Characterization of ion-beam-sputtered molybdenum films on n-type silicon

The introduction of defect levels in the band gap of silicon after ion beam sputtering of molybdenum contacts, was investigated with deep level transient spectroscopy and scanning electron microscopy (electron-beam-induced current mode). Molybdenum contacts were fabricated with beam voltages of 700, 1100 and 1500 V at a beam current density of 2.5 mA cm-2. Defect levels were observed at energies ranging from 0.18 to 0.55 eV below the conduction band. It was established that the introduction of these defect levels depends on the processing conditions and that they reside very close to the Mo-Si interface (less than 0.4 μm). A correlation was observed between the fabrication conditions, the current-voltage and capacitance-voltage characteristics of the contacts, and the concentrations of the defects present. Charge collection micrographs confirmed the presence of a defective layer close to the surface. (Auth.)