G. Caratti - Böcker

Amorphous silicon PV panel mass production will require to mas­ ter plasma chemical deposition in terms of large sizes, cost, maintenance and all other problems related to industrialization. Since plasma deposition is a novel technique, the development of all this production related know how involves a considerable technical research effort. The major problems related to the design of a production deposi­ tion machine are the following - deposition should be uniform on very large area substrate (typical dimension 1 meter) ; - the deposited amorphous silicon should have good electronic properties (density of state of the order or less than 16 3 10 cm /eV) and very low impurities concentrations (for exam­ ple oxygen atomic concentration should idealy be less than 0. 01 %) ; - the film stress should be limited, the density of ponctual defects (particulates) should remain reasonable (less than 2 per 100 cm ) ; - dopant level control should be stable and efficient ; - silane consumption should remain reasonably efficient - financial cost being important the machine productivity should be high hence deposition rate optimized ; - downtime due to maintenance should be reduced to a minimum. We present here some results on the R&D effort addressed to the above mentioned problems. An original single chamber was designed. This machine will be made available on the market for R&D purposes by a process machine company. Finally the maintenance problem is considered. Plasma cleaning based on a fluorine containing etchant gases is studied and evaluated. 2.