EUV Microscope Free-Form Illumination Using Spherical Mirrors
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Solution Overview
Problem
Conventional EUV microscope devices with freeform illumination systems are costly due to the use of expensive aspherical lenses, and they suffer from non-uniform illumination and limited control over illumination structures.
Innovation Solution
A high-performance EUV microscope device with a freeform illumination system that utilizes a spherical mirror, a plane mirror, and an elliptical mirror to achieve uniform illumination and precise control over incident angles and positions without relying on expensive aspherical lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If aspherical lenses are used in the illumination system, then freeform illumination can be achieved, but the cost increases significantly and the structure becomes complex
Solution Approach 1:
The patent segments the illumination system into multiple spherical mirrors (first spherical mirror, second spherical mirror, third spherical mirror) that work together to achieve freeform illumination. Instead of using a single complex aspherical lens, the system divides the illumination function across multiple simpler spherical mirror components, each performing a specific function in the illumination path.
Solution Approach 2:
The patent combines multiple spherical mirrors with different functions (illumination, focusing, and freeform shaping) into a unified illumination system. The first spherical mirror provides initial illumination, the second spherical mirror focuses light, and the third spherical mirror creates the freeform illumination pattern, merging these functions into a coordinated system that replaces the need for expensive aspherical lenses.
2Adaptability or versatility
If aspherical lenses are used in the illumination system, then freeform illumination can be achieved, but the cost increases significantly
Solution Approach 1:
The patent employs spherical mirrors which are significantly cheaper to manufacture than aspherical lenses. Spherical mirrors can be produced using standard polishing and coating techniques, making them a cost-effective alternative to expensive aspherical optical elements while maintaining the required freeform illumination capability.
Solution Approach 2:
The patent changes the optical parameters by using multiple spherical mirrors with different radii of curvature and positioning them at specific locations. By adjusting the parameters of these spherical mirrors (their positions, orientations, and curvature radii), the system achieves freeform illumination without requiring expensive aspherical lenses, thus reducing manufacturing costs.
3Device complexity
If conventional illumination systems are used, then the structure is simple, but the illumination uniformity is poor
Solution Approach 1:
The patent introduces dynamic control of the illumination system through adjustable components. The illumination system can dynamically adjust the illumination pattern and uniformity by modifying the positions and orientations of the spherical mirrors, allowing optimization of illumination uniformity while maintaining a relatively simple structural basis.
Solution Approach 2:
The patent uses the second spherical mirror as an intermediary focusing element between the light source and the sample. This intermediary component helps to evenly distribute the light and improve illumination uniformity across the sample area, while the overall structure remains simpler than systems using aspherical lenses.
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 reduces the cost of the optical system, simplifies the structure, and achieves uniform illumination, enabling more precise measurement of EUV masks with improved control over illumination patterns.
Implementation Method 1
a spherical mirror having a two-axis driving unit which receives and reflects the EUV light output from the EUV light source and controls a reflection direction of the incident light through two-axis angle scanning
Implementation Method 2
an elliptical mirror which receives light from the EUV light source and irradiates the light to a target object to be measured
Implementation Method 3
a zone plate lens for focusing the light reflected after entering the target object
Implementation Method 4
a photodetector for receiving the light focused by the zone plate lens
Data Source
AI summary
A high performance EUV microscope device with a freeform illumination system having an elliptical mirror, includes: an EUV source for outputting EUV light; a spherical mirror having a two-axis driving unit which receives and reflects the EUV light output from the EUV light source and controls a reflection direction of the incident light through two-axis angle scanning; an optical path changing means for receiving the reflected light reflected from the spherical mirror and providing illumination light to a target object to be measured; a zone plate lens for focusing the light reflected after entering the target object; and a photodetector for receiving the light focused by the zone plate lens, wherein the spherical mirror is rotated by the driving unit to control the reflection direction of the reflected light, and the illumination light irradiated to the target object is controlled by the optical path changing means receiving the reflected light.