In the scope of this thesis, which was performed within the laser and plasma physics working group of the Institute of Nuclear Physics (IKP) of TU Darmstadt, it was possible to refurbish, modernize, optimize, expand and commission an existing process system for plasma-enhanced chemical vapour deposition (PEVCD). As part of this, an updated technical documentation was also created in order, for example, to be able to plan and carry out a future expansion in a comfortable way. In addition, the performance of this PECVD system was demonstrated by DLC coatings, which were used to produce deuterium-containing material (a-C:D) for self-supporting, free-standing thin films. For this purpose not only a suitable plasma process was selected and tested, but also the necessary deuterated process gas (CD4) was synthesized on a laboratory scale. Moreover, these deuterium-containing films were prepared in such a way that they are suitable as so-called targets for laser-ion experiments. As part of an experiment campaign, two such deuterated DLC targets could be tested successfully.
With the “Plasma-Therm SLR-770 ECR” process system, it is possible to carry out a chemical vapour deposition, which is activated or assisted by means of a low-pressure plasma. This PECVD process provides a versatile method for the synthesis and modification of thin films. This not only includes the coating of a surface, but with the PECVD system plasma etching processes can be performed for a material removal, for instance, for structuring on a micrometer scale. Therefore, this system represents an interesting tool for the production of tailor-made target materials, which are of particular interest for experiments with laser-induced plasmas. In order to be able to use the full potential of the process system, it has been extensively modernized.
For the modernization of the PECVD process system “Plasma-Therm SLR-770 ECR“ the vacuum system was first checked and overhauled. The separate vacuum system for the load lock has been extended so that, among other things, rapid loading and unloading of substrates to the process chamber is possible. The vacuum system for the process chamber was extensively overhauled and supplemented by relevant components. The system‘s electrical control and monitoring system has been completely replaced by a “retrofit“ that has been independently designed, developed, built and finally successfully commissioned. The associated user software was created in the programming environment NI LabVIEW(TM) and
also extended with functions that were not available in the original system. The program code of this so-called PECVD application has been extensively documented, so that a further development can comfortably follow. To demonstrate the performance of the PECVD system, thin layers of hydrogen-rich amorphous carbon were prepared (a-C:H), also commonly referred to as DLC (diamond-like carbon). Furthermore, deuterated layers were prepared to be tested as part of an experiment campaign. For this purpose, a method for the synthesis and preparation of deuterated methane (CD4) was developed on a laboratory scale. From the deposited layers (a-C:D), a special preparation method was used to obtain unsupported targets. To assess the plasma processes and thin films produced, inter alia, layer thickness measurements were carried out. A chemical analysis was done explicitly for the layers of a-C:D to confirm
the success of the film deposition. Finally, two targets were successfully tested on the high-energy laser system PHELIX, which consisted of a thin self-supporting foil of the deuterated material. | English |