Microstructural and electrical properties of Cu-germanide formed on p-type Ge wafer
Material properties of Cu3Ge were investigated as a function of RTA temperature.
Orthorhombic Cu3Ge was only phase formed, irrespective of RTA temperature.
RTA at 400 °C led to the formation of Cu3Ge having highly uniform surface and interface.
Minimum specific contact resistivity was obtained after RTA process at 400 °C.
After 700 °C, inverted pyramidal Cu3Ge islands aligned along Ge <110> were epitaxially grown on Ge.
We have investigated the microstructural and electrical properties of Cu-germanides formed by the deposition of Cu on Ge wafer, followed by rapid thermal annealing (RTA) process at the temperatures in the range of 300–700 °C. Regardless of RTA temperature, the Cu3Ge was the only phase formed as a result of solid-state reaction between Cu and Ge driven by RTA process. The RTA temperature dependency of specific contact resistivity of Cu3Ge was explained in terms of its structural evolution caused by RTA process. The RTA process at 400 °C led to the formation of Cu3Ge film having highly uniform surface and interface morphologies, allowing the minimum value of the specific contact resistivity. The samples annealed above 500 °C underwent the severe structural degradation of Cu3Ge, resulting in a rapid increase in the specific contact resistivity. After RTA at 700 °C, pyramidal Cu3Ge islands standing on a corner, distributed along Ge <110> direction were formed with epitaxial relationship on underlying Ge.