Lithography Scatterometer Beam Shaper for Target Matching
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Solution Overview
Problem
Current scatterometers face challenges in accurately measuring substrate properties due to beam size and shape mismatches with varying alignment targets, leading to cross-talk between signals from neighboring targets.
Innovation Solution
A scatterometer with a beam shaper that adjusts the radiation beam's cross-section based on the target configuration, allowing for flexible beam shaping to optimize measurement spot size and shape for precise substrate analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed-size beam is used for scatterometry measurements, then the measurement process is simple and fast, but the beam size does not match varying target sizes causing cross-talk between neighboring targets
Solution Approach 1:
The patent implements dynamic beam shaping by replacing fixed apertures with variable aperture masks that can change size and shape in real-time. The beam shaper includes variable aperture masks that dynamically adjust to match the dimensions and configuration of different targets, eliminating cross-talk while maintaining measurement precision across varying target sizes.
Solution Approach 2:
The patent applies local quality by customizing the beam cross-section to match the specific local characteristics of each target. Different aperture configurations are used for different target types and sizes, with the beam shape adapted to the specific measurement requirements of each target region, thereby optimizing measurement accuracy for diverse target configurations.
2Reliability
If the beam cross section is adjusted to match the target, then cross-talk between neighboring targets is reduced, but the device complexity increases due to additional beam shaping components
Solution Approach 1:
The patent introduces a beam shaper as an intermediary component between the light source and the target. This beam shaper includes variable aperture masks and optical elements that condition the beam to match the target configuration, acting as a mediator that translates diverse target requirements into optimized beam parameters, thereby improving signal quality without requiring fundamental redesign of the entire measurement system.
Solution Approach 2:
The patent implements universality through a multi-functional beam shaper that can handle various target types, sizes, and configurations using a single integrated system. The variable aperture masks and optical elements work together to provide universal beam shaping capability across different measurement scenarios, reducing the need for multiple specialized measurement setups.
3Ease of manufacture
If a single fixed aperture is used for all target types, then the device structure is simple, but measurement precision deteriorates due to mismatch with varying target dimensions
Solution Approach 1:
The patent applies segmentation by dividing the aperture system into multiple variable aperture masks that can be selectively activated or combined. Instead of using a single fixed aperture, the system segments the beam shaping function into adjustable components that can be independently configured to match different target dimensions, thereby improving measurement precision while maintaining manufacturing feasibility through modular design.
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 enhances measurement accuracy and sensitivity by ensuring the beam size and shape match the target, reducing cross-talk and improving the quality of measurement signals, thereby providing a more representative and reliable analysis of substrate properties.
Implementation Method 1
a scatterometer in which a beam of radiation is directed onto a target on the surface of the substrate and properties of the scattered or reflected beam are measured
Implementation Method 2
detecting a spectrum of the radiation beam reflected from a target on the surface of the substrate
Implementation Method 3
a beam shaper interposed in the radiation path between the radiation source and the detector, the beam shaper being configured to adjust the cross section of the beam dependent on the configuration of the target
Implementation Method 4
Spectroscopic scatterometers direct a broadband radiation beam onto the substrate and measure the spectrum (intensity as a function of wavelength) of the radiation scattered into a particular narrow angular range
Data Source
AI summary
A scatterometer configured to measure a property of a substrate, includes a radiation source configured to provide a radiation beam; and a detector configured to detect a spectrum of the radiation beam reflected from a target (30) on the surface of the substrate (W) and to produce a measurement signal representative of the spectrum. The apparatus includes a beam shaper (51, 53) interposed in the radiation path between the radiation source and the detector, the beam shaper being configured to adjust the cross section of the beam dependent on the shape and/or size of the target.