The ongoing miniaturization and the ever-increasing variety of materials in microelectronics and power electronics present new challenges for industry and research. To ensure the reliability of complex electronic systems, high-resolution analyses are required, which in certain cases necessitate precise sample preparation free of mechanical or chemical artifacts. Water-free preparation techniques, such as the combination of laser and ion beam methods, offer innovative solutions for this purpose.
The analysis of electronic systems requires the highest precision, especially when examining complex material structures such as metal-polymer-ceramic composites or nanoscale layered systems. In most cases, non-destructive analyses are insufficient to understand the causes of failures in detail and subsequently determine effective countermeasures. Standardized metallographic preparation routines – such as mechanical grinding and polishing or chemical etching – may be unsuitable for the high-resolution analysis of corrosion products and mechanically sensitive systems. Mechanical methods can lead to artifacts such as cracks, delamination, or undesirable deformations, while chemical approaches often selectively attack only certain material components. Today, precise ion- and laser-based preparation methods are well established, which largely avoid mechanically induced preparation artifacts and improve both the quality and precision of the preparation. Based on these methods, we at Fraunhofer IMWS have developed new, completely water- and suspension-free preparation concepts that combine laser and broadband ion beam techniques.
Water-free preparation is based on avoiding liquids such as water or chemical suspensions, which can trigger undesirable reactions with sensitive materials or leach them out – particularly when investigating corrosion and migration effects. Therefore, “dry” preparation methods are needed to minimize the influence of preparation artifacts on analytical results.
Ultrashort-pulse laser techniques with extremely short pulse durations in the femtosecond range (10-15 seconds) offer a good alternative to water- and suspension-cooled wire sawing methods for fast and efficient preliminary preparation. Followed by ion-based preparation methods, fast and efficient final preparation can be ensured. This method, using a broad ion beam, enables material-friendly preparation with precise control down to a few 10 µm.
Avoiding the use of water is particularly advantageous for electronic components containing moisture-sensitive materials. In the case of cracks, delaminations, or pores (e.g., in sintered layers), moisture can penetrate. Additionally, any corrosion products present can be removed.
Our water-free preparation process is based on a combination of innovative laser and ion beam technologies to ensure the highest precision and efficiency. The workflow consists of several steps that build on one another.
Laser-based pre-processing:
At the start of the process, the sample is subjected to a high-power ultrashort-pulse laser in the femtosecond range. This allows material to be removed in a targeted manner with virtually no thermal damage or microcracks. The size of the sample to be processed with the laser can be in the range of a few centimeters. Unlike conventional lasers, which can introduce heat into the material, ultrashort-pulse lasers operate with minimal energy input, thereby protecting sensitive material boundaries. Laser ablation is particularly well-suited for the targeted preparation of samples with larger volumes or widely varying material properties. The flexibility of the laser process also enables the exposure of deeper structures, such as contacts (through-silicon vias – TSVs), or the targeted removal and exposure of conductive traces in semiconductor structures (e.g., systems-in-package – SiP) for subsequent comprehensive analysis.
Ion Beam Polishing for Fine Processing:
Following laser processing, the sample surface is smoothed and refined using a wide ion beam. This involves using argon ions to produce high-quality, virtually artifact-free cross-sections. Ion beam preparation allows for processing in a width ranging from 1 to 5 millimeters, up to a maximum of 8 millimeters. This step is particularly important for revealing the finest structures and material transitions for subsequent high-resolution analyses, such as SEM, EDX, EBSD, and nanoindentation.
Optional finishing and adjustment:
In some cases, additional post-processing may be required, such as the localized preparation of specific areas using a focused ion beam (FIB). This enables even more precise processing at the micrometer or nanometer scale to reveal specific details such as pores, cracks, or layer boundaries. In addition, electron-transparent lamellae can be prepared very precisely on the generated cross-sections as needed for the highest-resolution TEM analysis.
The combination of these techniques allows samples to be prepare quickly, precisely, and with high accuracy. Furthermore, compared to metallographic preparation routines, the workflow can be more easily adapted to requirements such as different sample geometries, materials, or analytical objectives.
The combination of these preparation techniques offers a variety of advantages over traditional metallographic cross-section preparations:
These properties make water-free preparation techniques a good alternative for advanced material and reliability analyses.
Naturally, samples and materials that are less sensitive to water, , can also be prepared using this approach. Depending on the research question, this can offer a significant advantage in terms of precision and the effort required for preparation.
(August 6, 2026)
Fraunhofer Institute for Microstructure of Materials and Systems IMWS