Abstract:
This paper explores the effect of Ti's segregation and corresponding effect on the intrinsic thin film growth stress and microstructural evolution in a series of W1-x(Ti)x alloys where x is varied from 0 to 20 at. %. We report that the addition of the Ti solute reduces the compressive W growth stress, with further reductions achieved through in-situ annealing during growth. Upon examination of the microstructure, Ti did not appear to have a dramatic effect in altering the film's grain size and distribution, but it did increase the fraction of low angle grain boundaries. We confirmed that the A15 to bcc W phase transformation, which occurs in the early stages of W growth, diminished with increasing Ti content. This has been explained with respect to Ti's preference for gettering residual oxygen, a known stabilizer for the A15 phase. Collectively, this work demonstrates the impact of solute segregation in the control of residual stresses, specific grain boundary formations, and phase transformation control in growing thin films.
