We have studied low temperature plasma processes (T(sub) <= 200 degrees C) for the efficient cleaning and passivation of c-Si wafers, aiming for fully dry fabrication of heterojunction solar cells. We have experimented with H(2)-SiF(4) plasmas in a standard RF PECVD reactor in order to etch the native oxide from the c-Si wafer and a thin a-Si:H layer was deposited from SiH(4) to passivate the c-Si surface. In-situ ellipsometry was used to optimize the process conditions for an efficient surface cleaning. Various plasma treatments were performed before a-Si:H deposition in order to reduce the surface recombination. Optimized process conditions resulted in high effective lifetime values (tau(eff) approximate to 1.55 ms), low effective surface recombination velocities (S(eff) <= 9 cm s(-1)) and high implicit open circuit voltages (V(oc) approximate to 0.713 V). (C) 2009 Elsevier B.V. All rights reserved.