An i n s i t u x-ray study of gold/barrier-metal interactions with InGaAsP/InP layers

The effectiveness of barrier metal such as Cr, Ni, Pd, Pt, and Ti in gold metallization contacts on InGaAsP/InP was studied. Using a temperature-dependent in situ x-ray technique the alloy formation in the contacts was investigated in the temperature range 130–500 °C and compared with previous studies on contacts without the presence of a barrier. These results were further compared with x-ray analysis of gold/barrier contacts subjected to a standard metallization alloying procedure. The results of the slow temperature ramps (0.4 °C/min) used for the in situ x-ray analysis provided insight into the long-term stability of the contacts. From the temperatures at which alloy formation occurs with and without the presence of a barrier, a measure of the effectiveness of the incorporated barrier could be obtained. While Ni and Pd were found to be ineffective barriers, Pt and Ti are resonably effective in slowing down Au-semiconductor interactions. Cr and bimetallic Ti/Pt were found to exhibit long-term stability in both Au/InP and Au/InGaAs contacts.