Electron Beam Observation Device Frequency Domain Correction
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Solution Overview
Problem
Existing electron beam observation devices face challenges in accurately reducing machine differences due to variations in electron beam shape, which are difficult to grasp and correct, especially with the influence of aging and environmental factors.
Innovation Solution
An electron beam observation device that captures images of a reference sample with a specific pattern, calculates frequency characteristics, and uses these to generate correction coefficients for image processing, ensuring that the images from different devices match in frequency characteristics, thereby reducing machine differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If image correction is performed based on estimated primary beam profile using Fourier transformation, then machine difference can be reduced, but measurement precision is limited because the intensity distribution of the primary beam cannot be accurately obtained
Solution Approach 1:
The patent introduces a reference sample with a specific pattern as an intermediary object. By imaging this reference sample, the system indirectly obtains information about the primary beam's intensity distribution without needing to directly measure the beam itself. The reference sample acts as a mediator that converts unmeasurable beam properties into measurable image data.
Solution Approach 2:
The patent replaces the traditional approach of directly measuring and correcting electron beam parameters with an image processing-based correction method. Instead of mechanically adjusting the electron beam to eliminate shape variations, the system captures images and applies frequency domain corrections to compensate for beam shape differences, substituting physical beam control with computational image processing.
2Measurement precision
If hardware or software adjustment is performed to reduce machine difference, then measurement consistency can be improved, but the method approaches its limit with further miniaturization of semiconductor patterns
Solution Approach 1:
The patent changes the approach from adjusting physical hardware parameters (lens currents, stigmator settings) to modifying image processing parameters in the frequency domain. By transforming images to the frequency domain and applying correction coefficients to specific frequency components, the system can compensate for measurement errors without physical hardware adjustments, enabling accurate measurement of finer patterns.
Solution Approach 2:
The patent transitions from spatial domain image processing to frequency domain processing. By applying Fourier transformation, the system converts spatial variations in beam shape into frequency domain characteristics, allowing correction through frequency component adjustment. This dimensional transformation enables more effective compensation for beam shape variations that affect fine pattern measurements.
3Reliability
If electron beam shape variations due to aging or environmental factors are corrected through hardware adjustment, then device reliability can be maintained, but device complexity increases
Solution Approach 1:
The patent implements a self-diagnosis and self-correction system. The device automatically captures images of a reference sample, calculates frequency characteristics, determines correction coefficients, and applies corrections without requiring external intervention or complex hardware adjustment mechanisms. The system serves itself by using its own imaging capability to detect and correct its measurement errors.
Solution Approach 2:
The patent establishes a feedback loop where the device continuously monitors its own performance by imaging a reference sample, compares the measured frequency characteristics against expected values, and automatically adjusts its operation through correction coefficients. This closed-loop feedback system maintains measurement reliability by compensating for drift caused by aging or environmental changes.
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 method effectively reduces machine differences by processing captured images and adjusting them to match the frequency characteristics of a reference device, leading to more accurate length measurements and improved operational management across multiple devices.
Implementation Method 1
accelerates electrons emitted from an electron source
Implementation Method 2
concentrates the electrons by an electrostatic lens or an electromagnetic lens
Implementation Method 3
The sample emits secondary electrons (in some cases, electrons with low energy are referred to as secondary electrons, and electrons with high energy are referred to as reflection electrons) due to the incidence of the primary electrons
Data Source
AI summary
Provided is an electron beam observation device that includes: an electron source; an objective lens concentrating an electron beam emitted from the electron source; and a control unit configured to perform control such that a plurality of images is generated by capturing images of a reference sample having a specific pattern, and a frequency characteristic is calculated for each of the plurality of images, in which an image is generated based on a secondary signal generated from a sample due to irradiation of the sample with the electron beam, and the control unit holds the plurality of frequency characteristics.