Mechanisms of the low contact resistance properties for Ag-Pd-Mgcontacts

摘要

In order to improve the contact resistance properties of Ag(40wt%)-Pd(60 wt%) alloy, doping of Mg and Cr into the Ag-Pd alloy wascarried out. As previously reported, the Ag-Pd alloy with the Mg dopingagent indicated marked improvements in contact resistance. In thisstudy, the mechanism of the low level contact resistance of the Ag-Pd-Mgalloy was clarified. First, scanning tunneling microscopy (STM) imagesfor the Ag-Pd-Mg, Ag-Pd-Cr, and Ag-Pd alloys were observed. From theseimages, high conductivity was found throughout the entire surface of theAg-Pd-Mg alloy. However, the surfaces of the Ag-Pd-Cr and Ag-Pd alloysexhibited low conductivity. Furthermore, to determine the highconductivity mechanism of the surface of the Ag-Pd-Mg alloy, the elementdistribution depth profile was analyzed using X-ray photoelectronspectroscopy (XPS). The results revealed that Ag existed throughout theentire surface of the Ag-Pd-Mg alloy. On the other hand, for theAg-Pd-Cr alloy, no Ag was found anywhere. It was concluded that in thecase of the Ag-Pd-Mg alloy, even if the surface was covered with oxidefilms, Ag should diffuse from the substrate to the film layer and theexistence of Ag in the layer causes high conductivity. Therefore, lowcontact resistance properties can be obtained