Investigation of molybdenum-carbon films (Mo-C : H) deposited using an electron cyclotron resonance chemical vapor deposition system

We have recently proposed a technique for depositing metal incorporated car bon films (Me-C:H) based on an electron cyclotron resonance chemical vapor deposition (ECR) process. This technique employs an ECR plasma derived from the excitation of source gases CH4 and Ar, together with two grids embedde d within the chamber that serve as the source of the metal. It has been suc cessfully applied for the deposition of tungsten-carbon films (W-C:H) which have been shown to exhibit a wide range of electrical, optical, and micros tructural properties. These properties can be controlled through varying th e deposition conditions such as the bias voltages at the grids and the subs trate holder, and the flow ratio of CH4/Ar. In this work, we report on the growth and characterization of molybdenum-carbon (Mo-C:H) films deposited u sing the above technique incorporating two pure Mo grids. The effect of rad io-frequency induced direct-current (dc) bias at the substrates was investi gated. It was found that the resistivity of the films decreased by 9 orders of magnitude, and the optical gap decreased by more than 2 eV with increas ing bias voltage from -38 to -130 V. The results suggest that the substrate dc bias has a crucial effect on the incorporation of Mo into the a-C:H fil ms and the resulting microstructures, with larger bias voltages leading to an increase in the Mo fractions in the films. Concurrently, the hardness of the films was found to deteriorate from 22 to 10 GPa. The structures of th ese Mo-C:H films were characterized using x-ray diffraction and Raman scatt ering. Mo was found to exist in the forms of Mo and MoC and Mo2C. The exper imental results are interpreted in terms of the effects of ion energy on th e structure of the films having Mo clusters embedded within an amorphous ca rbon matrix. (C) 2000 American Institute of Physics. [S0021-8979(00)03918-9 ].