In-situ real time studies of nickel silicide formation

Abstract

NiSi, with its low resistivity and wide processing window (350 - 750°C), is an attractive candidate for use as a gate contact material. In order to follow the interface reaction that leads to the formation of NiSi in real time, ellipsometry and atomic force microscopy (AFM) were used to study changes on the surface resulting from the reaction between Ni and Si for various times and temperatures, and Rutherford Backscattering spectrometry (RBS) to determine compositional changes in the forming silicides. We report that ellipsometry can be used to monitor the various Ni-Si phases forming in real time, and we have observed agglomeration of the silicide, which has been reported to occur at 1000°C, at temperatures, as low as 550°C for long time anneals.

Real-Time Ellipsometry at High and Low Temperatures

“…The capability of SE to determine not only thicknesses but also both the real and imaginary parts of the dielectric function simultaneously has been utilized in many phase-transition studies in charge transfer solids (T = 150 → 400 K), 68 crystallization of amorphous Si 29,59 also in the presence of Al, 69 annealing of Si, 70 NiSi (T = 623 → 1023 K), 71 the switchable molecular solid RbMn[FeCN 6 ] (T = 150 → 400 K), 72 Ge 2 Sb 2 Te 5 phase changing material (T = 293 → 623 K), 73 relaxation in a-InGaZnO, 74 and phase change in vanadium oxides. 75−77 S. Bin Anooz et al 78 determined the phase transition in epitaxial NaNbO 3 films grown under tensile lattice strain on the (110) DyScO 3 substrate up to T = 823 K. The n is measured at an energy of 3.2 eV, i.e., near the band gap of 3.9 eV, to best observe variations with phase transitions and structural changes.…”