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Logo: IMPT - Institut für Mikropoduktionstechnik
Logo Leibniz Universität Hannover
Logo: IMPT - Institut für Mikropoduktionstechnik
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Chemical-Mechanical Planarization

Chemical-mechanical planarization (CMP), also called chemical mechanical polishing, is a process for the planarization and smoothing of surfaces that are typically made out of two or more different materials. CMP combines divisive, abrasive, and property-changing processes during machining, using nanoparticles as abrasive grains. This combination of chemical and mechanical material processing allows for the uniform removal and planarization of thin film technologically-produced wafer surfaces made out of composite materials. The planarization is accomplished locally (from structure to structure) as well as globally (across the entire wafer). Local planarization refers to the adjustment of height differences of adjacent structures, whereas global planarization refers to the adjustment of height differences across the entire substrate surface. CMP is the only surface processing technology with which global planarization can be achieved. It is also a standard procedure in the semiconductor industry to smooth out thin layers. Workable materials include dielectrics, polysilicon, and metals. Surfaces with high quality finishes can be produced through polishing. CMP allows for the production of multilayer systems and plays a key role in the development of high-performance and highly integrated circuit devices. Further applications of CMP lie in the field of optics, surface finishing, and the production of multilayered microsystems. At the IMPT, CMP processes are mainly used as an intermediate step in the construction of multi-layer electromagnetic actuators and sensors. Polishing embeds a composite material, made of Cu or some soft magnetic material (NiFe, CoFe), in a polymer (photoresist or epoxy resin). In addition, CMP is used for planarizing and finishing different wafer surfaces (Si, polysilicon, glass, ceramics, etc.). Further research is needed regarding the adaptation of the methods for increasingly complex material combinations.