Compact LEED Module for SEM Integration
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Solution Overview
Problem
Conventional LEED devices are too large to fit within the equipment ports of commercially available SEMs, limiting their use for analyzing surface structures and interfering with other detectors, and they lack the capability to image atomic structures due to a large probe electron beam spot size.
Innovation Solution
A compact LEED detection module with a first vacuum chamber, a two-dimensional electron detector, a potential shield, a magnetic lens, and a plane-shaped energy filter, designed to be inserted into an SEM's equipment port, allowing for focused and collimated electron beam analysis with a small probe beam spot size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LEED apparatus uses spherical shaped metal grids for energy filtering, then energy filtering capability is achieved, but the device size becomes large (5 cm to 10 cm in diameter) and cannot fit within SEM chambers
Solution Approach 1:
The patent changes the fundamental parameters of the energy filter by replacing spherical grids with plane-shaped grids and altering the geometric configuration from radial to planar. This parameter change enables the filter to achieve the same energy filtering function while reducing the device footprint to fit within SEM chambers.
Solution Approach 2:
The invention transitions from a three-dimensional spherical grid configuration to a two-dimensional plane-shaped grid configuration. This dimensional reduction allows the energy filter to maintain its filtering capability while occupying significantly less space, enabling integration into compact SEM chambers.
2Reliability
If conventional LEED uses spherical shaped metal grids, then energy filtering is achieved, but it is not easy to make finer meshes
Solution Approach 1:
The patent changes the geometric parameters of the grid structure from spherical to planar configuration. This parameter change fundamentally alters the manufacturing approach, allowing for the creation of finer meshes through standard planar fabrication techniques rather than complex spherical grid fabrication.
3Reliability
If LEED unit is made large, then energy filtering function is achieved, but it may interfere with other detectors such as STEM detector or XRD detector
Solution Approach 1:
The patent changes the spatial parameters of the energy filter by adopting a plane-shaped configuration with reduced dimensions. This parameter change enables the LEED unit to coexist with other detectors (STEM, XRD) within the SEM chamber without spatial interference, thereby improving system versatility.
4Quantity of substance
If probe electron beam spot size is around 100 micrometers in typical LEED apparatus, then sufficient electron flux is achieved, but the spot size is too large to resolve atomic structure interference fringes
Solution Approach 1:
The patent makes the electron beam system universal by enabling it to function effectively at nanometer-scale spot sizes (10 nm to 100 nm) while maintaining sufficient electron flux through optimized beam transport and focusing. This multi-functionality allows the same beam system to serve both high-resolution imaging and adequate signal generation requirements.
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 LEED analysis in the same chamber as SEM, facilitating the study of nano-size areas and providing powerful instrumentation for surface science and nanotechnology by allowing the module to be retractable and detachable, enabling simultaneous use with other instruments like XRF.
Implementation Method 1
a potential shield made of electrically conductive material disposed generally along an inner surface of the first vacuum chamber and an inner surface of the second vacuum chamber, the potential shield being configured to be applied with a first acceleration voltage to accelerate and focus the diffracted electrons from the specimen
Implementation Method 2
a magnetic lens disposed adjacent to a place where the first vacuum chamber is connected to the second vacuum chamber to expand a beam of the diffracted electrons that have been transported through the first vacuum chamber towards the two-dimensional electron detector
Implementation Method 3
a generally plane-shaped energy filter to repel electrons having an energy lower than the probe beam of electrons that impinges on the specimen, the energy filter being disposed to have a gap with respect to the potential shield and being configured to be applied with a second acceleration voltage to collimate the beam of the diffracted electrons expanded by the magnetic lens
Implementation Method 4
a two-dimensional electron detector disposed in the second vacuum chamber at an end opposite to said one end of the second vacuum chamber to which the first chamber is connected, to detect the diffracted electrons
Implementation Method 5
LEED has been widely used to analyze surface structure (crystalline) of solid material by the electron diffraction, i.e., Bragg's diffraction of de Broglie wave of low energy electron
Data Source
Figure 1
AI summary
A low energy electron diffraction (LEED) detection module (100) includes: a first vacuum chamber for receiving diffracted electrons from a specimen (109); a larger second vacuum chamber connected to the first vacuum chamber to receive the diffracted electrons that have been transported through the first vacuum chamber; a two-dimensional electron detector disposed in the second vacuum chamber to detect the diffracted electrons; a potential shield (106) disposed generally along an inner surface of the first vacuum chamber and an inner surface of the second vacuum chamber; a magnetic lens (105) to expand a beam of the diffracted electrons that have been transported through the first vacuum chamber towards the two-dimensional electron detector; and a generally plane-shaped energy filter (103) to repel electrons having an energy lower than the probe beam (203) of electrons that impinges on the specimen (109).