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Sample Preparation for Transmission Electron Microscopy

By Devendra Verma, 4 minutes to read
Industry: Technology:

TEM Sample Preparation with XTEMprep Preparation Kit

For study of interfaces (such as semiconductor devices, thin film layers, etc.) by transmission electron microscope (TEM) it is critical to use TEM samples of ultimate quality (perfectly embedded, mechanically pretreated and ion milled ones). TECHNOORG-LINDA offers a complete technology and product range for preparing cross-sectional samples of these quality including specially designed mechanical sample preparation tools and embedding ring. The XTEMprep Preparation Kit offers all the tools and materials that help the customer to prepare high-quality cross-sectional TEM specimens:

  • Microsaw – sectioning tool
  • Micropol – grinder and polisher
  • Microheat – embedding tool
  • Embedding rings (“Ti disc”)
  • Special purpose mechanical tools (HSS) for embedding
  • Ion beam resistant glue
  • LEIT-C conductive carbon cement
  • Thermoplastic transparent glue
  • Diamond paste

TEM UniMill

The Transmission Kikuchi Diffraction (TKD) is a new SEM method for measuring crystallographic properties with an order magnitude improvement in spatial resolution over Electron Back Scattered Diffraction (EBSD) technique. Working in transmission mode TKD needs electron transparent specimens like TEM. Ion beam milling using Technoorg’s UniMill is a proper method for preparing samples for these investigations.

TEM Sample Preparation Steps:

  • Cut an about 10x10mm piece from the studied material (e.g. from a Si wafer) and glue it by a TRANSPARENT THERMOPLASTIC GLUE on a glass plate. In order to protect the top thin films during the cutting it should face to the glass.
  • Two pieces of Si in size of 1.5×0.5mm are cut with the help of MICROSAW using the 0.15 thick diamond wheel.
  • The two pieces of Si are placed face to face to the central slot of the Ti DISC.
  • To fit the samples mechanically into the Ti disc use the HSS TOOLs No. 2
  • To fill up the space between the Si and the Ti disc a powdery ION BEAM RESISTANT GLUE is used: put a small amount of this powder onto an Al foil on the top of the hot plate of MICROHEAT. The melting powder has to be thoroughly mixed in order to eliminate bubbles in it.
  • Put the samples mounted into the Ti disc into the melted glue to fill up the gaps between the Si and Ti disc. The polymerization happens within 2 hours at 150 C. Before the next step of the preparation the surplus of solidified glue has to be removed with the help of the HSS tools
  • Now you can start with grinding and polishing of both sides of the sample with the MICROPOL machine.
  • First glue the Ti disc with the sample on the top of the steel stab of the Micropol with the transparent thermoplastic glue. There is a special socket on the stage of the Microheat for this purpose. It can be done easily under stereomicroscope.
  • Polishing takes place in three steps using three different bowls of Micropol provided with 1.) SiC paper; 2.) diamond paste of 10m grain size; 3.) diamond paste of 1m grain size.
  • The whole polishing procedure has to also be repeated on the other side of the material: put the stab of the Micropol back to the hot plate in order to remove the sample, then flip and glue it again. Please note, that the stab and the surface of the sample must be parallel.
  • Then start the polishing procedure of the other side of the Ti disc. Polish the sample down to about 50m using SiC paper. If you are close enough to the required thickness, finish polishing with the 2. and 3. bowls.
  • For removing the sample from the steel stab of Micropol put it back to the hot stage of Microheat in order to melt the glue. Then carefully separate it from the rod using tweezers and clean it with solvent. Now the Ti disc including the sample is ready to place it into the sample holder of an ion mill.

References and Notes:

1. T. Yaguchi et al.: A method for 3 dimensional structural and compositional imaging of nano-materials, Proceedings of Microsc Microanal 12 (Supp 2) 2006, 528-529

2. T. Yaguchi et al.: Development of sample preparation method for three-dimensional structural and elemental analyses of a specific site and its application, Proceedings of MRS Fall Meeting, Boston, USA, Nov. 26-30, 2006.

3. T. Yaguchi et al.: A site-specific structure analysis of a 65nm node device using an FIB-STEM/TEM system, Hitachi EM News, 2007, pp 25-30

4. T. Yaguchi et al.:A method for site-specific specimen preparation of Si device after 65nm node technology using FIB-STEM/TEM system, Proceedings of Microsc Microanal 13 (Supp 2) 2007, 790-791