Overlapping Mirror Light Modulator for Microlithography
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Solution Overview
Problem
In microlithographic projection exposure apparatuses, the risk of light heating up and damaging sensitive components underneath the mirror array is significant, and existing solutions often require complex and costly concentrating optics to mitigate this issue.
Innovation Solution
A light modulator with an array of mirrors supported by a modulator substrate, where adjacent mirrors overlap to shield sensitive components, and absorptive elements are used to prevent light from penetrating through gaps, either attached to the mirrors or ridges, reducing the need for additional light shields and minimizing stray light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If concentrating optics are used to separate projection light into sub-beams, then light-induced heating and damage to sensitive components is reduced, but device complexity and cost increase
Solution Approach 1:
The harmful projection light is extracted and blocked by absorptive elements positioned in the gaps between mirrors, separating the light-blocking function from the mirror array structure itself. This eliminates the need for complex concentrating optics while still protecting sensitive components underneath.
Solution Approach 2:
Absorptive elements serve as intermediary components placed between the projection light and sensitive components. These elements directly absorb the harmful light in the gaps between mirrors, providing protection without requiring the complex concentrating optics system.
2Object-affected harmful factors
If absorptive elements are placed in gaps between mirrors, then protection against projection light is improved, but stray light increases
Solution Approach 1:
The absorptive elements are selectively placed only in the specific locations where gaps between mirrors exist, providing localized light absorption exactly where needed. This targeted approach protects sensitive components while minimizing the overall impact on light distribution and reducing stray light generation.
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 effectively reduces the risk of light-induced heating and damage to sensitive components without requiring concentrating optics, thereby simplifying the illumination system and reducing costs while minimizing stray light.
Implementation Method 1
each absorber element comprises a surface that is absorptive for the projection light
Implementation Method 2
an array of mirrors that are supported by the modulator substrate
Data Source
AI summary
An illumination system of a microlithographic projection exposure apparatus comprises a light modulator which includes a modulator substrate and an array of mirrors that are supported by the modulator substrate. At least some adjacent mirrors partly overlap. The light modulator further comprises a plurality of actuators that are supported by the modulator substrate and are configured to tilt the mirrors individually.