ION BEAM THIN FILM DEPOSITION.

Ion beam deposition equipment was developed to sputter coat insulating SEM specimens with metal or carbon. A cold cathode saddle-field ion source, operating at low pressure (15 mPa), produces a 2 mm diameter beam of energetic ions (5 keV) and neutrals with a flux density equivalent to 15 mA/cm**2. When the beam is directed on to a target, the sputtered material coats the specimen, which should be rotated and oscillated to ensure best coverage. With the specimen stationary, sharp shadowing is obtained because of the small sputtering area on the target and because there is little scatter of the sputtered particles. AgBr crystals were coated without introducing the artefacts observed after diode sputtering, indicating that exposure of the specimens to actinic radiation is largely avoided. A crystallized fat specimen (melting point 38 degree C) gave no evidence of melting after 1 hour of coating. Transmission electron microscopy showed grain sizes in carbon, platinum and gold films of about 1 nm and thus below the present resolution of SEM of 3 nm.