Effects of Bias on the Bonding Structure and Mechanical Property of a-C:H Films Deposited by MFPUMST

Hydrogenated amorphous carbon (a-C:H) films on silicon wafers were prepared by middle frequency pulsed unbalanced magnetron sputtering technique (MFPUMST) at different substrate bias under the methane-argon mixed gases. Raman spectra show that the sp3 fraction in a-C:H films increases with increasing substrate bias voltage from 0 to 100 V, and then decreases when the substrate bias above 100 V. Nano-hardness for these films prepared under different substrate bias voltage show that nano-hardness increase with increasing substrate bias voltage from 0 to 100 V, and then decrease from 100 up to 200 V. The results above indicate that the sp3 fraction in the prepared a-C:H films is directly related to nano-hardness, therefore, substrate bias voltage is an important factor for influence on the bonding configuration of the deposited a-C:H films. The related mechanism is discussed by sub-plantation model in this paper.