New DLC coating method using magnetron plasma in an unbalanced magnetic field

Abstract

A new type of unbalanced magnet for planar magnetron cathode was developed to conduct PE-CVD by the assistance of magnetron discharge. A strong magnetic field was applied parallel to the electric field of the cathode to extract the plasma along the magnetic flux that decreases toward the substrate. The plasma generated by the cathode was measured at the substrate position with a Langmuir probe. The plasma density and saturation ion current density rose to about 10 times that of the conventional planar magnetron cathode and became 8×10 10 cm 3 and 3 mA/cm 2, respectively, in a 0.27 Pa Ar atmosphere with a dc cathode power of 1 kW. Furthermore, a carbon thin coating was formed on the negatively biased substrate with a dc cathode power of 400 W by supplying Ar and CH 4 with a flow rate of 42 and 18 sccm. This carbon thin coating had physical properties equivalent to those of the sample of ECR-CVD and was about twice as hard as the sample of reactive sputtering. In conclusion, it is found that the reconstruction of the cathode magnet enables the formation of the carbon thin coating by CVD with the magnetron sputtering equipment.