The properties of a‐C:H films deposited by bias sputtering of carbon

Carbon films were deposited by rf bias sputtering of a carbon target in argon. Bias voltage and argon pressure were varied systematically. Hardness, internal stress, density, hydrogen content, and infrared absorption were measured as functions of the preparation parameters. From the IR measurements the bond ratio of sp3 to sp2 was calculated and the total amount of hydrogen in the films was determined by elastic recoil detection. The hydrogen content was found to be much lower than for films prepared by plasma decomposition of hydrocarbons. Because the film thickness was in the range of 500 nm, the hardness was measured with an ultralow‐load diamond indenter. For these measurements the indentation depth was about 60 nm. The internal stress was determined by the bending beam method. The coordination number, number density, and the filling factor were calculated from the measured values. The results have been compared to those for films deposited by plasma decomposition of hydrocarbons.