In this work we describe a baseline fabrication process of interdigitated-back-contact c-Si(p) solar cells, which combines conventional diffusion oven stages to define base p+ and emitter n+ regions at the backside, with front surface passivation using atomic layer deposited Al2O3 films on textured surfaces with random pyramids. Very low reflectance with outstanding surface recombination velocity values around 3 cm/s are achieved in our precursors. Fabricated solar cells reach efficiencies up to 20.3% (AM1.5G 1 kW/m2, T=25°C), with short circuit density Jsc, open circuit voltage Voc and fill factor FF of 40.6 mA/cm2, 648 mV and 77.2% respectively.