Tribological properties of nitrogen-containing amorphous carbon film produced by dc plasma chemical vapor deposition

The nitrogen-contained amorphous carbon (a-C:N) films were deposited in a de plasma chemical vapor deposition system with different substrate bias voltages. The structural, mechanical, and tribological properties of the a-C:N films were investigated. The influence of the bias voltage on the tribological behaviors of the a-C:N films was evaluated under various environments (dry air, O-2, N-2, and vacuum) using a ball-on-disk friction tester. It showed that the sp(3) C and hydrogen concentration of the a-C:N films decreases with increasing the bias voltage. However, the nitrogen concentration increases with increasing the bias voltage. As a result, the hardness and internal stress decrease and the critical load for fracturing increases as the substrate bias increases. For the tribological properties of the a-C:N films, the friction coefficient of the films slightly decreases in the environments of N-2, O-2, or dry air, but increases slightly in the vacuum environment by increasing the bias voltage. It indicates that the incorporated nitrogen in the a-C:N films would decrease the friction coefficient of the films in N-2 or O-2 environments, but slightly increases the friction coefficient of the films in a vacuum. The excellent wear resistance of the a-C:N films, in the level of 10(-9)-10(-8) mm(3)/Nm, can be observed in N-2, vacuum, and dry air environments. In addition, the effect of the bias voltage on the wear rate of the a-C:N films becomes less obvious by nitrogen incorporation. So, we suggest the incorporated nitrogen, which bonded to carbon and restrained the increase of the fraction of sp(2) C-C, would restrain the wear of the a-C:N films in different environments, especially in dry air. (C) 2003 American Vacuum Society.