Effects of substrate bias and nitrogen flow ratio on the resistivity, composition, crystal structure, and reflectance of reactively sputtered hafnium-nitride film

Abstract

Hf-N films were sputtered in an Ar + N 2 atmosphere, with different substrate biases (0 to −200 V) at various nitrogen flow ratios (N 2% = 0–5%). The resistivity, composition, crystal structure, and reflectance of Hf-N films were examined. The resistivity of Hf-N films deposited at 0% nitrogen flow ratio decreases with increasing substrate bias. In addition, the resistivity of −200 V biased Hf-N films increases to a limited extent with increasing nitrogen flow ratio, whereas the resistivity of zero- and −100 V biased films increases abruptly with an increasing nitrogen flow ratio of up to 5%. The zero- and −100 V biased Hf-N films display a hafnium oxide phase when film is deposited at a 5% N 2 flow ratio, while Hf-N films deposited at −200 V bias show a HfN phase. The reflectance of zero- and −100 V biased films deposited at 5% N 2 flow ratio shows a significant interference hump in the visible region. In addition, the reflectance edge of Hf-N films is related to the density of the conduction electron. The connection among resistivity, composition, crystal structure, and reflectance and how they are influenced by the substrate bias and nitrogen flow ratio is discussed.