SAXS Tilt Measurement for High Aspect Ratio Semiconductor Structures
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Solution Overview
Problem
Current metrology techniques for characterizing high aspect ratio structures in semiconductor devices are time-consuming and destructive, requiring extensive sample preparation and prior information for analysis.
Innovation Solution
The use of small angle X-ray scattering (SAXS) to determine average parameters such as tilt, sidewall angle, and bowing in high aspect ratio structures without destructive sample preparation or prior information, employing tilted structural symmetry analysis (TSSA-SAXS) to analyze symmetry and detect asymmetry in scattering patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cross-sectional SEM imaging is used to determine tilt of HAR structures, then tilt measurement can be performed, but sample preparation becomes cumbersome, destructive, and time consuming
Solution Approach 1:
The patent replaces mechanical/sample-destructive SEM imaging with non-destructive X-ray scattering physics. X-rays penetrate the sample without requiring physical sectioning, and the scattering patterns provide tilt information through symmetry analysis, eliminating the need for destructive sample preparation while maintaining measurement capability
Solution Approach 2:
The patent introduces scattering patterns as an intermediary between the X-ray source and the tilt measurement. The patterns serve as a mediator that encodes structural information including tilt, allowing indirect but non-destructive measurement of HAR structure parameters without direct imaging or sample destruction
2Measurement precision
If traditional metrology techniques are used to characterize HAR structures, then structural parameters can be determined, but the processes become time-consuming
Solution Approach 1:
The patent performs preliminary symmetry analysis of scattering patterns to directly determine tilt and other structural parameters without requiring iterative modeling or multiple measurement steps. The symmetry-based approach provides immediate characterization of HAR structures, significantly reducing measurement time while maintaining precision
Solution Approach 2:
The patent changes the measurement parameter from direct imaging to scattering pattern symmetry analysis. By measuring how scattering intensity distributes symmetrically or asymmetrically at different angles, the method extracts structural parameters including tilt, sidewall angle, and bowing more efficiently than traditional techniques
3Measurement precision
If model-based analysis is used to determine structural parameters, then parameter determination can be performed, but the process requires prior information and becomes more complex
Solution Approach 1:
The patent extracts and utilizes only the symmetry information from scattering patterns, separating this essential measurement data from complex modeling requirements. By focusing exclusively on symmetry analysis, the method determines tilt and other parameters without requiring prior structural models or assumptions, simplifying the analysis process while maintaining precision
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 quick, non-destructive characterization of high aspect ratio structures with high resolution and sensitivity, capable of determining tilt to 0.05°, suitable for current and future semiconductor nodes, and applicable to densely packed samples with low resolution and noisy data.
Implementation Method 1
illuminating a sample including an array of structures with x-ray radiation such that the sample scatters the x-ray radiation
Data Source
AI summary
Provided herein are methods and apparatus for characterizing high aspect ratio (HAR) structures of fabricated or partially fabricated semiconductor devices. The methods involve using small angle X-ray scattering (SAXS) to determine average parameters of an array of HAR structures. In some implementations, SAXS is used to analyze symmetry of HAR structures in a sample and may be referred to as tilted structural symmetry analysis-SAXS (TSSA-SAXS) or TSSA. Analysis of parameters such as tilt, sidewall angle, bowing, and the presence of multiple tilts in HAR structures may be performed.