JP3875957B2 - Electron gun cooling system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electron gun cooling device, and more particularly, to an electron gun cooling device having a structure in which an electron gun body is suspended and supported via an insulator in a vacuum atmosphere.
[0002]
[Prior art]
In an electron beam type exposure apparatus that performs microfabrication using an accelerated electron beam, an electron beam type electron microscope, and the like, an electron gun that emits an electron beam is installed in a chamber maintained in a vacuum state. Yes.
In the electron gun having such a structure, it is necessary to heat the filament portion in order to emit electrons, and FIG. 2 shows an outline of the electrical connection state of the electron gun employed at that time.
[0003]
The electron gun 1 shown in the figure includes a bombarded filament portion 1a constituting an electron gun body and a cathode electrode 1b disposed in front of the bombarded filament portion 1a. A target 2 for irradiating an electron beam in front of the cathode electrode 1b Has been placed.
[0004]
A secondary coil of an insulating transformer 3 is connected to the bombarded filament portion 1 a, and an AC power source 4 is connected to the primary coil of the insulating transformer 3, and the bombarded filament portion 1 a is heated by the AC power source 4. It is like that.
[0005]
The bombarded filament portion 1a is applied with a high voltage potential from the DC bombard power source 5 with the ground side being positive. Similarly, a high-voltage potential is applied to the cathode electrode 1b from the DC high-voltage power source 6, and the thermoelectrons generated from the bombarded filament portion 1a are applied to the tantalum crystal in the cathode electrode 1b, so that The thermoelectrons emitted from the crystal are turned into a beam and emitted toward the target 2 side. In addition, the member shown with the code | symbol 7 in FIG. 2 is a rectifier which converts alternating current into direct current.
[0006]
In the electron gun 1 having such a structure, heating power is applied to the bombarded filament portion 1 a via the insulating transformer 3. Further, since the thermoelectrons from the bombarded filament 1a strike the cathode electrode 1b, it becomes very hot. As a result, the temperature of the chamber in which the electron gun 1 is installed becomes high.
The influence of such a high temperature can be almost ignored when the current of the electron beam is small, but for example, when the electron beam of high current such as 110 kV and 10 mA is continuously irradiated, the electron gun 1 Cooling is required.
[0007]
For such a problem, for example, it seems that by installing a cooling device in the electron gun 1, it is possible to easily avoid the high temperature in the chamber. When installing the cooling device 1, there was a technical problem described below.
[0008]
[Problems to be solved by the invention]
That is, in the electron gun 1 shown in FIG. 2, for example, when the bombarded filament portion 1 a and the cathode electrode 1 b are cooled by a cooling device, they are installed in a vacuum chamber, and therefore, an air cooling method is adopted. Therefore, the liquid refrigerant is supplied to these portions to be cooled.
[0009]
However, this type of electron gun 1 is normally grounded on the chamber side, and the bombarded filament portion 1a and the cathode electrode 1b of the electron gun 1 are on the high-voltage side, so that liquid refrigerant is supplied to the heat generating portion. Since it has to be accessed from the ground side, it has been difficult to easily provide a cooling device.
[0010]
The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an electron gun cooling device capable of preventing a temperature rise by cooling a heat generating portion. There is to do.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an electron gun cooling apparatus installed in a chamber maintained in a vacuum state, wherein the electron gun includes an electron gun body including a filament part and a bombard part, A holder for hanging and supporting the electron gun body; a lower end side fixed to the chamber; an upper end side supporting the holder; and an insulator for electrically insulating the chamber and the holder. The cooling device includes an annular groove provided in the holder, and a coolant supply and discharge pipe that passes through the chamber in an airtight state and communicates with the annular groove. In addition to being formed of an electrically insulating resin, an electrically insulating oil for cooling is supplied from the supply pipe to the annular groove and is discharged from the pipe.
[0012]
According to the electron gun cooling apparatus configured as described above, the electron gun installed in the chamber maintained in a vacuum state is supplied to the annular groove using electric insulating oil as a cooling liquid. Heat can be exchanged with a holder made of a good thermal conductor, and the holder can be cooled.
[0013]
When the holder is cooled in this way, the filament part and the bombard part, which are the heat generation part of the electron gun body, are suspended and supported by the holder, and as a result, the heat generation part of the electron gun is cooled. Can do.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of a cooling device for an electron gun according to the present invention. The cooling device 10 shown in the figure is used for an electron gun 14 that is grounded in a chamber 12 maintained in a vacuum state.
[0015]
The chamber 12 has a hollow container shape that is closed from the outside. The chamber 12 is maintained in a predetermined vacuum state by a vacuum pump (not shown), and is provided with a mounting flange 12a that protrudes inward.
[0016]
The electron gun 14 includes an electron gun body 16, a holder 18, and an insulator 20. The electron gun body 16 includes a filament portion 16a and a bombard portion 16b.
[0017]
As in the filament 1a shown in FIG. 2, the secondary coil of the insulating transformer 3 is connected to the filament portion 16a, and the AC power supply 4 is connected to the primary coil of the insulating transformer 3. The part 1a is heated by the AC power source 4.
[0018]
Similarly to the case of FIG. 2, a high voltage potential with the ground side being positive is applied to the filament portion 16 a from a DC high voltage power supply (3 kV, 150 mA, 450 W) 5.
[0019]
Similarly to the cathode electrode 1b shown in FIG. 2, a high voltage potential is applied to the bombard portion 16b from a DC high voltage power supply (110 kV, 10 mA, 1100 W), and the thermoelectrons generated from the filament portion 16a are beamed. And emitted toward the target side (not shown) provided below the bombard portion 16b of FIG.
[0020]
The holder 18 suspends and supports the electron gun body 14, and in the case of the present embodiment, the holder 18 is made of stainless steel with priority on rigidity. The constituent material of the holder 18 is not limited to this. For example, the holder 18 may be made of a metal such as aluminum or copper which is a good thermal conductor. The holder 18 includes a base portion 18a, a cylindrical portion 18b, and a disk portion 18c.
[0021]
The base portion 18a has one end side of the cylindrical portion 18a and a disc portion 18b disposed therein, and the hollow cylindrical cylindrical portion 18a extends downward so as to cover the outer periphery of the filament portion 16a. On the side, the outer periphery of the bombard portion 16b is fixed, and the bombard portion 16b is held on the lower end side of the cylindrical portion 18a.
[0022]
The disk part 18c is attached to the cylinder part 18a by screwing, and the filament part 16a is supported at the center via the insulator rod 22. A connecting wire for supplying a potential to the filament portion 16a is embedded in the insulator rod 22.
[0023]
The insulator 20 is fixed to the chamber 12 at the lower end side, supports the holder 18 at the upper end side, and electrically insulates the chamber 12 and the holder 18 from each other. In the case of the present embodiment, the insulator 20 is formed in a cylindrical shape having both ends opened, and the opening edge on the lower end side is fixedly provided on the upper end of the mounting flange 12 a of the chamber 12.
[0024]
The inner surface of the base portion 18a of the holder 18 is fixed to the opening edge on the upper end side of the insulator 20 so that the holder 16 is electrically insulated into the chamber 12 through the insulator 22. And is supported in a suspended state.
[0025]
On the other hand, the cooling device 10 includes an annular groove 10a, a supply pipe 10b for the coolant O, and a discharge pipe 10c. The annular groove 10a is provided in the holder 18 so as to go around.
[0026]
In the case of the present embodiment, the annular groove 10a is formed by notching the outer peripheral surface of the cylindrical portion 18b of the holder 18 in a concave shape, and is provided so as to make one round of the outer periphery of the cylindrical portion 18b.
[0027]
The supply and discharge pipes 10b and 10c pass through the chamber 12 in an airtight state at one end side and are connected to a supply source of a coolant O (not shown) so that the coolant O circulates.
[0028]
The other end sides of the supply and discharge pipes 10b and 10c are connected to the annular groove 10a, respectively, and these connecting portions are positioned to face each other with respect to the circulating groove 10a.
[0029]
In the case of this embodiment, the supply and discharge pipes 10b and 10c are made of an electrically insulating resin, for example, polytetrafluoroethylene resin. When the pipes 10b and 10c made of such a material are used, the electric charge is not stored on the surfaces of the pipes 10b and 10c, so that the discharge accompanying the accumulation of electric charges can be avoided.
[0030]
Furthermore, in the present embodiment, an electrically insulating oil is used as the coolant O. In the cooling device 10 configured as described above, the electrically insulating oil is supplied from the supply pipe 10b to the annular groove 10a as the cooling liquid O, and the cooling liquid O that has circulated in the annular groove 10a is discharged to the outside through the discharge pipe 10c. Discharge.
[0031]
In such a circulation process of the coolant O, when this circulates in the annular groove 10a, heat is exchanged with the holder 18, heat is taken from the holder 18 side, and the holder 18 is cooled.
[0032]
When the holder 18 is cooled in this manner, the filament portion 16a and the bombard portion 16b, which are the heat generating portions of the electron gun body 16, are supported by the holder 18 in a suspended manner. The exothermic part can be cooled.
[0033]
Now, according to the electron gun cooling apparatus configured as described above, the electron gun 14 installed in the chamber 12 maintained in a vacuum state is supplied into the annular groove 10a using the electrically insulating oil as the coolant O. As a result, the heat generating portion of the electron gun 14 can be cooled via the holder 18.
[0034]
When the electron gun 14 is cooled in this manner, it is possible to continue irradiation with a high-current electron beam at a high voltage of 110 kV and 10 mA.
[0035]
【The invention's effect】
As described above in detail, according to the cooling apparatus for an electron gun according to the present invention, it is possible to prevent an increase in temperature by cooling the heat generating portion that is insulated in a vacuum state.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a main part explanatory view showing an embodiment of an electron gun cooling device according to the present invention.
FIG. 2 is an explanatory diagram showing an electrical configuration of an electron gun.
[Explanation of symbols]
10 cooling device 10a annular groove 10b supply pipe 10c discharge pipe 12 chamber 14 electron gun 16 electron gun body 16a filament part 16b bombard part 18 holder 18a base part 18b cylinder part 18c disk part 20 insulator 22 insulator rod

Claims (1)

In a cooling device for an electron gun installed in a chamber maintained in a vacuum state,
The electron gun includes an electron gun body including a filament part and a bombard part,
A holder for hanging and supporting the electron gun body;
The lower end side is fixed to the chamber, the holder is supported on the upper end side, and an insulator that electrically insulates between the chamber and the holder,
The cooling device includes an annular groove provided in the holder;
A cooling liquid supply and discharge pipe penetrating the chamber in an airtight state and communicating with the annular groove,
The supply and discharge pipes are formed of an electrically insulating resin,
A cooling apparatus for an electron gun, wherein an electrical insulating oil for cooling is supplied from the supply pipe to the annular groove and is discharged from the pipe.

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