Scanning Electron Microscope On-Axis Angle Discrimination
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Solution Overview
Problem
Scanning electron microscopes face challenges in accurately discriminating the angle of electrons ejected from miniaturized samples without relying on angle restriction openings, which are typically required to guide electrons outside the electron beam axis, and in maintaining energy resolution when detecting secondary electrons from deep patterns in semiconductor devices.
Innovation Solution
A scanning electron microscope configuration that includes a deflector to control the electron beam, a secondary signal deflector to direct electrons toward an opening for the electron beam, and a control unit to manage the deflection, allowing for accurate angle discrimination of electrons without external angle restriction openings and maintaining energy resolution by using a secondary electron restriction plate and energy filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an opening for angle restriction is installed outside the electron beam axis to guide electrons, then electron angle discrimination is improved, but device complexity increases due to additional opening requirements
Solution Approach 1:
The patent combines the electron beam passage opening and the angle restriction function into a single opening located on the electron beam axis. The opening serves dual purposes: allowing the electron beam to pass through to irradiate the sample and simultaneously restricting electron angles for detection. This merging eliminates the need for separate angle restriction openings outside the beam axis, reducing device complexity while maintaining angle discrimination capability.
Solution Approach 2:
The opening configured in the electron beam passage serves multiple functions: it acts as both the beam transmission channel and the angle restriction aperture. By making the opening universal, the patent eliminates the need for additional specialized components, thereby simplifying the overall device structure while achieving the desired electron angle discrimination.
2Measurement precision
If electrons are detected by being deflected outside the electron beam axis, then angle discrimination is achieved, but detection efficiency decreases due to electron loss
Solution Approach 1:
Instead of deflecting electrons outside the beam axis for angle discrimination as in conventional systems, this patent inverts the approach by using an on-axis opening to achieve angle restriction. Electrons are detected while maintaining their passage through the central opening, eliminating the need for external deflection and reducing electron loss in the process.
3Productivity
If the visual field moves at high speed for high throughput measurement, then productivity is improved, but measurement precision may deteriorate due to reduced sampling time
Solution Approach 1:
The patent implements preliminary focusing and alignment of the electron beam and detection system to ensure that even during high-speed visual field movement, the beam remains properly positioned and focused on the sample. This preliminary preparation allows the system to maintain measurement precision during rapid scanning by eliminating the need for complex real-time adjustments.
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
Enables precise angle discrimination of electrons from samples without external angle restriction, maximizing detection efficiency and maintaining constant energy resolution, even in complex three-dimensional patterns, by directing electrons through the electron beam opening and using energy filters to emphasize specific pattern contrasts.
Implementation Method 1
a deflector for deflecting an orbit of an electron ejected from the sample
Implementation Method 2
an electron source, a deflector to deflect an irradiating position of an electron beam emitted from the electron source
Data Source
AI summary
It is an object of the present invention to provide a scanning electron microscope for discriminating an angle of an electron ejected from a sample without providing an opening for restricting the angle at outside of an axis. In order to achieve the object described above, there is proposed a scanning electron microscope which includes a deflector to deflect an irradiating position of an electron beam, and a control unit to control the deflector, and further includes a detector to detecting an electron provided by irradiating a sample with the electron beam, an opening configuring member arranged between the detector and the deflector and having an opening for passing the electron beam, and a secondary signal deflector to deflect an electron ejected from the sample, in which the secondary signal deflector is controlled to deflect the electron ejected from the sample toward an opening of passing the electron beam in accordance with a deflection control of the deflector.