Photoresistor-Equipped Optical Elements for Lithography Heat Correction
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Solution Overview
Problem
Microlithography processes face issues with non-rotationally symmetrical light-induced heating of optical elements, leading to aberrations due to non-uniform expansion and refractive index distribution, which current temperature-based correction methods are slow and inefficient.
Innovation Solution
Incorporation of photoresistors on optical elements that measure luminous energy directly, allowing for rapid compensation of deformations and refractive index changes by heating regions with a heating element, controlled by the photoresistor's resistance value, to maintain optical symmetry and reduce aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If temperature sensors and heating elements are used to counter-heating optical elements, then imaging quality can be improved, but the response time is slow (time delay of minutes) and cannot keep up with illumination time changes
Solution Approach 1:
The patent replaces the mechanical/thermal measurement system (temperature sensors) with an optical measurement system (photoresistors). The photoresistors directly measure the optical parameters (luminous energy) that cause thermal effects, providing immediate feedback without the thermal inertia of temperature sensors. This substitution enables real-time detection and correction of illumination-induced aberrations.
Solution Approach 2:
The patent measures the optical parameters (luminous energy distribution) before thermal effects fully develop. By using photoresistors to detect the incident light patterns that will cause heating, the system can proactively apply counter-heating measures before the thermal aberrations occur, rather than reacting after temperature changes are detected.
2Manufacturing precision
If temperature-based correction methods are used, then imaging quality can be improved, but the correction process is laborious and requires separate temperature measurement and calculation
Solution Approach 1:
The patent combines the measurement and correction functions into a more integrated system. The photoresistors are positioned to directly measure the luminous energy at the optical element locations, and the control unit processes this information to activate corresponding heating elements. This merging eliminates the need for separate temperature measurement, calculation, and correction steps, simplifying the overall process.
Solution Approach 2:
The patent enables the optical element regions to essentially self-diagnose and self-correct. Each region's photoresistor measures the local luminous energy that causes heating in that specific region, and the control unit activates the corresponding heating element for that same region. This localized self-service approach eliminates the need for complex system-wide temperature mapping and calculation.
3Manufacturing precision
If image distortion sensors are used to detect image quality, then temperature adjustment can be guided, but the exposure can only be implemented after temperature adjustment and the process is laborious
Solution Approach 1:
The patent replaces the complex image distortion measurement system with a simpler optical parameter measurement system using photoresistors. Instead of capturing and analyzing full images for distortion, the photoresistors directly measure the luminous energy distribution that causes the distortion, providing simplified real-time feedback for rapid correction.
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
Enables rapid and effective correction of optical aberrations by directly sensing light absorption and adjusting heating in real-time, ensuring high imaging quality without time delays.
Implementation Method 1
a photoresistor having an electrical photoresistance value which varies dependent on an amount of luminous energy incident on a region of the optical surface
Implementation Method 2
heating elements, which heat the optical element dependent on the temperature measured by the sensors
Data Source
AI summary
An optical element for a lithography system comprises an optical surface and a photoresistor having an electric photoresistor value that varies according to an amount of light incident on a region of the optical surface.