Microlithographic Mirror Substrate Sensing for Direct Temperature Measurement
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Solution Overview
Problem
Existing temperature measurement methods for mirrors in microlithographic projection exposure apparatuses are inaccurate and indirect, leading to potential degradation in imaging quality due to thermal expansion and shape changes.
Innovation Solution
Integrate a sensor element within the substrate of the mirror body, utilizing electrical conductor tracks whose resistance changes with temperature, allowing direct measurement of the mirror's temperature through electrical signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are arranged in the vicinity of the mirror or indirect measurement methods are used, then the device complexity is reduced, but the measurement precision is insufficient
Solution Approach 1:
The sensor element is integrated directly into the mirror substrate, merging the temperature sensing function with the mirror structure itself. This eliminates the need for separate sensor components and reduces overall device complexity while achieving direct contact temperature measurement.
Solution Approach 2:
The mirror substrate serves dual functions: as the optical component and as the temperature sensor medium. The conductor tracks embedded in the substrate utilize the substrate material itself as the sensing element, allowing the same component to perform both optical reflection and temperature measurement.
2Measurement precision
If indirect measurement methods are used to determine mirror temperature, then the device complexity is reduced, but the measurement precision deteriorates
Solution Approach 1:
The mirror substrate performs self-measurement of its own temperature through the embedded conductor tracks. The substrate material itself serves as the sensing medium, eliminating the need for external sensor components and achieving direct temperature measurement without indirect inference.
3Measurement precision
If the sensor element is integrated into the mirror substrate, then the measurement precision is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The conductor tracks are formed within the substrate using standard semiconductor manufacturing techniques, transforming the substrate into an active sensing component. This approach leverages existing precision manufacturing capabilities while achieving integrated temperature sensing.
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
Provides accurate, direct temperature measurement of the mirror, enabling precise control of heating/cooling systems to maintain consistent mirror temperature and improve imaging quality.
Implementation Method 1
The conductor tracks are electrically conductively connected to one another at the crossing points. The sensor element comprises a plurality of electrical conductor tracks integrated into the substrate of the mirror body. The conductor tracks form a plurality of crossing points.
Implementation Method 2
The electrical conductor track can be configured such that the electrical resistance changes depending on the temperature of the mirror body in the region of the conductor track. Suitable materials are known both in the form of positive temperature coefficient (PTC) thermistors and in the form of negative temperature coefficient (NTC) thermistors.
Implementation Method 3
The sensor element comprises a plurality of electrical conductor tracks integrated into the substrate of the mirror body. The conductor tracks form a plurality of crossing points.
Data Source
AI summary
A mirror device, such as for a microlithographic projection exposure system, comprises a mirror, a sensor unit and a control unit. The mirror comprises a mirror body and a reflective surface provided on the mirror body. The sensor unit comprises a sensor element and a signal path extending to the control unit to transmit a measurement signal representing the temperature of the sensor element to the control unit. The sensor element is provided in the substrate of the mirror body. The sensor element comprises a plurality of electrical conductor paths integrated in the substrate of the mirror body. The conductor paths form a plurality of crossing points electrically conductively connecting the conductor paths to one another.