Electron Backscattering Thickness Estimation by Direct Electron Counting
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Solution Overview
Problem
Conventional methods for determining the thickness of thin films in semiconductor components face challenges such as difficulty in measuring on a small scale, evaluating signal strength, and inaccuracies in results, particularly for specific film materials.
Innovation Solution
A method using electron backscattering data with a direct charged particle detector to count backscattered electrons and determine a statistical electron characteristic, fitting this to a thickness function to estimate film thickness, independent of detector brightness and gain settings, and applicable to samples with varying crystal orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional backscattering methods are used for thickness determination, then measurement capability is provided, but measurement precision and reliability are reduced due to signal evaluation difficulties and inaccuracies
Solution Approach 1:
The patent replaces conventional indirect signal detection methods with direct electron counting using a direct electron detector. This substitution of the detection mechanism eliminates the need for complex signal strength evaluation and provides accurate electron count data for thickness measurement, directly resolving the contradiction between measurement precision and detection difficulty
Solution Approach 2:
The patent creates a thickness function model that maps statistical electron characteristics to physical thickness values. This modeling approach copies the relationship between electron backscattering statistics and thickness, enabling accurate thickness determination from electron count data without direct physical measurement, thus improving precision while simplifying detection
2Reliability
If conventional backscattering methods are used, then thickness measurement is attempted, but reliability is reduced due to sensitivity to detector brightness and gain settings
Solution Approach 1:
The patent replaces conventional detectors that require brightness and gain adjustments with a direct electron detector that directly counts electrons. This substitution eliminates the complex detector settings and their variability, ensuring reliable and repeatable measurements without sensitivity to operational parameters
Solution Approach 2:
The patent changes the fundamental measurement parameter from analog signal strength (affected by brightness/gain) to discrete electron counts (invariant to detector settings). This parameter transformation ensures that measurements are independent of detector configuration, improving reliability while reducing operational complexity
3Measurement precision
If conventional methods are used for thin film measurement, then general applicability is provided, but measurement precision is reduced for specific film materials and small scales
Solution Approach 1:
The patent develops a thickness function model that captures the relationship between electron backscattering statistics and thickness for different materials. This modeling approach allows the system to adapt to various film materials by establishing material-specific relationships, improving precision for thin films while maintaining versatility through the generalizable modeling framework
Solution Approach 2:
The patent uses statistical electron characteristics (mean, variance, higher-order moments) as measurement parameters that scale appropriately with film thickness and material properties. By changing from fixed measurement parameters to scalable statistical parameters, the system achieves high precision for thin films while remaining adaptable to different materials and thickness ranges
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
Provides accurate and repeatable thickness measurements by directly counting backscattered electrons, compensating for crystal orientation variations, and enabling precise thickness estimation of thin films and layers.
Implementation Method 1
obtaining backscattered electron data of the sample using a direct charged particle detector... when an electron beam is incident upon the sample
Data Source
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AI summary
There is described a method of determining parameters of a thickness function for estimating a thickness of a sample. The thickness function defines a relationship between the thickness of the sample and a statistical electron characteristic. The method comprises obtaining backscattered electron data of the sample using a direct charged particle detector comprising an array of pixels and configured to count the number of backscattered electrons detected by each pixel of the array when an electron beam is incident upon the sample. The backscattered electron data comprises data sets. The data sets comprise the number of backscattered electrons detected by each pixel of the array when the electron beam is incident upon a respective region of the sample. The method further comprises determining, for each data set, a respective statistical electron characteristic, and then fitting the known thicknesses and the determined statistical electron characteristic to the thickness function to determine the parameters of the thickness function. As part of the method, the thickness of the sample at each respective region is known. A system for determining parameters of the thickness function for estimating the thickness of the sample is also described.