Control of ion energy distribution at substrates during plasma processing

Control of ion energy distribution functions (IEDF) at the substrate during plasma processing is achieved using a specially tailored voltage waveform for substrate bias, consisting of a short voltage spike in combination with a slow ramp. A much narrower IEDF is possible compared to the conventional approach of applying a sinusoidal waveform to the substrate electrode. Mea surements in a helicon plasma combined with a time-dependent spherical-shel l plasma fluid model demonstrate the benefits of this method in producing a narrow IEDF of precisely controllable energy, independent of ion mass. (C) 2000 American Institute of Physics. [S0021-8979(00)03411-3].