In-Line Optical Scatterometry for Roll-to-Roll Web Metrology
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Solution Overview
Problem
Current metrology techniques, such as SEM and AFM, are inadequate for in-line monitoring of semiconductor manufacturing due to their destructive nature, limited sampling, and slow measurement speeds, while existing 2θ scatterometry tools are incompatible with roll-to-roll processes requiring rapid, non-destructive, and areal coverage metrology.
Innovation Solution
A 2θ scatterometry system integrated into a roll-to-roll manufacturing tool, using a laser source with controlled polarization and variable angle of incidence, combined with optical components to focus and collect reflected light, allowing rapid measurement of periodic structures on a moving web.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SEM or AFM is used for dimensional metrology, then measurement precision is improved, but measurement speed and productivity deteriorate
Solution Approach 1:
The patent replaces mechanical scanning systems (SEM/AFM) with a moving web system where the sample moves continuously under a stationary optical sensor. This substitution enables high-speed measurements compatible with roll-to-roll manufacturing while maintaining dimensional metrology precision through optical scatterometry techniques.
Solution Approach 2:
The system transitions from static sample measurement to dynamic measurement on a moving web. The optical sensor captures scatterometry data in real-time as the web moves through the system, enabling continuous monitoring at manufacturing speeds without compromising measurement precision.
2Measurement precision
If SEM or AFM is used for metrology, then measurement precision is improved, but the process becomes destructive or requires vacuum environment
Solution Approach 1:
The patent replaces mechanical contact methods (AFM) and vacuum-based methods (SEM) with non-contact optical scatterometry. This eliminates the need for vacuum environments and destructive sample preparation while maintaining dimensional measurement precision through optical interaction with the sample structures.
3Object-affected harmful factors
If 2θ scatterometry is used for metrology, then non-destructive measurement is achieved, but measurement speed and areal coverage are insufficient for roll-to-roll processes
Solution Approach 1:
The system transforms static scatterometry measurement into a dynamic process where the web moves continuously through the measurement zone. This enables high-speed non-destructive measurement with areal coverage sufficient for roll-to-roll manufacturing by capturing data across the entire web surface during motion.
Solution Approach 2:
The measurement process becomes continuous rather than discrete. As the web moves through the system, scatterometry measurements are continuously captured across multiple locations and time points, providing comprehensive areal coverage and high measurement throughput while maintaining non-destructive operation.
4Manufacturing precision
If multiple metrology steps are added for complex semiconductor devices, then manufacturing precision is improved, but process time and cost increase
Solution Approach 1:
The patent combines multiple metrology functions into a single integrated scatterometry system that simultaneously measures critical dimensions, film thickness, and structural parameters. This consolidation maintains comprehensive quality control for complex semiconductor devices while eliminating the time and cost associated with multiple separate metrology steps.
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
Enables rapid, non-destructive, and areal coverage metrology compatible with roll-to-roll processes, providing real-time monitoring of structure dimensions and defects with improved measurement speed and accuracy.
Implementation Method 1
an optical system configured to control the polarization of the optical beam and to focus the optical beam with a first NA1 on a sample surface
Implementation Method 2
to sweep the angle of incidence across a range of angles with an approximately fixed focal position on a sample surface
Implementation Method 3
additional optical components configured to receive the optical beam reflected from the sample surface and to focus the reflected beam onto a detector
Data Source
AI summary
A system for measuring a periodic array of structures on a sample is provided. The system includes an optical source configured to produce an optical beam; an optical system configured to control the polarization of the optical beam and to focus the optical beam with a first NA1 on a sample surface and to sweep the angle of incidence across a range of angles with an approximately fixed focal position on a sample surface with a second NA2 wherein NA2>NA1; additional optical components configured to receive the optical beam reflected from the sample surface and to focus the reflected beam onto a detector; and a recording system to record the reflectivity of the sample surface as a function of the angle of incidence. In an embodiment, the optical system provides a spot on the sample such that both the angle of incidence and the position on the sample are varied during a sweep. Electronic filtering is provided to separate low frequency signals, corresponding to structural details of the sample, and high frequency signatures, corresponding to localized defects on the sample.