Full-Beam X-Ray Scatterometry for Low-Correlation 3D Metrology
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Solution Overview
Problem
Current x-ray scatterometry systems face challenges in accurately measuring complex, three-dimensional semiconductor structures due to penetration issues and parameter correlation, especially with the increasing use of opaque materials and smaller feature sizes.
Innovation Solution
The implementation of full beam x-ray scatterometry systems that simultaneously measure the zero diffraction order and higher diffraction orders, using photon counting detectors with high dynamic range and thick, highly absorptive crystal substrates to absorb the direct beam without damage, thereby improving measurement accuracy and reducing parameter correlation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional scatterometry measures only higher diffraction orders while blocking zero order, then measurement dynamic range is reduced, but direct beam information is lost
Solution Approach 1:
The patent combines the measurement of both zero order (direct beam) and higher diffraction orders into a single unified measurement process. The detector simultaneously captures both the direct beam and scattered radiation, merging previously separate measurement channels into one comprehensive system that preserves all beam information.
Solution Approach 2:
The patent extends the measurement from traditional single-dimension (higher orders only) to multi-dimension by incorporating zero order measurements alongside higher diffraction orders. This dimensional expansion in measurement space allows simultaneous capture of direct beam and scattered radiation intensities, providing more complete structural information.
2Length of stationary object
If longer wavelengths are used to penetrate deep into 3D FLASH structures, then depth penetration is improved, but light intensity decreases and sensitivity is lost
Solution Approach 1:
The patent changes the illumination wavelength parameter to X-ray range, which fundamentally alters the penetration characteristics. X-rays provide both deep penetration capability and sufficient interaction strength with the material, resolving the trade-off between penetration depth and measurement sensitivity that plagues longer wavelength optical methods.
Solution Approach 2:
The patent substitutes optical radiation with X-ray radiation, replacing the optical measurement mechanism with an X-ray scattering mechanism. This substitution enables deep penetration into opaque and high-aspect-ratio structures while maintaining measurement sensitivity through the detection of X-ray diffraction patterns.
3Loss of information
If multiple angles of illumination and shorter wavelengths are used, then measurement information is increased, but device complexity increases
Solution Approach 1:
The patent creates a universal X-ray scatterometry system that can measure multiple parameters (critical dimensions, material composition, layer thicknesses) simultaneously through a single measurement configuration. The system uses fixed-angle X-ray illumination with detection of both zero and higher orders, providing multi-functional measurement capability without requiring complex multi-angle scanning mechanisms.
4Device complexity
If conventional optical metrology is used on opaque high-k materials, then measurement simplicity is maintained, but measurement capability is lost
Solution Approach 1:
The patent changes the fundamental measurement parameter from optical wavelength to X-ray wavelength, enabling penetration through and scattering from opaque high-k materials. This parameter change transforms the measurement capability to handle previously inaccessible materials while maintaining a relatively simple scatterometry measurement configuration.
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 enables high throughput measurements with improved accuracy, allowing for the characterization of dimensions and material properties of semiconductor devices, including those with high aspect ratios and opaque materials, while reducing measurement uncertainty and parameter correlation.
Implementation Method 1
photon counting detectors with high dynamic range and thick, highly absorptive crystal substrates that absorb the direct beam without damage
Implementation Method 2
scatterometry and reflectometry implementations and associated analysis algorithms are commonly used to characterize critical dimensions, film thicknesses, composition and other parameters of nanoscale structures
Implementation Method 3
detecting the intensities of the resulting zero diffraction order and higher diffraction orders
Data Source
AI summary
Methods and systems for characterizing dimensions and material properties of semiconductor devices by full beam x-ray scatterometry are described herein. A full beam x-ray scatterometry measurement involves illuminating a sample with an X-ray beam and detecting the intensities of the resulting zero diffraction order and higher diffraction orders simultaneously for one or more angles of incidence relative to the sample. The simultaneous measurement of the direct beam and the scattered orders enables high throughput measurements with improved accuracy. The full beam x-ray scatterometry system includes one or more photon counting detectors with high dynamic range and thick, highly absorptive crystal substrates that absorb the direct beam with minimal parasitic backscattering. In other aspects, model based measurements are performed based on the zero diffraction order beam, and measurement performance of the full beam x-ray scatterometry system is estimated and controlled based on properties of the measured zero order beam.