Microstructural evolution of tantalum nitride thin films synthesized by inductively coupled plasma sputtering
Sung‐Il Baik, Yong‐Woon Kim
Abstract
Abstract Tantalum nitride (TaN x ) thin films were grown utilizing an inductively coupled plasma (ICP) assisted direct current (DC) sputtering, and 20–100% improved microhardness values were obtained. The detailed microstructural changes of the TaN x films were characterized utilizing transmission electron microscopy (TEM), as a function of nitrogen gas fraction and ICP power. As nitrogen gas fraction increases from 0.05 to 0.15, the TaN x phase evolves from body-centered-cubic (b.c.c.) TaN 0.1 , to face-centered-cubic (f.c.c.) δ-TaN, to hexagonal-close-packing (h.c.p.) ε-TaN phase. By increasing ICP power from 100 W to 400 W, the f.c.c. δ- TaN phase becomes the main phase in all nitrogen fractions investigated. The higher ICP power enhances the mobility of Ta and N ions, which stabilizes the δ-TaN phase like a high-temperature regime and removes the micro-voids between the columnar grains in the TaN x film. The dense δ-TaN structure with reduced columnar grains and micro-voids increases the strength of the TaN x film.