EP2638182A1

EP2638182A1 - Apparatus and method for surface processing

Info

Publication number: EP2638182A1
Application number: EP10778640.2A
Authority: EP
Inventors: Sergueï MIKHAÏLOV
Original assignee: NCI - Swissnanocoat SA
Current assignee: NCI - Swissnanocoat SA
Priority date: 2010-11-11
Filing date: 2010-11-11
Publication date: 2013-09-18
Also published as: WO2012062369A1; TW201233830A; CN103459652A; RU2013126583A

Abstract

An apparatus for coating parts, comprising a deposition chamber (1) and a plurality of coating equipments (2, 3) for simultaneously or successively providing coating materials to said deposition chamber, wherein at least one of said coating equipment (2) is a metal filtered arc ion source, wherein at least one other of said coating equipment (3) is a laser ablation source, At least two of said coating equipments are removably connected to said deposition chamber via connecting flanges (10). At least two of said flanges are identical, so that one said coating equipment (2, 3) can be connected via different flanges to said deposition chamber.

Description

Apparatus and method for surface processing

Field of the invention

The present invention concerns an apparatus and a method for coating parts, especially an apparatus which generates a plasma of various coating materials for deposition on surfaces of parts to be coated. This coating apparatus can be used, without limitation, in the coating and hardening of tools, instruments, electronic components, goods including watches and glasses, etc.

Description of related art

Various methods and apparatus are known for coating and hardening parts. Conventional physical vapour deposition (PVD) methods use a cathode and an anode. Application of an electric field between the cathode and the anode evaporates material from the cathode, which forms a beam that can be deflected and filtered to reach a vacuum deposition chamber where the parts to coat are placed. The evaporated material from the anode deposites on the parts within the deposition chamber, which are progressively coated with this material.

An example of PVD equipments using a metal filtered arc ion source is described in US6663755. In order to increase the rate of

deposition, this apparatus uses two plasma sources that generate two plasma flows directed toward the same deposition chamber. Since the two sources are directed toward each other, a conductive shield is required to serve as a baffle for preventing the plasma flow generated by one plasma source to reach the other plasma source. This baffle increases the cost and volume of the equipment, and needs to be cleaned or even replaced periodically. Moreover, the quality of the filtration could be improved; ion particles of different sizes reach the target, producing uneven coatings.

Similar equipments for coating parts with a metal filtered arc ion source are disclosed in WO2007089216 and in WO2007136777. Laser ablation equipments have also been used for coating parts; they generally utilize a pulsed laser source directed toward the material to be ablated, such as a bloc of carbon material. The laser pulses produce ablation of material which is projected and possibly deflected toward the parts within the deposition chamber.

An example of laser ablation equipment is described in US5747120. In this document, the target which is ablated with the laser is placed right in the chamber. This setting makes replacement of the target difficult, especially if the chamber is maintained at vacuum conditions. Moreover, the parts to be coated are placed in a small volume outside of the main chamber, so that only a limited number of parts can be coated at the same time.

Another laser ablation system is disclosed in US6372103. In this document, a laser outside of the deposition chamber generates a laser beam that crosses a window and reaches a cylindrical target rotating within the deposition chamber. Again, replacement of the target requires opening of the whole deposition chamber, which can be time-consuming and expensive if the chamber is at vacuum conditions. Moreover, the laser beam makes a perpendicular angle with the surface of the rotating target, so that at least a part of the ablated material bounces against the window, whose inner side is rapidly covered and needs cleaning to keep its transparency.

Other example of laser arc system for carbon deposition are disclosed in US6231956. Some parts require sophisticated coatings with different layers of different materials; the manufacturing process typically utilizes different steps performed in different deposition chambers in order to deposite the different layers successively. This is an expensive method, since it requires multiple deposition chambers with associated vacuum generating equipments, etc. Moreover, the manufacturing throughput is reduced since the parts needs to be transferred from one deposition chamber to the next; vacuum often needs to be re-generated after each transfer.

WO200801 5016 describes an apparatus for the coating of substrates with diamond-like layers, in which different coating equipment of different types are arranged toward a common deposition chamber, or in line each in a separate chamber. This allows coating of large number of parts within a single batch process, and without any need to open the deposition chamber between depositions of two different layers with source equipments of different types. An aim of the present invention is to increase the flexibility of the apparatus and methods described in WO2008015016.

Another aim is to allow coating and manufacturing of different parts, with different layers, without replacing the whole apparatus.

Brief summary of the invention According to the invention, these aims are achieved by means of an apparatus for coating parts, comprising a deposition chamber and a plurality of coating equipments for simultaneously or successively providing coating materials to said deposition chamber,

wherein at least one of said coating equipment is a metal filtered (or not filtered) arc ion source,

wherein at least one other of said coating equipment is a laser ablation source,

wherein at least two of said coating equipments are removably connected to said deposition chamber over connecting flanges,

wherein at least two of said flanges are identical, so that one equipment can be mounted at different positions around said deposition chamber.

The use of similar or identical flanges for connecting different source equipments of different types to a common deposition chamber is advantageous since it allows easy replacement of one coating equipment of one type by a coating equipment of any other type. The coating equipments around the common chambers are thus entirely

interchangeable. For example, one part may requires one metal filtered arc ion source equipment for metal deposition, and one laser ablation source for carbon deposition, while another part will use two metal filtered arc ion source equipments for faster deposition of one layer, or for deposition of two different metals in two successive layers.

Conventional apparatus having similar flanges for different equipment may be existing, but each of the flange is nevertheless specifically adapted for a particular equipment, which are not

interchangeable and can't be mounted at any position or on any flange.

According to another, possibly independent aspect, the apparatus for coating parts comprises a deposition chamber and at least one metal filtered arc ion source with at least one pair of metal ion sources, each metal ion source having at least one cathode, at least one anode and associated coils, wherein the angle between the emission directions of the two sources within each said pair is larger than 90° but lower than 175°.

The angle lower than 175° avoids the risk that each source emits material in the direction of the other source, and removes the need for a shield between the two sources. The angle between the emission directions of the two sources within each said pair may be larger than 90° but lower than 135°. Having an angle between the two sources larger than 90°, and preferably lower than 135°, allows for an important deflection angle toward the parts to be coated, and ensure efficient filtering of the flows.

In one embodiment, the directions of emissions of the two sources within each pair are not in a same plane. This allows a better spreading of the two flows within the deposition chamber, and a more homogeneous coating. The metal ion source preferably each comprise two focusing coils for focusing the metal ion beam. A common deflection system comprises one first coil traversed by the metal ion beam produced by each of the metal ion sources, and one second coil behind said metal ion source, both coils cooperating for deflecting said metal ion beam toward said deposition chamber. This allows efficient deflection with a limited number of coils.

According to another, possibly independent aspect, the apparatus for coating parts comprises a laser ablation equipment with a laser, a mirror for deflecting the laser beam produced by said laser toward a target, a first motor for rotating said target, and a second motor for displacing said mirror so as to ablate different portions of said target. A third motor can be used for displacing the target relatively to said laser beam along an axis parallel to the rotation axis of the target. The second and third motor allows use of very large targets from which different parts are successively ablated, and increase the duration of the period between successive replacements of a target.

According to another, possibly independent aspect, the apparatus for coating parts comprises a laser ablation equipment in which a laser beam is directed so as to make an angle with the target which is lower than an angle between the laser beam and a tangent of the target. This reduces the risk that ablated material bounces toward the entry window, and cancels the requirement for cleaning this window.

Faster coating can be achieved with the use in one source equipment of two lasers for ablating the same target, or for ablating two different targets.

Brief Description of the Drawings

The invention will be better understood with the aid of the description of an embodiment given by way of example and illustrated by Fig. 1 that shows a sectional view of the apparatus of the invention. Detailed Description of possible embodiments of the Invention

Fig. 1 shows an apparatus according to the invention which has a single deposition chamber 1. Parts to be coated (not shown), such as substrates, drills, mechanical parts and so on, are placed on one or several part holders in the deposition chamber 1. Depending on the application, vacuum can be applied to the deposition chamber 1 using a vacuum generation system (not shown).

The deposition chamber 1 comprises a plurality of connecting flanges 10 for connecting various coating equipments. In the present document, the expression "coating equipment" generally designates equipment that can be used as a source for generating a flow of material directed toward the deposition chamber 1 , in order to coat the parts within this chamber. According to an aspect of the invention, at least two connecting flanges 10 are identical or at least compatible, so that one equipment can equivalently be connected to one flange or to the other.

In the illustrated example, the deposition chamber 1 has two identical connecting flanges 10, although more than two flanges could be used. The flanges are preferably vacuum flanges. A first coating equipment, in the form of a metal filtered arc ion source 2, is connected to one of the connecting flanges 10, while a second coating equipment, in the form of a laser ablation source 3, is connected to the other connecting flange 10 of the illustrated example. Since the apparatus has two compatible connecting flanges 10, it would also be possible in other arrangements to mount different types of equipments to the same deposition chamber 1 , for example:

^■ Two or more metal filtered arc ion source of the same

type, for faster and/or more homogeneous deposition of metal coating;

^■ Two or more metal filtered arc ion source of different

types, for coating parts with two layers of different metals. ^■ Two or more laser ablation sources of the same type, for faster or more homogeneous deposition of material (such as Carbon) with this process.

^■ Two or more laser ablation sources of different types, for coating parts with two layers of different materials.

^■ One or more low energy ion gun 5, for example based on a Hall accelerator, for example in order to polish parts with an ion beam, or in order to harden a surface by ion implantation ■ One or more magnetron, which can be balanced or

unbalanced.

^■ One or more CVD device, such as a plasma enhanced CVD device.

^■ One or more heating or cooling devices. ■ Or any combinations thereof.

All those equipments have identical flanges and can

interchangeably be mounted on any of the different flanges of the apparatus.

In a preferred embodiment, one of the equipment is used for deposition of a sublayer, such as metal layer, while another equipment is used for deposition of an external layer, such as a hard carbon or DLC layer. It is thus possible with a single equipment to deposit various successive layers on a surface of the same part.

A single chamber can thus be proposed or sold with sets comprising various coating equipments that a user can select and mount to the various equivalent positions around the deposition chamber 1 , in order to adapt to his needs and to various coating requirements for different parts.

Although in most situations the different coating equipments will be used one after the other in order to successively coat superposed layers of coating material on a single part, it is also possible for some processes to use two equipments at the same time, for example two identical equipments in order to fasten the deposition process, or two different equipments in order to mix beams and deposite layers with mixed materials from different sources. Moreover, the different coating

equipments could be used in different processes for coating different parts if the parts in the chamber are replaced between use of each equipment.

According to one aspect of the invention, at least one metal filtered arc ion source 2 comprises two different metal ion sources 28. The use of two sources increases the deposition rate and improves the homogeneity of plasma formed within the deposition chamber 1 when coating parts, resulting in a faster and more regular coating. Each source has one cathode 20 of metal or material that will be used for the coating, and one or several anodes 21 to create an electric arc discharge when at least one current source is activated, so as to extract material from the cathode.

The cathodes have preferably a conical shape in order to homogenise deposition during service time. When the surface cathode is eroded so that its distance to the target increases, its surface is increased due to the conical shape, so that the deposition rate remains approximately constant.

A deflecting system comprises two coils 23, 24 surrounding a portion of a duct just after the cathode 20. Those coils 23, 24 are used to focus the flow of particles extracted from the cathode 20 along an axis 200 of the cathode 20, and to reduce dispersion against side walls of the duct. The axis 200 of each cathode 20 makes an angle a with the axis 100 of introduction into the deposition chamber 1, which is also the central axis of the flange 10. The emitted beam of particles therefore needs to be deflected from the initial emission direction 100 to the direction of introduction into the deposition chamber 1. This deflection is produced by at least one first deflecting coil 27, which is mounted around the

connecting flange 10, so as to be crossed by the deflected beam just before its introduction into the deposition chamber 1 . Another optional coil 25 which is provided behind the metal ion sources 28 cooperate with the coil 27 for deflecting said metal ion beam toward said deposition chamber. Those coils 25 and 27 preferably each have a cylindrical or torical shape with an axis corresponding to the axis of the connecting flange 10 and to the axis of introduction 100. This deflection acts as a filtering means for filtering neutral particles from particles with weight different from the average of desired weight, which are not deflected respectively in a different direction. A metal trap 29 crossed by the beam is maintained at a varying potential for trapping ions with a different weight.

A second coil 26 is preferably arranged close and parallel to the first coil 27, so as to be crossed by the deflected beam. This second coil cooperates with another coil 38 on the other side of the deposition chamber, so as to control and homogenise the cloud of particles produced by the arc ion source 2 or by the laser ablation source 3 within the deposition chamber

The angle a is preferably lower than 135°, even preferably lower than 120°, to provide enough deflection and enough filtering. However, according to an aspect of the invention independent from all other aspects, this angle is also greater than 90°, preferably greater than 95°, to avoid a situation where the axis 200 of both metal filtered arc ion source 2 are aligned and in which the beam produced by one source would be directed toward the other source. This specific arrangement avoids the need for any shield or baffle element at the intersection between the two beams, thus resulting in a simpler and more compact design, which is also easier to clean. Moreover, since the beams are not aligned, this setting improves the mixing and the spatial diffusion of the two beams, thus resulting in a more homogen distribution of the particles within the chamber 1 .

In a preferred embodiment, the axis 200 of the two metal ion sources 28 are not in a same plane, but in two parallel or non-parallel planes, so that the two beams from the sources 28 are introduced in the deposition camber 1 along a common duct but along two distinct directions. This is useful for improving the distribution of the particles in a direction perpendicular to the plane of the figure, and improving homogeneity of plasma formed within the deposition chamber 1 when coating, thus resulting in an improved coating quality.

In one embodiment, the coating equipment comprises two pairs of metal ion sources 28 superposed over each other, thus providing even faster coating, and/or successive replacement of the different cathodes without complete interruption of the coating process. The current generator that drives the two metal ion sources 28 preferably generates a pulsed current with a frequency comprised between 1 and 100 Hz, substantially lower than the frequency of 1 '000 Hz and more used in conventional metal ions sources. In a preferred embodiment, the current delivered to the second ion source 28 is dephased with respect to the current delivered to the first ion source 28, thus resulting in less perturbations to the electric network system, and more continuous flow of particles into the deposition chamber 1 . Each pulse has preferably an energy of 1 50mJ, or more. Each current pulse is preferably higher than 4Ό00 A, thus is substantially more than the conventional currents of about 1 Ό00 A used in conventional systems. Test and experiments have shown that this high current, although requiring more complicated electronics, provide for an improved and more regular coating of the parts.

The apparatus illustrated in the figure further comprises a pulsed laser ablation source 3 mounted to the deposition chamber 1 over a second connecting flange 10 which is identical or compatible with the first connecting flange 10 to which the ion source 2 is connected. The pulsed laser ablation source 3 is suitable for ablating a target 32, such as a graphite or carbon target. This pulsed laser ablation source 3 is useful due to its ability to produce high purity films, such as diamond-like coatings (DLC) for example. A laser source 30 generates a pulsed laser beam 300 that is directed via a window 37 to a carbon target 32. A focusing lens (not shown) may be used to focus the laser beam.

The laser beam reaches the cylindrical target 32 at a substantial tangential angle, so that carbon ions that instantly evaporate from the target 32 are projected in directions different from the originating direction of the laser. This is useful for preventing deposition of carbon on the window 37. In a preferred embodiment, the laser beam 300 thus makes an angle lower than 45°, preferably lower than 20°, with a tangent of the target 32. A moving mirror 31 , controlled by a step motor 34, is preferably controlled in order to deflect the laser beam at the desired location of the target 32.

A first motor 33 is used for rotating the cylindrical target 32 continuously, or in successive steps. The second motor 34 is used for moving the mirror 32 relative to the target along the axis of the cylindrical target 32, so as to chnge the longitudinal portion of the cylinder which is ablated. Both motors 33, 34 are controlled to produce a regular ablation of the whole surface of the target 32. An additional motor can optionally be used for moving the target 32 relatively to the laser in a direction perpendicular to the incoming laser beam, thus insuring the laser beam always reaches the surface of the target 32. In an option, this displacement for

compensating the reduction in diameter of the target is done manually.

In one embodiment, two lasers 30 are provided within the same pulsed laser ablation source 3, and are used for simultaneously attacking the same carbon target 32, or two different targets 32, thus resulting in faster ablation and faster coating. The flow of particles ablated from the target 32 is directed to a bended duct that links it to the deposition chamber 1 , and deflected within this duct using a deflecting coil 38 crossed by the beam of particles. This coil 38 is preferably mounted on a rail, so that it can be manually rotated and displaced along the duct in order to control the deflection. A second coil 39, already mentioned, is crossed by the beam and cooperates with the coil 26 on the other side of the deposition chamber in order to control the homogeneity of the cloud within the deposition chamber.

The bending angle within the duct is preferably comprised between 30° and 60°, and is preferably 45°, in order to provide for moderated filtering and keeping some of the larger carbon particles within the bended beam, thus resulting in faster and better coating than if a more bended or even a double bended duct is used. A trap 35 traps particles with a different weight within the duct.

The method also relates to a method of fabricating a coated part starting from a non coated part, said method using a plurality of coating equipments around a common deposition chamber, wherein said

deposition chamber comprises a plurality of equivalents flanges and wherein the method comprising mounting a metal filtered arc ion source to any one of said flange, mounting a laser ablation source to any other said flange, and successively depositing different layers of different coating materials to parts within said deposition chamber. This method, and the use of the new metal filtered ion source and laser ablation source as described above, results in the manufacturing of new parts having coating properties never reached before, especially in term of purity and regularity.

List of parts

1 deposition chamber

2 1 ^st coating equipment: metal filtered arc ion source 10 connecting flanges

100 axis of introduction into deposition chamber

20 cathode

200 axis of the cathode

21 anode

23, 24 focusing coils

25-27 deflecting coils

28 metal ion source

29 metal trap

3 2^nd coating equipment: laser ablation source

30 laser

300 laser beam

31 mirror

32 target (such as carbon target)

33 first motor

34 second motor

35 trap

36 anode

37 window

38, 39 deflecting coils

5 ion gun

Claims

1 . An apparatus for coating parts, comprising a deposition chamber (1) and a plurality of coating equipments (2, 3) for simultaneously or

successively providing coating materials to said deposition chamber (1 ), wherein at least one of said coating equipment (2) is a metal filtered arc ion source (2),

wherein at least one other of said coating equipment (3) is an

equipment selected among a laser ablation source (3), a magnetron, a CVD equipment, or a low energy ion gun (5),

characterized in that at least two of said coating equipments (2, 3) are removably connected to said deposition chamber (1 ) via connecting flanges (10),

wherein at least two of said flanges (10) are identical, so that one said coating equipment (2, 3) can be connected via different flanges (10) to said deposition chamber (10).

2. The apparatus of claim 1, wherein said metal filtered arc ion source (2) comprises at least one pair of metal ion sources (28), each metal ion source having at least one cathode (20), at least one anode (21 ) and associated coils (23, 24, 25, 26, 27), wherein the angle (β) between the emission directions of the two metal ion sources (28) within each said pair is larger than 90° but lower than 170°.

3. The apparatus of claim 2, wherein said directions of emissions of said two metal ion sources (28) within each or the pair are not in a same plane

4. The apparatus of one of the claims 2 or 3, comprising two pairs of metal ion sources (28) superposed over each other.

5. The apparatus of one of the claims 2 to 3, wherein said cathode (20) has a conical shape in order to homogenise deposition during service time.

6. The apparatus of one of the claims 2 to 5, each of said metal ion sources (28) comprising two focusing coils (23, 24) for focusing the metal ion beam.

7. The apparatus of one of the claims 2 to 6, said metal filtered arc ion source (2) comprising at least one first coil (27) crossed by the metal ion beam produced by each of the metal ion source.

8. The apparatus of claim 7, said metal filtered arc ion source (2)

comprising at least one second coil (25) behind said metal ion source, said first coil and said second coils cooperating for deflecting said metal ion beam toward said deposition chamber.

9. The apparatus of one of the claims 1 to 8, further comprising at least one current source for generating a pulsed current for powering said metal arc ion source, wherein said current source is arranged for producing a current with a maximal amplitude higher than 4000 A at a frequency between 1 and 100 Hz.

10. The apparatus of one of the claims 1 to 9, wherein said laser ablation source (3) comprises at least one deflecting coil (39) for deflecting and filtering the particles ablated by said laser ablation source.

1 1 .The apparatus of claim 10, said deflecting coil (39) for deflecting and filtering the particles ablated by said laser ablation source being rotatable for controlling the deviation of the beam of particles.

12. The apparatus of one of the claims 10 or 1 1, further comprising at least one coil (26) crossed by the metal ion beam and at least one coil (38) crossed by the beam of particles ablated by said laser ablation source, said coils (26, 38) cooperating for controlling the dispersion of particles within said said deposition chamber (1 ).

13. The apparatus of one of the claims 1 to 12, wherein said laser ablation source (3) comprises a laser (30), a mirror (31 ) for deflecting the laser beam produced by said laser toward a target (32), a first motor (33) for rotating said target, and a second motor (34) for displacing said mirror so as to ablate different portions of said target.

14. The apparatus of claim 13, wherein said laser beam (300) makes an angle lower than 45° with a tangent of said target (32).

1 5. The apparatus of one of the claims 13 to 14, further comprising a third motor for displacing said target relatively to said laser beam along an axis parallel to a rotation axis of the target.

16. The apparatus of one of the claims 1 to 1 5, wherein said laser ablation source comprises two lasers (30) for ablating one or more targets.

17. A method of fabricating a coated part from a non-coated part, said method using a plurality of coating equipments (2, 3) around a common deposition chamber (1 ), wherein said deposition chamber (1) comprises a plurality of compatible connecting flanges (10),

the method comprising mounting a metal filtered arc ion source (2) on any one of said connecting flanges (10), mounting a laser ablation source

(3) to any other of said connecting flanges (10), and successively depositing different layers of different coating materials on one or more parts within said deposition chamber (1 ).