Magnetically enhanced high density plasma-chemical vapor deposition plasma source for depositing diamond and diamond-like films
A magnetically enhanced HDP-CVD plasma source includes a hollow cathode target and an anode. The anode and cathode form a gap. A cathode target magnet assembly forms magnetic field lines that are substantially perpendicular to a cathode target surface. The gap magnet assembly forms a cusp magnetic field in the gap that is coupled with the cathode target magnetic field. The magnetic field lines cross a pole piece electrode positioned in the gap. This pole piece is isolated from ground and can be connected with a voltage power supply. The pole piece can have a negative, positive, or floating electric potential. The plasma source can be configured to generate volume discharge. The gap size prohibits generation of plasma discharge in the gap. By controlling the duration, value and a sign of the electric potential on the pole piece, the plasma ionization can be controlled. The magnetically enhanced HDP-CVD source can also be used for chemically enhanced ionized physical vapor deposition (CE-IPVD). Gas flows through the gap between hollow cathode and anode. The cathode target is inductively grounded, and the substrate is periodically inductively grounded.
1. A magnetically enhanced sputtering apparatus comprising:
a hollow cathode target assembly;
an anode positioned on top of the hollow cathode target assembly, thereby forming a gap between the anode and the hollow cathode target assembly;
a cathode magnet assembly;
two rows of magnets facing each other with the same magnetic field direction that generate a cusp magnetic field in the gap and a magnetic field on a surface of the hollow cathode target assembly with the cathode magnet assembly, the magnetic field comprising magnetic field lines that are substantially perpendicular to the hollow cathode target assembly; and
a pole piece positioned between the two rows of magnets and connected to a voltage power supply, the voltage power supply generating a train of negative voltage pulses that generates a pulse electric field in the gap perpendicular to the cusp magnetic field, the electric field igniting and sustaining plasma during a pulse of the train of negative voltage pulses, a frequency, duration and amplitude of the train of negative voltage pulses being selected to increase a degree of ionization of feed gas atoms.
2. The magnetically enhanced apparatus, as defined by claim 1 , further comprising a second gap positioned inside the anode such that a portion of the magnetic field lines forming the cusp magnetic field cross the gap and terminate on top of a second row of magnets.
3. The magnetically enhanced apparatus, as defined by claim 1 , further comprising a radio frequency (RF) power supply connected to the hollow cathode target assembly, the RF power supply generating output voltage with a frequency in a range of about 1 MHz to 100 MHz.
4. The magnetically enhanced apparatus, as defined by claim 1 , wherein the power supply connected to the hollow cathode target assembly generates output current in a range of about 20 A to 200 A.
5. The magnetically enhanced apparatus, as defined by claim 1 , further comprising:
a substrate holder; and
a substrate bias power supply, the substrate bias power supply being connected to the substrate holder and generating a bias voltage on the substrate in a range of about −10 V to −2000 V.
6. The magnetically enhanced apparatus, as defined by claim 1 , wherein the magnetic field in the gap is in a range of about 50 G to 10000 G.
7. The magnetically enhanced apparatus, as defined by claim 1 , wherein the cathode target material comprises carbon.
8. The magnetically enhanced as defined by claim 1 , wherein the cathode target material comprises aluminum.
9. A method of magnetically enhanced sputtering comprising:
providing a hollow cathode target assembly;
forming a gap between the hollow cathode target assembly and an anode;
positioning a cathode magnet assembly;
generating a cusp magnetic field in the gap such that magnetic field lines are substantially perpendicular to a surface of the hollow cathode target assembly;
positioning a pole piece in the gap connected to a power supply;
providing a pulse DC power to the hollow cathode target assembly to ignite and sustain volume discharge;
generating a train of negative voltage pulses using the power supply; and
selecting a frequency, duration, and amplitude of the train of negative voltage pulses to increase a degree of ionization of sputtered target material atoms.
10. The method of magnetically enhanced sputtering, as defined by claim 9 , further comprising positioning a second gap inside the anode such that the portion of the magnetic field lines forming the cusp magnetic field cross the gap and terminate on top of a second row of magnets.
11. The method of magnetically enhanced sputtering, as defined by claim 9 , further comprising connecting a radio frequency (RF) power supply to the hollow cathode assembly and generating output voltage with a frequency in a range of about 1 MHz to 100 MHz.
12. The method of magnetically enhanced sputtering, as defined by claim 9 , wherein the voltage power supply generates output voltage in a range of about −100 V to −3000 V.
13. The method of magnetically enhanced sputtering, as defined by claim 9 , further comprising connecting a substrate bias power supply to a substrate holder and generating a bias voltage on a substrate in a range of about −10 V to −2000 V.
14. The method of magnetically enhanced sputtering, as defined by claim 9 , wherein the magnetic field in the gap is in a range of about 50 G to 10000 G.
15. The method of magnetically enhanced sputtering, as defined by claim 9 wherein the cathode target material comprises carbon.
16. The method of magnetically enhanced sputtering, as defined by claim 9 wherein the cathode target material comprises aluminum.