TITANIUM AND TANTALUM COATINGS ON ALUMINUM NITRIDE

Thin films of titanium and tantalum were deposited on aluminum nitride substrates by vacuum evaporation at T = 573 K. Pull tests of film/substrate interfacial strengths yielded 57.57 +/- 14.41 and 67.71 +/- 9.31 MPa for Ti/AlN and Ta/AlN, respectively. The coatings have been examined by profilometry, scanning electron microscopy, x-ray diffraction, Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS). Depth profiles were performed with both AES and XPS. The data indicate that nitrogen, from either the substrates or their surfaces, diffuses into the titanium films and combines with them chemically. No clear evidence for a similar reaction between tantalum films and the AlN substrates was found.