Apparatus and method for sputtering hard coatings
A plasma generator includes a chamber for confining a feed gas. An anode is positioned inside the chamber. A cathode assembly is positioned adjacent to the anode inside the chamber. A pulsed power supply comprising at least two solid state switches and having an output that is electrically connected between the anode and the cathode assembly generates voltage micropulses. A pulse width and a duty cycle of the voltage micropulses are generated using a voltage waveform comprising voltage oscillation having amplitudes and frequencies that generate a strongly ionized plasma.
1. A method of sputtering a hard coating, the method comprising:
a) supplying feed gas proximate to an anode and a cathode assembly comprising a magnet assembly and a sputtering target;
b) generating a pulsed voltage waveform between the anode and the cathode assembly, the pulsed voltage waveform comprising voltage oscillations having an amplitude, a frequency, and a duration that generates a magnetron discharge with an oscillating discharge current, wherein the amplitude and the frequency of the voltage oscillations are chosen to generate an arc free magnetron discharge during a pulsed voltage waveform, a duration of the voltage oscillations being chosen to increase an ionization rate of sputtered target material atoms; and
c) applying a negative bias voltage to a substrate holder supporting a substrate, the negative bias voltage attracting positive ions from sputtered target material atoms to the substrate, thereby forming a coating on the substrate with a desired hardness.
2. The method of claim 1 , further comprising moving the magnetic field.
3. The method of claim 1 , wherein the sputtering target comprises at least one of Al, Cu, Ti, C, Ta, Mo, Ni, V, Si, B, In, Sn, W, Cr, Fe, Zr, Au, Ag, Pt, Re, Co, and Zn.
4. The method of claim 1 , wherein the desired hardness of the coating is in the range of 20-60 GPa.
5. The method of claim 1 , wherein the substrate comprises a cutting edge of a razor blade.
6. The method of claim 1 , wherein the oscillating discharge current generates a current density on the target in a range of 0.1 A/cm 2 10 A/cm 2 .
7. A method of claim 1 , wherein the voltage oscillations is in a range of 1-1,000 kHz.
8. A method of claim 1 , wherein the amplitude of the voltage oscillations is in the range of 500 V and 3000 V.
9. A sputtering source comprising:
a) means for supplying feed gas proximate to an anode and a cathode assembly;
b) means for generating a pulsed voltage waveform between the anode and the cathode assembly, the pulsed voltage waveform comprising voltage oscillations having an amplitude, a frequency, and a duration that generates a magnetron discharge with an oscillating discharge current, wherein the amplitude and the frequency of the voltage oscillations are chosen to generate an arc free magnetron discharge during a pulsed voltage waveform; and
c) means for applying a negative bias voltage to a substrate holder supporting a substrate to attract positive ions from sputtered target material atoms to the substrate, thereby forming a coating on the substrate with a desired hardness.
10. The sputtering source of claim 9 , wherein a duration of the voltage oscillations is chosen to increase an ionization rate of sputtered target material atoms.
11. The sputtering source of claim 9 , further comprising a means for moving a magnetic field proximate to an anode and a cathode assembly.