Thin Layer Deposition

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Thin layers with thicknesses in the range of nanometres up to a few micrometres are an integral component of modern micro and nano systems. They incur several functions within the finished MEMS. The layers can serve as contact surfaces, conducting paths, passivation layers or diffusion barriers. Furthermore, they serve as hard masks or as sacrificial layers within the processing of the MEMS device. Mostly standardized processes such as photolithography lift-off processes, wet chemical and dry etching processes allow the structuring of those layers in the lateral range of micrometres down to nanometres. A versatile standard method of depositing thin layers is the sputter deposition. Ions generated in a plasma are accelerated to the target material and therefor erode its surface. Starting from the target, a particle stream is created, the target material subsequently condenses as a growing layer on the wafer. The layer properties are mainly determined by the kinetic energy of the particles and thus the diffusion length on the surface. Accordingly, the properties can be influenced by a variety of parameters during the deposition. Here the superposition of a high-frequency field, the use of magnetic sources (magnetron) and the application of a bias should be mentioned. Last but not least, the wide range of possible materials to be deposited (metals, semiconductors, dielectrics) makes sputter deposition a fundamental process of the production of micro- and nanosystems. This selection can be further expanded by the consideration of reactive processes during deposition. As part of the high-tech centre of the University of Applied Sciences Zwickau, a laboratory complex with 680 square meters of ISO class 4 and 5 clean rooms is being built. The concept of this cleanroom includes the interdisciplinary research and teaching with a focus on microsystems technology and nanotechnology with the participation of two faculties. The sputtering tool plays a key role within in the closed process chain of research and development in these research fields. In addition to the use of the tool for routine tasks of the semiconductor device development such as metallization, it also offers the opportunity to continue and intensify existing fields of research and add fundamentally new aspects.