Thin film interaction between titanium and polycrystalline silicon

Abstract

The low resistivity of the titanium disilicide makes this material attractive for gate and interconnect metallizations. TiSi2 has been formed by reacting Ti films with polycrystalline and monocrystalline silicon in the temperature range 400–1100 °C. The interaction is investigated by use of sheet resistance, x-ray diffraction, and stress measurements. It has been found that Ti and Si react very rapidly to form both TiSi and TiSi2 at temperatures ? 700 °C and only TiSi2 at temperatures ≳ 700 °C. The TiSi2 films are associated with a very low resistivity (∼15 μΩ cm), high tensile stress [∼ (1–2) ×1010 dyn/cm2)], and a rough surface. Silicided structures are mechanically stable. It is proposed that the silicon, as the predominant diffusing species, first diffuses into titanium to completely convert titanium into TiSi and then into TiSi to form TiSi2.

The process window of a-Si/Ti bilayer metallization for an oxidation-resistant and self-aligned TiSi/sub 2/ process

“…The (h, k , I) values of the TiSiz phase indicate that the cystallographic s p c t u r e is orthorhoombic with a = 8.267 A , b = 4.799 -4, and c = 8.550 A . On the other hand, the behavior of the X-ray intensities for TiSi and Tis& as a function of the annealing temperature also shows a similar tendency as reported in the previous study [7], e.g., TiSi and TiSi2 are first detected after annealing at 600"C, and only TiSiz exists after annealing at 800°C. These results imply that the final crystallographic structure and the phase growth with respect to the annealing temperature can be basically retained in an a-Si/Ti bilayer process.…”

“…Due to the abundant supply of Si atoms from the a-Si film, the surface silicide layer will act as an "anti-snow-plow" barrier during thermal annealing, and thus a large amount of oxygen impurities may still remain within the silicide film after the silicidation process. The presence of oxygen impurities in either Ti film or silicide layer will impede the grain growth and thus increase the impurity scattering [7], so the buried oxygen impurities are believed to con-tribute to the higher sheet resistance v$ue for the a-Si/Ti bilayer with a-Si thicker than 100 A after thermal annealing, as observed in Fig. 1.…”

In-situ neutron diffraction of titanium silicide, Ti5Si3, during self-propagating high-temperature synthesis (SHS)

“…The fifth silicide phase, Ti 5 Si 3 is the only phase to exhibit a degree of nonstoichiometry (Si solubility of 3.3 wt%) over a temperature range of 1443-1603 K. Ti 5 Si 3 is the most thermodynamically stable of the five intermetallic phases with the highest formation enthalpy (DH f (Ti 5 Si 3 )ZK579 kJ mol K1 ). By depositing Ti thin films onto polycrystalline Si substrates, then annealing between 673 and 1373 K, Murarka identified Si to be the major diffusant in the Ti-Si system [2]. Additionally, Lee et al using Auger Electron Spectroscopy (AES) sensitivity factors, were able to determine the onset of Si diffusion into similar Ti films to be between 673 and 773 K [21].…”

“…Titanium silicide (Ti 5 Si 3 ) has been investigated as a material suitable for high temperature applications [1,2]. It has a combination of a high melting point (2403 K), a low density (4.32 g/cm 3 ), high hardness (11.3 GPa), and a relatively high Young's modulus (225 GPa) [1].…”

Reaction of CVD ‐ WSi x Film and Al Film

“…The resistivity, oxidation rate, contact resistance, adhesion to the silicon substrate, stress breakdown voltage of the gate SiOz, and the interaction with polycrystalline silicon have been investigated in order to characterize CVD-WSix and other silicide films (5)(6)(7)(8)(9)(10)(11)(12)(13)(14). However, there are few papers investigating the interaction between CVD-WSix and aluminum films (15).…”