Optical Temperature Detection for EUV Lithography Elements
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Solution Overview
Problem
Existing methods for temperature control and surface form correction of optical elements in EUV lithography face challenges such as indirect surface temperature measurement, delayed temperature regulation, and inefficiencies in managing thermal radiation.
Innovation Solution
A device and method for detecting surface temperature of optical elements using a temperature recording device and a temperature-controlled element, where the element is configured to emit a significant proportion of thermal radiation, reducing error contributions from reflected thermal radiation. This setup includes a filter to polarize thermal radiation and minimize parasitic radiation, and a heating system with directional radiation to control surface temperature accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are recessed in cutouts to measure surface temperature, then temperature measurement is enabled, but measurement precision deteriorates due to time delay and spatial separation from the surface
Solution Approach 1:
The patent replaces the mechanical temperature sensor system (requiring physical contact or proximity to the surface) with an optical measurement system. The optical sensor measures thermal radiation emitted by the surface directly, eliminating the need for physical proximity and associated time delays. This substitution of measurement methodology resolves the contradiction between enabling temperature measurement and avoiding time delay.
2Reliability
If heating power is increased to accelerate decompaction, then surface form stability improves, but thermal radiation errors increase
Solution Approach 1:
The patent introduces a mathematical model as an intermediary between the heating system and temperature measurement system. This model accounts for the thermal radiation emitted by the heated surface and allows for compensation of measurement errors. By using the model to predict and correct for radiation effects, the system can maintain both high heating power for decompaction and accurate temperature measurement.
Solution Approach 2:
The patent implements a feedback mechanism where temperature measurements are continuously monitored and used to adjust heating power. The system also uses mathematical modeling to predict thermal radiation effects and compensates for them in real-time. This feedback loop allows the system to maintain optimal heating conditions while correcting measurement errors caused by thermal radiation.
3Manufacturing precision
If optical element surface is homogeneously heated to accelerate decompaction, then surface form accuracy improves, but device complexity increases due to indirect temperature measurement requirements
Solution Approach 1:
The patent replaces complex mechanical temperature sensing systems with a simpler optical measurement approach. By measuring thermal radiation optically and using mathematical models to interpret the data, the system achieves accurate temperature control without requiring complex sensor arrays or invasive measurement systems. This substitution reduces device complexity while maintaining manufacturing precision.
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
The solution enables precise and accurate surface temperature measurement and control, reducing errors and improving the stability of optical elements in EUV lithography, thereby minimizing surface form changes due to decompaction over time.
Implementation Method 1
the element is configured to emit a significant proportion of thermal radiation
Implementation Method 2
a filter to polarize thermal radiation and minimize parasitic radiation
Implementation Method 3
a heating system with directional radiation to control surface temperature accurately
Data Source
AI summary
A device (20) for detecting a temperature on a surface (15) of an optical element (14) for semiconductor lithography. The device includesan optical element (14) having a face (16) irradiated with electromagnetic radiation (7, 8, 43),a temperature recording device (21), anda temperature controlled element (22) configured to be temperature-controlled and arranged so that the predominant proportion of the intensity of the thermal radiation (25.2) detected by the temperature recording device and reflected by reflection at the surface of the optical element is emitted by the temperature-controlled element.Also disclosed are an installation (1) for producing a surface (15) of an optical element (14) for semiconductor lithography and a method for producing a surface (15) of an optical element (14) of a projection exposure apparatus (30), wherein the surface is temperature-controlled and the surface temperature is detected during the temperature control.