STRUCTURAL AND CHEMICAL-STABILITY OF TA-SI-N THIN-FILM BETWEEN SI ANDCU

Thermal stability and barrier performance of reactively sputter deposi ted Ta-Si-N thin films between Si and Cu were investigated. RF powers of Ta and Si targets were fixed and various N-2/Ar flow ratios were ad opted to change the amount of nitrogen in Ta-Si-N thin films. The stru cture of the films are amorphous and the resistivity increases with ni trogen content. After annealing of Si/Ta-Si-N(300 Angstrom)/Cu(1000 An gstrom) structures in Ar-H, (10%) ambient, sheet resistance measuremen t, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Auger electron spectroscopy (AES) w ere employed to characterize barrier performance. Cu3Si and tantalum s ilicide phase are formed at the same temperature, and the interdiffusi on of Si and Cu occurs through the local defect sites. In all characte rization techniques, nitrogen in the film appears to play an important role in thermal stability and resistance against Cu diffusion. A 300 Angstrom thick Ta43Si4N53 barrier shows the excellent barrier property to suppress the formation of Cu3Si phase up to 800 degrees C. (C) 199 8 Elsevier Science S.A. All rights reserved.