Immersion Lithography Measurement Structure Material Design
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Solution Overview
Problem
Existing projection exposure apparatuses face challenges in measuring projection lenses effectively, particularly when immersed in liquid, due to degradation issues and limited resistance to immersion liquids, which affect the accuracy and longevity of measurement structures.
Innovation Solution
A microlithographic projection exposure apparatus with a measurement structure comprising silicon oxide, silicon oxynitride, and nitride materials, including absorption layers made of metal silicon dioxide, molybdenum silicon oxynitride, and metal nitrides, arranged in the immersion liquid to generate measurement patterns and perform polarized wavefront, stray light, and shearing interferometer measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a measurement structure is placed in immersion liquid for measuring projection lenses, then measurement capability is enabled, but the measurement structure degrades due to immersion liquid exposure
Solution Approach 1:
The measurement structure uses a composite material system consisting of a silicon oxide base layer combined with nitride layers (such as silicon nitride or tantalum nitride). This composite structure provides both the mechanical stability needed for measurement and enhanced resistance to immersion liquid degradation, resolving the contradiction between enabling measurement in liquid and maintaining structure longevity.
Solution Approach 2:
The patent modifies the chemical composition parameters of the measurement structure by incorporating nitride materials with higher chemical stability and lower reactivity toward immersion liquids. This parameter change in material composition maintains measurement functionality while significantly improving resistance to liquid-induced degradation.
2Adaptability or versatility
If conventional measurement structures are used in immersion liquid, then measurement can be performed, but degradation resistance is limited
Solution Approach 1:
The measurement structure employs a multi-layer composite design where silicon oxide provides structural integrity and nitride layers provide chemical resistance. This composite approach maintains the adaptability needed for various measurement tasks while significantly enhancing reliability in immersion liquid environments.
Solution Approach 2:
Different regions of the measurement structure have different material compositions optimized for their specific functions: silicon oxide in areas requiring structural stability and nitride materials in areas requiring maximum chemical resistance. This local differentiation maintains overall functionality while maximizing immersion liquid resistance.
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 proposed solution significantly enhances the measurement structure's resistance to degradation, improves reproducibility, and extends its lifetime, enabling more accurate and reliable measurements of projection lenses, even in immersion liquid environments.
Implementation Method 1
the measurement structure is set up for scattering or diffracting a light beam in an exposure apparatus
Implementation Method 2
the measurement structure is set up for scattering or diffracting a light beam in an exposure apparatus
Implementation Method 3
The measurement structure can have an optical density in the range of 3 at a wavelength of 193 nm
Data Source
AI summary
Microlithographic projection exposure apparatus (100) has a projection lens (150) configured to image an object plane (155) onto an image plane (156), wherein an immersion liquid is at least temporarily provided during operation of the projection exposure apparatus between the projection lens and the image plane, wherein a measurement structure (121) is arranged in the immersion liquid, and wherein the measurement structure is configured to generate a measurement pattern. The projection exposure apparatus also has a measurement device (130, 160) configured to measure the measurement pattern. The measurement structure has an absorption layer (125) including silicon oxide and/or silicon oxynitride and/or nitride.