Effect of internal stresses and microstructure of sputtered TiN films on solid-phase reactions with Al-Si-Cu alloy films

Abstract

Solid-phase reactions at the interface between Al-Si-Cu and reactively sputtered TiN thin films have been investigated by cross-sectional transmission electron microscopy, Auger electron spectroscopy, and x-ray diffraction. In the case in which the internal stress in the TiN thin film is extremely compressive at 209 MPa, a very thin amorphous Al-Ti-Si ternary compound layer (a-Al-Ti-Si) containing microcrystallites, about 4 nm thick, is found to form at the Al-Si-Cu/TiN interface by annealing at the temperature of 450 °C for 30 min. On the other hand, in the case of a minimally compressive stress of 21 MPa, it is in a marked contrast to form a polycrystalline TiAl3 layer (c-TiAl3) on the amorphous intermediate layer ununiformly. Behavior of the internal stress in the latter TiN film as a function of heating and cooling temperature shows nonlinear characteristics, indicating that a rearrangement of the TiN film actively occurs even at low temperatures below 300 °C. Monte Carlo simulations of internal microstructures based on a ballistic aggregation model suggest to us that a short migration length corresponding to the condition of low internal stress brings about numerous vacancies and disordered regions in the TiN films. It is considered that the rearrangement of the TiN films with a diffusion of Ti atoms governs the solid-phase reactions at the Al-Si-Cu/TiN interfaces and that the formation of the bilayer of c-TiAl3/a-Al-Ti-Si originates in phase separation of the resultant Al-Ti mixing layer.

Transition metal nitride formed by simultaneous physisorption and thermal evaporation; TiN/Si(100)

“…Remembering, from the argument in the previous paragraph, that the broad peak near 400.5 eV in Fig. 3͑a͒ consists of physisorbed NH 3 and TiN x H y , the intensity increment ratio of the Ti nitride shown in Fig. 3͑b͒, which is larger than that of Si 2p, must be due to the fact that the annealing process induces removal of H from the precursor TiN x H y ͑i.e., increment of Ti nitride͒ in addition to NH 3 desorption.…”

“…1, the survey spectra obtained from ͑a͒ the NH 3 and Ti co-deposited, ͑b͒ the 300°C postannealed, and ͑c͒ the 800°C postannealed surfaces, are shown. The exposing NH 3 pressure was kept at 5ϫ10 Ϫ8 mbar, while 10 Å of Ti was evaporated for 5 min.…”

“…[3][4][5] The major advantages of nitrides in such applications reside in their structural stability as well as chemical inertness. That is, once the nitrogen atom reacts with other elements, their bondings are so stable that the nitrogen compounds are not easily dissociated by other elements in their environment.…”

Mechanical Properties of TiN Films with the Preferred Orientations by Nano-Indentation Method

“…TiN coatings have been widely applied to cutting tools and bio-compatible materials because of their excellent wear-and corrosion-resistance [1]. In recent years, TiN films have also been found useful in the electronic industry as a diffusion barrier layer in metallization and contact technology for Si devices [2]. In an attempt to improve the mechanical properties of TiN films, it is necessary to clarify the precise relationship between the preferred orientation and mechanical properties.…”