T-SAXS Overlay Metrology for Translation and Deformation Defects
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Solution Overview
Problem
Existing methods for measuring defects in microelectronic components, such as overlay defects resulting from the superposition of two networks of lines, are limited in their ability to extract information on the geometry of the control pattern beyond simple translations.
Innovation Solution
A method utilizing small-angle X-ray scattering (SAXS) techniques, specifically Critical-Dimension Small Angle X-ray Scattering (CD-SAXS) by transmission (T-SAXS), to measure defects by analyzing the spatial Fourier transform of the control pattern, allowing for the extraction of parameters such as translation angle α and deformation angle β moy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If T-SAXS technique is used to measure overlay defects, then measurement capability is improved, but the ability to extract comprehensive geometric information is limited
Solution Approach 1:
The patent transforms the measurement approach by moving from analyzing only the position of the main maximum (one-dimensional information) to analyzing the positions of multiple secondary maxima (multi-dimensional information). This dimensional expansion in the data analysis space enables extraction of both translation angle α and deformation angle β moy, comprehensively characterizing the overlay defect geometry.
Solution Approach 2:
The patent segments the diffraction pattern analysis into multiple independent components: the main maximum position provides translation information (angle α), while secondary maxima positions provide deformation information (angle β moy). This segmentation allows independent extraction of different geometric parameters from the same measurement data, resolving the information extraction limitation.
2Ease of operation
If only main maximum position is analyzed, then measurement simplicity is maintained, but measurement completeness deteriorates
Solution Approach 1:
The patent applies partial action by selectively using only the necessary secondary maxima (at least one, preferably the first) for deformation measurement, while maintaining the main maximum for translation measurement. This partial use of available data achieves complete geometric characterization without requiring excessive complex analysis of all possible maxima, balancing simplicity and completeness.
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 the precise measurement of both translation and deformation defects in microelectronic components, providing a comprehensive description of the overlay geometry and improving manufacturing quality control.
Implementation Method 1
An X-ray source S emits an X-ray beam in a direction z 0 , perpendicular to an observation plane P
Implementation Method 2
The image in the observation plane P is related to the spatial Fourier transform of the control pattern Z illuminated by the incident beam
Implementation Method 3
method for measuring by small angle X-ray scattering - CD-SAXS (according to the English "Critical-Dimension Small Angle X-ray Scattering") by transmission (called T-SAXS for "transmission - Small Angle X-ray Scattering")
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
This method (100) measures, by a small-angle X-ray scattering technique by transmission, a defect affecting a pattern resulting from the superposition of two line arrays carried by a microelectronic component, an xyz frame being associated with the component, the lines being oriented along the y direction and the arrays being superimposed along the z direction. This method consists of: acquiring (110) intensity measurements for a plurality of X-ray beam incidence angles; reconstructing (120), from the intensity measurements, two Bragg rods; determining (130) a translation angle from a difference between the positions according to the spatial frequency qz of the principal maxima of the two Bragg rods; and determining (140) a deformation angle from a difference between the positions according to the spatial frequency qz of the ith secondary maxima of the two Bragg rods.