High rate deposition of Mgh hardness carbide thin films using a dual source dc magnetron sputtering method

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Reactive sputtering is one of the most promising techniques for depositing carbide films, such as TiC, because it allows to deposit carbide coatings on the substrate at a low temperature. For depositing the carbide films by means of reactive sputtering, a pure metal target is usually sputtered by Ar and hydrocarbon mixed gas. In this case, the deposition rate should not be so high since the low-sputter-yield carbide is formed on the target surface. Control of the film composition is also difficult because of the so-called hysteresis problem. If the solid carbon target can be used as a carbon source for depositing carbide films, these disadvantages should be dispelled. In this study, we have tried to deposit TiC films by a dual source magnetron sputtering method. Furthermore, the Ti/C, TiC/C and TiC/Ti multilayer films have also been investigated as advanced hard coatings.Firstly, we have determined the deposition conditions for depositing stoichiometric TiC films by dual source magnetron sputtering. Then, Ti/C, TiC/C and TiC/Ti multilayer films with various periods were deposited onto glass substrates by an alternative sputtering. Ti/C and TiC/C multilayer structures, of which periods were shorter than 1.7nm, can be realized. On the other hand, TiC/Ti multilayer structure with the period less than 2.6nm can not be confirmed. The hardness of Ti/C multilayer films increases rapidly as the period decreases less than 2nm. The hardness of TiC/Ti increases monotonically with decreasing its period. On the contrary, the hardness of TiC/C films decreases as the period decreases because of micro-cracking. Among these multilayer structures, TiC/C films showed the highest thermal stability in vacuum. In the air atmosphere, on the contrary, TiC/Ti films revealed the highest stability. This should be caused by the instability of the pure carbon layer at above 600°C.