In the fabrication process for a microchip or microsensor, the presence of dust, smoke, bacteria and other very small particles can lead to critical functional disruptions. Consequently, microanalysis and microprocessing are conducted in cleanrooms in which the air is filtered to prevent particle contamination and the temperature, humidity, vibrations and electrical interference are strictly and continuously controlled. Overall, CTR’s cleanroom floor space amounts to 320 m² distributed across 2 cleanroom zones, providing ideal conditions for the new high-tech equipment.
ELECTRON MICROSCOPY WITH THE DUAL BEAM SYSTEM
A scanning electron microscope with a focused ion beam – an FIB-SEM for short – was recently placed at the disposal of the CTR team to enable precision 3D analysis as well as micro and nanoprocessing of ultra-fine structures. With the dual beam system, the FIB-SEM enables both analysis and material processing on the nanoscale in a single device. The scanning electron microscope (SEM) allows the imaging of the 3D topography of micro and nanostructures. The characteristic X-rays generated due to the interaction of the electron beam with the specimen can be harnessed for energy-dispersive X-ray analysis (EDX) in order to determine both the quality and quantity of the chemical elements in the specimen. The electron beam can also be used for electron-beam lithography.
The 2nd beam, a focused ion beam (FIB) composed for example of gallium ions, can – in contrast to the virtually mass-free electrons – knock atoms out of the specimen surface (ion beam milling), thereby structuring the surface (subtractive nanostructuring). In the same manner, it is also possible to deposit specific atoms (e.g. platinum) on the surface (additive nanostructuring) and thereby create features such as conductive paths. In addition to a comprehensive 3D characterization, this also enables direct nanostructuring of the specimens. Microscopy with focused ion beams is now considered to be a routine process in maskless microstructuring and surface characterization. The special feature CTR’s unit offers is that wafers up to a size of 8 inches (200 mm) can be handled.
APPLICATIONS AND RESEARCH ACTIVITIES
Areas of application range from semiconductor technology to the structuring involved in biomedical research. FIB-SEM 04 CTR Times 2/2018 FIB SEM Probe instruments enable precise analysis on very accurately defined locations and on ultra-fine structural features. The FIB function also makes it possible to remove the surface after the measurement and thereby – in a manner comparable to archaeological digs – to examine the depths as well. This is of great importance for comprehensive investigations of the specimen cross-section, e.g. of multilayer structures with regard to topology and composition, but also for the analysis of reaction and corrosion layers, etc.
FROM A CHIP TO AN INTEGRATED SYSTEM
In the manufacturing of microchips, microelectromechanical systems (MEMS) and micro or nanosensors, many processes are repeated time and again. The newly acquired FIB-SEM complements the existing research infrastructure, which includes a profilometer (Bruker Dektak XT) for 2D or 3D measurements of microscopic structures, a white light interferometer (Polytech MSA 500) for 3D topography measurements, microscopes, spectral analysers, electrical and electronic test setups, etc. This comprehensive array of analysis and test equipment, the existing devices for thin-film technology, lithography, structuring and cleaning, and the new possibilities in assembly and connection technology and micro assembly (see page 3) make it possible for the CTR team to cover the entire spectrum of microprocessor development processes. In combination with CTR’s existing expertise and system competence, the way is now open to conduct comprehensive research – from the chip to the full integrated system.
This project has been co-financed with funds from the ERDF (European Regional Development Fund).
3 questions for Dr. Mohssen Moridi, Area Manager, Microsystem Technologies at CTR
CTR has two research cleanrooms. Waht is the focus there?
With our new, state-of-the-art cleanroom, CTR is reinforcing its position in Austria with regard to MEMS devices from advanced simulation to microfabrication and process development. Our main focus will be on Photonic MEMS and Piezo MEMS. The 320 m² ISO5 and ISO8 can be used for customized microfabrication process development, from the sensor concept to packaging and system integration.
Recently you have acquired a Focues Ion Beam Scanning Electron Microscope, FIB-SEM for short. What makes this microscope special?
One of the latest pieces of equipment installed in our clean room was a highly advanced dual beam system, which will be used not only as an inspection tool for the MEMS structures but also to produce complex nanoscale structures and patterns such as photonic devices. This feature will be used mainly for fast production of test structures in a small area, but the device can handle a wafer size of up to 8 inches and is equipped with a high precision piezo stage.
Thich research or applications will benefit from this CTR microfabrication infrastructure?
Our cleanroom facilities are an essential part of the microfabrication research infrastructure of the MEMS devices, which are mainly required by the automotive or telecommunication sectors. We can provide an all-round service delivered with high professional expertise which meets all the needs and requirements of our research partners. The CTR microfabrication facility will facilitate the entire development chain, from basic research and process development through to prototyping and transfer technologies for mass production.