Microstructure and barrier properties of reactively sputtered Ti-W nitride

Characterization of Ti diffusion in PVD deposited WTi/AlCu metallization on monocrystalline Si by means of secondary ion mass spectroscopy

“…According to Wang et al [10] a grain size of approximately 13-15 nm is estimated, which is not illustratable with our TEM resolution. The diffraction pattern during TEM analysis showed a bcc-crystal structure which is consistent with previous investigations by Raaijmakers et al [7]. Furthermore, it is striking that the WTi thin film on the substrate is stoichiometrically different from the composition of the sputtering target.…”

“…This effect was also observed in similar investigations by Bergstrom et al [4]. This stress enhancement is known as the ''peening effect'' and it is supposed to be a result of incorporated Ar ions [7]. In Table 2 measured film properties of WTi are shown.…”

“…A Ti difference of 12 at.% was measured by XRF (see Table 2), which is caused by the resputtering effect. High-energy Ar + ions are scattered back because of the high mass difference to W, and they themselves sputter Ti out of the deposited layer [7,11]. This effect can be described by the theoretical model of an ideal elastic collision [12] in which the ratio of the reflected energy E r to the primal energy E 1 is…”

“…For that reason diffusion barriers are implemented in semiconductors to avoid Si saturated metallization. Tungsten Titanium (WTi) is well known as a diffusion barrier between Al based metallization and Si [2,[4][5][6][7][8]. Previous investigations examined stressed Si/WTi/Al metallization in temperature ranges above 673 K. Activation energies and diffusion coefficients were mostly calculated using electrical failures or resistivity curves [2,4,6].…”

Deposition and properties of Mo–N films

“…Doping of this Ti-W layer with oxygen or nitrogen makes it possible to raise the interaction temperature with Al from 300 to 550°C. 30 Interstitial compounds, e.g., borides, carbides, and silicides of Ti, Zr, Hf, and V, 31 have also been mentioned as alternative diffusion barriers. Several types of diffusion barriers have been described, 31,32 among which a stable compound is also a possible choice.…”