Impact of Ge Preamorphization Implantation on Both the Formation of Ultrathin TiSi<italic>x</italic> and the Specific Contact Resistivity in TiSi<italic>x</italic>/n-Si Contacts

Abstract

In this paper, the impact of different Ge preamorphization implantation (PAI) conditions on the formation of ultrathin TiSi x as well as on the specific contact resistivity ( $\rho _{c}$ ) in TiSi x /n-Si contacts was investigated systematically. Extensive material characterizations, such as cross-sectional transmission electron microscopy, X-ray diffraction, and angle-resolved X-ray photoelectron spectroscopy, as well as electrical characterizations such $\rho _{c}$ values, Schottky barrier height (SBH), and leakage current of p-n junctions, were performed. It is found that Ge PAI indeed promotes Ti silicidation at 550 °C and the resultant ${t}_{\text {TiSix}}$ values are strongly dependent on the thickness of amorphous Si ( ${t}_{\boldsymbol {\alpha -{\mathrm{ Si}}}}$ ) created by Ge PAI. The stoichiometry of TiSi x films is rather graded than constant from the TiN/Ti side to Si side. Proper Ge PAI is beneficial in reducing the $\rho _{c}$ values in TiSi x /n-Si contacts, and this reduction in $\rho _{c}$ cannot attribute to the reduction of SBH. Though proper Ge PAI leads to reduced $\rho _{c}$ values, the leakage current of p-n diodes is increased as a penalty which needs to be compromised in practical applications.