Cathode Arc Ignition Device

Abstract

1. An arc ignition device for cathodic arc deposition of target material onto a substrate, comprising: a trigger finger movably arranged between a contact position and a stationary position, wherein in the contact position a side of an adjacent target can physically contact the trigger finger, and in the stationary position the adjacent target cannot contact the trigger finger, and during cathodic arc deposition of the target material the trigger finger is movably arranged between the contact position and the stationary position, such that contamination of the trigger finger by deposited target material during cathodic arc deposition of the target material can be minimized.

Description

[Technical Field]

[0001] The present invention relates generally to equipment for physical vapor deposition, and more particularly to arc ignition devices, assemblies and methods for cathodic arc deposition in a coating chamber. [Background technology]

[0002] prior art Cathodic arc deposition is a known physical vapor deposition method. To perform cathodic arc deposition, a means for igniting a high-current discharge is typically used to cause evaporation of a target material placed in an arc evaporator (hereinafter also referred to as an arc evaporation source, arc source, or spark source), which is located within the vacuum chamber of the coating equipment. The arc evaporator typically includes a target material operable as a cathode during arc evaporation. The arc evaporator may also include at least one electrode operable as an anode during arc evaporation. If the arc evaporator does not include an integrated anode, another electrode located within the vacuum chamber may also function as the anode. In some cases, it is also known for the wall of the vacuum chamber to function as the anode.

[0003] To initiate the cathodic arc deposition process, an electric arc must be ignited at the surface of the target material that is to be vaporized and acts as the cathode.

[0004] During an arc deposition process, a substrate (e.g., a workpiece such as a component or tool) is processed under high vacuum, in particular to subject the substrate to a plasma treatment such as plasma etching or plasma coating (e.g., cathodic arc physical vapor deposition coating).

[0005] Ignition devices for different types of arc evaporation sources are already known and are described, for example, in the US application with application number US 2011 / 0220495 A1, which explains that the types of ignition devices are essentially divided into three groups: a) devices for mechanically opening and closing contacts between the cathode and the anode; b) devices for ignition of an arc discharge by means of an electric sparkover; c) devices for ignition by means of a conductive bridge.

[0006] Prior to coating deposition, in arc deposition, the substrate to be coated is placed in a coating chamber, which is then evacuated. As mentioned above, an electric arc is used to evaporate material from the surface of the target, thereby providing the coating material for coating deposition. The cathodic arc evaporation process begins with the application of a high-current, low-voltage electric arc onto the surface of the target, which acts as the cathode, resulting in the emission of electrons from the surface of the target (operated as the cathode) toward the anode.

[0007] As described above, ignition of the electric arc can be achieved by using an ignition finger that must contact the target surface to be vaporized. Such an ignition finger is commonly referred to as a trigger finger. Traditionally, during and sometimes even after ignition of the electric arc, the ignition finger is exposed to material vaporized from the target surface. This exposure can result in the accumulation of a coating film (e.g., a metal or ceramic film, such as a nitride film, or an oxide film, or another type of film) on the ignition finger. Such accumulation can reduce the ability of the ignition finger to perform its function (e.g., ensuring electrical contact and subsequent ignition of the electric arc). Thus, regular maintenance is required to remove undesired coatings. However, frequent maintenance reduces operating time and, as a result, the overall efficiency of the coating manufacturing process. Meanwhile, if maintenance is not performed frequently enough, not only the ignition finger's ability to perform initial ignition but also the speed and reliability of the necessary re-energization can be reduced. This, in turn, can reduce the efficiency of the coating manufacturing process and even the quality of the coating. In operation, the cathode spot remains active for only a short time before self-extinguishing and self-reigniting in a new area near the previous cathode spot. This behavior results in the apparent operation of an electric arc. When the cathode spot completely disappears and is unable to self-reignite in the new area, the electric arc will be extinguished during the process (i.e., a blackout period occurs). In such a case, the ignition finger must be used again for re-energization to ignite a new electric arc on the target surface. Re-ignition of this new electric arc using a conventional ignition device with an ignition finger conventionally takes longer than 50 ms.Sometimes, for example, if the contact surface of the ignition finger is no longer suitable to ensure electrical contact for initiating the electric arc due to an undesired coating material on the ignition finger, or if the ignition system requires maintenance for some other reason, the entire process may even have to be shut down so that the maintenance can be performed on the ignition finger. Therefore, known trigger devices that include known finger ignition systems (i.e., ignition systems for igniting an electric arc at a target surface in an arc cathode evaporator) do not allow for sufficiently fast retriggering of the trigger finger to achieve fast re-ignition of the electric arc. Unfortunately, known systems interrupt the evaporation process based on the undesired extinction of the electric arc during the execution of the process (resulting in a blackout period longer than 50 ms). Summary of the Invention [Problem to be solved by the invention]

[0008] Object of the invention It is an object of the present invention to alleviate or overcome one or more of the difficulties associated with the prior art. In particular, it is an object of the present invention to provide an arc ignition device and assembly for cathodic arc deposition to provide a simple and inexpensive arc initiation device and cathodic arc deposition assembly that provides high speed, high quality, reliable, and low maintenance cathodic arc deposition. [Means for solving the problem]

[0009] BRIEF DESCRIPTION OF THE INVENTION In order to overcome these problems, an arc ignition device according to independent claim 1, an assembly for cathodic arc deposition according to independent claim 11 and a method for sparking an arc for cathodic arc deposition according to independent claim 20 have been invented. The invention particularly relates to an ignition device (hereinafter also referred to as ignition equipment) for igniting the high-current discharge of an arc evaporator in a vacuum coating system (vacuum coating system hereinafter also referred to as vacuum coating equipment).

[0010] The ignition device provided by the present invention makes it possible, in particular, to reduce or eliminate the maintenance required due to the buildup of coatings on the ignition finger of the ignition device. Furthermore, the ignition device according to the present invention allows for fast regeneration of an electric arc that has been unintentionally extinguished, thereby eliminating blackout periods. In this context, "fast regeneration of an electric arc" means re-ignition of the electric arc within a period of 50 ms or less, preferably between 20 ms and 50 ms. In a first aspect of the present invention, an arc ignition device for cathodic arc deposition of target material on a substrate is provided, comprising a trigger finger movably arranged between a contact position and a rest position, in which the side of the adjacent target is in physical contact with the trigger finger. And In the rest position, adjacent targets can be brought into contact with the trigger finger. And An ignition device is disclosed in which the trigger finger cannot be moved between a contact position and a rest position during cathodic arc deposition of target material, and in this way contamination of the trigger finger by deposited target material during cathodic arc deposition of target material can be minimized. In the context of the present invention, a trigger finger is preferably understood to be an essentially elongated, in particular rod-shaped, release unit. Minimization of contamination of the trigger finger according to the present invention is achieved in particular by a special arrangement of the trigger finger according to the present invention and the type and speed of movement of the trigger finger between the contact position and the rest position.

[0011] The arc ignition device according to the present invention can be installed inside a vacuum chamber, in particular on the wall of the vacuum chamber, which preferably has a location for receiving one or more substrates to be coated. The vacuum chamber can be preferably evacuated to a predetermined pressure below atmospheric pressure (e.g., less than 10 Pa - the total pressure adjusted to achieve physical vapor deposition is typically in the range between 0.01 Pa and 8 Pa, although this range should not be understood as a limitation of the present invention - the vacuum quality pressure range is typically divided into the following vacuum types: low: 760-0 Torr, medium: 0-10 -3 Torr, high: 10 -3 ~10 -8 Torr, super high: 10 -8 ~10 -12 Torr, extremely high:<10 -12 , outer space:~10 -16 Torr).

[0012] In an example of the first aspect, the arc ignition device includes a housing in which the arc ignition device is at least partially disposed, the housing including adjacent The housing may be provided outside the deployable vacuum chamber. The housing may be fluidly connected to the interior of the chamber so that a vacuum exists within the housing, or at least in a portion of the housing. In particular, the housing may serve to protect against contamination and provide electrical insulation. In addition, the arc igniter may be maintained at the pressure level of the vacuum coating chamber by the housing in a simple and flexible manner.

[0013] In another example of the first aspect, the ignition device includes an actuator for moving the trigger finger between the contact position and the rest position, and the trigger finger can be moved by the actuator between the contact position and the rest position in less than 50 ms, preferably between 50 ms and 20 ms, and more preferably between 20 ms and 10 ms. Such high-speed movement particularly enables rapid ignition and re-ignition of the arc. To efficiently avoid contamination by the deposition target material, the actuator can be designed so that the trigger finger can leave the contact position after a maximum of 200 μs, preferably a maximum of 150 μs, and particularly a maximum of 150 μs to 100 μs. More preferably, the actuator can be provided to linearly move the trigger finger in the axial direction of the trigger finger.

[0014] In another example of the first aspect, the actuator is an electromagnetic actuator. In such a case, the electromagnetic actuator may generate an electromagnetic field to stretch a spring to a predetermined extension (stretch) length, moving the trigger finger from the rest position to the contact position. When the electromagnetic field is released, the spring may return to its free or preloaded length so that the trigger finger returns to its rest position. To ensure sufficient contact between the trigger finger and the side of the target, the inventors propose generating a magnetic field that results in a spring stretch corresponding to a distance longer than the actual distance traversed by the tip of the trigger finger when moved from its rest position to its contact position. For example, if the actual distance the tip of the trigger finger must travel (between the rest position and the contact position) is 3 mm, a force should be provided that results in an expected spring stretch and a corresponding stretch distance greater than 3 mm. This means that if the target is not located within the movement envelope of the tip of the trigger finger at the contact position, the force should be selected to provide, for example, a 4 mm stretch distance. In other words, the predetermined extension length mentioned above corresponds to a calculated or predetermined spring extension, which may be the total distance traveled by a compression spring from its free or preload length to its extension length when a preselected force acts on the compression spring and no obstacles are placed in between to prevent the spring from extending, which may be the case, for example, when an electromagnetic field force acts on the compression spring and no obstacles are placed in between.

[0015] In another example of the first aspect, the arc igniter comprises a current limiting element for limiting the current in the contact phase to a value less than 5 A, preferably between 2 A and 5 A. The current limiting device may be used here in particular in connection with material feed ignition and re-ignition of the arc.

[0016] In another example of the first aspect, the arc igniter includes a rod having a first end and an opposite second end, preferably the first end being adjacent The second end is disposed within the disposable chamber and the second end is disposed within the housing.

[0017] In another example of the first aspect, the arc ignition device further includes a spring (e.g., a tension spring) that moves the trigger finger to a rest position. Moving the trigger finger can preferably be achieved by relieving the tensile stress of the spring that was generated when the spring was extended and the trigger finger was in the contact position. In particular, the use of a spring provides a simple design option for fast and accurately determinable movement of the trigger finger.

[0018] In another example of the first aspect, the trigger finger is at least partially constructed of tungsten. The trigger finger may also be constructed of a conductive material other than tungsten, but includes a trigger tip constructed of tungsten or tungsten alloyed with other materials as described below. alloy The material is used as a trigger finger or as the tip of the trigger finger to act as a contact material (non-consumable electrode) for carrying the current required to generate (ignite) a combustible electrode arc on the target surface. Pure tungsten electrodes are cost-effective but have poor heat resistance, so other alloying elements, such as cerium, lanthanum, or thorium, may be used to affect the performance of tungsten. Tungsten alloy materials are known for use in TIG welding processes and typically contain the above-mentioned alloying elements at concentrations of 2% or less. These types of tungsten alloy materials can be used to manufacture the trigger finger of the present invention.

[0019] In a second aspect of the present invention, there is disclosed an assembly for cathodic arc deposition of a material onto a substrate, the assembly comprising: an arc ignition device as described above; a chamber for receiving a substrate to be coated, the chamber being evacuated to a predetermined pressure less than atmospheric pressure; a cathode back support provided within the chamber; and a target located adjacent to the cathode back support plate, the target having a first surface facing away from the cathode back support, a second surface spaced from the first surface and facing the cathode back support, and a side surface connecting the first and second surfaces, wherein plasma material is emitted from the first surface.

[0020] In an example of the second aspect, an anode can be provided within the chamber and spaced apart from the target. Similarly, the anode can be spaced outwardly and away from the first surface of the target.

[0021] In another example of the second aspect, in the contact position, the trigger finger of the arc igniter physically contacts a side of the target, and in the rest position, the trigger finger does not contact the target.

[0022] In another example of the second aspect, particularly with regard to reliable protection of the trigger finger against contamination by deposited target material, the assembly may further include a confinement member for protecting the trigger finger from contamination by the deposited material. The confinement member may be disposed within the chamber and may have a groove formed on its surface. Preferably, in the contact position, the first end of the trigger finger physically contacts the target, and in the rest position, the first end of the trigger finger does not contact the target but is located within the groove of the confinement member to prevent the first end from being exposed to the deposited material. Thus, the confinement member may be located adjacent to the side of the target, preferably between the cathode back support and the anode. For example, the confinement member may be ring-shaped with a central opening defined by an inner wall, and the groove may extend radially from the outer wall to the inner wall of the confinement member. Thus, the central opening may have a diameter greater than the width of the target so that the confinement member is disposed around the target.

[0023] In a third aspect of the present invention, a method of sparking an arc for cathodic arc deposition of material, particularly by using the aforementioned assembly, is disclosed, the method including the steps of providing an anode and a target in an evacuated chamber; providing a trigger finger having a first end disposed within the chamber and a second end disposed outside the chamber; causing movement of the trigger finger to a rest position in which the first end of the trigger finger is housed within the confinement member such that the first end is hidden from the plasma material; moving the trigger finger from the rest position to a contact position in which the first end of the trigger finger is not disposed within the confinement member and the first end physically contacts a side of the target; and returning the trigger finger from the contact position to the rest position.

[0024] In an example of the third aspect, particularly with regard to the structurally simple possibility of ensuring fast and precisely definable movement of the trigger finger, the step of bringing about the movement of the trigger finger to the rest position can be achieved via a spring, and the step of returning the trigger finger from the contact position to the rest position can be achieved via the force of the spring returning to its free length.

[0025] In order to adjust the positioning of the trigger finger as precisely as possible, moving the trigger finger from the rest position to the contact position can be achieved via an actuator located outside the chamber.

[0026] In another example of the third aspect, particularly with regard to the possibility of rapid ignition and re-ignition of the arc, the total time the trigger finger remains in the contact position is less than 250 μs, preferably less than 200 μs, and more preferably between 150 μs and 100 μs. To minimize contamination of the trigger finger with deposited target material during arc deposition, the total time it takes the trigger finger to move from the rest position to the contact position may not exceed 50 ms, preferably between 20 ms and 50 ms, and more preferably between 20 ms and 10 ms. Furthermore, by adjusting the movement time to, for example, 20 ms, trigger repetition (retriggering) may correspond to a frequency of 50 Hz.

[0027] In a fourth aspect of the present invention, the use of the aforementioned arc ignition device in a pulsed cathodic arc deposition process is disclosed.

[0028] In a fifth aspect of the invention, the use of the aforementioned assembly in a pulsed cathodic arc deposition process is disclosed. The use of the arc igniter according to the invention or the arrangement according to the invention in a pulsed process is particularly suitable for re-ignition, which can be practically achieved as frequently and quickly as desired due to low contamination of the trigger finger.

[0029] Detailed Description [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a schematic cross-sectional side view of an assembly for cathodic arc deposition having an arc igniter, the trigger finger of which is shown in a rest position. [Figure 2A] FIG. 2 is a schematic top view of the containment member shown in FIG. 1. [Figure 2B] FIG. 2 is a schematic isometric view of the containment member shown in FIG. 1. [Figure 3] FIG. 2 is a schematic side cross-sectional view of the assembly of FIG. 1, with the trigger finger shown in the contact position. [Figure 4] 1 is a diagram of the electrical behavior of one embodiment of a cathodic arc deposition assembly. DETAILED DESCRIPTION OF THE INVENTION

[0031] Referring now to the drawings, FIG. 1 illustrates a cathodic arc deposition assembly 100 for depositing a coating (i.e., material) onto one or more substrates S to be coated. The cathodic arc deposition assembly 100 includes a chamber 102 defined by an outer shell 104. At least during operation of the cathodic arc deposition assembly 100, the chamber 102 is provided with a vacuum. That is, the chamber 102 is evacuated to a predetermined pressure below atmospheric pressure (e.g., less than 10 Pa—the total pressure adjusted to achieve physical vapor deposition typically ranges between 0.01 Pa and 8 Pa, although this range should not be understood as a limitation of the present invention—vacuum-quality pressure ranges are typically categorized into the following vacuum types: low: 760-0 Torr, medium: 0-10 -3 Torr, high: 10 -3 ~10 -8 Torr, super high: 10 -8 ~10 -12 Torr, extremely high:<10 -12 , outer space:~10 -16 Torr). This is accomplished by a vacuum pump (not shown) provided in fluid connection with the chamber 102.

[0032] As further shown, a cathode back support 106 is provided within the chamber 102. A target 108 (i.e., a cathode) is located adjacent to the cathode back support 106 and includes a first surface 108a, a second surface 108b spaced apart from the first surface 108a, and a side surface 108c connecting the first surface 108a and the second surface 108b. The target 108 is positioned such that the second surface 108b faces the cathode back support 106 and the first surface 108a faces away from the cathode back support 106. In particular, the second surface 108b of the target 108 physically contacts the cathode back support 106 such that the target 108 rests thereon.

[0033] An anode 110 is disposed within the chamber 102 at a location spaced apart from the target 108. In particular, the anode 110 is spaced outward and away from the first surface 108a of the target 108 such that the anode 110 is disposed vertically above the target 108. It should be understood that the disclosure herein has been made with respect to a schematic depiction of a cathodic arc deposition assembly, and that the disclosure is not limited thereto. For example, although the schematic depiction in FIG. 1 and the disclosure associated therewith herein have been made with respect to a vertical orientation (i.e., the target 108 is located on top of the cathode backplate 106, and the anode 110 is spaced vertically above the target 108), it is contemplated that other orientations (e.g., horizontal) are possible.

[0034] Target material (not shown) is evaporated from the first surface 108a of the target 108, and a plasma is formed from the evaporated material, from which material is deposited onto the substrate S to be coated to form a coating. This is accomplished by providing a power supply 112 that generates and maintains the electric arc of the cathodic arc deposition assembly 100. In particular, the positive terminal of the power supply 112 is operatively connected to the anode 110, and the negative terminal of the power supply 112 is operatively connected to the target 108 through the cathode back support 106. The power supply 112 provides an idle voltage in the range of 40V to 200V.

[0035] To generate an electric arc, the target 108 is struck by a striking means (i.e., a trigger finger, described further below), thereby creating a closed electrical circuit from the power supply 112 through the target 108 and through the striking means. When the striking means is released from the target 108, the electrical circuit path between the striking means and the target 108 is broken, and the electric arc jumps the gap between the striking means and the target 108, thereby generating an electric arc on the target 108. Upon generation of the electric arc, the arc path immediately extends between the target 108 and the anode 110 and is thereafter maintained by the power supply 112.

[0036] The high current levels passing through the target 108 during operation cause the target 108 to become extremely hot. As such, the cathodic arc deposition assembly 100 may include cooling means (not shown) configured to cool the target 108. The cooling means may be integrally formed with the cathode back support 106 or may be a separate, distinct component.

[0037] As further shown in FIG. 1 , the cathodic arc deposition assembly 100 includes an arc igniter 114 configured to generate an electric arc. The arc igniter 114 includes a housing 116 disposed outside the chamber 102 and a trigger finger 118 configured for linear movement in an axial direction X of the trigger finger 118. The housing 116 is attached to the outer shell 104 of the chamber 102 at an opening formed therein. In particular, a seal is disposed between the outer shell 104 and the housing 116, sealingly engaging the former with the latter. The seal includes a first sealing ring 120 a and a second sealing ring 120 b that physically contact the outer shell 104 and the housing 116, respectively. As further shown, an electrical insulator 122 is disposed between the first sealing ring 120 a and the second sealing ring 120 b, providing electrical insulation between the chamber 102 and the arc igniter 114.

[0038] Although other actuators (e.g., other forms of electromechanical actuators) may be used, electromagnetic actuators are preferred because they allow the trigger finger to move while the moving portion of the actuator is in a vacuum (sealed and attached to the arc evaporation source) and the stimulating electrical coil is in air, thus allowing for the construction of an arc igniter with a very compact design.

[0039] The arc igniter 114 further includes an actuator 124 disposed within the housing 116. The actuator 124 moves (i.e., moves) the trigger finger 118 between a rest position and a contact position, as described below. Furthermore, the actuator 124 may be a mechanical actuator, but is preferably an electromagnetic actuator (e.g., a linear servo motor, a solenoid, etc.). In particular, the actuator 124 may be in the form of an electromagnetic actuator, which produces mechanical motion after electrical stimulation of a coil. The electrical stimulation of the coil may be produced by discharging a capacitor (not shown). The actuator 124 may be activated in the form of pulses, imparting a constant impulse motion to the arc igniter 114, with repetition frequencies of up to 50 Hz being achieved.

[0040] The cathodic arc deposition assembly 100 further includes a confinement member 126 disposed within the chamber 102. As shown in Figures 2A and 2B, the confinement member 126 is preferably ring-shaped. However, other configurations are contemplated. For example, the confinement member 126 may be square-shaped or rectangular-shaped.

[0041] 2B, the outer circumferential surface of containment member 126 may be finished to include upper and lower chamfered edges 127a, 127b. In another example, the outer circumferential surface of containment member 126 may be finished to include rounded corners (e.g., radius corners). Alternatively, the outer circumferential surface may be unfinished (e.g., 90° square corners).

[0042] 2A and 2B, the confinement member 126 includes a notch or groove 128. The groove 128 is formed in the confinement member 126 and is configured to allow the trigger finger 118 to extend therethrough. In particular, the confinement member 126 is positioned adjacent to (preferably surrounding, but not directly contacting) the side surface 108c of the target 108 and is disposed vertically between the cathode back support 106 and the anode 110. The lateral distance between the confinement member and the target is preferably 1.5 mm or less (considering the radial distance). That is, the confinement member 126 is positioned above the cathode back support 106 and below the anode 110. The confinement member 126 is typically made of steel (magnetic or non-magnetic).

[0043] 2A and 2B, a schematic top view (FIG. 2A) and a schematic isometric view (FIG. 2B) of containment member 126 are shown. Containment member 126 is ring-shaped having an inner wall 126a and an outer wall 126b. Containment member outer wall 126b may be formed to define a recessed circumferential channel. However, outer wall 126b may be finished with a convex protrusion extending along the periphery of outer wall 126b. Alternatively, outer wall 126b may not include a circumferential channel. In another aspect, outer wall 126b may be formed to include an outwardly extending ridge or flange (e.g., a retention member) extending along the circumferential surface of containment member 126.

[0044] Groove 128 of confinement member 126 extends radially from inner wall 126a to outer wall 126b. The confinement member must be designed with groove 128 sized to provide an unobstructed passage for the trigger finger as it moves through it. At the same time, the groove must be narrow enough to prevent the plasma from burning therein, particularly to avoid the deposition of coating material on the inner surface of the groove. This means, for example, that if a trigger rod with a diameter of 2 mm is used, the axial dimension of groove 128 may be 3 mm, as shown schematically in FIG. 2b. Furthermore, inner wall 126a defines a central opening in confinement member 126 having a diameter d1. The diameter d1 of the central opening is greater than the width W1 of target 108, so that confinement member 126 is disposed around target 108. In other words, the confinement member 126 circumferentially surrounds the target 108 , with the inner wall 126 a of the confinement member 126 facing the side surface 108 c of the target 108 .

[0045] Returning to FIG. 1 , trigger finger 118 is a rod having a first end 118a and an opposite second end 118b. Trigger finger 118, and particularly the first end of the trigger finger (also referred to as the tip of the trigger finger), may be constructed of tungsten. Alternatively, trigger finger 118 may be constructed of other materials, as already mentioned above. The trigger finger extends into groove 128 of containment member 126 and is positioned to strike side surface 108c of target 108. As shown, second end 118b of trigger finger is disposed within housing 116 of arc igniter 114.

[0046] 1 , trigger finger 118 is shown in a rest position. In particular, first end 118 a of trigger finger 118 is positioned within groove 128 of containment member 126. In this manner, containment member 126 prevents first end 118 a of trigger finger 118 from being exposed to plasma material (e.g., from ignition of an electric arc) disposed within chamber 102. As further shown, spring 130 is disposed within housing 116 and configured to effect movement of trigger finger 118 to the rest position. While spring 130 is shown as a helical compression spring, other types of springs (e.g., tension springs, conical springs, disc springs, etc.) are also contemplated and may be used to effect movement of trigger finger 118 to the rest position.

[0047] Turning to FIG. 3 , trigger finger 118 is shown in a contact position. In particular, as described above, actuator 124 linearly moves trigger finger 118 from a rest position (i.e., first end 118 a of trigger finger 118 is located within groove 128) to a contact position, where first end 118 a of trigger finger 118 physically contacts side surface 108 c of target 108. That is, trigger finger 118 is movable (e.g., in a direction perpendicular to an imaginary plane in which side surface 108 c lies) to strike (i.e., contact) side surface 108 c of target 108. This orientation and placement results in a small movement of the trigger finger, as opposed to striking first surface 108 a or second surface 108 b of target 108. The total distance traveled by trigger finger 118 between the rest position and the contact position may be, for example, 3 mm, although this distance should not be understood as a limitation of the present invention. The shorter the distance that the trigger finger must cover during movement from the rest position to the contact position and vice versa, the shorter the time consumed by retriggering. Similarly, if a shorter distance for the trigger finger movement is selected, the higher the efficiency and the reduced system complexity can be achieved. Further advantages of using the trigger device (arc ignition device) according to the present invention include, for example: a) no erosion of the side surface 108c occurs by using the present invention, thereby ensuring a stable trigger structure; b) no or significantly reduced deposition of a coating film on the trigger finger (meaning the first end or tip of the trigger finger) because the movement of the trigger finger to the rest position largely hides the trigger finger in the housing of the ignition device or in a groove in the containment member; and c) a compact design including the actuator and components for the trigger function, including electrical isolation and vacuum sealing.

[0048] When the trigger finger 118 is in the contact position, a closed electrical circuit is created from the power supply 112 through the target 108 and through the arc igniter 114 (i.e., via the trigger finger 118). As shown, the cathodic arc deposition assembly 100 further includes a resistor 132 electrically connected to the trigger finger 118. The resistor 132 limits the current to less than 5 A, preferably in the range of 2 A to 5 A, during the contact position.

[0049] The operation of the cathodic arc deposition assembly 100 will now be described. Initially, the power supply 112 is activated, delivering an idle voltage of 40V to 200V. At this time, the trigger finger 118 is moved to a rest position via the spring 130. To generate an electric arc, the actuator 124 is activated (e.g., by priming the coil via discharging a capacitor), and the actuator 124 exerts a force on the trigger finger 118 sufficient to overcome the inherent force of the spring 130 to maintain it at its free or preloaded length (also referred to as the relaxed length or relaxed position of the spring). In doing so, the trigger finger 118 moves linearly from the rest position to a contact position, where the first end 118a of the trigger finger 118 physically contacts the side surface 108c of the target 108.

[0050] Notably, the total time it takes to move the trigger finger 118 from the rest position to the contact position does not exceed 50 ms, preferably between 10 ms and 50 ms. When the first end 118a of the trigger finger 118 strikes the side 108c of the target 108, a closed electrical circuit is formed, delivering a current of 2 A to 5 A. The actuator 124 is then deactivated and no longer supplies force to the trigger finger 118. Thus, the trigger finger 118 moves back to its rest position under the force of the spring 130, which returns it to its free length. The total time the trigger finger 118 remains in the contact position (i.e., the first end 118a of the trigger finger 118 is in contact with the side 108c of the target 108) is 100 μs or less, preferably less than 50 μs.

[0051] When the electrical circuit is broken, an electric arc (i.e., plasma material) is emitted from the target 108. This plasma material is then guided (e.g., magnetically) to the substrate S and coats the substrate S. In this embodiment, because the trigger finger 118 immediately returns to its rest position after the actuator 124 is deactivated (i.e., by the spring 130's own force to relax itself), and because the first end 118a of the trigger finger 118 is positioned within the groove 128 of the containment member 126 in the rest position, the trigger finger 118 is hidden from the plasma material. In other words, the trigger finger 118 is always in the rest position (i.e., hidden from the plasma material) unless the actuator 124 is activated. In this way, the trigger finger 118 is not exposed to the plasma material, and therefore film buildup on the trigger finger 118 cannot occur.

[0052] With reference to FIG. 4, a diagram of the electrical behavior of one embodiment of the cathodic arc deposition assembly 100 is shown. The diagram is divided into a first time interval T1, a second time interval T2, and a third time interval T3. The first time interval T1 represents the cathodic arc deposition assembly 100 after the power supply 112 is activated and before the generation of an electric arc. That is, during the first time interval T1, the trigger finger 118 is in a rest position. The second time interval T2 represents the trigger finger 118 in a contact position (i.e., as shown in FIG. 3). In particular, the second time interval T2 occurs over a period of 50 μs. That is, the total time that the first end 118 a of the trigger finger 118 contacts the side surface 108 c of the target 108 is equal to or less than 50 μs. A third time interval T3 represents the creation of an electric arc, which occurs when the first end 118a of the trigger finger 118 is released from the side surface 108c of the target 108. That is, the trigger finger 118 is again in a stationary position during the third time interval T3.

[0053] As shown, three lines (i.e., lines "A," "B," and "C") are placed on the diagram to represent the electrical behavior of the cathodic arc deposition assembly 100 during each time interval (i.e., T1-T3). The first line "A" represents the electric arc discharge current (i.e., in amperes). From the first time interval T1 to the second time interval T2, line "A" remains substantially constant, with the electric arc discharge current equal to 0 A. However, during the third time interval T3, the electric arc discharge current rises to 200 A.

[0054] A second line "B" represents the amount of current (in amperes) in the trigger finger 118. As shown, the trigger finger 118 experiences no current (i.e., 0 A) during a first time interval T1. During a second time interval T2, the trigger finger 118 experiences a current of 3 A. The trigger current (i.e., line "B") is substantially reduced during a third time interval T3, but does not reach zero (i.e., 0 A).

[0055] Finally, the third line "C" represents the voltage (i.e., in volts) of the cathodic arc deposition assembly 100. During the first time interval T1, the voltage remains relatively constant and is approximately equal to 140V. This voltage is supplied by the power supply 112. After the generation of the electric arc (i.e., after the second time interval T2), the voltage is reduced to a range of 20V to 40V.

[0056] The present invention has been described with reference to the exemplary embodiments set forth above. Modifications and alterations will occur to others upon reading and understanding this specification. The exemplary embodiments incorporating one or more aspects of the present invention are intended to include all such modifications and alterations insofar as they come within the scope of the appended claims.

Claims

1. 1. An arc ignition apparatus for cathodic arc deposition of a target material onto a substrate, said arc ignition apparatus comprising: a trigger finger movably arranged between a contact position and a rest position, wherein in the contact position a side of an adjacent target can be physically contacted by the trigger finger and in the rest position the adjacent target cannot be contacted by the trigger finger, wherein during cathodic arc deposition of target material the trigger finger is movably arranged between the contact position and the rest position, such that contamination of the trigger finger by deposited target material during the cathodic arc deposition of the target material can be minimized; The arc ignition device is an actuator for moving the trigger finger between the contact position and the rest position, the arc igniter configured such that the trigger finger can be moved by the actuator between the contact position and the rest position in less than 50 ms and is prevented from exposure to the vaporized material by a containment member having a groove for hiding the trigger finger from exposure to the vaporized material.

2. The arc ignition device is 10. The arc ignition device of claim 1, comprising a housing disposed at least partially therein, the housing being external to a vacuum chamber that may be disposed adjacent thereto.

3. The arc ignition device of claim 1 or claim 2, wherein the trigger finger can be moved between the contact position and the rest position in between 50 ms and 20 ms.

4. 4. The arc ignition device of claim 1, wherein the actuator is designed such that the trigger finger can leave the contact position after a maximum of 200 μs.

5. 5. An arc igniter according to any one of claims 1 to 4, wherein the arc igniter comprises a current limiting element for limiting the current in the contact phase to a value below 5A.

6. 6. The arc igniter of any one of claims 1 to 5, wherein the arc igniter comprises a rod having a first end and an opposite second end.

7. 7. An arc ignition device according to any one of claims 1 to 6, wherein the actuator is provided for linearly moving the trigger finger in an axial direction of the trigger finger.

8. The arc igniter of any one of claims 1 to 7, wherein the arc igniter further comprises a spring that moves the trigger finger to the rest position.

9. 9. The arc ignition device of claim 1, wherein the actuator is an electromagnetic actuator.

10. 10. The arc ignition device of any one of claims 1 to 9, wherein the trigger finger is constructed at least in part from tungsten.

11. 1. An assembly for cathodic arc deposition of a material onto a substrate, said assembly comprising: The arc ignition device according to any one of claims 1 to 10; a chamber for receiving a substrate to be coated, the chamber being evacuated to a predetermined pressure below atmospheric pressure; a cathode back support provided within the chamber; a target located adjacent to the cathode back support, the target having a first surface facing away from the cathode back support, a second surface spaced from the first surface and facing the cathode back support, and a side surface connecting the first surface and the second surface, wherein plasma material is emitted from the first surface; an anode disposed within the chamber and spaced from the target; In the contact position, the trigger finger of the arc igniter physically contacts the side of the target, and in the rest position, the trigger finger does not contact the target.

12. The assembly of claim 11 , wherein the anode is spaced outwardly and away from the first surface of the target.

13. 13. An assembly for cathodic arc deposition of a material onto a substrate according to claim 11 or claim 12, wherein the assembly further comprises a containment member for protection of the trigger finger from being contaminated by deposited material.

14. 14. The assembly for cathodic arc deposition of a material onto a substrate of claim 13, wherein the confinement member is disposed within the chamber and has a groove formed therein.

15. 15. The assembly for cathodic arc deposition of a material onto a substrate of claim 14, wherein in the contact position, a first end of the trigger finger physically contacts the target, and in the rest position, the first end of the trigger finger does not contact the target and is located within the groove of the containment member to prevent the first end from being exposed to the deposited material.

16. 16. An assembly according to any one of claims 13 to 15, wherein the containment member is located adjacent the side of the target.

17. 16. The assembly of claim 14 or claim 15, wherein the containment member is ring-shaped with a central opening defined by an inner wall, and the groove extends radially of the containment member from the outer wall to the inner wall of the containment member.

18. 18. The assembly of claim 17, wherein the central opening has a diameter greater than a width of the target such that the containment member is disposed around the target.

19. 19. The assembly of any one of claims 11 to 18, wherein the arc igniter comprises a housing disposed outside the chamber.

20. 20. A method for sparking an arc for cathodic arc deposition of material by using an assembly according to any one of claims 11 to 19, said method comprising the steps of: providing an anode and a target in an evacuated chamber; providing a trigger finger having a first end disposed within the chamber and a second end disposed outside the chamber; causing movement of the trigger finger to a rest position, the first end of the trigger finger being contained within a containment member such that the first end is hidden from plasma material, the method further comprising: moving the trigger finger from the rest position to a contact position, wherein the first end of the trigger finger is not disposed within the containment member and the first end physically contacts a side of the target; The method includes returning the trigger finger from the contact position to the rest position.

21. 21. The method of claim 20, wherein causing the trigger finger to move to the rest position is accomplished via a spring, and returning the trigger finger from the contact position to the rest position is accomplished via a force of the spring returning to its free length.

22. 22. The method of claim 21, wherein moving the trigger finger from the rest position to the contact position is accomplished via an actuator located outside the chamber.

23. 23. The method of any one of claims 20 to 22, wherein the total time that the trigger finger remains in the contact position is less than 250 μs.

24. 23. The method of any one of claims 20 to 22, wherein the total time taken for the trigger finger to move from the rest position to the contact position does not exceed 50 ms.

25. Use of the arc ignition device according to any one of claims 1 to 10 in a pulsed cathodic arc deposition process.

26. Use of an assembly according to any one of claims 11 to 19 in a pulsed cathodic arc deposition process.

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