Effects of Ni Film Thickness on the Properties of Ni-Based Silicides Formed on Both Highly Doped n- and p-Si Substrate

Abstract

Ni-based silicides continue to play an indispensable role during the remarkable development of microelectronics. In this work, on both highly boron (B)-doped n-Si and phosphorus (P)-doped p-Si substrate, the effects of the thickness of initial Ni films on Ni-based silicides properties are investigated comprehensively. Ni films with varying thicknesses from 1–10 nm are deposited followed by rapid thermal annealing (RTP) to form Ni-based silicides. Sheet resistance, phase identity, thermal stability and dopant redistribution are versatilely characterized by four-point probe, X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Secondary Ion Mass Spectroscopy (SIMS). It is found that the dopants tend to segregate at silicides/Si interface when the thickness of Ni films is 3 nm or less, which is paramount beneficial to reduce effective Schottky barrier heights (SBHs) thus lowering specific contact resistivity (ρc).