JPH05325809A - Ion source - Google Patents

Abstract

PURPOSE:To reduce the cost of manufacture and to simplify a seal structure by using a plurality of struts instead of a cylindrical ceramic to connect an ion source chamber to a vacuum chamber, and by surrounding the whole ion source unit by a jacket chamber. CONSTITUTION:An accelerating electrode 1 is mounted in an ion source chamber 6, and suppressing and earthing electrodes 2, 3 are mounted in a vacuum chamber 8, to connect the chambers 6, 8 by a plurality of ceramic struts 5. The chamber 6 is insulated from an upper cover 7 by an insulator 43, and an RF power supply 41 is applied across the chamber 6 and the upper cover 7, to generate an RF discharge. The chamber 6 is coated with a jacket chamber 9, to hold a vacuum to also earth the chamber 9. Further in an upper cover 10 of the chamber 9, a stock gas introducing pipe 42 is provided to supply stock gas to the chamber 6. On the other hand, power supplies 41, 22, 24 are supplied to the electrodes through a field through 13 of the chamber 9. In this way, necessity for a large ceramic cylinder is eliminated to reduce the cost of manufacture, and a seal structure can be simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion source which is easy to assemble and maintain and suitable for upsizing. The ion source excites the raw material gas or raw material vapor by heat, electric discharge, etc., turns this into plasma, applies a voltage, and extracts it as an ion beam. The ion source is an ion irradiation device, an ion implantation device,
It is used for ion etching equipment. It is equipped with a chamber, power supply, electrodes, filaments, etc. A high voltage is applied to the chamber. Moreover, the chamber must maintain a vacuum state.

FIG. 2 is a sectional view of an ion source according to a conventional example. At the outlet of the chamber, three extraction electrode system electrode plates are provided. These are conductor plates having a plurality or single holes for extracting ions. From the chamber side, they are called acceleration electrode 1, suppression electrode 2, and ground electrode 3. A cylindrical insulator 4 connects the ion source chamber 6 and the vacuum chamber 8. The ion source chamber 6 is a space for generating plasma. This also comprises a cylindrical wall surface and an upper lid 7 for closing the wall surface. A filament 12 is inserted through the upper lid 7. It is at the cathode potential and is energized to generate thermoelectrons.

The upper lid 7 is provided with a raw material gas inlet 15. Electric power is supplied to the filament 12 by a filament power supply 16. An arc power supply 17 is connected between the ion source chamber 6 and the filament 12. This causes an arc discharge between the ion source chamber 6 and the filament 12. The other end flange portion of the ion source chamber 6 is joined to a large-diameter flange 19 via an insulator 18. The acceleration electrode 1 is fixed to the flange 19. The flange 19 is connected to the connecting flange 20 on the side of the vacuum chamber 8 by the aforementioned cylindrical insulator 4. A conical support portion 21 is provided inwardly of the connection flange 20 in an oblique direction. The ground electrode 3 is fixed to this tip. Acceleration power supply 22
The positive electrode is the arc power source 17 and the filament power source 16 described above.
Connected to one pole. The positive electrode of the accelerating power supply 22 is further connected to the flange 19 and the accelerating electrode 1 to maintain it at a high voltage.

An insulator 23 is provided at the tip of the conical support portion 21.
The suppression electrode 2 is attached via. A negative voltage is applied to the suppression electrode 2 by the suppression power supply 24. This prevents secondary electrons emitted from the sample from entering the ion source. Since the ion source chamber 6 and the vacuum chamber 8 must be maintained in a high vacuum, an airtight member such as an O-ring is provided at the connecting point of the members. An O-ring 30 is provided between the upper lid 7 and the flange of the ion source chamber 6.
An O-ring 31 is provided between the other flange portion of the ion source chamber 6 and the insulator 18. An O-ring 32 is provided between the insulator 18 and the flange 19. Cylindrical insulator 4
And O-rings 33, 34 between the flange 19 and the connecting flange 20. There is also an O-ring 35 between the connecting flange 20 and the vacuum chamber 8.

The vacuum chamber holds a sample or the like to be irradiated with the ion beam. In such a structure, an arc discharge occurs between the filament 12 and the ion source chamber 6. The raw material gas is excited by this to become plasma. This passes through the holes of the acceleration electrode 1, the suppression electrode 2, and the ground electrode 3 and is extracted as an ion beam. The extracted ion beam is used for various purposes.

[0006]

The ion source of FIG. 2 is commonly used. However, this has some drawbacks. One is that there are many airtight parts and many airtight members are required. Also in this example, a large number of O-rings 30 to 3
5 is used. There is a high probability that vacuum leakage will occur in many airtight parts. Both the ion source chamber 6 and the vacuum chamber 8 have a high vacuum inside. However, the outside of these chambers is immediately atmospheric. This is the first difficulty.

It suffices if the device is small, but if the device is to be made larger, it becomes difficult to make the intermediate insulator 4. The insulator 4 that insulates the ion source chamber 6 and the vacuum chamber 8 is cylindrical, has a large diameter, and has a considerable height. This is, for example, ceramic. It is made by putting the material in a mold, molding it, and heating it in a furnace. It is a pottery. We have to make something of this size from the beginning. The larger the ion source, the larger the size of the cylindrical insulator. Then, a mold for molding this and a furnace for baking must be large. Further, the volume of ceramic is reduced to 70 to 80% by baking. This reduction is not necessarily spatially uniform. Because of this, it is difficult to design the mold to be molded before baking. Moreover, the yield as a pottery is low. Moreover, the insulator 4 is a member for maintaining airtightness in addition to electrical insulation. Then, the flatness of the end face must be highly accurate. Sintering and post-processing become extremely difficult. Even if a large-sized insulator is made, it will be very expensive. This has a similar tendency even if it is formed of a thermosetting resin such as an epoxy resin.

A large ion source is difficult to assemble with such a structure. This is because there are many airtight parts and it is necessary to pay close attention to assembly. In addition, maintenance work is troublesome, and maintainability is poor.

A high voltage is applied to the ion source chamber and an accelerating voltage is also applied to the flange 19 in the middle. Since there is a large voltage difference between this and the portion of the vacuum chamber 8 that is at the ground potential, a wide insulation distance must be provided between the two. Then it becomes bulky in the axial direction.

The high-voltage part is exposed to the outside, which is dangerous. SUMMARY OF THE INVENTION It is an object of the present invention to solve these problems and provide an ion source that is easy to manufacture and assemble, and is cheaper and safer even if it is larger.

[0011]

SUMMARY OF THE INVENTION The ion source of the present invention does not have a cylindrical cylindrical insulator to separate the chambers. Multiple columns are used instead of this cylindrical insulator. The column connects the ion source chamber and the vacuum chamber. The vacuum cannot be maintained only by erecting multiple columns. Therefore, the entire ion source chamber and insulator are surrounded by a larger envelope chamber. The mantle chamber holds the vacuum. The ion source chamber is no longer exposed to the outside.
This no longer requires an airtight member in the part connecting the ion source chamber, the insulator and the flange.

[0012]

In the present invention, the outer chamber covers the entire ion source, and the outer chamber maintains the vacuum. Therefore, a cylindrical insulator that can keep airtight is not required in the portion connecting the ion source chamber and the vacuum chamber. Instead, you can set up multiple small stanchions. It is extremely difficult to make a large-sized cylindrical ceramic. However, if it is a pillar, it is extremely easy to make this. The amount of ceramic material is small. Since it is small, molding is easy. The furnace for baking this may also be small.
Since it has a simple shape and is small, the weight loss due to baking is also small and can be calculated. The yield is high.

Although it depends on the size, it costs several million yen to make an insulator of a large-diameter ceramic cylinder as shown in FIG. Because it is large, the furnace must be large, material costs are high, and yield is low. The length of this cylinder is L, the outer diameter is D ₂ , and the inner diameter is D ₁ . Since the present invention intends to replace this with a plurality of columns, the column diameter d is about (D ₂ −D ₁ ). The length may be L. Since d << D ₁ and D _2, it is natural that the manufacturing is easy. This also depends on the size, but the cost of the insulator becomes extremely low when four or eight are used.

Since the column cannot maintain a vacuum, the entire ion source chamber is surrounded by the mantle chamber. This maintains the vacuum. Since the number of vacuum seal parts is reduced, there is less chance of leak. It also facilitates assembly and maintenance. Further, since the whole is surrounded by the mantle chamber, the high voltage portion is not exposed. Therefore, safety is also improved.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. The electrode of the ion source is the same as the conventional one. The acceleration electrode 1 is provided first, then the suppression electrode 2, and finally the ground electrode 3. The container forming the ion source is a cylindrical ion source chamber 6
And the upper lid 7. In front of the ion source is a vacuum chamber 8 which is a space where a sample should be placed. In this example, the acceleration electrode 1
Is attached to the ion source chamber 6, and the other electrodes 2 and 3 are attached to the vacuum chamber. Flange 20 on top of ion source chamber 6 and vacuum chamber 8
A plurality of ceramic pillars 5 are connected to each other. Figure 3
Shows a cross-sectional view of the column part. FIG. 4 is a cross-sectional view of a conventional cylindrical insulator portion (shown in FIG. 2). Comparing the two, it is clear that the pillar is smaller than the cylindrical insulator.

One end of the column 5 is connected to the flange 19 of the ion source chamber 6. The other end of the column 5 is fixed to the flange 20 on the vacuum chamber 8 side. A conical support portion 21 is provided on the surface of the flange 20 on the ion source side, and the suppression electrode 2 and the acceleration electrode 1 are attached to the tip thereof. This is similar to that shown in FIG. However, this is an example of generating plasma using high-frequency discharge instead of an ion source using a filament. The present invention can be applied to an ion source having any discharge excitation mechanism.

RF between the ion source chamber 6 and the upper lid 7
A power supply 41 is connected, which causes an RF discharge. The chamber 6 and the upper lid 7 are insulated by the insulator 43. The most characteristic structure of the present invention is the mantle chamber 9 which largely covers the ion source chamber. This maintains the internal vacuum. A raw material gas introduction pipe 42 is provided through the lid 10 of the outer chamber 9. This can further supply the source gas into the ion source chamber 6 through the inner upper lid 7. A large opening 44 and a flange 45 forming an outer edge of the large opening 44 are provided at one side of the outer jacket chamber 9. A disc-shaped feedthrough 13 is attached to the flange 45. This is for passing a current from an external power supply to the internal electrodes. RF power supply 41, acceleration power supply 22,
An electric wire from the suppression power source 24 is connected to an internal electrode through the feedthrough-13.

The lid 10 is attached to the body of the outer chamber 9 via an O-ring 51. An O-ring 52 is also provided between the outer chamber 9 and the flange 20. There is also an O-ring 53 between the flange 20 and the vacuum chamber 8. An O-ring 54 is also provided between the feedthrough 13 attached to the opening 44 and the flange 45. The outer chamber 9 has a ground potential. The high voltage part is not exposed to the outside. The outer chamber 9, the lid 10 thereof, the vacuum chamber 8 and other exposed portions are all at the ground potential. It is extremely safe. A high voltage is applied between the outer chamber 9 and the ion source chamber 6 inside. However, since this is a vacuum and only low-pressure gas such as nitrogen is present, the dielectric strength is higher than that in the atmosphere.

[0019]

In contrast to the conventional ion source, the ion source of the present invention covers the chamber, which should be at high pressure and vacuum, with the mantle chamber. There are fewer places to seal and the possibility of vacuum leaks is reduced. Further, it is not necessary to keep the internal ion source chamber airtight, and it is not necessary to attach an O ring or the like. The number of places to be kept airtight and connected is reduced.
This makes assembly and disassembly extremely easy.

It should be noted that the cylindrical insulator is unnecessary. Since the mantle chamber surrounds the ion source chamber, no function of maintaining a vacuum on the insulator is imposed. You can replace this with multiple smaller stanchions. Insulators are made of ceramics, but the furnace itself must be made large in order to make large cylindrical ones. Moreover, since the weight is unevenly reduced by baking, the shape differs from the initial shape. It must be polished to improve surface accuracy. Since the material cost and the equipment cost are high and the yield is low, the cylindrical insulator having a large size becomes extremely expensive. However, in the present invention, a plurality of small-diameter columns may be used. Since the material cost is low, the manufacturing is easy, and the yield is high, the price of the insulator is significantly reduced. This advantage is especially noticeable when trying to make a large ion source.

Further, since the ion source chamber is collectively surrounded by the mantle chamber, the seal structure is simplified. Naturally, the possibility of vacuum leakage is reduced. It becomes a highly reliable ion source device. Also, the high voltage part is not exposed to the outside. All exposed parts are at ground potential. Therefore, the safety is extremely high, and the device of this type can be made compact.
The ion source of the present invention is most suitable for designing and manufacturing a large ion source.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an ion source according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of an ion source according to a conventional example.

FIG. 3 is a cross-sectional view of an insulator portion of the ion source of FIG.

4 is a cross-sectional view of an insulator portion of the ion source of FIG.

[Explanation of symbols]

 1 Acceleration Electrode 2 Suppression Electrode 3 Grounding Electrode 4 Cylindrical Insulator 5 Insulating Strut 6 Ion Source Chamber 7 Top Lid 8 Vacuum Chamber 9 Outer Chamber 10 Lid 12 Filament 13 Feedthrough 14 Vent Hole 15 Raw Material Gas Inlet 16 Filament Power Supply 17 a -Power supply 18 Insulator 19 Flange 20 Flange 22 Acceleration power supply 23 Insulator 24 Suppression power supply

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Eisuke Murasaka 47 Umezu Takaunecho, Ukyo-ku, Kyoto Nissin Electric Co., Ltd.

Claims (1)

[Claims] 1. An ion source chamber, which is a space for introducing a source gas into the interior thereof and exciting it by discharge to generate plasma, an extraction electrode system provided at the outlet of the ion source chamber for extracting an ion beam, and an extraction electrode system. Ion Bee
Vacuum chamber to use the sample for sample processing, a plurality of insulating columns for insulatingly connecting the ion source chamber and the vacuum chamber, and a vacuum chamber that surrounds the ion source chamber and is vacuumed inside. An ion source comprising a mantle chamber that can be pulled, and a high voltage is applied to the ion source chamber and the extraction electrode system, but the mantle chamber is grounded.