Lithographic Measurement System Using Optical Fiber Bundle
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Solution Overview
Problem
Conventional measurement systems in lithographic apparatuses generate heat near the substrate, leading to thermal drift, instability, and reduced signal-to-noise levels, which can affect position accuracy and cause the substrate to heat up, especially with increased power dissipation and digital signal processing.
Innovation Solution
A measurement system comprising a sensor plate, a detector with an array of detector areas, a randomly ordered optical fiber bundle, and a control unit to position the sensor plate within the patterned radiation beam, where the optical fiber bundle's first free end receives light from the sensor plate and the second free end illuminates the detector, allowing the control unit to match each detector area with a corresponding location in the pupil plane, thereby collecting measurement data and maintaining the short-stroke module's position relative to the long-stroke module within a predetermined range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the measurement system is provided on the short-stroke module, then the position measurement capability is improved, but thermal drift and stability deteriorate due to heat generation near the substrate
Solution Approach 1:
The measurement system is segmented into two separate modules: the sensor plate remains on the short-stroke module for precise position measurement, while the detector is relocated to the long-stroke module to avoid heat generation. This segmentation allows each component to be optimally positioned for its function without compromising thermal stability.
Solution Approach 2:
An optical fiber bundle serves as an intermediary to transmit light signals between the sensor plate (on short-stroke module) and the detector (on long-stroke module). This optical connection enables the separation of the measurement components while maintaining functional integrity, allowing the detector to be positioned in a thermally stable environment.
2Measurement precision
If the measurement system is provided on the short-stroke module, then the position measurement capability is improved, but the substrate temperature increases due to heat generation
Solution Approach 1:
The measurement system is segmented into two separate modules: the sensor plate remains on the short-stroke module for precise position measurement, while the detector is relocated to the long-stroke module to avoid heat generation. This segmentation allows each component to be optimally positioned for its function without compromising thermal stability.
Solution Approach 2:
The detector, which is the primary heat-generating component, is extracted from the short-stroke module and relocated to the long-stroke module. This extraction removes the heat source from proximity to the substrate, preventing temperature increases while maintaining measurement capabilities through the optical fiber connection.
3Stability of the object's composition
If the detector is relocated to the long-stroke module, then thermal stability is improved, but the device complexity increases due to additional optical components
Solution Approach 1:
An optical fiber bundle serves as an intermediary to transmit light signals between the sensor plate (on short-stroke module) and the detector (on long-stroke module). This optical connection enables the separation of the measurement components while maintaining functional integrity, allowing the detector to be positioned in a thermally stable environment.
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 configuration reduces heating issues, improves stability, and maintains accurate position control by separating the detector and electronics from the short-stroke module, allowing for effective cooling and minimizing mechanical coupling between the modules, thus enhancing the accuracy of the positioner.
Implementation Method 1
a first free end of the optical fiber bundle is arranged to receive light from the sensor plate, wherein a second free end of the optical fiber bundle opposite the first free end of the optical fiber bundle is arranged such that light emanating from fibers of the optical fiber bundle at the second free end illuminates the detector
Data Source
AI summary
The invention relates to a measurement system for a projection system of a lithographic apparatus, comprising: —a sensor plate; —a detector comprising an array of detector areas; —a randomly ordered optical fiber bundle; —a positioner to position the sensor plate in the projection system; and —a control unit to control the positioning of the sensor plate and to obtain measurement data from an output of the detector, wherein a first free end of the optical fiber bundle is arranged to receive light from the sensor plate, wherein a second free end of the optical fiber bundle opposite the first free end of the optical fiber bundle is aligned with the array of detector areas of the detector, and wherein the control unit is configured to match each detector area with a corresponding location in a pupil plane of the projection system by collecting measurement data corresponding to different positions of the sensor plate relative to the projection system.