CrN films deposited by rf reactive sputtering using a plasma emission monitoring control

Abstract

We have studied the influence of the nitrogen partial pressure ( P N 2 ) on composition, crystal structure, internal stress, resistivity and hardness of the rf reactive sputtered Cr–N films. Cr–N films have been deposited onto glass substrates by rf reactive magnetron sputtering using a plasma emission monitoring control system, where a signal in proportion to the light emitted by the sputtered Cr in the glow discharge plasma was used to control the admission of the reactive nitrogen into the system. Applied rf power and argon partial pressure ( P Ar) were kept constant at 140 W and 0.3 Pa, respectively. It is found that the composition of nitrogen in as-deposited films increases with increasing P N 2 . Stoichiometric CrN films seemed to grow at a P N 2 of about 1∼2×10 −2 Pa. The crystal structure of the film deposited at P N 2 lower than 1×10 −2 Pa is of hexagonal Cr 2N, while the film deposited at P N 2 higher than 1×10 −2 Pa is of single phase CrN with an NaCl-type structure. The CrN film with good mechanical property is found to grow within a very narrow region of P N 2 .