JP5159724B2 - Electron gun, vacuum processing equipment using electron gun - Google Patents

Description

  The present invention relates to a cathode electrode holding ring for the purpose of preventing displacement of a cathode electrode position in a high-power electron gun and deformation of a cathode electrode holding pin.

An electron gun (electron beam gun) is mainly used for vacuum deposition and metal purification.
The electron gun is formed by a filament, a cathode electrode, and an anode electrode.
The electron gun is used in a vacuum chamber, the cathode electrode is heated by a filament, and electrons are emitted from the cathode electrode. The emitted electrons are narrowed by the Wehnelt electrode, extracted and accelerated by the potential difference between the anode electrode and the cathode electrode, emitted from the opening of the anode electrode, and irradiated into the vacuum chamber.

The cathode electrode is held by a holding ring via a pin.
Conventionally, the cathode electrode and the pin are tungsten, and molybdenum or tungsten is used for the holding ring.
When the retaining ring is made of molybdenum, if a vacuum treatment is performed a plurality of times using an electron gun, a phenomenon occurs in which a portion in contact with the pin of the retaining ring is fixed due to heat conduction or radiation from the cathode electrode. In the case where the retaining ring is tungsten, if the vacuum treatment is performed a plurality of times and the high temperature and the low temperature are repeated, the pin and the retaining ring are deformed by thermal expansion, and a phenomenon that the pin cannot be removed from the retaining ring occurs. Further heating causes displacement of the cathode electrode.
Therefore, the holding ring is also used as a consumable item together with the cathode electrode and the pin.

JP 2005-268177 A

  In an electron gun used for silicon purification, it is required to increase the amount of electrons emitted from the cathode electrode for the purpose of increasing the processing capability. In order to release the necessary amount of electrons from the cathode electrode, it is necessary to increase the temperature when the cathode electrode is heated by the filament, but when the cathode electrode becomes high temperature, the cathode electrode is held by radiation and heat conduction. Therefore, the surrounding structure is also exposed to high temperature.

The pin exposed to high temperature adheres to the cathode electrode and the cathode electrode holding ring, and the adhered portion causes problems such as misalignment of the cathode electrode accompanying deformation of the cathode electrode pin.
An object of the present invention is to provide a high-power electron gun or a device equipped with a high-power electron gun by preventing the above-described sticking.

In order to solve the above problems, the present invention electrically connects a ring-shaped holding member, a cathode electrode that emits electrons, a heating device that heats the cathode electrode, and the holding member and the cathode electrode. Three or more pins, and the cathode electrode is an electron gun held by the holding member via the pins, and the holding side contact surface that contacts the pins of the holding member includes carbon, Alternatively, it is an electron gun with tantalum carbide exposed.
Further, according to the present invention, the holding member is provided with three or more holding side holes, an inner peripheral side surface of the holding side hole is the holding side contact surface, and the pin of the holding side hole is the holding side hole. And an electron gun in which the cathode electrode is held by the holding member.
In the present invention, the holding member is an electron gun made of carbon or tantalum carbide.
Further, in the present invention, the holding member has a tantalum carbide film formed on at least a part of the surface of a core material made of tantalum, and the surface of the tantalum carbide film serves as the holding side contact surface. An electron gun with tantalum carbide exposed on the surface.
The present invention is the electron gun in which the pin and the cathode electrode are formed of tungsten.
The present invention also includes a vacuum chamber, a vacuum pump, and any one of the above electron guns, wherein the electron gun is configured to emit electrons into the vacuum chamber, and the processing of an object to be processed is performed in the vacuum It is the vacuum processing apparatus performed in a tank.

According to the present invention, it is possible to prevent the pin from being pulled out due to the fixation of the pin for holding the cathode electrode and the cathode electrode holding ring and the friction of the contact portion between the pin and the cathode electrode holding ring, and withstand the rise in cathode electrode temperature. It becomes possible.
Further, as the cathode electrode temperature rises, the amount of current emission from the cathode electrode can be increased and used as a high-power electron gun.

The figure for demonstrating the vacuum processing apparatus using the electron gun of this invention Sectional view of the electron gun of the present invention (A): Plan view of cathode electrode (b): A-A 'line cut-away sectional view of cathode electrode (A): Plan view of holding member (b): Enlarged perspective view of holding member An enlarged perspective view of a holding member having a film formed on the holding side contact surface

Reference numeral 50 in FIG. 1 is a vacuum processing apparatus using the electron gun of the present invention.
The vacuum processing apparatus 50 includes a vacuum chamber 25 and an electron gun 10. A vacuum pump 39 is connected to the vacuum chamber 25, and when the vacuum pump 39 is operated, the inside of the vacuum chamber 25 can be in a vacuum atmosphere.
The electron gun 10 is hermetically inserted through the side surface of the vacuum chamber 25.

At the bottom of the vacuum chamber 25, the vapor deposition material 35 is placed in a crucible 36, and the surface of the substrate 30 and the surface of the evaporation source are located facing each other. The vacuum chamber 25 and the crucible 36 are connected to the ground potential.
The muzzle of the electron gun 10 is directed to the vapor deposition material 35.
The electron gun 10 will be described in detail. FIG. 2 is a sectional view of the electron gun.

The electron gun 10 has a housing 11, and a cathode member 31, a heat generating device 32, and an anode electrode 3 are disposed inside the housing 11.
The cathode member 31 includes the cathode electrode 1 and the holding member 5.
The cathode electrode 1 has a cylindrical shape, and three or more (here, four) electrode side holes 60 are formed on the outer peripheral side surface thereof.
The holding member 5 has a ring shape, and the same number of holding side holes 70 as the electrode side holes 60 are formed on the inner peripheral side surface of the ring shape.

A plan view of the cathode electrode 1 is shown in FIG. 3A, and a cross-sectional view taken along line AA ′ of the cathode electrode 1 is shown in FIG.
A plan view of the holding member 5 is shown in FIG. 4A, and an enlarged perspective view of the holding member 5 is shown in FIG.
The inner periphery of the holding member 5 is formed larger than the outer periphery of the cathode electrode 1, and the holding member 5 and the cathode electrode 1 are arranged in the same plane and the cathode electrode 1 is disposed on the inner side of the inner periphery of the holding member 5. It is configured to be able to.

When the cathode electrode 1 is arranged at the center of the holding member 5 and aligned, the electrode side hole 60 and the holding side hole 70 can be arranged at positions facing each other.
The cathode member 31 has the same number of linear pins 15 as the number of electrode side holes 60 and the number of holding side holes 70, and the shape and thickness of the ends of the pins 15 are determined according to the electrode side holes 60. Or a size that fits into the holding side hole 70.

With the electrode side hole 60 and the holding side hole 70 facing each other, one end of the pin 15 is fitted into the electrode side hole 60, the other end is fitted into the holding side hole 70, and the cathode electrode 1 and the holding member 5 are 15 are fixed to each other.
A filament 2 is disposed inside the housing 11. On the side of the filament 2, support portions (not shown) are arranged at a plurality of positions.

The holding member 5 is placed on the support part, and the holding member 5 and the cathode electrode 1 fixed to each other are stationary in the housing 11 by the support part. In this state, the cathode electrode 1 is held by the holding member 5 via the pin 15 so that the cathode electrode 1 and the holding member 5 do not directly contact each other.
The filament 2 is not in contact with the cathode electrode 1, the pin 15, and the holding member 5, so that the electron acceleration power source 22 does not flow a short-circuit current.

  In a state where the cathode electrode 1 is held by the holding member 5, the inner peripheral surface of the holding side hole 70 and the outer peripheral surface of one end of the pin 15 are in contact with each other. Since the outer peripheral surfaces of the end portions are in contact with each other, the inner peripheral surface of the holding side hole 70 is referred to as a holding side contact surface, and the inner peripheral surface of the electrode side hole 60 is referred to as an electrode side contact surface. Either carbon or tantalum carbide is exposed.

When carbon is exposed, the case where the carbon thin film is formed on the surface and the case where the holding member 5 is formed of carbon are included. Carbon includes a crystal type such as a graphite type and a diamond type, and an amorphous type.
Therefore, one end of the pin 15 is in contact with either carbon or tantalum carbide, and the other end is in contact with the material exposed on the electrode side contact surface, and the cathode electrode 1 is supported by the holding member 5. .

  The holding member 5 is electrically connected to the output terminal of the negative voltage power supply 20. The cathode electrode 1, the pin 15, and the holding member 5 are conductive materials, and one end of the pin 15 and the holding-side contact surface come into contact with each other to electrically connect the pin 15 and the holding member 5. When the electrode-side contact surface comes into contact, the pin 15 and the cathode electrode 1 are electrically connected, the negative voltage power source 20 is activated and a negative voltage is output from the output terminal, the cathode electrode 1 is passed through the holding member 5 and the pin 15. Is configured to be applied with a negative voltage.

On the surface of the cathode electrode 1, a recess 16 made of a depression is formed.
On the back surface of the cathode electrode 1, a filament 2 is disposed at a lower position away from the back surface.
A heating power source 21 is connected to the filament 2. The heating power source 21 is configured to cause a current to flow through the filament 2 so that the filament 2 generates heat to a predetermined temperature. When the filament 2 is energized in vacuum, the cathode 2 heats the cathode electrode 1 and supplies electrons. discharge.

  An electron acceleration power source 22 is further connected to the filament 2. When the electron acceleration power source 22 is operated, the filament 2 has negative electrons so that the voltage of the filament 2 is lower than the voltage of the cathode electrode 1. An acceleration voltage is applied. Here, a voltage is applied to the filament 2 so as to be 1.5 kV lower than the voltage of the cathode electrode 1.

When electrons are emitted from the filament 2 in this state, the electrons are accelerated toward the cathode electrode 1 and collide with the cathode electrode 1. The cathode electrode 1 is heated by the collision of the electrons with the cathode electrode 1 and the current flowing through the cathode electrode 1 to raise the temperature.
On the surface of the cathode electrode 1, an anode electrode 3 is disposed at an upper position separated from the surface.

The anode electrode 3 has a cylindrical shape, and one opening (cathode side opening 18) of the anode electrode 3 faces the recess 16 of the cathode electrode 1.
The other opening of the anode electrode 3 is directed to the inside of the vacuum chamber 25, and the inside of the vacuum chamber 25 and the inside of the anode electrode 3 are connected via the opening.
The anode electrode 3 is connected to the housing 11 and has a ground potential.

The vapor deposition process using the electron gun 10 will be described in detail.
A carry-in chamber and a carry-out chamber (not shown) are connected to the vacuum chamber 25 via a vacuum valve.
The vacuum chamber 25, the carry-in chamber, and the carry-out chamber are connected to a vacuum pump, and the inside of the vacuum chamber 25 is evacuated by a vacuum pump 39 connected to the vacuum chamber 25, and is placed in a vacuum atmosphere. The substrate 30 is loaded into the vacuum chamber 25 through the loading chamber while the vacuum atmosphere of the vacuum chamber 25 is maintained, and is held by the substrate holder 29.

  The heating device 32 is activated to heat the cathode electrode 1 to a predetermined temperature (here, about 2850 K), and the cathode electrode 1 is heated. When the negative voltage power supply 20 is activated after heating to a predetermined temperature and a voltage is applied between the anode electrode 3 and the cathode electrode 1, the heated electrons are caused by the potential difference (40 kV in this case) between the anode electrode 3 and the cathode electrode 1, It is pulled out from the surface of the cathode electrode 1.

A ring-shaped Wehnelt electrode 4 is disposed above the cathode electrode 1.
A negative voltage power supply 20 is connected to the Wehnelt electrode 4, and an equal voltage to the cathode electrode 1 is applied.
The shape of the cathode electrode 1 is a cylinder, and a concave portion 16 having a circular outer periphery is formed at the center of the surface. The surface of the recess 16 has a concave lens shape.

The Wehnelt electrode 4 converges the electrons emitted from the cathode electrode 1, extracts the electrons by the potential difference between the anode electrode 3 and the cathode electrode 1, and emits them to the vacuum chamber 25.
The electrons drawn from the recess 16 are configured to converge inside the cylindrical anode electrode 3 due to the shape of the surface of the recess 16, and the electrons narrowed in the Wehnelt electrode 4 are converged in the anode electrode 3. Then, it travels through the anode electrode 3 and is discharged into the vacuum chamber 25 from the opening of the anode electrode 3 on the vacuum chamber 25 side.

  The electrons emitted into the vacuum chamber 25 are irradiated onto the vapor deposition material 35, and the vapor deposition material 35 is heated and evaporated. The vapor of the evaporated vapor deposition material 35 reaches the surface of the substrate 30, and a thin film made of the vapor deposition material 35 is formed on the surface of the substrate 30. When a thin film having a predetermined thickness is formed on the surface of the substrate 30, the negative voltage power source 20 and the heating power source 21 are turned off, and the substrate 30 on which the thin film is formed is taken out from the vacuum chamber 25 into the atmosphere through the carry-out chamber. Finish the process once.

  The holding member 5 is made of any one of carbon, graphite, or tantalum carbide, and the cathode electrode 1 and the pin 15 are made of tungsten. Since the melting points of carbon, graphite, and tantalum carbide are higher than those of tungsten, the cathode electrode 1 is heated to a predetermined temperature by the above process, and radiation from the cathode electrode 1 and the cathode electrode 1 through the pin 15 are performed. Even if the holding-side contact surface is heated to a temperature about the melting point of tungsten due to the heat conduction, the pin 15 is not fixed.

  The friction coefficient between tungsten of carbon, graphite, and tantalum carbide and tungsten is smaller than the friction coefficient between tungsten and molybdenum and the friction coefficient between tungsten. Therefore, when the above process is performed a plurality of times and the cathode member 31 is repeatedly formed at a high temperature and a low temperature and the pin 15 and the holding member 5 are thermally expanded, the holding-side contact surface and Even when the contacting pin 15 is rubbed, the phenomenon that the pin 15 does not come off the holding member 5 does not occur, and the position of the cathode electrode 1 does not shift.

  In the above, the holding member 5 is made of any one of carbon, graphite, and tantalum carbide. However, the holding member 5 is formed of a tantalum carbide film on at least a part of the surface of the core material made of tantalum. The holding member 5 may be formed with the surface as the holding side contact surface, and the core material may be exposed except for the holding side contact surface.

In FIG. 5, a holding side hole 70 is formed on the surface of a core material made of tungsten or tantalum, and a carbon film, a graphite film, or a tantalum carbide film is formed on the inner peripheral surface of the holding side hole 70, or An enlarged perspective view of the holding member 5 in which two or more kinds of films 71 are formed and the core material is exposed except for the holding side hole 70 is shown.
Alternatively, a tantalum carbide film may be formed on the entire surface of the core material made of tantalum, and the holding member 5 may be formed using the surface of the tantalum carbide film as the holding-side contact surface.

In order to expose the tantalum carbide on the holding side contact surface, it is manufactured by a method called carburizing. In the carburizing, the holding member 5 including the inner peripheral surface of the holding side hole 70 is heated by exposing and embedding the entire surface of the core material in which the holding side hole 70 made of tantalum is formed in the solid carbon powder. Convert all surfaces to tantalum carbide.
The holding side hole 70 and the electrode side hole 60 described above may be through holes or bottomed holes.

  In the description of the above embodiment, the filament 2 is disposed vertically downward and the cathode electrode 1 is disposed vertically upward. However, both ends of the pin 15 are fitted in the electrode side hole 60 and the holding side hole 70, respectively. Since the holding member 5 is fixed to a support portion (not shown), the cathode electrode 1 does not fall off the holding member 5 even when it is disposed upside down or obliquely.

However, the present invention is not limited to the case where both ends of the pin 15 are fitted in the electrode side hole 60 and the holding side hole 70, but the vertical position of the electron gun with respect to gravity is determined and can be arranged so as not to fall. Instead of the holding side hole 70, a groove may be provided in the holding member 5, and one end of the pin 15 may be placed on the bottom surface of the groove.
In this case, the inner circumferential surface of the groove becomes the holding side contact surface, and carbon or tantalum carbide can be exposed.

DESCRIPTION OF SYMBOLS 1 ... Cathode electrode 2 ... Filament 3 ... Anode electrode 5 ... Holding member 10 ... Electron gun 15 ... Pin 25 ... Vacuum chamber 31 ... Cathode member 32 ... Heating device 35 ... Deposition material 39 ... ... Vacuum pump 50 ... Vacuum processing equipment

Claims (6)

A ring-shaped holding member; a cathode electrode that emits electrons; a heating device that heats the cathode electrode; and three or more pins that electrically connect the holding member and the cathode electrode. Is an electron gun held by the holding member via the pin,
An electron gun in which carbon or tantalum carbide is exposed on a holding-side contact surface that contacts the pin of the holding member.   The holding member is provided with three or more holding side holes, an inner peripheral side surface of the holding side hole is set to the holding side contact surface, and the pins of the holding side holes are fitted into the holding side holes, respectively. The electron gun according to claim 1, wherein a cathode electrode is held by the holding member.   The electron gun according to claim 1, wherein the holding member is made of carbon or tantalum carbide.   In the holding member, a tantalum carbide film is formed on at least a part of the surface of a core material made of tantalum, the surface of the tantalum carbide film is used as the holding side contact surface, and the tantalum carbide is formed on the holding side contact surface. The electron gun according to claim 1, wherein is exposed.   The electron gun according to claim 1, wherein the pin and the cathode electrode are made of tungsten. A vacuum chamber, a vacuum pump, and the electron gun according to any one of claims 1 to 5,
The electron gun is configured to emit electrons into the vacuum chamber;
The vacuum processing apparatus which processes a process target object in the said vacuum chamber.

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