Low-temperature chemical vapor deposition of tantalum nitride from tantalum pentabromide for integrated circuitry copper metallization applications

Abstract

A low-temperature (>450 °C) thermal chemical vapor deposition (CVD) process was developed for the growth of TaNxfrom the reaction of tantalum pentabromide, ammonia, and hydrogen. Studies of process reaction kinetics yielded two sequential rate-controlling steps, with an activation energy of 0.45 eV for the kinetically limited reaction regime. Additionally, a systematic design of experiments approach examined the effects of key process parameters, namely, substrate temperature, source temperature, and hydrogen and ammonia flows, on film properties. A wide CVD process window was established for nitrogen-rich amorphous TaNxwith contamination below 1 at.%. Film conformality was higher than 95% in nominally 0.30 μm, 4.5: 1 aspect ratio, trench structures.