Preparation machine

TEM lamellas much thinner than 50 nm cannot be prepared by conventional focused ion beam techniques so far. The polishing of the lamella surfaces creates amorphous layers which are several tens of nanometers thick on both sides of the sample. Within SALVE we are using a newly developed Argon-ion preparation instrument (Carl ZEISS NVison 40 Argon) and are investigating sample preparation methods for a variety of materials in order to satisfy the stringent requirements for samples to be studied at low voltages.

Milling strategies have been developed that give an optimum tradeoff between processing time and final amorphous surface layer thickness. The required thickness of the Si sample imaged at 20 kV is less than 5 nm thin (Fig. 1).

20 kV SALVE I TEM image of Si [110]
Figure 1: 20 kV CS-corrected HR-TEM images obtained with the SALVE I TEM of [110] Si. The lattice can be clearly imaged, which was made possible by sample preparation strategy newly developed by the group of EMMS using NVision 40. Sample preparation and image: Ulm University.

This thickness has been achieved by using an improved sample preparation technique [1-4].

References

  1. Lechner, L., J. Biskupek, and U. A. Kaiser (2012) Improved Focused Ion Beam Target Preparation of (S)TEM Specimen - A Method for Obtaining Ultrathin Lamellae. Micros. Microanal., 18: 379-384, doi: 10.1017/S1431927611012499

  2. Lechner, L., Kaiser, U., & Biskupek, J. (2015). U.S. Patent No. 9,103,753. Washington, DC: U.S. Patent and Trademark Office.

  3. L. Lechner, J. Biskupek, U. Kaiser, Methode und Apparate zur Präparation von TEM-Proben, German patent # P18420DE

  4. Lechner, L., Kaiser, U., & Biskupek, J. (2015). U.S. Patent No. 9,103,753. Washington, DC: U.S. Patent and Trademark Office.

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