REACTIVE-ION-BEAM-SPUTTERED WNX FILMS ON SILICON - GROWTH MODE AND ELECTRICAL-PROPERTIES

WN films were deposited on clean Si(100) substrates via reactive-ion-b eam sputtering a W target by a nitrogen ion beam in an UHV system. The energy of the incident ions varied in the range of 0.250 to 3 keV. Th e growth mode dependence of the films on the nitrogen ion energy was s tudied by in situ Auger electron spectroscopy measured as a function o f coverage. Nitridation of the Si at the first stage of deposition has been found. This nitridation was more pronounced for the lower N beam energies, and minimal for the 2 keV beam. A similar trend was observe d for the bulk film composition. In a complementary way, the dependenc e of electrical properties of the WN/Si junctions on the nitrogen ener gy has been studied. A higher barrier height on p-type Si than on n-ty pe Si was found, unlike the expectation for regular metallization of W and its compounds on Si. The electrical characteristics can be attrib uted to the deposition technique. For the low-energy beams, the format ion of the interfacial layer was probably dominating, while at higher energies radiation damage and possibly also N implantation played a mo re important role.