Patent Application
20080105657
The present invention relates to a plasma source; more particularly, relates to coating metal or ceramic film on a workpiece with enhanced quality, prolonged lifetime, improved flexibility and shortened producing time.
An arc plasma coating is operated in a vacuum environment, where a plasma is obtained between a node and cathode with low voltage. A target is set at the cathode to generate metal ions through a discharging to be deposited on a surface of a workpiece. In such a process, a high current passes through the surface of the target to evaporate the target owing to the heat generated under a great power. As a result, microcraters may happen on the surface of the target and macroparticles from the target are scattered around. And, when the macro particles are deposited on the surface of the workpiece, the surface becomes rugged and porous and so the quality of the film obtained is reduced.
One of the best device now for filtering the macroparticles is a filtered cathodic vacuum arc (FCVA), where the target ions are biased by a magnetic field to deposit on the surface of the workpiece after passing through a curve duct. Because the macroparticles are heavier than the ions, they do not pass through the duct and so are filtered. The duct may be also equipped with a series of stopping rings to avoid macro particles from escaping out of the duct.
Yet the FCVA device has only one channel and is hard to bear high heat so that it is not suitable for a high-energy ion source. Besides, the device does not output a pulse ion current. Hence, the prior arts do not fulfill users' requests practically.
The main purpose of the present invention is to enhance an ion amount and control an ion energy with combinations of modules of various biases or various magnetic fields; to improve deposition rate; to reduce impurities in a film; and to enhance a film quality.
To achieve the above purpose, the present invention is a macroparticle-filtered coating plasma source device, comprising a plasma source, a curve ion duct, a controller, an arc source and a multi-channel power source, where the plasma source has a target, a trigger rod and a guiding rod; the curve ion duct is connected with the plasma source at an end; the curve ion duct comprises a plurality of duct segments each having an individual electricity; the curve ion duct obtains a pulse ion source by swiftly changing among the duct segments between a bias power source and a power source of an electromagnetic coil through a multi-channel power source; the duct segments are assembled with a 2-dimensional arrangement or a 3-dimensional arrangement; and the curve ion duct is cooled down with a cooling water, has an electromagnetic field guidance, and has reverse thorns on an inside wall surface of the curve ion duct. Accordingly, a novel macroparticle-filtered coating plasma source device is obtained.
The present invention will be better understood from the following detailed description of the preferred embodiment according to the present invention, taken in con junction with the accompanying drawings, in which
The following description of the preferred embodiment is provided to understand the features and the structures of the present invention.
Please refer to
The plasma source 10 is set at an end of the curve ion duct 20; the plasma source 10 has a target 11 connected to a cathode of the arc power source 40; a guiding rod 111 is connected on a side surface of the target 11; and a trigger rod 163 is set at a nearby position on a wall of the curve ion duct 20 and is connected to an anode of a power source driven at outside of the wall of the curve ion duct 20. The target is made of a solid metal, a metal alloy, graphite, silicon, boron metal oxide, a metal oxide, a metal carbide, a silicide or a metal silicide.
A flash guard 12 is deposed under the target 11 with a floating connection and is connected with a target frange 131. The target frange 131 has an electrical insulating plate 132 for fixing a target supporting rod 14 and being insulated. The target supporting rod 14 has a cooling water channel inside; and the cooling water channel is provided with cooling water from a water inlet 15 of the plasma source 10 to cool down the target 11. An electromagnetic coil 161 outside the target flange 131 together with a driving rod 162 is welded with a trigger rod 163 in front of the driving rod 162 to obtain an arc-driving device, where the trigger rod 163 is moved forward to be in touch with the guiding rod 111 to drive an arc. The plasma source 10 has a metal anode duct wall 133 having a cooling water channel inside; and has reverse thorns 135 on an inner wall to avoid macro particles in plasma from escaping out of the duct. The reverse thorns are located on the inside wall forming a plurality of circles or being distributed randomly. An electromagnetic coil 134 outside the duct adjusts a surface magnetic field of the target 11 to maintain a stable discharge of the arc. The target 11 has an electrode connected with the cathode of the arc power source 40. And the controller 30 controls a relay 60 for connecting the anode of the arc power source 40 to the driving rod 162 and the metal anode duct wall 133.
The curve ion duct 20 has a function of filtering macro particles in plasma. The curve ion duct 20 comprises three metal duct segments connected with each other through a flange 21 by fixing on a flange having a screw hole a buckle or a plurality of bolts and rabbets; and each two neighboring duct segments are separated with an electrical insulating plate (not shown in the figure.) The duct segment has a radius between 3 and 50 centimeters (cm), and two flanges at two ends of the duct segment obtain an angle between 10° and 180°. The duct segment has a cooling water channel inside and a water-and-electricity fast connector; has reverse thorns 22 on the inner wall to avoid macroparticles in plasma from escaping out of the duct; and has an electromagnetic coil 23 outside to drive ions in the duct to be biased to an ion source exit 24. According to various requirements, the present invention controls the multi-channel power source 50 through the controller 30 to enhance ions amount with combinations of modules of various biases or various magnetic fields, where the multi-channel power source 50 comprises a plurality of power channels; and the controller performs processes of (a) deciding when an arc is started and how long the arc is lasted; (b) adjusting output power of each channel of the multi-channel power source; (c) comparing the output power of the channel with a default value; and (d) automatically adjusting the output power of the channel to obtain a best ion output.
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When using the present invention, air is exhausted out of the device first. Then a gas is fed in through a gas supplier 17 at the plasma source 120. The target 11 is connected with the cathode of the arc power source 40. The arc power source 40 is switched on and an arc current is produced through the trigger rod 163. At the moment, arc pits move from top of the guiding rod 111 to a surface of the target 11 while wondering around with eruptions of ions to form a plasma. The plasma formed has macroparticles. When the plasma passes through the curve ion duct 20, the duct segments has positive bias and a magnetic intensity at center area is kept steady to filter out 99 percents of macroparticles. And so a plasma without macro particles is obtained to be sputtered on a workpiece at the exit of the duct, where the workpiece is applied with a negative pulse bias. After a period of time, a metal film having a certain thickness is deposited.
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Another method for starting an arc is to weld a guiding rod 111, having a diameter more than 2 millimeters, on a side surface of a target 11, where the guiding rod 111 is made of the same material as the target 11. Then the guiding rod 111 is connected to a position near an arc-driving device on a wall of a duct. A trigger rod 163 of an arc-driving device is directly connected with the guiding rod 111 to form an arc. At this moment, arc pits automatically move from top of the guiding rod 111 to the side surface of the target 11. And then the arc spots wonder around the side surface of the target 11. Because a size of a closed electromagnetic field in the arc space is minimized, the arc spots do not return back to the guiding rod 111.
To sum up, the present invention is a macroparticle-filtered coating plasma source device, where ion amount is enhanced and ion energy is controlled with combinations of modules of various biases or various magnetic fields; a speed for film deposition is improved; impurities in a film is reduced; and a film quality is enhanced.
The preferred embodiment herein disclosed is not intended to unnecessarily limit the scope of the invention. Therefore, simple modifications or variations belonging to the equivalent of the scope of the claims and the instructions disclosed herein for a patent are all within the scope of the present invention.
