Magnetron-plasma ion beam etching: A new dry etching technique

A new dry etching technique called magnetron-plasma ion beam etching (MIBE) is described which allows for decoupling of the chemical etch component from the ionic (physical) component which cannot be achieved in other conventional plasma processing methods. In MIBE, a rf discharge at 10−4 Torr is sustained and confined by a magnetic field. Concurrently, a broad beam ion source is used to independently deliver an energetic physical flux of Ar+ ions with energies ranging from 400 to 1500 eV which passes through the confined plasma to the substrate with little interaction or deflection. It was observed that the MIBE etch rates of Si using SF6 as the etch gas were greater than the independent magnetically enhanced reactive ion etching (MIE) and the Ar+ ion milling rates combined. However, the structure profiles were observed to be directly related to the separately controllable etch components. Isotropic etching of silicon was obtained from the chemical MIE plasma but as the energy of the ionic flux was increased, physical ion milling characteristics were observed to dominate the etch profile.