FILMS OF NI-7 AT-PERCENT V, PD, PT AND TA-SI-N AS DIFFUSION-BARRIERS FOR COPPER ON BI2TE3

Films of Ni-7 at% V, Pt, Pd, and Ta40Si14N46, each approximately 100 n m thick, were magnetron-deposited and Interposed between about 250 nm thick copper overlayers and Bi2Te3 single-crystalline substrates. The samples were then annealed in vacuum up to 350 degrees C. The performa nce of the metal and the tantalum-silicon-nitride films as diffusion b arriers for in-diffusion of Cu and out-diffusion of Bi and Te was eval uated by 2.0 MeV He-4 backscattering spectrometry and x-ray diffractio n. The Ni-7 at%:V, Pd and Pt films all fail to prevent interdiffusion of Cu and Bi2Te3 after a few hours of annealing at 200 degrees C. Howe ver, the Ta40Si14N46 barrier preserves the integrity of the contact: a fter 250 degrees C for 50 h and 350 degrees C for 1 h anneals. These r esults confirm the superior characteristics of the metal-silicon-nitri de films as diffusion barriers.