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Magnetron assisted PECVD process for deposition of a-Si:H and µc-Si:H from a silane-hydrogen-argon gas mixture

: Frach, P.; Pötschick, P.; Bartzsch, H.; Delan, A.

Society of Vacuum Coaters -SVC-, Albuquerque/NM:
Society of Vacuum Coaters. 55th Annual SVC Technical Conference 2012 : April 28-May 3, 2012; Santa Clara, Calif.; Proceedings
Albuquerque: SVC, 2012
ISBN: 978-1-878068-32-3
ISBN: 1-878068-32-6
Society of Vacuum Coaters (Annual Technical Conference) <55, 2012, Santa Clara/Calif.>
Conference Paper
Fraunhofer FEP ()

Amorphous and microcrystalline hydrogen doped silicon layers are used for several applications. Here a magnetron assisted PECVD process (magPECVD) using a magnetron sputter source for plasma excitation with a medium frequency (50 kHz) pulse power supply in a silane-hydrogen-argon atmosphere was investigated with emphasis on amorphous layers. The influence of different process parameters like silane-hydrogen-ratio and substrate temperature on dark and photoconductivity, microstructure parameter (ratio between different hydrogen bonds) and microcrystalline fraction was investigated. The process pressure ranges from 0.5 to 5Pa. Therefore magPECVD is well suited for in-line processing together with magnetron sputter processes in one process chamber. The achieved deposition rate for amorphous silicon is about 5 times higher than in established processes. The measured layer properties of amorphous layers show a very good ratio of photo and dark conductivity of 2.5x106. This ratio has a maximum at approximately 225°C. The achieved values for photo conductivity of around 10-6(? cm)-1 were still one order of magnitude lower than required. A high microstructure parameter of about 0.6 indicates that hydrogen is mainly bonded in Si-H2 and Si-H3 state instead of Si-H. The initial experiments for depositing microcrystalline silicon were successful and a deposition rate of more than 1nm/s was obtained. The estimated Raman crystallinity was around 70%. Resultantly the magnetron PECVD process shows potential for the deposition of amorphous (a-Si:H) and microcrystalline (?c-Si:H) layers with high deposition rate but further investigations are necessary.