High Temperature Reliability of Refractory Metal Ohmic Contacts to Diamond

Several metallization schemes using refractory metals have been demonstrated to produce ohmic contacts to diamond via a solid-state reaction process. This process utilizes existing microelectronic techniques and provides strongly adherent contacts which exhibit low contact resistance. Measurements of the long-term reliability of Mo/Au contacts formed by this process on a type IIb diamond crystal are presented here for the temperature range 450 to 625 deg C. The measurements consist of the resistance between two contacts as a function of isothermal annealing time over time intervals in excess of 130 h in a purified inert ambient. The Mo/Au contacts appeared to be stable and reliable at these high temperatures with no indications of deterioration or degradation of performance.