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The semiconductor industry continues to move forward, bringing with it a growing demand for materials analysis. |
The Transmission Electron Microscope (TEM) is the analytical tool most commonly used for observing microstructures and atomic arrangements. With the development of IC semiconductors, lithium (Li) batteries for vehicles, Quantum Computers, fourth generation III-V compound semiconductors, new 2D materials such as Graphene and more, the demand for the analysis of new materials is increasing day by day. Similarly, the resolution required of electron microscopes is also growing higher and higher.
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How can we improve the resolution of electron microscopes? |
Reducing the aberrations of the TEM machine is the way to improve TEM resolution. There are three main reasons for TEM aberrations:
1.Astigmatism
2.Chromatic Aberration
3.Spherical Aberration
Astigmatism can be improved using the astigmatism adjustment function of the machine. Chromatic aberrations, on the other hand, are related to the coherence of TEM’s electron energy. At present, all TEM machines use field emission-type electron emission sources, and the electron energy can evenly improve the chromatic aberration. However, though this has been of great help for Electron Energy Loss Spectroscopy (EELS), there is no significant improvement in the spatial resolution of the TEM. Therefore, ameliorating spherical aberrations is the most effective way to improve TEM resolution.
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Ultra-High Resolution Cs-STEM |
The Spherical Aberration Corrected Scanning Transmission Electron Microscope (Cs-STEM) is an analytical instrument used in the development of new materials. Using spherical aberration corrected TEM can improve the spatial resolution of the machine. A TEM paired with scanning functions is called a Scanning Transmission Electron Microscope (STEM). Combining STEM with Energy-Dispersive X-ray Spectroscopy (EDS) and EELS can enable the realization of compositional analysis with a high spatial resolution.
Beginning with basic materials analysis, MA-tek developed its own world-class analysis laboratories equipped with advanced technologies for MA (Material Analysis), FA (Failure Analysis), RA (Reliability Analysis), SA (Surface Analysis), and CA (Chemical Analysis) etc. in order to serve the needs of customers from the industry, research institutions and academia. To this end, MA-tek has introduced Cs-STEM technology.
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Cs-STEM Applications |
MA-tek’s Cs-STEM technology is being developed constantly according to the different materials to be tested and various customer needs. Below are three examples illustrating this development.
Figure 1 shows the structure of III-V light-emitting diode semiconductor materials. The high spatial resolution allows the arrangement of Ga and N atoms to be distinguished. After the position of each atom is determined, the spacing and angles of the arrangement can be calculated, and the crystal structure of the GaN material can be deduced. With a typical TEM without spherical aberraction correction, the positions of Ga and N atoms are indistinguishable. In addition, Cs-STEM can be paired with the EDX function to perform high resolution EDX component analysis.
 Figure 1. Structure of III-V Semiconductor Materials for Light Emitting Diodes |
At present, silicon carbide materials are commonly used in high power components, and their use in automotive electronics is very popular. Silicon carbide crystal structures are complex and can be divided mainly into two types:
1.Cubic, also known as β-SiC or 3C-SiC
2.Hexagonal, also known as α-SiC
More than 200 hexagonal crystal phases have been proposed in existing literature. The more common structures include 2H, 4H, 6H and 15R, etc.. Figure 2 shows the atomic structure arrangement of 4H-SiC as observed via Cs-STEM. The viewing direction (vertical screen direction) is <11-20>.
 Figure 2. Atomic Structure Arrangement of 4H-SiC Material |
Figure 3 shows the analysis of lithium battery materials for vehicles. The Li component of lithium battery materials cannot be analyzed via EDX but can be identified via EELS. The Cs-STEM paired with the EELS can not only observe the distribution of main materials such as Li/Mn/O simultaneously but also be synchronized with the EELS spectrum function to observe the Li energy loss spectrum, which can be used to analyze the Li atomic bonding state.
 Figure 3. Analysis of Automotive Lithium Battery Materials Via Cs-STEM with the EELS Function |
MA-tek’s Neo ARM TEM machine is not only equipped with spherical aberration correction but also able to provide ultra high resolution images. Furthermore, it is equipped with the EELS function. This technology will enable us to more closely meet the testing needs of customers and bolster the analytical power of our structural analysis laboratory as MA-tek continues to play a leading role in the field of analysis.
Please feel free to reach out to us if you have any questions : marketing@matek.com
