Formation of high temperature phases in sputter deposited Ti-based films below 100 °C

Abstract

This article reports on the sputtering of pure Ti and Ti-based alloy films onto substrates where the temperature Ts was kept below 100 °C, using the magnetron sputter ion plating process. It was found that while the pure Ti film is a hexagonal low-temperature phase film (h–αTi), the Ti–Cr, and Ti–Fe alloy films, containing a relatively small amount of Cr or Fe of about 10 wt %, are cubic high-temperature beta phase Ti alloy films [c-βTi(Cr) or c-βTi(Fe)]. This finding is of immense importance both scientifically and practically. The conditions under which high-temperature phases are formed in alloy films sputtered at substrate temperatures below 100 °C, which is much lower than the temperature necessary to form these high-temperature phases (Thtp) according to the equilibrium phase diagram, will be discussed in detail. X-ray diffraction analyses of these films will also be presented.

Effect of Al Addition on Structure and Properties of Sputtered TiC Films

“…= −215.8 kJ · mol −1 12. This result can, however, be explained by a freezing of the liquid TiC phase (3 250 °C13) due to an extremely fast cooling at atomic level in magnetron sputtering 6,14. We believe that fast cooling prevents the formation of Al 4 C 3 with lower melting point (2 800 °C15).…”

Photoactivated Properties of TiO2 Films Prepared by Magnetron Sputtering

“…We believe that the oxygen added to high energy (1 to several tens of eV) Ti in reactive sputtering can act as “doping” element sputtered Ti in TiO x compound and high energy of atoms are sufficient to form high‐ T rutile phase. In this context the formation of high‐ T rutile phase at low substrate temperature T surf ≤ T htp is a result of the rapid cooling that accompanies the highly nonequilibrium sputter deposition process operating at an atomic level;17 T htp is here the formation temperature of high‐ T phase at equilibrium. This hypothesis is based on our previous experiments which already confirmed the formation of high‐ T phases in Ti‐based alloys; high‐ T c‐ β Ti(Fe) and c‐ β Ti(Cr) 17.…”

“…In this context the formation of high‐ T rutile phase at low substrate temperature T surf ≤ T htp is a result of the rapid cooling that accompanies the highly nonequilibrium sputter deposition process operating at an atomic level;17 T htp is here the formation temperature of high‐ T phase at equilibrium. This hypothesis is based on our previous experiments which already confirmed the formation of high‐ T phases in Ti‐based alloys; high‐ T c‐ β Ti(Fe) and c‐ β Ti(Cr) 17. Our experiments indicate that formation of high‐ T rutile phase is created at the conditions far form the equilibrium (low p, low p T , low T surf , high a D ) while low‐ T anatase is preferred at the conditions closer to equilibrium (high p, high p T , high T surf , low a D ).…”

The phase, morphology and surface characterization of Ti–Mo alloy films prepared by magnetron sputtering

“…One is the interface reaction between the lm and the substrate at such high T s , the other is a subsequent stabilization of b-Ti phase to low temperatures when cooled down. To the best of our knowledge, Musil et al 27 rstly reported the formation of metastable b-Ti alloy lms formed by magnetron sputtering. Because of atomic scale heating from particle bombardment, btype Ti-10 wt% Cr and Ti-10 wt% Fe lms can be formed when T s is below 100 C (T b,Ti-Cr $ 667 C, 27 T b,Ti-Fe $ 595 C (ref.…”

“…For instance, from XRD results, Ti-10 wt% Cr alloy lms have a a-Ti growth without substrate bias, but change into an amorphous growth at À150 V. 23 Also, they could have a b-Ti growth when under proper bombardment conditions. 27 The second problem is to keep the metastable b-Ti phase in the lms during the whole deposition, which depends on alloy composition of the lms and the T s . Substrate heating could partly decrease defects, and improve lm/substrate interface bonding, crystallinity or structural density of the lms, but it may cause the decomposing of metastable b-Ti phase during the deposition.…”