Preparation of titanium nitride onto molybdenum, stainless steel and carbon by gas absorption and reactive r.f. sputtering

Abstract

Titanium nitride layers were prepared by gas absorption and reactive r.f. sputtering. In the gas absorption method, a Ti foil was heated at 540 – 740 °C under nitrogen pressure of 1 – 5 × 10 −3 torr. A UHV microbalance was utilized to observe an absorption process of nitrogen gas and showed that there were two processes in Ti nitridation. The absorption rate curve obeyed a linear rate law in the initial stage and then followed a parabolic rate law. Depth profile measurements of the coatings by XPS along with argon ion sputter-etching revealed that the nitride film followed the parabolic law had a thick and uniform nitride layer ( N Ti = 2 3 ) while the specimen following the linear law had the nitride layer only near the surface region and the concentration of nitrogen decreased sharply toward the bulk. On the other hand, a homogeneous nitride layer was easily prepared on Mo, 304 stainless steel and carbon substrates even at such low temperature as less than 150°C by the reactive r.f. sputtering method. The quantitative depth composition profile of the nitride layer was performed by means of RBS. It was found that the almost stoichiometric Ti-nitride (TiN) formed in the certain nitrogen partial pressure region.