Pure bulk A1N substrates were prepared by hot pressing to eliminate the influence of an aid-sintering substance on the interface reactions. AlN thin films were deposited on Si(111) substrates to decrease the influence of charging on the analyses of metal/AlN interfaces with x-ray photoelectron spectroscopy (XPS). Thin films of titanium and nickel were deposited on bulk AlN substrates by e-gun evaporation and ion-beam assisted deposition (IBAD) and deposited on AlN films in situ by e-gun evaporation. The samples of the evaporated Ti films on bulk AlN and Ni films on bulk AlN were annealed at temperatures from 600 to 800 degrees C and from 600 to 850 degrees C for 1 h, respectively. Solid-state reaction products between the metal films and bulk AlN substrates under annealing and IBAD were investigated by x-ray diffraction (XRD) and Ruthford backscattering spectroscopy (RES). TiAl3, TiN, and Ti4N3-x including Ti2N were found at the interface between the Ti films and AlN substrates for the annealed samples and IBAD sample. No interaction phase was detected for the sample as-deposited by evaporation. However, XPS depth profile of the Ti/AlN/Si sample showed that Ti-N bonding existed at the interface between the AlN film and Ti film. In the Ni/bulk AlN system, NiAl3 and Ni3N were formed at the interface between the Ni thin film and bulk AlN substrate for the samples annealed above 600 degrees C for 1 h. No interaction phase was detected by XRD and RES for as-deposited samples and no evidence for Ni-N or Ni-Al bonding was obtained by XPS depth profile of Ni/AlN/Si.