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Sample Preparation

Fig. 1
Fig. 1: Operating laser cutter tool Synova LSC 300W.

The research programs typically require very specific preparation of samples. This preparation can include deposition of thin films and layers, thermal treatment of samples, patterning by lithography and etching, as well as sample cutting, grinding, polishing and engravings. For this purpose, the 330 m² cleanroom facility includes various types of deposition tools: physical vapor deposition (PVD), atomic layer deposition (ALD), chemical vapor deposition (CVD), and molecular beam epitaxy (MBE). Post deposition anneals can be performed in various hot and cold wall ovens, which cover a temperature range for room temperature up to 1200°C. There are fast ramping Rapid Thermal Processing machines available as well as furnaces for long term treatment. Structures can be defined by e-beam lithography and shadow masking including etching by wet chemical and reactive ion etching (RIE).

Fig. 2
Fig. 2: Various possibilities to perform controlled wet chemical and reactive ion etching.

 

 

 

Additional requirements of the scientific processing is adapting wafer geometries, chip dicing and creation of process compatible gadgets e.g. for sample handling. Therefore, NaMLab provides several tools to meet these requirements.
A Synova LSC 300 W Laser cutter (Fig. 1) is located in NaMLabs clean room. Its 532 nm Laser beam is guided by a 50 µm in diameter water beam which additionally cools the sample during the cutting process. It offers the possibility to process wafers with diameters up to 300 mm and substrate thicknesses up to 1 mm. Via a CNC based vacuum chuck any shape can be produced as well as wafer recess and surface roughening is possible. This technique leads its benefit in reducing silicon wafers to small pieces especially uncontrollable breaking (111) wafers. Single chip dicing without destroying whole processed and reusable wafer also increases the efficiency.

Fig. 3
Fig. 3: (back) FEI Expida 1285 Focused Ion Beam (FIB) system and (front) SEM image of a FIB milled transistor cross section.

 

 

Further, to analyze produced layer stack structures by scanning electron microscopy NaMLab uses a Bühler MetaServ250 chemical-mechanical polishing tool for preparing previously cut or broken sample edges. In addition with the aid of special polishing rags and suspensions high-precise cross sections and the removal of indi-vidual layers is possible.
For cleaning and wet chemical treatment (Fig. 2) of samples NaMLab own four wet benches equipped with overflow basins. They are located in a DIN ISO 5 cleanroom. Ultra and mega sonic tools for mechanical supported surface cleaning in deionized water are in operation. Also cleaning steps like RCA clean and selective material etching can be performed. Spin coaters for photo resists are used for in-house electron beam lithography.
For sample preparation and combined surface analysis in the micro and nanometer range NaMLab holds a FEI Expida 1285 Focused Ion Beam (FIB) system. The used gallium beam current can be set between 1 pA and 30 nA. Cross section formation and milling of TEM lamellas are as well scopes of application as localized removal and deposition of material. Via several gas inlets samples can be in-situ covered with protecting or decorating layers.

 

Contact: Dr. Matthias Grube

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NaMLab gGmbH
Nöthnitzer Str. 64 a
01187 Dresden
Germany 

Phone: +49.351.21.24.990-00
Fax: +49.351.475.83.900

info (at) namlab.com

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