The problem of scattering in ribe

In todays semiconductor fabrication dry etching is based on Reactive-Ion-Etch processes (RIE) or Plasma-Etch processes (PE). This works quite well, but it is difficult to develop and optimize dedicated processes because of the strongly coupled machine, plasma and process parameters. Ion beam assisted processes such as ion-milling or Reactive-Ion-Beam Etching (RIBE) can overcome some of these problems because plasma and wafer are no longer in direct contact, and independent parameter control is possible. In practice one has to pay for these advantages with low etchrates and scattering interference within the ion beam. An investigation is presented, showing some of the reasons for the problems involved. RIBE and RIE processes are compared by computer simulations based on Monte-Carlo methods of analyzing the ion transport from the ion source to the target (RIBE) and from the plasma to the cathode (RIE), respectively.