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Influence of metal electrodes on crystal orientation of aluminum nitride thin films

2004; Elsevier BV; Volume: 74; Issue: 3-4 Linguagem: Inglês

10.1016/j.vacuum.2004.01.052

1879-2715

Morito Akiyama, Keigo Nagao, Naohiro Ueno, Hiroshi Tateyama, Tetsuo Yamada,

Metal and Thin Film Mechanics

We have investigated the influence of various bottom metal electrodes on the crystallinity and crystal orientation of aluminum nitride (AlN) thin films prepared on them in order to develop thin film bulk acoustic wave resonators. AlN films were prepared on 15 kinds of bottom metal electrode (Ag, Al, Au/Ti, Co, Cr, Cu, Fe, Mo, Nb, Ni, Pt/Ti, Ti, W, Zn, Zr) using rf magnetron reactive sputtering method. The crystallinity and crystal orientation of the AlN films strongly depend on the bottom metal electrodes. The AlN films prepared on the metal electrodes with the face centered cubic lattice structure show high c-axis orientation, except Ni. The AlN films prepared on Au/Ti and Pt/Ti show the highest crystallinity and orientation among them. The high crystallinity and orientation are due to the fact that the crystallinity of the Au/Ti and Pt/Ti electrodes is high, the surface roughness of the Au/Ti and Pt/Ti is low, and Au and Pt (1 1 1) planes match well with hexagonal AlN crystal structure. These results suggest that the crystallinity and orientation of AlN films are strongly influenced by bottom metal electrodes.