Optical Element Thermal Correction in Semiconductor Lithography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current projection exposure apparatuses for microlithography face challenges in dynamically compensating for wavefront aberrations due to thermal loads, as existing mechanical and thermal manipulators are limited in correcting radial orders and have long time constants, making them unsuitable for transient aberrations.
Innovation Solution
A projection exposure apparatus with an optical element and an irradiation mechanism for targeted local heating using electromagnetic radiation, combined with a mechanism for dissipating thermal energy through fluid flow or thermal conductive elements, allowing for flexible correction of wavefront aberrations with minimal impact on optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical manipulators are used for wavefront correction, then correction of low-order aberrations is achieved, but radial orders are limited and cannot be circumvented
Solution Approach 1:
The patent replaces mechanical manipulators with acoustic waves (ultrasound) to manipulate optical properties. Acoustic waves induce periodic changes in refractive index and physical dimensions of optical elements, enabling wavefront correction without mechanical contact. This substitution overcomes the radial order limitations of mechanical systems while maintaining correction precision.
Solution Approach 2:
The patent changes physical parameters of optical elements through acoustic excitation, including refractive index, physical dimensions, and curvature radius. These dynamic parameter changes enable correction of various wavefront aberrations including radial orders that mechanical manipulators cannot address.
2Reliability
If edge-actuated thermal manipulators are used, then temporally steady-state aberrations are compensated, but long time constants prevent compensation of transient aberrations
Solution Approach 1:
The patent employs periodic acoustic waves (ultrasound) to manipulate optical elements. The periodic nature of acoustic excitation enables rapid response to changing thermal conditions, with response times much faster than thermal manipulators. This allows compensation of transient aberrations while maintaining steady-state correction stability.
Solution Approach 2:
The patent replaces slow thermal manipulation at the edge with acoustic wave manipulation that propagates through the optical element volume. This substitution reduces the time constant from seconds (thermal diffusion) to microseconds (acoustic wave propagation), enabling rapid compensation of transient aberrations.
3Ease of operation
If mechanical elements are placed in the optical beam path, then lens edge manipulation is enabled, but shading and scattered light occur
Solution Approach 1:
The patent replaces mechanical elements in the optical path with acoustic waves that propagate through the lens material itself. This eliminates physical obstructions that cause shading and scattered light, while still enabling effective manipulation of the lens optical properties for aberration correction.
4Manufacturing precision
If compensation plates with correction aspheres are used, then aberration compensation is achieved, but dynamically rapidly variable aberrations cannot be compensated
Solution Approach 1:
The patent creates a dynamic correction system using acoustic waves that can rapidly adjust optical element properties in real-time. Unlike static compensation plates, the acoustic manipulation responds dynamically to changing thermal conditions, enabling correction of rapidly variable aberrations throughout the objective lifetime.
Solution Approach 2:
The system uses wavefront sensors to detect aberrations and controls acoustic actuators to compensate them in real-time. This feedback loop enables adaptive correction of dynamically changing aberrations, including those caused by thermal loads during objective operation.
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 controlled and flexible correction of wavefront aberrations with efficient thermal energy dissipation, effectively addressing the limitations of existing technologies by maintaining optical performance and adapting to dynamic changes in aberrations.
Implementation Method 1
an irradiation mechanism for the targeted local irradiation of the optical element with electromagnetic radiation for the targeted local heating of the optical element
Implementation Method 2
a mechanism for dissipating the thermal energy introduced into the optical element by the at least one irradiation mechanism
Implementation Method 3
This thermal load causes wavefront aberrations: in the case of lenses by way of the temperature-dependent refractive index and the surface deformation; in the case of mirrors predominantly as a result of the surface deformation on account of the thermal expansion of the mirror substrate
Data Source
AI summary
The disclosure relates to an optical correction arrangement including at least one optical element and at least one irradiation mechanism for the targeted local irradiation of the optical element with electromagnetic heating radiation for the targeted local heating of the optical element. The optical correction arrangement also includes a mechanism for dissipating the thermal energy introduced into the optical element by the at least one irradiation mechanism. The disclosure furthermore relates to a projection exposure apparatus for semiconductor lithography including an optical correction arrangement according to the disclosure.