Mechanical Micro Machining

The field of mechanical micro machining at the institute comprises: chemical-mechanical planarization, face machining and cutting-off grinding.


Chemical Mechanical Planarization (CMP), also often referred to as Chemical Mechanical Polishing, is a process for planarizing and smoothing surfaces, which usually consist of two or more different materials. Separating, removing and changing material properties are combined in the process, using nanoparticles as abrasive grains. This combination of chemical and mechanical material processing enables the uniform removal and planarization of thin-film wafer surfaces made of material combinations. Planarization is achieved both locally, from structure to structure, and globally, across the entire wafer.



Planar machining of brittle-hard materials usually requires a multi-stage process control: Grinding processes are used for preliminary shaping, the final machining is then carried out with lapping and polishing processes. At the IMPT, surface grinding, fine lapping, nano-grinding and purely mechanical surface polishing are used.



By means of cut-off grinding, materials that are difficult to machine such as silicon ceramics (e.g. SiC) or aluminium ceramics (e.g. Al2O3), as well as brittle hard crystalline silicon can be machined. The axial accuracy of the processing machine is 0.2µm for the X-axis, respectively 0.1µm for the Y- and Z-axis. The repeat accuracy is 2-3µm for the X and Y axis and 1µm for the Z axis. Due to this high precision, structures on substrates / wafers can preferably be produced individually (cut-off grinding) or in solid material (profile grinding). The abrasive sheets used have cutting widths of 25 µm to 500 µm thickness. There is a selection of the most common types of abrasive sheets, such as plastic and metal "Hub-less" cut-off wheels (75µm - 500µm thickness), as well as plastic and metal "Hub-type" cut-off wheels (25µm - 75µm thickness).


In the laboratories of the institute one can find equipment for polishing and lapping a substrate, milling and cutting as well as characterization instruments.