XPS Film Measurement in Small Boxes Using Multi-Spot Deconvolution
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Solution Overview
Problem
The challenge in characterizing and measuring film layers within small box regions using X-ray photoelectron spectroscopy (XPS) arises due to the difficulty in distinguishing signals from within the box and those from surrounding areas, as the X-ray beam size often exceeds the box dimensions, leading to spillage and inaccurate analysis.
Innovation Solution
The method employs multiple XPS measurements with beams of different spot sizes to determine the mixing fraction of the X-ray beam inside and outside the box, allowing for the calculation of the film layer thickness by using a merit function that accounts for the attenuation of signals and the contribution of species signals from both regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single XPS measurement is performed with a fixed beam size, then the measurement process is simple and fast, but the signal contains mixed contributions from inside and outside the box making it impossible to accurately determine the film layer properties within the small box region
Solution Approach 1:
The measurement process is segmented into multiple measurements with different beam spot sizes. The first measurement uses a larger beam to capture signals from both inside and outside the box, while the second measurement uses a smaller beam to capture signals primarily from inside the box. This segmentation allows the mixing fraction to be calculated and used to deconvolve the mixed signals, thereby achieving accurate film layer characterization within the small box region.
2Measurement precision
If the X-ray beam size is reduced to fit within the small box region, then the signal originates only from within the box, but the beam may be too small to collect sufficient signal for accurate measurement
Solution Approach 1:
The invention merges the information from two measurements with different beam spot sizes. The larger beam provides sufficient signal intensity by collecting electrons from a larger area, while the smaller beam provides spatial selectivity. By combining these measurements and using the mixing fraction to separate the contributions, the method achieves both sufficient signal intensity and spatial selectivity for accurate film layer characterization.
3Quantity of substance
If a larger X-ray beam is used to ensure sufficient signal collection, then the signal intensity is adequate, but the signal becomes a mixture from inside and outside the box region making it difficult to ascertain the contribution from within the box
Solution Approach 1:
The invention uses feedback by performing a second measurement with a smaller beam spot size that provides information about the signal from inside the box. This second measurement feeds back into the analysis of the first measurement, allowing the mixing fraction to be calculated. The mixing fraction then serves as a correction factor to accurately determine the film layer properties within the box region, even when using the larger beam for sufficient signal intensity.
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 enhances the accuracy of film layer thickness measurement and composition analysis within small box regions by effectively separating the signals from within and outside the box, providing precise characterization of thin film layers.
Implementation Method 1
XPS spectra are obtained by irradiating the substrate with a beam of X-rays, while simultaneously measuring the kinetic energy and number of electrons that escape from the top layers of the substrate
Data Source
AI summary
A system to characterize a film layer within a measurement box is disclosed. The system obtains a first mixing fraction corresponding to a first X-ray beam, the mixing fraction represents a fraction of the first X-ray beam inside a measurement box of a wafer sample, the measurement box represents a bore structure disposed over a substrate and having a film layer disposed inside the bore structure. The system obtains a contribution value for the measurement box corresponding to the first X-ray beam, the contribution value representing a species signal outside the measurement box that contributes to a same species signal inside the measurement box. The system obtains a first measurement detection signal corresponding to a measurement of the measurement box using the first X-ray beam. The system determines a measurement value of the film layer based on the first measurement detection signal, the contribution value, and the first mixing fraction.