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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 of two or more different materials. It combines divisive, abrasive and property-changing processes during machining, thereby 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 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. CMP is a standard procedure in the semiconductor industry to smooth out thin layers. Workable materials include dielectrics, polysilicon and metals. By polishing, surfaces with high quality finishes can be produced. CMP allows for the production of multilayer systems and has a key role in the development of high-performance and highly integrated circuit devices. Further applications of CMP in optics includes surface finishing and the production of multilayer 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.). Research is needed on the adaptation of the method for increasingly complex material combinations.