Beam Deflection Array for Microlithography Mask Illumination
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Solution Overview
Problem
Current microlithographic projection exposure systems face limitations in adjusting illumination settings, particularly in producing a wide range of angular distributions on the mask, due to the complexity and inefficiency of existing systems, which often require multiple optical components and are inflexible in adapting to different illumination needs.
Innovation Solution
An illumination system with a beam deflection array of variable reflective or transparent elements, positioned near the object plane, allows for precise control of light deflection angles to achieve a variety of angular distributions on the mask, integrated with a field defining raster element and optional pupil defining raster element to produce field-dependent and arbitrary intensity distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple optical components are used to adjust illumination settings, then a wide range of angular distributions can be achieved, but the system complexity increases
Solution Approach 1:
The illumination system is segmented into multiple independently controllable beam deflection elements (micro-mirrors) arranged in a grid pattern. Each micro-mirror can be individually tilted to deflect light rays at different angles, enabling precise control of angular distributions without requiring complex optical components. This segmentation allows the system to achieve versatile illumination settings through simple, modular elements.
Solution Approach 2:
The beam deflection elements are made dynamically adjustable through active control mechanisms. Each micro-mirror can change its tilt angle in real-time based on control signals, allowing the system to adapt illumination settings dynamically. This dynamic capability replaces static multiple optical components with a single reconfigurable array, reducing system complexity while maintaining adaptability.
2Adaptability or versatility
If conventional illumination systems are used, then the system structure is simple, but the flexibility in adapting to different illumination needs is limited
Solution Approach 1:
The beam deflection array serves multiple functions simultaneously: it defines the illuminated field shape, controls angular distributions, and adjusts intensity patterns. This multi-functional element replaces what would traditionally require separate optical components for each function, achieving versatility without proportional increases in system complexity.
Solution Approach 2:
The system achieves different illumination settings by changing the tilt angles of beam deflection elements rather than physically reconfiguring optical components. This parameter-based control (adjusting angles through electrical signals) provides flexible adaptation to different illumination needs while maintaining a fixed, simple system structure.
3Productivity
If existing systems are used to produce various angular distributions, then the basic illumination function is achieved, but the efficiency and uniformity are insufficient
Solution Approach 1:
The system incorporates feedback control mechanisms where control signals are adjusted based on desired illumination patterns. The tilt angles of beam deflection elements are precisely controlled through feedback loops that ensure uniform angular distributions across the illuminated field, improving both efficiency and uniformity compared to conventional systems.
Solution Approach 2:
The patent replaces mechanical optical component adjustments with electronic control of micro-mirror tilt angles. This substitution enables faster, more efficient adjustment of angular distributions while achieving superior uniformity through precise electronic actuation and control, eliminating the limitations of mechanical reconfiguration systems.
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 enables flexible and efficient production of various illumination settings with reduced system complexity, allowing for continuous adjustment of angular distributions and improved uniformity, enhancing the capability to adapt to different mask patterns and structures.
Implementation Method 1
Each beam deflection element is adapted to deflect an impinging light ray by a deflection angle which is variable in response to a control signal
Data Source
AI summary
An illumination system for illuminating a mask in a scanning microlithographic projection exposure apparatus has an objective with an object plane, at least one pupil surface and an image plane in which a mask can be arranged. A beam deflection array of reflective or transparent beam deflection elements is provided, where each beam deflection element is adapted to deflect an impinging light ray by a deflection angle that is variable in response to a control signal. The beam deflection elements are arranged in or in close proximity to the object plane of the objective.