The TaSiO6 films, similar to6 Angstrom thick, were formed by sputter deposition of Ta onto ultrathin SiO2, substrates at 300 K, followed by annealing to 600 K in 2 Torr O-2. X-ray photoelectron spectroscopy (XPS) measurements of the films yielded a Si(2p) binding energy at 102.1 eV and Ta(47/2) binding energy at 26.2 eV, indicative of Ta silicate formation. O(1s) spectra indicate that the film is substantially hydroxylated. Annealing the film to >900 K in ultra-high vacuum resulted in silicate decomposition to SiO2 and Ta2O5. The Ta silicate film is stable in air at 300 K. XPS data show that sputter-deposited Cu (300 K) displays conformal growth on Ta silicate surface (TaSiO6) but 3D growth on the annealed and decomposed silicate surface. Initial Cu/silicate interaction involves Cu charge donation to Ta surface sites, with Cu(I) formation and Ta reduction. The results are similar to those previously reported for air-exposed TaSiN, and indicate that Si-modified Ta barriers should maintain Cu wettability under oxidizing conditions for Cu interconnect applications.