Scanning magnetron-sputtered TiN coating as diffusion barrier for silicon devices

Abstract

Scanning magnetron-sputtered titanium nitride (TiN) films were deposited onto silicon substrates under varying nitrogen and argon pressures. Golden TiN films with (220) orientation were deposited at different substrate bias voltages (0to−120V). Auger electron spectroscopy measurements show N∕Ti ratio between 1.18 and 1.07, and oxygen content between 11% and 5% in the as-deposited TiN film samples. Dependence of the stress and grain size on substrate bias voltage and dependence of resistivity on bias voltage and annealing temperature have been studied for the deposited TiN films. Resistivity was found minimum for the TiN samples deposited at −40V bias, which decreases from 320to132μΩcm on annealing, up to 750°C. Copper was sputter deposited on the as-grown TiN films deposited at −40V bias. The Cu∕TiN∕Si samples were annealed at different temperatures. Resistivity, x-ray diffraction, scanning electron microscopy, and energy dispersive x-ray analysis results of the Cu∕TiN∕Si structure are consistent with each other, and show that scanning magnetron sputtering deposited TiN film is a good diffusion barrier for copper metallization of the silicon devices, up to 750°C.