The formation of NiSi films from the reaction of Ni2Si with (100) and (111) silicon substrates was found to be controlled by a lattice diffusion process with an activation energy of 1.70 eV. In order to correlate kinetic information obtained by Rutherford backscattering with x‐ray diffraction data, ‘‘standard’’ diffraction powder patterns for both Ni2Si and NiSi have been established. The existence of a metastable hexagonal form of NiSi has been confirmed. Observations on the formation of Ni2Si confirm previous investigations. The diffusion process at work during the formation of NiSi is discussed in terms of the crystalline anisotropy of this compound and compared to what is known about diffusion in other silicides.

Formation of thin films of NiSi: Metastable structure, diffusion mechanisms in intermetallic compounds

Influence of the nitrogen partial pressure on the properties of d.c.-sputtered titanium and titanium nitride films

Oxygen has been found to play a dominant role in TiN barrier performance between Si(100) and Al. When TiN is exposed to air prior to Al deposition, interdiffusion of the Si/TiN/Al structure is not observed until heating to a temperature of 560 °C, whereas the barrier fails already below 400 °C when Al is deposited in situ onto TiN.

Oxygen in titanium nitride diffusion barriers

Transport studies have been performed on thin films of CoSi2 and NiSi2 in the temperature range 1–300 K. The conductivities are metallic with essentially the same temperature dependence; however, the residual resistivities are markedly different even though the two silicides are structurally similar (the room‐temperature resistivity of NiSi2 being at least twice that of CoSi2 of 15 μΩ cm). The difference is attributed to intrinsic defects in NiSi2. This defect has been simulated by ion bombardment of the film where it is also shown that Matthiessen’s rule is obeyed over a remarkable range of bombardment doses.

Electrical transport properties of CoSi2 and NiSi2 thin films

Electrical and optical properties of silicide single crystals and thin films

We have determined the resistivity, carrier concentration, and Hall mobility as a function of thickness (700–3000 A) of Ni2Si, NiSi, and NiSi2 layers formed by vacuum annealing at 270÷v300°C, ≈ 400°C, and ≈ 800°C, respectively, of nickel films vacuum-deposited on a silicon substrate (111 n-type and 100 p-type Si ρ ≈ 1KΩ). The layer thicknesses were measured by 2 MeV4He+ backscattering spectrometry. The silicide phase was confirmed by x-ray measurements. The electrical measurements were carried out using van der Pauw configuration. We found the electrical transport parameters to be independent of the film thickness within the experimental uncertainty. The Hall factors were assumed to be unity. The majority carriers are electrons in NiSi and holes in Ni2Si and NiSi2. The resistivity values are 24±2, 14±1, and 34±2 μΩcm, the electron concentrations are 9±3, 10 and 7±1, and ≈ 2 × 1022 cm−3, and the Hall mobilities are 3±1, ≈ 4.5 and 6, and ≈ 9 cm2/Vs for Ni2Si, NiSi (〈100〉 and 〈111〉), and NiSi2, respectively. The systematic error in the measured values caused by currents in the high resistivity substrate is estimated to be less than 6% for the Hall coefficient. The results show that Ni2Si, NiSi, and NiSi2 layers formed by a thin film reaction are electrically metallic conductors, a result which concurs with those reported previously (1) for refractory metal silicides. The Hall mobility increases with the Si content in the silicide. The electron concentration is lowest for NiSi2 leading to the highest resistivity for the epitaxial phase of NiSi2.

E. G. Colgan

Papers

Electrical characteristics of thin Ni2Si, NiSi, and NiSi2 layers grown on silicon

Contact resistivities of sputtered TiN and TiTiN metallizations on solar-cell-type-silicon