Spatial Light Modulator Alignment for Precise Exposure Measurement
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Solution Overview
Problem
Existing exposure apparatuses using spatial light modulators face challenges in accurately measuring and correcting positional deviations of reflecting surfaces due to manufacturing errors and thermal expansion, which affect the precision of pattern formation on substrates.
Innovation Solution
The apparatus incorporates a detection unit with a larger field of view and a position changing mechanism to adjust the relationship between detection units and the spatial light modulator, allowing for precise measurement of reflecting surface positions and rotations, using a combination of illumination and detection optical systems to calculate positional information and correct deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a detection unit with a larger field of view is used, then the measurement coverage area is improved, but the measurement precision for individual reflecting surfaces deteriorates
Solution Approach 1:
The detection unit is divided into multiple sub-detectors, each responsible for detecting light from specific reflecting surfaces. This segmentation allows the system to maintain a large overall field of view while preserving high measurement precision for individual surfaces through dedicated detection resources.
Solution Approach 2:
The patent introduces a positional relationship adjustment mechanism that changes the spatial arrangement between the detection unit and the spatial light modulator. By adjusting detection positions in addition to field of view, the system achieves both comprehensive coverage and precise measurement capability.
2Measurement precision
If the positional relationship between detection units and spatial light modulator is adjusted, then the measurement accuracy is improved, but the device complexity increases
Solution Approach 1:
The position changing mechanism is designed to serve multiple functions: it adjusts the positional relationship for accurate measurement, compensates for thermal expansion effects, and maintains optimal detection geometry. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity.
Solution Approach 2:
The system changes detection parameters including detection position, detection angle, and field of view to optimize measurement accuracy. These parameter adjustments are achieved through controlled movement of the detection unit or spatial light modulator, allowing high precision without requiring overly complex mechanical structures.
3Area of stationary object
If multiple detection units with different fields of view are used, then the measurement coverage is improved, but the device complexity increases
Solution Approach 1:
Instead of using multiple static detection units with different fixed fields of view, the patent employs a single detection unit with adjustable field of view and position. The dynamic adjustment capability allows the system to adapt its detection parameters to match different measurement requirements, reducing the overall number of components while maintaining comprehensive coverage.
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 solution enables accurate measurement and correction of positional errors in spatial light modulators, enhancing the precision of pattern formation on substrates and improving the overall performance of the exposure apparatus.
Implementation Method 1
a first detection unit including a first detection optical system and configured to detect light from the reflecting surface
Implementation Method 2
a detection optical system forming an image of the disposition plane based on light from a plurality of reflecting surfaces
Data Source
AI summary
An exposure apparatus includes: an exposure illumination optical system illuminating a spatial light modulator which has a plurality of spatial light modulation elements having a reflecting surface disposed on a disposition plane; a projection optical system projecting light from the spatial light modulator to an exposed substrate; a first detection unit detecting light from the reflecting surface; a second detection unit which is a detection unit detecting light from the reflecting surface and has a detection field of view larger than that of the first detection unit; and a position changing mechanism changing a positional relationship among the first detection unit, the second detection unit, and the spatial light modulator to either a first positional relationship in which the spatial light modulator faces the first detection unit and a second positional relationship in which the spatial light modulator faces the second detection unit.