Mirror Array Optical Sensing for EUV Lithography
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Solution Overview
Problem
In EUV lithography systems, achieving a suitable signal-to-noise ratio for controlling the tilting angles of microsystem mirrors is challenging due to electrical disturbances from EUV radiation pulses and capacitive interactions among closely spaced components, which affects the precision and accuracy of structure miniaturization.
Innovation Solution
An optical arrangement using a microsystem with a mirror array that reflects both working light and a measuring beam, employing optical sensors to measure tilting angles instead of capacitive sensors, thereby improving signal-to-noise ratio and reducing sensitivity to electrical disturbances, and incorporating an integrated optical unit and sensor units for accurate tilting angle detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive sensors are used to sense tilting angles, then the control system can operate, but the signal-to-noise ratio is insufficient due to electrical disturbances from EUV radiation pulses
Solution Approach 1:
The patent replaces capacitive sensors with optical sensors (such as laser sensors or position-sensitive detectors) to measure the tilting angles of mirrors. This substitution eliminates the electrical measurement system that is susceptible to electromagnetic interference from EUV radiation pulses, thereby improving the signal-to-noise ratio and reliability of the control system.
2Manufacturing precision
If the number of individual mirrors is increased and their size reduced, then smaller structures can be produced, but capacitive interactions among components increase
Solution Approach 1:
By replacing capacitive sensors with optical sensors, the patent eliminates the capacitive measurement system that causes harmful interactions among closely spaced mirror components. The optical measurement system does not rely on electrical fields, thereby avoiding capacitive coupling effects while enabling the use of numerous small mirrors for producing finer structures.
3Measurement precision
If optical sensors are used instead of capacitive sensors, then measurement accuracy improves, but the system complexity increases
Solution Approach 1:
The patent extracts the measurement function from the electrical domain and places it in the optical domain. By using optical sensors and optical beams to measure tilting angles, the system achieves higher measurement precision while the apparent complexity is managed by integrating the optical measurement components into the existing optical path of the lithography system.
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 solution enhances the accuracy and precision of tilting angle control, allowing for the production of smaller structures with improved sensitivity and reduced electrical interference, facilitating the miniaturization of microsystems in lithography apparatuses.
Implementation Method 1
a respective mirror of the mirror array is set up to reflect working light of the lithography apparatus on its front side and also a measuring beam on its rear side
Data Source
AI summary
An optical arrangement for a lithography apparatus has a microsystem with a mirror array. A respective mirror of the mirror array is set up to reflect working light of the lithography apparatus on its front side and also a measuring beam on its rear side. One or more radiation sources, which are provided outside the microsystem, are set up to provide the respective measuring beam. One or more sensor units are set up to sense a tilting angle of a respective mirror in dependence on the respectively reflected measuring beam.