Study of CoSi2 formation from a CoNi alloy
CoSi2 formation from CoNi alloys with 25 and 10% Ni content was investigated. Samples with various CoNi/Ti stacks were characterized by four-point probe, AES, XRD, RBS and TEM. Light scattering measurements were carried out for roughness evaluation. Stress build-up was estimated from room temperature measurements of wafer curvature. It was found that Co disilicide formation temperature decreases with an increase of the Ni percentage. CoSi2 growth at temperatures around 450500C depending on Ni concentration and Ti cap thickness was observed. Sheet resistance of 56.5 ?/sq. was measured for various CoNi/Ti compositions. CoSi2(220) and CoSi2(111) peaks were detected on XRD spectra for both Ni-rich and Ni-poor layer. Stress values of 0.91.9 GPa were calculated for silicidation of various CoNi/Ti stacks. The roughness of the silicide film was found to be dependent on Ni concentration, Ti cap thickness and anneal temperature.
roughness stress sheet resistance coni silicide nucleation temperature