic signal. The sensor apparatus may for part of a lithographic apparatus or a metrology apparatus.