阅读说明：本技术 阴极电弧引弧装置 (Cathode arc striking device ) 是由 西格弗里德·克拉斯尼策 于尔格·哈格曼 安德烈亚斯·彼得·特雷霍尔茨 多米尼克·埃尔温·威德默 于 2019-12-20 设计创作，主要内容包括：一种用于将靶材阴极电弧沉积到基材上的引弧装置,该引弧装置包括触发指,其活动布置在接触位置与静止位置之间,其中在该接触位置中该触发指能物理接触相邻靶的侧表面,而在该静止位置中相邻靶不能被该触发指接触,其中在靶材的阴极电弧沉积期间,该触发指如此活动布置为在所述接触位置与静止位置之间,即,能将该触发指在靶材阴极电弧沉积期间被沉积的靶材污染减至最小。(An arc ignition device for cathodic arc deposition of a target onto a substrate, the arc ignition device comprising a trigger finger movably arranged between a contact position in which the trigger finger is able to physically contact a side surface of an adjacent target and a rest position in which the adjacent target is not able to be contacted by the trigger finger, wherein during cathodic arc deposition of the target the trigger finger is movably arranged between said contact position and the rest position in such a way that contamination of the trigger finger with the deposited target during cathodic arc deposition of the target is minimized.)

1. An arc ignition apparatus for cathodic arc deposition of a target material onto a substrate, the arc ignition apparatus comprising:

a trigger finger movably arranged between a contact position and a rest position,

wherein in the contact position the trigger finger is able to physically contact a side surface of an adjacent target, and in the rest position the adjacent target is not able to be contacted by the trigger finger,

wherein the trigger finger is movably arranged between said contact position and a rest position during cathodic arc deposition of the target in such a way that contamination of the target deposited by the trigger finger during cathodic arc deposition of the target is minimized.

2. The arc ignition device according to claim 1,

wherein the arc ignition device comprises a housing in which the arc ignition device is at least partially located,

wherein the housing can be arranged outside of the vacuum chamber which can be arranged adjacently.

3. The arc ignition device according to claim 1 or 2,

wherein the arc ignition device comprises an actuator for moving the trigger finger between said contact position and a rest position,

wherein the trigger finger can be moved by the actuator between said contact position and rest position in less than 50ms, preferably between 50ms and 20ms, more preferably between 20ms and 10 ms.

4. The arc ignition device according to one of the preceding claims, wherein the actuator is designed such that the trigger finger can leave the contact position after a time of at most 200 μ s, preferably at most 150 μ s, in particular at most between 150 μ s and 100 μ s.

5. Arc ignition device according to one of the preceding claims, wherein the arc ignition device comprises a current limiting component which limits the current during the contacting step to a value smaller than 5A, preferably to a value between 2A and 5A.

6. The arc ignition device according to one of the preceding claims,

wherein the arc ignition device comprises a rod having a first end and an opposite second end,

wherein preferably said first end is located in adjacently arrangeable chambers and said second end is located in the housing.

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

8. The arc ignition device of any one of the preceding claims, wherein the arc ignition device further comprises a spring which moves the trigger finger to the rest position.

9. The arc ignition device of one of the preceding claims, wherein the actuator is an electromagnetic actuator.

10. The arc ignition device of any one of the preceding claims, wherein the trigger finger is at least partially formed of tungsten.

11. An assembly for cathodic arc deposition of a material onto a substrate, the assembly comprising:

the arc ignition device according to one of the preceding claims,

a chamber for containing a substrate to be coated, the chamber being evacuated to a predetermined pressure below atmospheric pressure;

a cathode backside support disposed within the chamber;

a target disposed adjacent the cathode backside support plate, the target having a first surface facing away from the cathode backside support, a second surface spaced apart from the first surface and facing the cathode backside support, and a side surface connecting the first surface and the second surface, wherein plasma material is to be ejected from the first surface;

an anode disposed within the chamber and spaced apart from the target,

wherein in the contact position a trigger finger of the arc ignition device physically contacts the side surface of the target, and in the rest position the trigger finger does not contact the target.

12. An assembly according to claim 11, wherein the anode is spaced outwardly from the first surface of the target.

13. Assembly for cathodic arc deposition of a material onto a substrate according to claim 11 or 12 wherein the assembly further comprises a limiting member for protecting the trigger finger from contamination by the deposited material.

14. The assembly for cathodic arc deposition of a material onto a substrate according to claim 13 wherein said confinement member is positioned within said chamber and has a recess formed therein.

15. Assembly for the cathodic arc deposition of a material onto a substrate according to claim 13 or 14,

wherein in the contact position the first end of the trigger finger physically contacts the target,

and wherein in the rest position the first end of the trigger finger is not in contact with the target and is located within the recess of the limiter to inhibit exposure of the first end to the deposition material.

16. Assembly according to one of claims 11 to 15, wherein the restriction is located near a side surface of the target, preferably between the cathode backside support and the anode.

17. Assembly according to one of the claims 11 to 16,

wherein the restraint is annular in shape having a central opening defined by an inner sidewall,

wherein the groove extends from an outer side wall to an inner side wall of the restriction member in a radial direction of the restriction member.

18. The assembly of claim 17, wherein the diameter of the central opening is greater than the width of the target such that the restraint is disposed about the target.

19. Assembly according to one of claims 11 to 18, wherein the arc ignition device comprises a housing arranged outside the chamber.

20. An arc-initiating method for cathodic arc deposition of a material, in particular using an assembly according to one of claims 11 to 19, comprising the steps of:

providing an anode and a target within an evacuated chamber;

providing a trigger finger having a first end located inside the chamber and a second end located outside the chamber;

generating movement of the trigger finger to a rest position, wherein the first end of the trigger finger is received within a confinement member such that the first end is clear of plasma material;

displacing the trigger finger from the rest position to a contact position, wherein the first end of the trigger finger is not located within the restraint, and wherein the first end physically contacts a side surface of the target; and

moving the trigger finger from the contact position back to the rest position.

21. The method of claim 20, wherein the first and second portions are selected from the group consisting of,

wherein the step of generating movement of the trigger finger to the rest position is accomplished by a spring,

and wherein moving the trigger finger back from the contact position to the rest position is accomplished by the force of a spring for returning to its free length.

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

23. Method according to one of claims 20 to 22, wherein the trigger finger stays at the contact position for an amount of time of less than 250 μ s, preferably less than 200 μ s, more preferably between 150 μ s and 100 μ s.

24. Method according to one of claims 20 to 22, wherein the amount of time it takes for the trigger finger to move from the rest position to the contact position does not exceed 50ms, preferably between 20ms and 50ms, more preferably between 20ms and 10 ms.

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

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

Technical Field

The present invention relates generally to physical vapor deposition apparatus and, more particularly, to arc ignition devices, assemblies, and methods of cathodic arc deposition within a coating chamber.

Background

Cathodic arc deposition is a known physical vapor deposition process. In order to perform a cathodic arc deposition process, a mechanism for igniting a large-current discharge to generate evaporation of a target material placed in an arc evaporator (hereinafter also referred to as an arc evaporation source, an arc source, or a spark source) placed in a vacuum chamber of a coating apparatus is generally used. Arc evaporators generally include a target that can act as a cathode during arc evaporation. The arc evaporator may further comprise at least one electrode which may act as an anode during arc evaporation. In case the arc evaporator does not comprise any integrated anode, other electrodes placed inside the vacuum chamber may also be used as anodes. It is also known that in some cases the vacuum chamber wall is considered as an anode.

In order to start the cathodic arc deposition process, it is necessary to ignite an arc on the surface of the target to be evaporated while using the target to be evaporated as a cathode.

In arc deposition processes, substrates (e.g., workpieces such as parts or tools) are treated under high vacuum, in particular for subjecting the substrates to a plasma treatment such as plasma etching or coating (e.g., coating by means of a cathodic arc physical vapor deposition process).

Different types of ignition devices for arc evaporation sources are known and described, for example, in US2011/0220495a 1. It is explained there that the types of ignition devices can be basically divided into three groups: a) means for mechanically switching the contact between the cathode and the anode; b) means for igniting an arc discharge by an electric spark discharge; c) a device that ignites through a conductive bridge.

In the arc deposition process, the substrate to be coated is placed in a coating chamber and the coating chamber is evacuated prior to the deposition of the coating. As just described, the arc is used to evaporate material from the target surface, thereby providing coating material for coating deposition. The cathodic arc evaporation process begins with a high current, low voltage arc striking the target surface as the cathode, which produces electron emission from the target surface (acting as the cathode) to the anode.

As just described, ignition of the arc can be achieved by using ignition fingers, which must be brought into contact with the target surface to be evaporated. Such ignition fingers are also commonly referred to as trigger fingers. Typically, during and sometimes even after the arc is ignited, the ignition fingers are exposed to material evaporated from the target surface. Such exposure results in the formation of a coating film (e.g., a metal or ceramic film such as a nitride film, oxide film, or other type of film) on the firing fingers. Such film formation may impair the ability of the ignition fingers to perform their function (e.g., ensure electrical contact and subsequent arc ignition). Therefore, routine maintenance is required to remove these unwanted coatings. However, frequent maintenance shortens the working time, which in turn reduces the overall efficiency of the coating manufacturing process. On the other hand, if maintenance is not performed frequently enough, not only will the ability to ignite the fingers to perform the initial ignition be reduced, but the speed and reliability associated with any required reactivation also be reduced. This then likewise leads to a reduced efficiency of the coating production process and possibly also to a reduced coating quality. In operation, the cathode spot is only active for a short time, then it is automatically extinguished and automatically reignited in a new region close to the previous cathode spot. This action causes significant movement of the arc. When the cathode spot is completely extinguished and cannot be automatically reignited in a new area as described above, the arc is extinguished during the process (i.e., a blackout period occurs). In this case, the ignition fingers must be reactivated again to ignite a new arc at the target surface. It usually takes more than 50 milliseconds to ignite a new arc again by using a conventional ignition device with ignition fingers. It is sometimes even necessary to shut down the entire process so that the ignition fingers can be serviced, for example when the contact surfaces of the ignition fingers are no longer suitable for ensuring electrical contact for igniting the arc due to unwanted coating material on the ignition fingers, or when the ignition system requires servicing for some other reason. Therefore, known triggering devices including known finger ignition systems (i.e., ignition systems for igniting an arc at a target surface in an arc cathode evaporator) do not allow the trigger fingers to be retriggered quickly enough to obtain rapid reignition of the arc. Unfortunately, known systems interrupt the arc evaporation process (resulting in outage times in excess of 50 ms) based on undesirable arc extinguishment during the performance of the work process.

Object of the Invention

It is an object of the present invention to mitigate 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 starting apparatus and an assembly for cathodic arc deposition to provide a simple and inexpensive arc starting apparatus and cathodic arc deposition assembly which provides a fast, high quality, reliable and maintenance-free cathodic arc deposition.

Brief introduction to the invention

In order to overcome these problems, an arc starting apparatus according to independent claim 1, a cathodic arc deposition assembly according to independent claim 11 and an arc initiation method for cathodic arc deposition according to independent claim 20 have been created. The invention relates in particular to an ignition device (also referred to below as an igniter) for igniting a high-current discharge of an arc evaporator in a vacuum coating system (vacuum coating system is also referred to below as a vacuum coating device).

The present invention provides a pilot that allows, among other things, reducing or eliminating the maintenance required to form a coating film on the pilot fingers in the pilot. Furthermore, the pilot burner according to the invention allows a rapid re-generation of the arc that is accidentally extinguished, thus eliminating any blackout periods. In this connection, the term "rapid re-generation of the arc" means that the arc is re-ignited within a time period of 50ms or less, preferably between 20ms and 50 ms. In a first aspect of the present invention, an arc starting device for cathodic arc deposition of a target onto a substrate is disclosed, comprising a trigger finger movably arranged between a contact position in which a side surface of an adjacent target can be physically contacted by the trigger finger and a rest position in which the trigger finger cannot contact the adjacent target, wherein during cathodic arc deposition of the target the trigger finger is movably arranged between the contact position and the rest position in such a way that contamination of the deposited target by the trigger finger during cathodic arc deposition can be minimized. In the context of the present invention, the trigger finger is preferably understood as a substantially elongated, in particular rod-shaped release unit. A minimization of the contamination of the trigger finger according to the invention is obtained, in particular because of the specific arrangement of the trigger finger according to the invention and because of the type and speed with which the trigger finger is moved between the contact position and the rest position.

The arc ignition device according to the invention can be placed inside a vacuum chamber, in particular at a wall of the vacuum chamber, which preferably has a position for receiving one or more substrates to be coated. The vacuum chamber is preferably evacuated to a predetermined pressure below atmospheric pressure (e.g., less than 10 Pa-the total pressure adjusted to complete the physical vapor deposition process is typically in the range between 0.01Pa and 8Pa, but this range should not be construed as limiting the invention-the vacuum mass pressure range is typically divided into the following vacuum types: low: 760-0 Torr, medium: 0-10 Pa^-3Support, height: 10^-3-10^-8Support, superelevation: 10^-8-10^-12Support, the height is extremely high:<10^-12and outer space: 10 to^-16Tray).

In one example of the first aspect, the arc ignition device comprises a housing in which the arc ignition device is at least partially located, wherein the housing is positionable outside of an adjacently arrangeable vacuum chamber. The housing may be fluidly connected to the interior of the chamber such that a vacuum is present within the housing or at least within a portion of the housing. In particular, the housing may be used for anti-fouling protection and to provide electrical insulation. Furthermore, the arc ignition device can be maintained at the pressure level of the vacuum coating chamber by the housing in a simple and flexible manner.

In another example of the first aspect, the arc ignition means comprises an actuator for moving the trigger finger between the contact position and the rest position, wherein the trigger finger can be moved between the contact position and the rest position by the actuator in less than 50ms, preferably between 50ms and 20ms, more preferably between 20ms and 10 ms. This rapid movement allows, in particular, rapid ignition and re-ignition of the arc. In view of an effective avoidance of contamination by the deposition target, the actuator may be designed such that the trigger finger can leave the contact position after a time of at most 200 μ s, preferably at most 150 μ s, in particular at most between 150 μ s and 100 μ s. The actuator may preferably also be arranged for linearly moving the trigger finger in the axial direction of said trigger finger.

In another example of the first aspect, the actuator is an electromagnetic actuator. In this case, the electromagnetic actuator may be configured such that an electromagnetic field is generated to elongate the spring to a predetermined extended (elongated) length to move the trigger finger from the rest position to the contact position. When the electromagnetic field is deactivated, the spring may return to its free or preloaded length such that the trigger finger moves back to its rest position. In order to ensure sufficient contact between the trigger finger and the side surface of the target, the inventors propose to generate a magnetic field that causes the spring to elongate corresponding to a distance greater than the actual distance that the tip of the trigger finger travels when moving from the rest position to the contact position. For example, if the actual distance that the tip of the trigger finger needs to travel (between the rest position and the contact position) is 3 millimeters, a force should be provided that should produce the desired spring elongation and a corresponding elongation distance greater than 3 millimeters. This means that if no target is placed in the motion envelope of the tip of the trigger finger in the contact position, the force should be chosen to provide an elongation distance of e.g. 4 mm. In other words, the predetermined extended (elongated) length corresponds to a calculated or predetermined spring elongation that would be the total distance the compression spring would travel from its free or preloaded length to its extended (elongated) length in the event that a preselected force is acting on the compression spring without an intervening obstruction to the spring elongation. This would be the case, for example, if the electromagnetic field force acts on the compression spring without an obstacle in between.

In another example of the first aspect, the arc ignition device comprises a current limiting means for limiting the current during the contacting step to a value smaller than 5A, preferably between 2A and 5A. The current limiting device can be used here in particular in connection with the ignition and re-ignition of the arc in a material-saving manner.

In another example of the first aspect, the arc ignition device comprises a rod having a first end and an opposite second end, wherein the first end is preferably located in the adjacently arrangeable chamber and the second end is located in the housing.

In another example of the first aspect, the arc ignition device further comprises a spring (e.g., an extension spring) that moves the trigger finger to a rest position. Moving the trigger finger may preferably be accomplished by relaxing the spring tension that is created when the spring is elongated and the trigger finger is in the contact position. In particular, the use of a spring provides a simple design option for a fast and precisely determinable movement of the trigger finger.

In another example of the first aspect, the trigger finger is at least partially composed of tungsten. The trigger finger may also be made of other conductive materials than tungsten, but includes a trigger tip made of tungsten or made of tungsten alloyed with other materials as described below. Tungsten or tungsten-alloying material is used as a trigger finger or trigger fingertip end to act as a contact material (a non-consumable electrode) to conduct the current required to create (ignite) an arc to be ignited on the target surface. Since pure tungsten electrodes are cost-effective but have poor heat resistance, different kinds of alloying elements can be used to influence the properties of tungsten, such as cerium, lanthanum or thorium. Tungsten alloying materials are known to be used in TIG welding processes and typically contain the alloying elements described above in concentrations of not more than 2%. This type of tungsten alloyed material can be used for manufacturing the trigger finger according to the invention.

In a second aspect of the invention, an assembly for cathodic arc deposition of a material onto a substrate is disclosed, the assembly comprising: the arc striking device described above; a chamber for containing a substrate to be coated, the chamber being evacuated to a predetermined pressure below atmospheric pressure; a cathode backside support disposed within the chamber; a target disposed adjacent the cathode backside support plate, the target having a first surface facing away from the cathode backside support, a second surface spaced apart from the first surface and facing the cathode backside support, and a side surface connecting the first and second surfaces, wherein plasma material is to be ejected from the first surface.

In one example of the second aspect, the anode may be disposed within the chamber and spaced apart from the target. It is also possible that the anode is outwardly remote from the first surface of the target.

In another example of the second aspect, the trigger finger of the arc ignition device physically contacts a side surface of the target in the contact position, and the trigger finger does not contact the target in the rest position.

In another example of the second aspect, particularly with respect to reliable shielding of the trigger finger from contamination by deposition target material, the assembly may further comprise a restriction for protecting the trigger finger from contamination by deposition material. The restriction member may be located within the chamber and may have a groove formed on a surface thereof. Preferably, the first end of the trigger finger physically contacts the target in the contact position, and the first end of the trigger finger does not contact the target and is positioned within the recess of the restraint in the rest position to prevent exposure of the first end to the deposition material. The confinement member may thus be located near the side surface of the target, preferably between the cathode backside support and the anode. For example, the limiter is annular having a central opening defined by an inner sidewall, wherein the recess extends in a radial direction of the limiter from the outer sidewall to the inner sidewall of the limiter. The diameter of the central opening can be greater than the width of the target such that the restraint is positioned around the target.

In a third aspect of the invention, there is disclosed a method of arc discharge for cathodic arc deposition of a material, in particular using the aforementioned assembly, the method comprising the steps of: providing an anode and a target within an evacuated chamber; providing a trigger finger having a first end located inside the chamber and a second end located outside the chamber; generating movement of a trigger finger to a rest position, wherein a first end of the trigger finger is received within the confinement member such that the first end is clear of the plasma material; displacing a trigger finger from a rest position to a contact position, wherein a first end of the trigger finger is not located within the restraint, and wherein the first end physically contacts a side surface of the target; the trigger finger is moved back from the contact position to the rest position.

In an example of the third aspect, particularly with regard to the structurally simple possible way of ensuring a fast and precisely definable movement of the trigger finger, the step of generating the movement of the trigger finger into the rest position can be accomplished by means of a spring, wherein the movement of the trigger finger back from the contact position into the rest position can be accomplished by means of a spring force for returning to its free length.

In order to adjust the positioning of the trigger finger as precisely as possible, the step of displacing the trigger finger from the rest position into the contact position may be accomplished by an actuator located outside the chamber.

In another example of the third aspect, particularly with regard to the possible ways of rapid ignition and reignition of the arc, the trigger finger stays in the contact position for an amount of time of less than 250 μ s, preferably less than 200 μ s, more preferably between 150 μ s and 100 μ s. With respect to minimizing contamination of the trigger finger by the deposition target during arc deposition, the amount of time it takes for the trigger finger to move from the rest position to the contact position must not exceed 50ms, and may preferably be between 20ms and 50ms, and more preferably between 20ms and 10 ms. Furthermore, the trigger repetition (re-trigger) may correspond to a frequency of 50Hz, for example by adjusting the shift time to 20 ms.

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

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 inventive arc starting device or the inventive assembly for pulse processes is particularly suitable for re-ignition, which can be effected frequently and quickly as required in practice due to slight contamination of the trigger fingers.

Detailed Description

Fig. 1 shows a schematic side sectional view of a cathodic arc deposition assembly having an arc ignition device with trigger fingers in a rest position as shown.

Figure 2A shows a schematic top view of the limiter shown in figure 1.

Figure 2B shows an isometric view of the limiter shown in figure 1.

FIG. 3 shows a side cross-sectional schematic view of the assembly of FIG. 1 with the trigger fingers in a contact position as shown.

FIG. 4 shows a graph of electrical characteristics of an embodiment of a cathodic arc deposition assembly.

Referring now to the drawings, FIG. 1 illustrates a cathodic arc deposition assembly 100 for depositing a coating (i.e., material) on one or more substrates S to be coated. The cathodic arc deposition assembly 100 includes a chamber 102 defined by an outer enclosure 104. The chamber 102 is provided under vacuum at least during operation of the cathodic arc deposition assembly 100. That is, the chamber 102 is evacuated to a predetermined pressure below atmospheric pressure (e.g., below 10 Pa-the total pressure adjusted to complete the physical vapor deposition process is typically in the range between 0.01Pa and 8Pa, but this range should not be construed as limiting the invention-the vacuum mass pressure range is typically classified by the type of vacuum: low: 760-0 Torr, medium: 0-10 Pa^-3Support, height: 10^-3-10^-8Support, superelevation: 10^-8-10^-12Support, the height is extremely high:<10^-12and outer space: 10 to^-16Tray). This is accomplished by a vacuum pump (not shown) disposed in fluid communication with the chamber 102.

As further shown, a cathode backside support 106 is disposed within the chamber 102. Target 108 (i.e., the cathode) is positioned adjacent to cathode backside support 106 and includes a first surface 108a, a second surface 108b spaced apart from first surface 108a, and a side surface 108c connecting first and second surfaces 108a, 108 b. Target 108 is positioned with second surface 108b facing cathode backside support 106 and first surface 108a facing away from cathode backside support 106. Specifically, second surface 108b of target 108 physically contacts cathode backside support 106 such that target 108 rests thereon.

An anode 110 is located within the chamber 102 at a location spaced apart from the target 108. Specifically, the anode 110 is outwardly 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 is made with respect to schematic illustrations of cathodic arc deposition assemblies and that the disclosure is not limited thereto. For example, while the schematic in fig. 1 and its disclosure appended hereto are made with respect to a vertical orientation (i.e., target 108 is located above cathode backing plate 106, and anode 110 is vertically spaced above target 108), it is contemplated that other orientations (e.g., horizontal) are possible.

A target material (not shown) will be evaporated from the first surface 108a of the target 108, wherein a plasma is formed from the evaporated material, 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 an arc of the cathodic arc deposition assembly 100. Specifically, 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 a no-load voltage in the range of 40V-200V.

To generate an arc, the target 108 is struck by a striking mechanism (i.e., a trigger finger, discussed further below); doing so creates a closed circuit from the power supply 112 through the target 108 and the striking mechanism. When the striking mechanism disengages the target 108, the circuit path between the striking mechanism and the target 108 is broken, causing the arc to jump the gap between the striking mechanism and the target 108, thereby initiating an arc on the target 108. When an arc is initiated, an arc path extends immediately between the target 108 and the anode 110 and is thereafter maintained by the power supply 112.

Due to the high current levels flowing through the target 108 during operation, the target 108 can become very hot. Accordingly, the cathodic arc deposition assembly 100 may include a cooling mechanism (not shown) designed to cool the target 108. The cooling mechanism may be integral with the cathode backside support 106 or may be a separate stand-alone feature.

As further shown in FIG. 1, the cathodic arc deposition assembly 100 includes an arc ignition device 114 designed to generate an electric arc. The arc ignition device 114 comprises a housing 116 arranged outside the chamber 102 and a trigger finger 118 arranged for linear movement in the axial direction X of the trigger finger 118. The outer shell 116 is attached to the outer shell cover 104 of the chamber 102 at an aperture formed therein. Specifically, a seal is provided between the housing shell 104 and the housing 116 to sealingly engage the former to the latter. The seal includes first and second seal rings 120a, 120b in physical contact with the housing cover 104 and the housing 116, respectively. As further shown, an electrical insulator 122 is disposed between the first and second confinement rings 120a, 120b and is configured to electrically insulate the chamber 102 from the arc ignition device 114.

While other actuators (e.g., other forms of electromechanical actuators) may be used, an electromagnetic actuator is preferred because it allows the trigger finger to move when the moving parts of the actuator are in a vacuum (sealed and attached to the arc evaporation source) state and the energizing electrical coil is in the atmosphere. Thus, an arc starting device construction with a very small design can be achieved.

The arc ignition device 114 further comprises an actuator 124 disposed within the housing 116. The actuator 124 moves (i.e., translates) the trigger finger 118 between the rest position and the contact position, as will be explained below. Further, 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, wherein the electromagnetic actuator produces mechanical motion upon electrical excitation of a coil. The electrical excitation of the coil may be produced by discharging a capacitor (not shown). The actuator 124 may be activated in the form of pulses, giving the arc ignition device 114 a defined pulsed movement, where a repetition frequency of up to 50Hz is obtained.

The cathodic arc deposition assembly 100 also includes a confinement member 126 positioned within the chamber 102. As shown in fig. 2A and 2B, the limiting member 126 is preferably annular. Other configurations are also contemplated. For example, the restraint 126 may be square or rectangular.

As shown in fig. 2B, the outer peripheral surface of the restricting member 126 may be finished to include upper and lower beveled cutting edges 127a and 127B. In another example, the outer peripheral surface of the limiting member 126 may be finished to include a rounded corner (e.g., a radius corner). Alternatively, the peripheral surface may be unfinished (e.g., 90 ° square).

Referring to fig. 2A and 2B, the limiting member 126 includes a notch or groove 128. A recess 128 is formed within the limiter 126 and is configured to allow the trigger finger 118 to extend therethrough. Specifically, the restraint member 126 is located adjacent (preferably surrounding but not in direct contact with) the side surface 108c of the target 108 and vertically between the cathode backside support 106 and the anode 110. The lateral distance between the restriction and the target is preferably not more than 1.5 mm (considering the radial distance). That is, the restraint 126 is located above the cathode backside support 106 but below the anode 110. The restraint 126 is typically constructed of steel (magnetic or non-magnetic).

With respect to fig. 2A and 2B, a schematic top view (fig. 2A) and a schematic isometric view (fig. 2B) of the restraint 126 are shown. The limiting member 126 is annular, having an inner sidewall 126a and an outer sidewall 126 b. The outer side wall 126b of the limiting member may be formed to define a concave surrounding channel. Outer sidewall 126b may be finished with a convex protrusion extending along the circumference of outer sidewall 126 b. Alternatively, the outer sidewall 126b may not include a circumferential channel. In another aspect, the outer side wall 126b can be formed to include an outwardly extending ridge or flange extending along a periphery of the limiter 126 (e.g., the retainer).

The groove 128 of the limiting member 126 extends from the inner sidewall 126a to the outer sidewall 126b in the radial direction of the limiting member 126. The restraint must be designed with a recess 128 sized to ensure an unobstructed passage for the trigger finger to travel therein. At the same time, the grooves must be as narrow as possible to prevent plasma ignition therein, in particular to avoid deposition of coating material on the inner surfaces of the grooves. This means that, for example, if a 2 mm diameter trigger lever is used, the axial dimension of the recess 128 may be 3 mm, as shown schematically in fig. 2 b. Further, the inner sidewall 126a is defined in the limiting member 126 with a diameter d₁Is open at the center. Diameter d of the central opening₁Is greater than the width W of the target 108₁Such that the limiter 126 is disposed about the target 108. In other words, the limiter 126 circumferentially surrounds the target 108, with an inner sidewall 126a of the limiter 126 facing the side surface 108c of the target 108.

Returning to fig. 1, the trigger finger 118 is a rod having a first end 118a and an opposite second end 118 b. Trigger finger 118, particularly the first end of the trigger finger (also referred to as the tip of the trigger finger), may be comprised of tungsten; alternatively, the trigger finger 118 may be constructed of other materials as already described above. The trigger finger extends into the recess 128 of the limiter 126 and is disposed to abut the side surface 108c of the target 108. As shown, the second end 118b of the trigger finger is disposed within the housing 116 of the arc ignition device 114.

As shown in fig. 1, trigger finger 118 is shown in a resting position. Specifically, the first end 118a of the trigger finger 118 is positioned within the recess 128 of the limiter 126. As such, the restriction 126 prevents the first end 118a of the trigger finger 118 from being exposed to any plasma material (e.g., from arc ignition) disposed within the chamber 102. As further shown, a spring 130 is disposed within the housing 116 and is designed to produce movement of the trigger finger 118 to a rest position. Spring 130 is shown as a helical compression spring, it is also contemplated that other types of springs (e.g., extension springs, conical springs, coil springs, etc.) and spring orientations may be used to produce movement of trigger finger 118 to the rest position.

Proceeding to FIG. 3, trigger finger 118 is shown in a contact position. In particular, as described above, the actuator 124 linearly displaces the trigger finger 118 from a rest position (i.e., the first end 118a of the trigger finger 118 is located within the recess 128) to a contact position in which the first end 118a of the trigger finger 118 physically contacts the side surface 108c of the target 108. That is, the trigger finger 118 is movable (e.g., in a direction perpendicular to an imaginary plane in which the side surface 108c lies) to abut (i.e., contact) the side surface 108c of the target 108. Unlike the first or second surfaces 108a, 108b of the touchdown target 108, this orientation and arrangement provides small trigger finger movement. The total distance that trigger finger 118 moves between the rest position and the contact position may be, for example, 3 millimeters, but this distance is not to be construed as a limitation of the present invention. The shorter the distance that the trigger finger has to travel during the movement from the rest position to the contact position or vice versa, the shorter the time it takes to trigger again. Also, if a shorter distance for the trigger finger to move is selected, efficiency may be higher and system complexity may be reduced. Other advantages involved with the use of the triggering device (arc ignition device) according to the invention are for example the following: a) corrosion of the side surface 108c does not occur, so that a stable trigger geometry can be ensured using the present invention; b) no or significantly less coating film deposition on the trigger finger (which is the first end of the finger trigger finger or the trigger finger tip) because movement of the trigger finger to the rest position typically hides the trigger finger in the ignition device housing or within the limiter groove; c) a compact design including an actuator and components for triggering functions, including electrical isolation and vacuum sealing.

When the trigger finger 118 is in the contact position, a closed circuit is created from the power supply 112 through the target 108 and through the arc ignition device 114 (i.e., through the trigger finger 118). As shown, the cathodic arc deposition assembly 100 also includes a resistor 132 electrically connected to the trigger finger 118. Resistor 132 limits the current to no more than 5A, preferably in the range between 2A and 5A, during the contact position.

The operation of the cathodic arc deposition assembly 100 will now be described. Initially, the power supply 112 is activated, thereby providing a no-load voltage of 40V-200V. At the same time, trigger finger 118 is moved to the rest position by spring 130. To create an arc, the actuator 124 is activated (e.g., by discharging a capacitor to energize a coil) such that the force provided by the actuator 124 on the trigger finger 118 is large enough to overcome the force of the spring 130 itself to maintain its free or preloaded length (also referred to as a spring relaxed length or relaxed position). In doing so, the trigger finger 118 is linearly displaced from the rest position to a contact position, wherein the first end 118a of the trigger finger 118 physically contacts the side surface 108c of the target 108.

It is noted that the amount of time it takes for the trigger finger 118 to move from the rest position to the contact position does not exceed 50ms, preferably between 10ms and 50 ms. When the first end 118a of the trigger finger 118 abuts the side surface 108c of the target 108, a closed circuit is formed in which the current of 2A-5A is carried. Thereafter, the actuator 124 is deactivated; and thus no longer provides force to the trigger finger 118. Thus, the trigger finger 118 moves back to the rest position under the force of the spring 130 itself returning to its free length. The amount of time that trigger finger 118 remains in the contact position (i.e., first end 118a of trigger finger 118 is in contact with side surface 108c of target 108) does not exceed 100 μ s, and is preferably less than 50 μ s.

When the circuit is open, the target 108 emits an arc (i.e., plasma material). The plasma material is then directed to the substrate (e.g., by magnetic force) to coat the substrate S. In this manner, the trigger finger 118 is kept clear of plasma material because the trigger finger 118 returns to the rest position immediately after the actuator 124 is deactivated (i.e., due to the force of the spring 130 itself to create its own slack) and because the first end 118a of the trigger finger 118 is seated within the recess 128 of the limiter 126 in the rest position. In other words, unless the actuator 124 is activated, the trigger finger 118 is always in a resting position (i.e., out of the way of the plasma material). Thus, trigger finger 118 is not exposed to the plasma material and therefore, film formation on trigger finger 118 will not occur.

With respect to fig. 4, a graph of electrical characteristics of an embodiment of a cathodic arc deposition assembly 100 is illustrated. The graph is divided into a first time interval T₁A second time interval T₂And a third time interval T₃. First time interval T₁Representing the cathodic arc deposition assembly 100 after the power supply 112 has been activated but before an arc is generated. That is, at a first time interval T₁The trigger finger 118 is in a rest position. A second time interval T₂Representing the trigger finger 118 in the contact position (i.e., as shown in fig. 3). In particular, the second time interval T₂Occurring over a period of 50 mus. That is, the amount of time that the first end 118a of the trigger finger 118 contacts the side surface 108c of the target 108 is equal to or less than 50 μ s. Third time interval T₃Representing the generation of an arc that occurs when the first end 118a of the trigger finger 118 disengages the side surface 108c of the target 108. That is, the trigger finger 118 is in the third time interval T₃During which it is again in the rest position.

As shown, three lines (i.e., lines "A", "B", and "C") are arranged on the graph and represent the cathodic arc deposition assembly 100 at each time interval (i.e., T)₁-T₃) Electrical characteristics during the period. The first line "a" represents the arc discharge current (i.e., in amperes). Line "A" is in the first and second time intervals T₁-T₂Is kept substantially constant, with the arc discharge current equal to 0A. But in a third time interval T₃During this period, the arc discharge current increased to 200A.

The second line "B" represents the amount of current (in amperes) at the trigger finger 118. As shown, at a first time interval T₁During this time, trigger finger 118 experiences no current (i.e., 0A).At a second time interval T₂During this time, trigger finger 118 sees a current of 3A. Trigger current (i.e., line "B") for a third time interval T₃The duration is significantly reduced but not zero (i.e., 0A).

Finally, a third line "C" represents the voltage (i.e., in volts) of the cathodic arc deposition assembly 100. At a first time interval T₁During this time, the voltage remains relatively constant and approximately equal to 140V. This voltage is provided by the power supply 112. After the arc is generated (i.e. in the second time interval T)₂After that), the voltage is reduced to the range of 20V-40V.

The invention has been described with reference to the above embodiments. Modifications and alterations will occur to others upon a reading and understanding of this specification. Embodiments incorporating one or more aspects of the invention are intended to embrace all such modifications and variations as fall within the scope of the appended claims.