Hitachi High-Tech Europe
2 min read
Revealing complex, microscale internal structures with ion milling
A meaningful SEM analysis requires high-quality specimen preparation. Conventional mechanical sample preparation techniques for artefact-free surfaces or cross-sections, such as mechanical grinding and polishing, fracturing, or cutting by scissors or knifes, etc., can deliver usable results on some specimens. However, they can also fail, especially when it comes to composites and layered structures with different hardness, brittle materials, and so forth.
This facilitates the need for better techniques, one of which being the powerful Broad Ion Beam Milling method which will be explored in this article.
What is Broad Ion Beam Milling?
Broad Ion Beam (BIB) milling is a complementary SEM sample preparation technique that uses on a microscopic scale accelerated Argon ions to sputter material from a specimen surface, comparable to the macroscopic sand blasting for the cleaning of parts. As this does not apply any mechanical force that could cause material deformation or displacement, the outputs are clean surfaces on a millimetre-order revealing the “true” nature of the specimen, thus being ideally suited for SEM imaging and analysis.
There are two different milling methods which are used for preparing samples: cross-section milling and flat milling.
In cross-section milling, a mask is placed between the ion gun and the sample, with part of the sample protruding beyond the mask and thus being exposed to irradiation by the argon ions. This method is ideal for the preparation of complex multi-layered structures that are difficult to polish.
Flat milling is commonly used after mechanical polishing to create defect-free and extremely smooth sample finishes. The depth and rate of milling can be controlled by adjusting parameters such as ion energy and the angle of milling. The argon beam impinges on the surface of the sample at an angle, and a wide sample area can be processed by deflecting the beam’s axis from the sample’s rotation axis.
Both cross-section milling and flat milling provide benefits for multiple industries such as energy storage and renewable energy, semiconductors and microelectronics, metallurgy, coatings, and packaging. It can be utilized for critical applications such as investigating active material layer thickness and homogeneity in lithium-ion batteries or checking thin film properties in the coatings industry, to mention just two.
Combining BIB Milling and SEM Analysis
Hitachi High-Tech also offers a diverse product lineup in the electron microscope field, ranging from compact tabletop SEM with integrated elemental analysis via conventional large-chamber SEM, field-emission electron source driven high resolution SEM (FE-SEM) up to Transmission Electron Microscopes (TEM) for performing precise detailed analysis.
Having both ion beam sample preparation and SEM analysis tools in house opens powerful combinations for specific applications such as direct tool-to-tool specimen transfer under inert gas conditions, which is essential for the study of oxidation- or humidity- sensitive specimens, for example samples from the Lithium-ion Battery field.
BIB Milling for a Wide Range of Applications
The ArBlade 5000 platform is modular and offers ample adaptations for specific application needs. For cross section preparations, widths can be flexibly set according to actual requirements up to 10mm, temperature-sensitive specimens can be actively cooled, multiple specimens can be set at once for sequential auto processing, etc.
Flat milling provides benefits such as the capability to finish milling with ultra-low ion beam energies, providing optimum surface quality for EBSD analysis.
In Summary
BIB milling is a powerful sample preparation method that can handle even highly complex and sensitive specimens. With a dynamic solution such as the ArBlade 5000 or its smaller sibling the IM4000II, users in multiple industries can unveil the inner structure of a sample to reveal and understand its true nature without any defects that conventional mechanical methods would otherwise produce.
Speak with an expert to learn more and request a live demonstration with your material sample.
