Electron Beam Device Deconvolution for Deep Groove Imaging
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Solution Overview
Problem
Conventional scanning electron microscopes face challenges in accurately measuring the intensity distribution of a primary beam, leading to difficulties in improving image resolution, especially when observing deep grooves or holes, due to low signal detection efficiency and uncontrollable electron source images.
Innovation Solution
An electron beam device with an electron optical system that projects a first aperture image onto a sample, using a detector to capture secondary electrons and an image processing unit to deconvolute electron beam intensity distribution information, generating a high-resolution image by processing two-dimensional data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amperage of electron beam is increased to increase signal amount for observing deep groove or deep hole, then the signal amount is improved, but the beam blur caused by defocus increases and it becomes difficult to observe the bottom of deep groove or deep hole separately from the upper part
Solution Approach 1:
The patent applies preliminary action by measuring the electron beam intensity distribution before image acquisition using a beam intensity distribution measurement method. This allows the point spread function to be determined in advance, enabling subsequent deconvolution processing to remove beam blur effects from the observed image, thereby resolving the contradiction between signal amount and observation precision.
Solution Approach 2:
The patent introduces an intermediary element - the point spread function derived from electron beam intensity distribution measurement - that mediates between the raw observed image and the final processed image. By using this intermediary to characterize the beam blur and applying deconvolution, the system can maintain high signal amounts while eliminating the corresponding blur to achieve precise observation of deep groove bottoms.
2Measurement precision
If image processing is used to improve resolution, then the resolution is improved, but accurate measurement of primary beam intensity distribution is required which is difficult to obtain due to low detection efficiency
Solution Approach 1:
The patent extracts the electron beam intensity distribution information separately from the actual sample observation process. By using a dedicated measurement mode that captures beam profile data independently, the system obtains the necessary point spread function without the complications of low signal detection during normal imaging, enabling accurate image processing while maintaining detection efficiency for sample observation.
Solution Approach 2:
The patent performs beam intensity distribution measurement as a preliminary step before sample observation. This allows the system to obtain accurate beam profile data when detection conditions can be optimized for this specific measurement, rather than attempting to measure it during low-signal sample imaging. The pre-obtained intensity distribution is then used for deconvolution processing to improve resolution.
3Quantity of substance
If large current is used for observing deep groove or deep hole, then the signal amount is sufficient, but the electron source image cannot be controlled and machine difference increases
Solution Approach 1:
The patent measures the electron beam intensity distribution and determines the device-specific point spread function in advance, before sample observation. This preliminary characterization captures the unique beam properties of each device under large current conditions, allowing subsequent deconvolution processing to compensate for machine differences. This enables consistent results across different devices despite variations in electron source images under high current operation.
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-resolution imaging of deep grooves or holes under large current conditions, effectively improving image resolution and reducing machine differences between electron beam devices.
Implementation Method 1
accelerating electrons emitted from an electron source
Implementation Method 2
converging the electrons on the sample surface by an electrostatic lens or an electromagnetic lens
Implementation Method 3
Secondary electrons are emitted from the sample by the incidence of the primary electrons
Implementation Method 4
an electron beam is deflected and scans the surface of the sample
Data Source
AI summary
An electron beam device suitable for observing the bottom of a deep groove or hole with a high degree of accuracy under a large current condition includes: an electron optical system having an irradiation optical system to irradiate a first aperture with an electron beam emitted from an electron source and a reduction projection optical system to project and form an aperture image of the first aperture on a sample, detectors to detect secondary electrons emitted by irradiating the sample with the electron beam through the electron optical system. An image processing unit generates a two-dimensional image from detection signals obtained by irradiating the sample while the electron beam scans the sample two-dimensionally by scanning deflectors of the electron optical system. Further, generates a reconstructed image by deconvoluting electron beam intensity distribution information of an ideal aperture image of the first aperture from the generated two-dimensional image information.