Combined X-ray Optical Metrology for Semiconductor Structures
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Solution Overview
Problem
Current semiconductor metrology techniques face challenges in accurately measuring complex 3D structures and opaque materials due to limitations in optical penetration and increased parameter correlation, especially as devices approach nanometer-scale dimensions.
Innovation Solution
A combined analysis system that utilizes both x-ray and optical measurement technologies to determine structural and material characteristics by treating shared parameters as constants, reducing correlations and improving measurement sensitivity and accuracy through sequential or parallel data analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If optical metrology techniques are used to measure semiconductor structures, then high throughput is achieved, but measurement precision deteriorates for complex 3D structures and opaque materials
Solution Approach 1:
The patent combines x-ray reflectometry and x-ray fluorescence measurements with optical scatterometry measurements into a unified analysis framework. By merging multiple measurement technologies, the system achieves both high throughput (from optical methods) and high precision (from x-ray methods), resolving the contradiction between productivity and measurement precision for complex semiconductor structures
Solution Approach 2:
The patent creates a composite measurement approach that integrates data from different physical measurement modalities (optical and x-ray). This composite measurement strategy allows the system to leverage the strengths of each technique—optical for throughput and x-ray for precision—thereby achieving both high productivity and high measurement precision simultaneously
2Measurement precision
If multiple measurement technologies are combined to characterize complex structures, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent implements a universal analysis framework that processes multiple types of measurement data (optical scatterometry and x-ray reflectometry/fluorescence) through a single unified model fitting engine. This multi-functional approach improves measurement accuracy while avoiding the need for separate complex analysis systems for each measurement type, thereby managing device complexity
3Reliability
If optical radiation is used to measure high-aspect ratio 3D structures, then non-destructive measurement is achieved, but measurement precision deteriorates due to penetration limitations
Solution Approach 1:
The patent uses x-ray radiation as an intermediary measurement modality that can penetrate high-aspect ratio 3D structures where optical radiation fails. The x-ray measurements serve as a mediator that provides precise data for deep structural parameters, while optical measurements continue to provide non-destructive surface and near-surface information, together achieving both reliability and precision
4Loss of information
If more parameters are used to characterize complex structures, then measurement completeness improves, but parameter correlation increases reducing measurement accuracy
Solution Approach 1:
The patent segments the measurement parameters into distinct categories handled by different measurement modalities: optical scatterometry handles surface and near-surface parameters, while x-ray reflectometry and fluorescence handle deep structural and compositional parameters. This segmentation reduces parameter correlation by assigning related parameters to the same measurement type, thereby improving both measurement completeness and accuracy
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
Enhances measurement precision and accuracy by leveraging the complementary nature of x-ray and optical techniques, effectively addressing the challenges of complex geometries and opaque materials in semiconductor fabrication.
Implementation Method 1
x-ray measurement data of a specimen is analyzed
Implementation Method 2
x-ray and optical metrology
Implementation Method 3
optical metrology techniques including scatterometry and reflectometry
Implementation Method 4
scatterometry measurements are performed
Data Source
AI summary
Structural parameters of a specimen are determined by fitting models of the response of the specimen to measurements collected by different measurement techniques in a combined analysis. X-ray measurement data of a specimen is analyzed to determine at least one specimen parameter value that is treated as a constant in a combined analysis of both optical measurements and x-ray measurements of the specimen. For example, a particular structural property or a particular material property, such as an elemental composition of the specimen, is determined based on x-ray measurement data. The parameter(s) determined from the x-ray measurement data are treated as constants in a subsequent, combined analysis of both optical measurements and x-ray measurements of the specimen. In a further aspect, the structure of the response models is altered based on the quality of the fit between the models and the corresponding measurement data.