Apparatus and method for depositing hydrogen-free ta-c layers on workpieces and workpiece

A method for manufacturing substantially hydrogen-free ta-C layers on a substrate using a magnetron sputtering apparatus, the magnetron sputtering apparatus including a vacuum chamber in communication with an inert gas source and a vacuum pump;

• at least one graphite cathode having a front surface disposed within the vacuum chamber;
• a magnet arrangement associated with and disposed behind the at least one graphite cathode and comprising a center pole of a first polarity and outside poles of an opposite polarity surrounding the center pole and generating a closed loop magnetic tunnel in front of the cathode thereby forming a magnetron, the graphite cathode serving as a source of carbon material;
• a bias power supply;
• and at least one unipolar cathode power supply for the at least one graphite cathode, which is connectable to the at least one graphite cathode and to an associated anode, wherein the method comprises:
• a) providing the substrate to the vacuum chamber;
• b) evacuating the vacuum chamber with the vacuum pump;
• c) providing an inert gas that does not include hydrogen to the vacuum chamber from the inert gas source;
• d) applying a negative bias voltage to the substrate from the bias power supply, the negative bias voltage being less than −150 V at an average bias current that is in a range of 1.8 A to 9 A, and
• e) transmitting macro pulses to the cathode from unipolar cathode power supply,
• wherein the macro pulses each include a sequence of high power micro pulses,
• the macro pulses each have a duration in the range of 10 to 5000 μsec and are spaced at intervals of time with a pulse repetition frequency in the range of 1 Hz to 2 kHz,
• each sequence of high power micro pulses includes a series of high frequency DC power pulses adapted to be supplied to the at least one graphite cathode with the high frequency DC power pulses having a peak power in the range from 100 kW to at least 2 megawatt,
• the micro pulses each have a total duration including the time during which the power to the cathode is switched on in the range from 2 to 25 μsec and the time during which the power to the cathode is switched off in the range from 6 to 1000 sec,
• the average power of the macro pulses average over a longer period of time including a plurality of macro pulses is comparable with the power of a DC sputtering system with a constant DC power, and
• the substantially hydrogen-free ta-C layers have a hardness selected in the range of 1546 HV to 4890 HV.