Muspel and Surtr : CVD system and control program for WF6 chemistry

Abstract: CVD (Chemical Vapour Deposition) is an advanced technique for depositing a coating on a substrate. CVD implies that a solid phase is deposited on a normally heated substrate surface using a reactive, gaseous mixture. The reaction gas mixture must be carefully chosen to prevent homogeneous nucleation in the gas phase. As the solid phase is formed, gaseous by-products are formed and they must be removed from the CVD system. The thermally activated CVD process requires a deposition system which can regulate the total pressure and mass flows of the separate gas components as well as maintain a sufficiently high temperature to initiate a chemical reaction on the substrate surface.In this thesis a new CVD system was constructed to meet these challenges. Initially it will be used to deposit hard, wear resistant coatings but by changing the gases, it is possible to explore other chemical systems. The CVD system functions well up to a deposition temperature of 1100 ºC as long as the CVD processes are thermally activated. Apart from manual operation, a LabView control interface was implemented that can automate process steps by reading recipe files as csv (comma-separated variables). In this way complex coating architectures can be deposited.The aim of this thesis is to give a detailed description of the hardware set-up and of the software developed for it. Provided in this work are also a few examples of W and WN (tungsten nitride) coatings, including a multi-layered structure to show the potential of complex structures. Since the system also contains a titanium precursor, a TiN (titanium nitride) coating is presented to conceptually show the flexibility of the equipment.