Impact of Ge Preamorphization Implantation on Both the Formation of Ultrathin TiSix and the Specific Contact Resistivity in TiSix/n-Si Contacts

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 (Pc) 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 Pc 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 tTiSi
_x
values are strongly dependent on the thickness of amorphous Si (tα-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 Pc values in TiSi
_x
/n-Si contacts, and this reduction in Pc cannot attribute to the reduction of SBH. Though proper Ge PAI leads to reduced Pc values, the leakage current of p-n diodes is increased as a penalty which needs to be compromised in practical applications.