The effect of silicon ion implantation on the structure of tantalum–silicon contacts

Abstract

The effect of ion beam mixing on the formation of tantalum–silicon contacts was studied. Silicon implantation into 50 nm Ta layers on n +-Si (1 0 0) was carried out at temperatures from 150 to 500 °C and fluences between 1×10 15 and 1×10 17 Si/cm 2. The microstructural changes were characterized by Auger electron spectroscopy, X-ray diffraction and cross-sectional transmission electron microscopy. The contact resistance was measured before and after implantation using the four-point Kelvin method. Implantation at low temperature (∼150 °C) leads to the formation of an amorphous Ta(Si) interface-layer. The width of the mixed layer increases linearly with implanted dose and temperature. Substrate amorphization results in an increase of the contact resistance. An improved contact resistance was achieved by implantation with 5×10 16 Si/cm 2 at 400 °C. TaSi 2 formation at the interface was observed in this case.