Effects of prolonged annealing on NiSi at low temperature (500°C)

Abstract

The effects of prolonged annealing (10 h) at low temperature (500°C) have been studied in 20-nm Ni/Si (100) thin films using Rutherford backscattering spectroscopy (RBS), x-ray diffraction (XRD), scanning electron microscopy (SEM) in conjunction with energy-dispersive spectrometry (EDS), and four-point probe techniques. We observe that nickel monosilicide (NiSi) is stable up to 4 h annealing at 500°C. It is also found that, after 6 h and 10 h annealing, severe agglomeration sets in and NiSi thin films tear off and separate into different clusters of regions of NiSi and Si on the surface. Due to this severe agglomeration and tearing off of the NiSi films, sheet resistance is increased by a factor of 2 despite the fact that no NiSi to NiSi 2 transition occurs. It is also observed that, with increasing annealing time, the interface between NiSi and Si becomes rougher.