JPH1154075A - Ion beam generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion beam generating device capable of surely generating pulse-like vacuum arc discharge ignited frequently repeatedly in a long time operation and realizing high reliability and reduction of manufacturing cost. SOLUTION: In this device having an anode 19 and a plurality of cathodes 16A to 16D, pulse-like vacuum arc discharge ignited, with a trigger discharge used as a trigger, between the plurality of cathodes 16A to 16D and the anode 19, is generated in fixed order, a cathode substance being vaporized from cathode vaporizing surfaces and ionized, an ion beam is taken out consisting of cathode substance ions of the respective cathodes 16A to 16D. A vacuum arc igniting mechanism is provided which is adapted such that the trigger discharge is generated by causing a trigger electrode 3 to make contact with, and part from, a plurality of the cathodes 16A to 16D in fixed order by rotating the single trigger electrode 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION An ion beam generator utilizing a vacuum arc discharge is a device in which a cathode is placed between an anode and a cathode made of a conductive material (eg, Ti) in a vacuum atmosphere. A vacuum arc discharge that is ignited by the trigger discharge of the cathode, thereby generating a cathode material (cathode material) from the cathode evaporation surface
Is evaporated and ionized to generate plasma containing the cathode material ions, and an electric field is applied to the plasma to extract an ion beam composed of the cathode material ions to the outside of the apparatus. The present invention relates to an ion beam generator using a vacuum arc discharge, and more particularly, to an ion beam generator having an anode and a plurality of cathodes, and a trigger discharge (pilot arc discharge) to the plurality of cathodes in a predetermined order. ) As a trigger to generate a pulsed vacuum arc discharge that is ignited between the anode and the anode to extract an ion beam composed of cathode material ions of each of the cathodes. It is.

[0002]

2. Description of the Related Art In recent years, for the purpose of extending the life of cutting tools, dies, mechanical parts, and the like, a technique for forming an abrasion-resistant film using an ion beam has attracted attention. For example, prior to forming a TiN film, which is a nitride of a high melting point metal, on a tool steel surface, a method utilizing ion implantation of ion implantation of Ti ions as a pretreatment for the purpose of improving the adhesion of the film is performed. Have been done. In addition, for example, a wear-resistant TiN film is formed on a tool steel surface by a dynamic mixing method in which film formation and ion implantation are simultaneously performed.

[0003] As one of ion beam generators for generating an ion beam used in this manner, an ion beam generator using vacuum arc discharge is known. FIG. 4 is a configuration explanatory view showing the configuration of a conventional ion beam generator, and FIG. 5 is a sectional view taken along line AA of FIG.

[0004] As shown in FIGS. 4 and 5, a conventional ion beam generating apparatus has a vacuum vessel whose inside is evacuated.
11, a cathode holder (cathode support conductor) 12 provided also in the vacuum vessel 11 and serving also as a current-carrying terminal, and a plurality of cylinders, four of which are interchangeably attached to the cathode holder 12, in this example, four Cathodes 16A, 16B, 16C, 16
D, one annular anode 19 provided in front of the cathodes 16A to 16D in the vacuum vessel 11, and provided for each of the four cathodes 16A, 16B, 16C, and 16D. surface _{16A 1, 16B 1, 16C 1} , 16D 1 in the insulating member 17A, 17B, 17C, ringed trigger electrode 13A in contact through 17D, 13B, 13C, and 13D,
Each of the trigger electrodes 13A, 13B, 13C, and 13D is provided for each of the trigger electrodes 13A, 13B, 13C, and 13D.
13B, 13C, 13D and the cathode evaporation surface _{16A 1, 16B 1, 16C 1} ,
Between 16D _1, wherein the insulating member 17A, 17B, 17C, trigger power 14A for causing the trigger discharge of a surface discharge form along the 17D surface, 14B, 14C, 14D and the four cathodes 16A, 16B, Each of the trigger power supplies 14A, 14B, and 14C is used to cause a trigger discharge in the predetermined order in 16C and 16D.
Discharge control device for controlling high voltage application timing by C and 14D
The negative terminal 15 is electrically connected to the anode 19, and the negative terminal is electrically connected to the cathode holder 12. The anode 19 and the cathodes 16A, 16B, 16C, in which trigger discharge is sequentially performed by the discharge control device 15. , 16D
And an arc power supply 18 for generating a short-time pulsed vacuum arc discharge in which the firing time is triggered by the trigger discharge as several milliseconds or less, and power supplies 21 and 22 for extracting ion beams, and An ion beam extraction grid 23, 24, 25 provided in a plasma chamber 20 in front of an anode 19 in a vacuum vessel 11 is configured to apply an electric field to the plasma generated by the vacuum arc discharge and to apply an electric field to each cathode 16A. , 16B, 16C, and 16D, and an ion beam extracting means for extracting an ion beam composed of cathode material ions to the outside of the apparatus.

The above-mentioned trigger electrode with a ring
13A, 13B, 13C, and 13D are ring-shaped trigger rings 13A ₁ , 13B ₁ , 13C ₁ , and the like, each having a conductive end portion.
13D ₁ is connected to the cathode evaporating surfaces 16A ₁ , 16B ₁ , 16C ₁ , and 16D ₁ via the cylindrical insulating members 17A, 17B, 17C, and 17D. A plurality of these, in this example four, trigger electrodes 13A with a ring
To 13D, four insulating members 17A to 17D, four trigger power supplies 14A to 14D, and a discharge control device 15 for sequentially triggering a vacuum arc discharge (for firing) to each cathode in a predetermined order. And a vacuum arc firing mechanism for causing a vacuum arc. Such an ion beam generator,
The interior for performing the above-described dynamic mixing process is connected as an ion source to a vacuum chamber VC for surface reforming process which is evacuated. In addition, as a specific example of a material constituting the cathodes 16A to 16D, for example, a material for performing long-time operation is used.
There is a case where all of them are made of Ti (titanium).

Next, the operation of the ion beam generator configured as described above will be described. First, the first trigger power supply 14A receiving a command from the discharge control device 15
By high voltage is very short is applied to the first ring with the trigger electrode 13A, the cathode evaporation surface 16A ₁ is a triggering 13A ₁ of the trigger electrode 13A and the front end surface of the first cathode 16A In the meantime, a trigger discharge in the form of a creeping discharge along the surface of the insulating member 17A is generated. Then, triggered by the trigger discharge for starting the arc,
Between the evaporation surface 16A1 of the _first cathode 16A and the anode 19, the arc discharge duration time t is several ms or less, for example, t =
A pulse-like short-time vacuum arc discharge of 1 ms occurs. Thus, ionized from the cathode evaporation surface 16A ₁ is evaporated cathode material (e.g. Ti), plasma containing the cathode material ion is generated. The arc discharge duration time t is set in advance by a controller built in the arc power supply 18.

The first cathode 16A and the anode 19
After a lapse of a predetermined short time after the pulsating vacuum arc discharge is extinguished, the second trigger power supply 14B, which has received a command from the discharge control device 17, supplies a second trigger with a ring. When a high voltage is applied to the electrode 13B for a very short time, the triggering of the trigger electrode 13B is performed.
Between 13B ₁ and the evaporation surface 16B ₁ of the second cathode 16B,
A trigger discharge in the form of a creeping discharge along the surface of the insulating member 17B occurs. By this trigger discharge trigger, between the cathode evaporation surface 16B ₁ and the anode 19, the duration t = 1 ms
Vacuum arc discharge occurs, which causes the cathode evaporation surface
Ionized from 16B ₁ is evaporated and the cathode material, the plasma containing the cathode material ion is generated.

[0008] Such an operation is, in this example, 4
For the cathodes 16A to 16D, the first cathode 16A
A, the second cathode 16B, the third cathode 16C, and the fourth cathode 16D are repeated in this order (see FIG. 3),
A plasma is generated containing the cathode material of four cathodes 16A-16D. For example, vacuum arc discharge is repeatedly performed on each of the cathodes 16A to 16D at a discharge frequency of 6 pulses / s (6 times / s).

The plasma in which the cathode material ions and electrons of each of the cathodes 16A to 16D are mixed is guided to the plasma chamber 20 through the opening of the annular anode 19. In the plasma chamber 20, the accelerating grid
23, a suppressor grid 24 and a ground grid 25 are provided. Each of these three grids 23, 24, and 25 has an opening.
Held at a positive high potential by the suppressor grid 24
Is maintained at a negative potential by a suppressor power supply 22, and the ground grid 25 is grounded. As a result, an electric field generated between the grids 23 and 25 acts on the plasma in the plasma chamber 20, and the plasma generates the cathodes 16A to 16A.
Only 16D cathode material ions are extracted, and an ion beam composed of these cathode material ions is extracted into the surface modification vacuum vessel VC for performing the above-described dynamic mixing process. Here, the suppressor grid 24 is provided to prevent back flow of free electrons existing in the vacuum vessel VC into the plasma chamber 20.

[0010]

In the above-mentioned conventional ion beam generator, an insulating member is provided between the trigger ring of the trigger electrode with a ring and the cathode evaporation surface, and the ion beam is generated between the trigger ring and the cathode evaporation surface. Since the trigger discharge to be performed is in the form of a creeping discharge along the surface of the insulating member, part of the cathode evaporating substance due to the vacuum arc discharge adheres and deposits on the surface of the insulating member over time during a long operation. However, between the trigger ring and the cathode evaporating surface, dielectric breakdown may occur through the conductive evaporating substance, resulting in an electrical short circuit. For this reason, there is a problem in that a trigger discharge to the cathode evaporation surface does not occur, so that a vacuum arc discharge that should follow the trigger discharge does not occur, and a predetermined ion beam cannot be obtained.

The present invention has been made in view of such a point, and has an anode and a plurality of cathodes. The plurality of cathodes are triggered by a trigger discharge to the cathodes in a predetermined order. In an ion beam generator that generates a pulsed vacuum arc discharge that is ignited between the anode and the cathode to extract an ion beam composed of cathode material ions of each of the cathodes, a trigger electrode is mechanically attached to a cathode evaporation surface. By providing a vacuum arc firing mechanism for contact and detachment, a pulsed vacuum arc discharge that is repeatedly fired repeatedly can be reliably generated even during long-time operation. Trigger discharges to multiple cathodes can be performed at the same time. And to provide a beam generator.

[0012]

In order to achieve the above object, an ion beam generator according to the present invention has an anode and a plurality of cathodes, and the plurality of cathodes are arranged in a predetermined order. Triggered discharge to the anode generates a pulsed vacuum arc discharge that is ignited between the anode and the anode, evaporates and ionizes the cathode material from the cathode evaporation surface, and comprises ions of the cathode material ions of the respective cathodes. In an ion beam generator for extracting a beam, a single trigger electrode is rotated to cause the plurality of cathodes to contact / separate the trigger electrodes in a predetermined order to cause a trigger arc to generate a trigger discharge. It is characterized by having a mechanism.

The ion beam generator according to the present invention has one trigger electrode, and by rotating this trigger electrode, the trigger electrode is brought into contact with the evaporation surfaces of a plurality of cathodes sequentially in a predetermined order. Since it is provided with a vacuum arc firing mechanism that causes a trigger discharge by performing separation, there is no danger of a short circuit accident between the trigger electrode and the cathode evaporation surface caused by the trigger discharge in the creeping discharge mode described above. A pulse-like vacuum arc discharge that is repeatedly fired repeatedly can be reliably generated even in a long-time operation, and one trigger electrode is drawn in a circle in which the tip of the trigger electrode connects each cathode evaporation surface in order. In this way, a trigger discharge can be performed on these cathodes by rotating them in such a way that, unlike the conventional device, trigger discharge is performed for each of a plurality of cathodes. There is no need to provide a pole and a trigger power source.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration explanatory view showing the configuration of an ion beam generator according to the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. Here, in this example, the same parts as those of the conventional ion beam generator shown in FIGS. 4 and 5 are denoted by the same reference numerals as in FIGS. 4 and 5, and the description thereof is omitted.

As shown in FIGS. 1 and 2, a cathode holder 2 serving also as a current-carrying terminal is disposed in a vacuum vessel 1 whose inside is evacuated to a degree of vacuum of about 2 × 10 ⁻⁴ Pa. . The cathode holder 2, which has a cylindrical shape as a whole,
A small-diameter axial through-hole and four through-holes extending in the axial direction of the holder around the center axis of the holder axis on the same circumference on the same circumference on the end surface of the cathode holder are provided. I have. Four cathodes 16A-16
D is exchangeably mounted by being fitted into the four through holes of the cathode holder 2 respectively.

The trigger electrode 3 is connected to one end of a rotating shaft 3a of an L-shaped rotating arm 3b extending in a direction perpendicular to the shaft 3a (radial direction of the cathode holder 2) and having a bent end. There is something. The trigger electrode 3 is rotatably supported by inserting its rotary shaft portion 3a into an insulating cylinder 4 fitted in the axial through hole of the cathode holder 2 and further rotatably supporting the trigger electrode 3 through the insulating cylinder 4. A base end of the drawn-out rotating shaft portion 3a is connected to a motor (not shown) of the trigger electrode rotating device 5 that drives the trigger electrode 3 to rotate so that the speed can be adjusted. That is, by rotating the rotating shaft 3a by the trigger electrode rotating device 5, the tip of the trigger electrode 3 (the tip of the rotating arm 3b) draws a circle with the shaft 3a as the center of rotation in this example. Moving around the cathode evaporating surface 16A ₁ → cathode evaporating surface 16B ₁ → cathode evaporating surface 16C ₁ → cathode evaporating surface 16D ₁ while contacting / separating (e.g. (Separation). In addition, the trigger electrode 3
Is made of a non-consumable conductive material such as tungsten.

The trigger electrode rotating device 5 includes a rotating shaft 3a.
A sliding contact mechanism (not shown) for supplying power to the trigger electrode 3 is provided on the rotating shaft 3 a of the trigger electrode 3.
Power supply 18 when the tip of
A power supply circuit (power supply cable) through which a current for trigger discharge flows through the current limiting resistor 6 is connected via the sliding contact mechanism. The one trigger electrode 3, the trigger electrode rotating device 5, the current limiting resistor 6, and the arc power source 18 also serving as a power source for vacuum arc discharge cause a trigger discharge in each of the cathodes 16 </ b> A to 16 </ b> D in a predetermined order. Of the vacuum arc firing mechanism.

7A is the cathode on the outer periphery of the cathode 16A.
This is a known shield having a cylindrical shape and arranged so as to be coaxial with a gap of about 0.5 mm from 16A. The shield 7a serves as a cathode evaporation surface 16A ₁ during vacuum arc discharge.
To confine the arc spot inside
For example, it is made of a magnetic material such as iron, and is provided in a state of being electrically floated by an insulating member 8A. Similarly, shields 7B, 7C, and 7D are provided for the other cathodes 16B, 16C, and 16D, respectively. Other configurations are the same as those of the above-described conventional device.

The operation of the ion beam generator configured as described above is described in addition to FIGS. 1 and 2 by referring to FIG. 3 of a time chart showing an example of vacuum arc discharge generated by four cathodes 16A to 16D. It will be described with reference to FIG.

When the tip of the trigger electrode 3 (the tip of the rotating arm 3b) comes into contact with the evaporation surface 16A1 of the _first cathode 16A during the extremely short contact period, the trigger electrode is rotated by the trigger electrode rotating device 5. , between the trigger electrode 3 and the cathode evaporation surface 16A _1, short-circuit current flows from the arc power supply 18 to the current value is limited by the current limiting resistor 6. Then, when pulled away from the cathode evaporation surface 16A ₁ is rotated moving the tip of the trigger electrode 3 is further between the trigger electrode 3 tip and the cathode evaporation surface 16A _1, by the action of the inductance component of the power supply circuit from the arc power supply 18 Trigger discharge occurs for a very short time due to high voltage. And
In the trigger to the trigger discharge subsequent thereto, between the cathode evaporation surface 16A ₁ and the anode 19, arc power supply 18
Set arc discharge duration time t is short pulsed vacuum arc discharge that t = 1 ms in this example is generated, thereby ionize evaporated cathode material from the cathode evaporation surface 16A ₁ by including the cathode material ion Plasma is generated. The arc power supply 18 has a built-in current detection sensor, and the vacuum arc discharge is continued for 1 ms after the sensor detects that the trigger discharge current has flowed.

Such an operation is accompanied by the rotation of the trigger electrode 3 by the trigger electrode rotating device 5, and in this example, the first cathode 16A, the second cathode 16A, and the second cathode 16D, as shown in FIG. The plasma including the cathode materials of the four cathodes 16A to 16D is generated by repeating the third cathode 16B, the third cathode 16C, and the fourth cathode 16D in this order. For example, the trigger electrode 3 is rotated at a rotation speed of 360 rpm, and each of the cathodes 16A to 16D
, Vacuum arc discharge is repeatedly performed at a discharge frequency of 6 pulses / s (6 times / s).

The generated plasma containing the cathode material ions and electrons of each of the cathodes 16A to 16D is led to the plasma chamber 20. Then, an electric field generated between the grids 23 and 25 acts on the plasma in the plasma chamber 20, and only the cathode material ions of the cathodes 13A to 13D are extracted from the plasma, and an ion beam composed of these cathode material ions is formed. In this example, it is drawn into the surface modification treatment vacuum vessel VC for performing the dynamic mixing treatment.

Here, specific examples of the material constituting the cathodes 16A to 16D include a case where all four are made of Ti and all four are made of C (carbon). Further, there may be a case where two titanium cathodes and two carbon cathodes are used. In this case, a Ti ion (T
An ion beam composed of i ⁺ ) and C ions (C ⁺ ) is extracted. In addition, by adjusting the rotation speed of the trigger electrode 3 by the trigger electrode rotation device 5, each cathode
Duty cycle of 16A ~ 16D vacuum arc discharge (du
ty cycle) can be arbitrarily adjusted, and the current amount of the obtained ion beam can be controlled.

As described above, the ion beam generator of this embodiment has one trigger electrode 3 unlike the conventional device, and by rotating this trigger electrode 3, four trigger electrodes 3 are sequentially arranged in a predetermined order. the cathode evaporation surface 16A ₁ ~16D ₁ of
Since a vacuum arc ignition mechanism is provided to cause a trigger discharge by contacting / separating the trigger electrode 3 from / to the trigger electrode 3, a pulse-like vacuum arc discharge for frequent and repeated ignition is operated for a long time. The trigger discharge to these cathodes 16A to 16D can be performed by rotating one trigger electrode 3 so that the tip of the trigger electrode 3 draws a circle connecting the cathode evaporation surfaces in order. Yes, unlike conventional equipment, each cathode
There is no need to provide a trigger electrode and a trigger power supply for each of 16A to 16D.

[0025]

As described above, the ion beam generator according to the present invention has an anode and a plurality of cathodes, and the plurality of cathodes are triggered by a trigger discharge to the cathodes in a predetermined order. A pulsed vacuum arc discharge that is ignited between the anode and the anode to generate an ion beam composed of cathode material ions of each of the cathodes.
A vacuum arc firing mechanism that mechanically contacts and separates the trigger electrode from the cathode evaporation surface is provided, so that pulsed vacuum arc discharge that fires frequently and repeatedly can be reliably generated even during long-time operation. Can also be
With a simple structure, a single trigger electrode can trigger a plurality of cathodes, and unlike a conventional device, there is no need to provide a trigger electrode and a trigger power supply for each cathode. That is, according to the present invention, it is possible to provide an ion beam generator which has high reliability and can realize a reduction in manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing a configuration of an ion beam generator according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a time chart showing an example of occurrence of vacuum arc discharge by four cathodes 16A to 16D.

FIG. 4 is a configuration explanatory view showing a configuration of a conventional ion beam generator.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vacuum container 2 ... Cathode holder 3 ... Trigger electrode 3a ... Rotating shaft part 3b ... Rotating arm part 4 ... Insulating cylinder 5 ... Trigger electrode rotating device 6 ... Current limiting resistance 7A, 7B, 7C, 7
D: Shield 8A, 8B, 8C, 8D: Insulating member 16
A, 16B, 16C, 16D ... cathode _{16A 1, 16B 1, 16C 1} ,
16D ₁ … Cathode evaporation surface 18… Arc power supply 19… Anode
20 ... plasma chamber 21 ... acceleration power supply 22 ... suppressor power supply
23 ... Acceleration grid 24 ... Suppressor grid 25 ... Grand grid VC ... Vacuum container for surface modification

Claims (1)

[Claims] 1. A pulsed vacuum having an anode and a plurality of cathodes, wherein said plurality of cathodes are fired between said plurality of cathodes in a predetermined order by being triggered by a trigger discharge to said cathodes. In an ion beam generator for generating an arc discharge, evaporating and ionizing a cathode material from a cathode evaporation surface, and extracting an ion beam composed of cathode material ions of each of the cathodes, by rotating a single trigger electrode, An ion beam generator comprising a vacuum arc firing mechanism for causing a trigger discharge by bringing the trigger electrode into and out of contact with the cathode in a predetermined order.