A system for ion-beam etching

A system for ion-beam and reactive ion-beam etching was developed. The system consists of an ion source generating ions with a certain energy and a vacuum chamber to hold the details to be processed on. The ion source consists of an ion chamber, cathode, anode, a system for creating a multi-polar magnetic field and an ion accelerating unit. The ion source characteristics are: ion-beam dia. - 7 cm; ion-energy 0-2keV; ion-beam density - up to 2 mA/cm2; ion-beam uniformity - for PHI 5.5 cm. - +-5%, for PHI 7 cm. -+-10%; beam divergence - up to 12 deg. The plasma uniformity in the chamber is due to the undermentioned three factors: 1) The design of the magnetic field unit permits a homogeneous ion beam. 2) The potential difference between the source (500-1000V) and the accelerating grid (with a negative tension of 100-250V to the mass) does not allow the neutralizing electrons to penetrate between the two molybdenum grids of the ion accelerating system. 3) The gass which comes from the anode disk through a system of holes has a permanent flow throughout the ion chamber. All details with the exception of the accelerating system are made of St.1x18495 which has a low gass release and high resistence to the active gasses. The device is provided with a forced water cooling. The profile of the ion layer was measured (the dependence between the current density and the distance from the ion beam centre) at a discharge tension (cathode - anode) of 50V and vacuum in the chamber - 1.33-2 Pa. The profile is characterized by peaks in the beam edges which is explained with the Mo thermal deformation. (authors)