Nickel silicide formation on shallow junctions

Abstract

Nickel silicide formation on shallow junctions is investigated in this paper by X-ray diffraction, micro-Raman spectroscopy, Rutherford backscattering spectroscopy, cross-sectional and plan-view transmission electron microscopy and secondary ion mass spectroscopy. A mixture of Ni2Si and NiSi with a grain size of 12nm is confirmed for silicidation on boron (B) doped junctions after annealing at 300°C, while a pure Ni2Si layer with a grain size of 19nm forms on arsenic (As) doped junctions. After annealing at 450°C NiSi formation is verified for both As and B doped junctions. Two significant dopant peaks are revealed after silicidation regardless of the As or the B case. One is located near silicide/Si interface and the other is found to be several nanometers below the silicide film surface. Dopant segregation and Kirkendall voiding effect are employed to explain these results. Comparing with the B case, for silicidation on the As doped junctions a rougher silicide/Si interface is revealed regardless of the anneal temperature of 300°C or 450°C. At 450°C a more ordered grain texture is demonstrated for silicidation on the B doped junctions.