Microlithography Illumination System Beam Deflection
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Solution Overview
Problem
Current illumination systems for microlithographic exposure apparatus face challenges in varying the geometry of the illuminated field without incurring substantial light losses, often requiring adjustable field stops that block light and complicate the system layout.
Innovation Solution
The system employs a beam deflecting device with reflective or transparent elements that adjust the deflection angles to form variable light patterns on the optical raster element's facets, allowing for precise control of the illuminated field geometry without the need for a field stop, thereby minimizing light losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If adjustable field stops are used to vary the illuminated field geometry, then the field geometry can be adjusted, but light losses increase and system complexity increases
Solution Approach 1:
The patent removes the field stop component entirely from the illumination system. Instead of using a field stop to define the illuminated field geometry, the system uses a programmable mirror array that can be controlled to illuminate only the required regions of the optical raster element, thereby eliminating light losses associated with field stops while maintaining geometric adaptability
Solution Approach 2:
The patent replaces the mechanical field stop system with a programmable mirror array controlled by electronic signals. The mirror array can dynamically adjust which regions of the optical raster element receive light, providing geometric adaptability without the light losses and mechanical complexity of traditional field stops
2Adaptability or versatility
If adjustable field stops are used to vary the illuminated field geometry, then the field geometry can be adjusted, but the system layout becomes more complex
Solution Approach 1:
The patent removes the field stop component entirely from the illumination system. Instead of using a field stop to define the illuminated field geometry, the system uses a programmable mirror array that can be controlled to illuminate only the required regions of the optical raster element, thereby eliminating light losses while maintaining geometric adaptability
Solution Approach 2:
The programmable mirror array serves multiple functions: it performs the traditional role of field stops for defining illuminated geometry, while also enabling dynamic reconfiguration of illumination patterns without requiring additional mechanical components. This multi-functionality reduces overall system complexity while maintaining adaptability
3Loss of energy
If conventional illumination systems illuminate the entire optical raster element, then maximum light is utilized, but the illuminated field geometry cannot be varied
Solution Approach 1:
The patent implements a dynamic illumination system where the programmable mirror array can change its configuration in real-time. This allows the system to adaptively illuminate only the necessary regions of the optical raster element corresponding to the desired field geometry, providing both high light utilization and geometric variability through dynamic control
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 approach enables flexible variation of the illuminated field geometry with reduced light losses, potentially eliminating the need for a field stop and simplifying the system design, while ensuring sharp edges and consistent intensity across the field.
Implementation Method 1
a beam deflecting device including a beam deflection array of reflective or transparent beam deflecting elements
Implementation Method 2
a beam deflecting device including a beam deflection array of reflective or transparent beam deflecting elements
Data Source
AI summary
An illumination system of a microlithographic projection exposure apparatus includes an optical raster element configured to produce a plurality of secondary light sources located in a system pupil surface. The optical raster element has a plurality of light entrance facets, each being associated with one of the secondary light sources. A beam deflecting device includes a beam deflection array of reflective or transparent beam deflecting elements, each being configured to illuminate a spot on one of the light entrance facets at a position that is variable by changing a deflection angle produced by the beam deflecting element. A control unit is configured to control the beam deflection elements such that variable light patterns assembled from the spots can be formed on at least one of the plurality of light entrance facets.