A VHF plasma for a large-area a-Si:H films deposition has been produced using the ladder-shaped electrode and the phase modulation method. These techniques enable to average the voltage distribution along the electrode by a high-speed scanning of the voltage standing wave. The effects of these techniques are demonstrated on the a-Si:H films deposition using 1.4 m x 1.1 m substrates and on the self-cleaning using NF3 plasmas. The spatial irregularity of the deposition rate is about +/- 15% and the self-cleaning rate is 5 nm/s. (c) 2005 Elsevier B.V. All rights reserved.