The effect of target power on the nitrogen partial pressure level and hardness of reactively sputtered titanium nitride coatings

• Published in: Thin solid films 1989-04, Vol.171 (1), p.171-181
• Main Authors: Sproul, William D., Rudnik, Paul J., Gogol, Carl A.
• Format: Article
• Language: English
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Metallic coatings; Metals, semimetals and alloys; Metals. Metallurgy; Physics; Production techniques; Specific materials; Surface treatment
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/0040-6090(89)90042-4

Target power and deposition rate have a significant effect on the properties of titanium nitride (TiN) coatings prepared by high rate reactive sputtering. As the target power is increased from 2.3 to 10.0 kW and the deposition rate from 1000 to 4800 Å min -1, the Vickers microhardness (50 gf) increases from 970 to 3160 kgf mm -2 and the crystallographic orientation goes from a very strong (111) texture to a more random orientation for the TiN coatings. The partial pressures of the argon and nitrogen gases measured through the target show an apparent drop as power is applied to the titanium target. This apparent drop in pressure is actually a density reduction of the gases in front of the target due to gas rarefaction and heating. In order to maintain stoichiometry in the coatings, the partial pressure of the nitrogen reactive gas must be increased as the target power is increased to offset the N 2 density reduction and to compensate for the increase in density of the titanium atoms.