Microlithographic Imaging Optical System with Deformable Mirror
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Solution Overview
Problem
Imaging optical systems face challenges in minimizing transmission losses and deformations of mirrors adjacent to the field, which affect imaging behavior, and require a compact design with minimal spacing from the field while maintaining high stability and thermal compensation.
Innovation Solution
The system incorporates a deformable mirror in an optically conjugated plane to compensate for deformations and uses a neighboring mirror with a high modulus of elasticity material, such as silicon carbide, to minimize spacing and stabilize the imaging optical system, along with a pupil facet mirror in the entry pupil plane to reduce optical components and enhance light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the mirror most closely adjacent to the object field is positioned closer to reduce system size, then the compactness is improved, but the transmission losses increase and imaging precision deteriorates
Solution Approach 1:
The patent positions the entry pupil plane at a different longitudinal location than the mirror closest to the object field, creating a spatial separation in the beam path. This dimensional arrangement allows the system to maintain compact transverse dimensions while preserving optimal transmission characteristics through proper pupil-mirror spacing along the optical axis.
Solution Approach 2:
The patent applies different spacing relationships to different optical components: the entry pupil plane is positioned at one spacing from the object field, while the closest mirror is positioned at a greater spacing. This local differentiation of spacing parameters optimizes both transmission efficiency and imaging precision while maintaining overall system compactness.
2Volume of moving object
If the mirror most closely adjacent to the object field is positioned closer to reduce system size, then the compactness is improved, but the imaging precision deteriorates
Solution Approach 1:
By separating the entry pupil plane position from the closest mirror position along the optical axis, the patent creates independent optimization zones. This allows the mirror spacing to be optimized for imaging precision while the overall system size is controlled through the pupil plane positioning, resolving the contradiction between compactness and precision.
Solution Approach 2:
The patent implements local optimization by assigning different spacing parameters to different components: the entry pupil plane spacing is optimized for one aspect of imaging quality, while the closest mirror spacing is optimized for another. This local differentiation maintains high imaging precision without requiring excessive system size.
3Illumination intensity
If optical components are added to illuminate the object field, then the illumination coverage is improved, but the device complexity and transmission losses increase
Solution Approach 1:
The entry pupil plane structure serves multiple functions: it defines the aperture for imaging, controls the illumination angle, and acts as a reference for the beam path geometry. This multi-functionality eliminates the need for separate illumination control components, reducing device complexity while maintaining comprehensive illumination coverage.
Solution Approach 2:
The patent extracts the illumination control function from separate optical components and integrates it into the entry pupil plane definition. By taking out the need for additional illumination optics and embedding the control function in the pupil plane geometry itself, the system achieves comprehensive illumination with minimal components.
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 configuration reduces illumination light losses, compensates for mirror deformations, and allows for a compact, high-resolution imaging optical system with improved thermal stability and imaging error correction, suitable for projection exposure systems and microscope applications.
Implementation Method 1
a deformable further mirror, which is arranged in a plane, which is optically conjugated to an arrangement plane of the neighboring mirror in the imaging optical system
Implementation Method 2
a support body of a mirror, which is most closely adjacent to one of the two fields, which is also called a neighboring mirror, is made of a material, the modulus of elasticity of which is at least twice as great as the modulus of elasticity of the material of the support body of at least one of the other mirrors
Implementation Method 3
The imaging optical system includes a plurality of mirrors that image an object field in an object plane into an image field in the image plane along the beam path
Data Source
AI summary
An imaging optical system includes a plurality of mirrors configured to image an object field in an object plane of the imaging optical system into an image field in an image plane of the imaging optical system. An illumination system includes such an imaging optical system. The transmission losses of the illumination system are relatively low.