Abstract:
This paper addresses the in situ growth stress evolution and phase transformation of bcc to hcp Ti
in Ti/W multilayered thin films. A series of equal layer thicknesses from 20 nm to 1 nm were
deposited. As the bilayer thickness reduced, the overall film stress became less compressive until
the Ti transformed from hcp (at the larger layer thicknesses) to bcc in the 1 nm/1 nm multilayer.
The pseudomorphic bcc stabilization resulted in a recovery of the compressive stress to values near
that for the bulk phase stabilized for the 5 nm/5 nm multilayer. A discernable change in stress slope
was noted for the bcc to hcp Ti transition as a function of Ti layer thickness. The stress states for
each film, during film growth, are rationalized by the lattice matching of the phase with the growth
surface. These results are coupled to a molecular dynamics deposition simulation which revealed
good agreement with the experimentally observed transformation thickness.
