By George-Felix Leu, Reactor Development Engineer, Oerlikon Solar; Chris Egli, PECVD Product Manager, Oerlikon Solar; Edgar Hepp, Manager of Product Lifecycle Management Team, Oerlikon Solar; Bertrand Le Faou, Commercial Manager of the F2 Division, The Linde Group; Jean-Charles Cigal, OEM Programm Manager, The Linde Group; Greg Shuttleworth, Product Manager Equipment, The Linde Group
The cleaning performance of three different fluorine-containing precursors – sulphur hexafluoride (SF6), nitrogen trifluoride (NF3) and molecular fluorine (F2) – is compared from theoretical, experimental and commercial points of view. Experiments were performed using an Oerlikon Solar KAI Gen 5 (1300mm x 1100mm) R&D platform. For the experiments with F2, an ‘on-site/on-demand’ generator from The Linde Group was installed at the Oerlikon Solar facility in Trübbach, Switzerland. The SF6-based cleaning process was found to be up to 75% less efficient than the corresponding NF3 or F2 process. A comparison between NF3 and F2 indicates that a significantly larger process window is available for reactor cleaning when F2 is used in place of NF3. This leads to both time and gas mass savings, improving productivity and bringing down the cost of ownership of the reactor cleaning process. As a direct consequence, Oerlikon Solar has decided to transfer the process to their production KAI MT plasma-enhanced chemical vapour deposition (PECVD) platforms.