KR102717459B1 - Inductively Coupled Plasma ion beam source with high voltage application and modular replacement - Google Patents

Abstract

The present invention relates to an inductively coupled plasma ion beam source capable of high voltage application and modular replacement, comprising: a plasma chamber having an inlet and an outlet, and inner and outer walls for generating and maintaining plasma using gas introduced through the inlet; an inlet cover electrode mounted at the inlet of the plasma chamber, an inlet cover holder, an inlet holder mount, a gas injection device mounted on the inlet cover electrode, an outlet cover disposed at the outlet of the plasma chamber, an accelerating electrode disposed on the outlet cover, and an accelerating electrode holder supporting the accelerating electrode; an extractor electrode disposed at a predetermined distance below the accelerating electrode; an RF coil disposed outside the outer wall of the plasma chamber to provide RF power; and an insulating material circulation means for circulating an insulating material between the inner and outer walls of the plasma chamber.

Description

Inductively Coupled Plasma Ion Beam Source with High Voltage Application and Modular Replacement

The present invention relates to an inductively coupled plasma (ICP) ion beam source capable of high voltage application and modular replacement, and more specifically, to a plasma ion beam source configured with a double-tubular plasma chamber so as to enable high voltage application to an ICP ion beam source, and circulating an insulating material between the inner and outer walls of the double-tubular chamber to solve problems such as insulation breakdown that may occur due to high voltage application, and enabling modular replacement.

Plasma is a group of charged positive ions and electrons generated by an electrical discharge, and includes radicals, which are atomic groups with unpaired electrons. Since there are actively moving electrons, ions, and radicals inside the plasma, it can cause a chemical reaction that excites or ionizes other substances. In addition, by applying an electric field to the outside of the plasma, the movement speed of the electrons and ions can be controlled, causing a physical reaction that causes a collision with other substances. The chemical and physical reactions caused by the plasma can be applied not only to the process of depositing a substance, but also to the process of etching a substance.

In general, processing devices using plasma include PECVD (Plasma Enhanced Chemical Vapor Deposition) devices for thin film deposition, etching devices that etch and pattern the deposited thin film, sputtering and ashing devices, ion beam sources, and electron beam sources. In addition, these plasma generating devices are classified into capacitively coupled plasma (CCP) and inductively coupled plasma (ICP) devices depending on the method of applying RF (Radio Frequency) power.

The above capacitively coupled type is a method that generates plasma by applying RF power to opposing parallel plate electrodes and through an RF electric field formed vertically between the electrodes, whereas the inductively coupled type is a method that installs a high-frequency antenna outside a plasma chamber capable of maintaining a vacuum, forms an induced electric field inside the plasma chamber by supplying high-frequency power to the high-frequency antenna while the wall (window) between the high-frequency antenna and the plasma processing room is composed of a dielectric, and causes a processing gas introduced into the plasma chamber to be plasma-ized by the induced electric field. The inductively coupled type is classified into ICP (Inductively Coupled Plasma), TCP (Transformer Coupled Plasma), Helical Plasma, Helicon Plasma, ECR, etc. depending on the shape of the high-frequency antenna and the external magnetic field.

Fig. 1 is a schematic diagram illustrating a conventional ICP ion beam source. Referring to Fig. 1, a conventional plasma ion beam source is equipped with an accelerating electrode and an extractor electrode for accelerating or focusing an ion beam at the exit of a plasma chamber, and by applying a predetermined voltage to the electrodes, an ion beam (a group of ionized atoms) of desired high energy is provided from the plasma.

However, in order to process a sample in a short period of time using a plasma ion beam source, it is necessary to emit a large amount of ions and accelerate them with a large potential difference. To emit a large amount of ions, methods such as increasing the RF power, supplying more gas, increasing the diameter of the outlet, or generating plasma near the outlet can be used. Among these, the most effective method is to generate plasma near the outlet. In this case, the outlet is located at the center of the accelerating electrode, and the accelerating electrode is located at the lower end of the plasma chamber. If the RF coil is positioned close to the accelerating electrode, the capacitive coupling between the RF coil and the accelerating electrode increases in the atmospheric pressure environment when the accelerating electrode is exposed outside the vacuum, which can cause insulation breakdown. In addition, even if the accelerating electrode is positioned inside the vacuum, if a high voltage of about 30 kV is applied, a high voltage zone is generated even in a vacuum environment, which not only makes the area around the accelerating electrode unstable, but also overlaps with the electromagnetic field zone caused by the RF coil, which increases the capacitive coupling and causes insulation breakdown. Therefore, the RF coil cannot be positioned close to the accelerating electrode and is usually placed in the middle of the plasma chamber.

In addition, since the high-voltage cable must be directly connected to the accelerating electrode in order to place the accelerating electrode inside a vacuum and apply a high voltage, a feed-through connector for high-voltage application must be used. However, if a feed-through connector for high-voltage application is used, it is difficult to apply the length of the accelerating electrode short in the direction of the length of the plasma chamber. As a result, the space under the plasma chamber must increase, and the overall length of the ion beam source becomes longer. This not only acts as an obstacle to obtaining the desired ion beam trajectory and current value, but as the length of the accelerating electrode increases, the high-voltage zone also increases, which causes a problem in that stable operation of the ion beam source becomes difficult.

In addition, the plasma ion beam source is not a device that can be used permanently by simply injecting gas, and there are problems such as the need to disassemble the ion beam source, remove the insulating material, and periodically clean or replace the inside of the plasma chamber due to contamination issues inside the plasma chamber.

Patent Publication No. 10-1995-0013431 (published on November 8, 1995) Patent Registration No. 10-1668822 (Published on October 24, 2016)

Accordingly, the purpose of the present invention is to solve the above-mentioned conventional problems, and to provide a plasma ion beam source in which insulation is not destroyed even when a high voltage is applied and the RF coil is positioned close to the accelerating electrode without installing a Faraday shield.

Another object of the present invention is to provide a plasma ion beam source having improved electrode shape and gas injection device to enable maintenance of stable plasma and emission of a constant amount of ions.

Another object of the present invention is to provide a plasma ion beam source improved in a capsule type so that the plasma chamber assembly can be replaced in a modular manner without removing the insulating material between the inner and outer walls of the plasma chamber or without excessive disassembly of the ion beam source when the interior of the plasma chamber needs to be cleaned or replaced.

In addition to the above-mentioned purposes explicitly stated, the present invention also includes other purposes that can be derived from the composition of the present invention.

In order to achieve the above-described object of the present invention, a plasma ion beam source comprises a plasma chamber having an inlet and an outlet, and inner and outer walls for generating and maintaining plasma using gas introduced through the inlet; an inlet cover electrode disposed at the inlet of the plasma chamber and having an insulating material inlet and an insulating material outlet formed therein; an inlet cover holder; an inlet holder mount; a gas injection device mounted on the inlet cover electrode; an outlet cover disposed at the outlet of the plasma chamber; an accelerating electrode disposed on the outlet cover; and an accelerating electrode holder supporting the accelerating electrode; a capsule-shaped plasma chamber assembly including: an extractor electrode disposed at a predetermined distance below the accelerating electrode; an RF coil disposed outside the outer wall of the plasma chamber and providing RF power; and an insulating material circulation means for circulating an insulating material between the inner and outer walls of the plasma chamber.

The plasma ion beam source according to the above-described features preferably has the inner and outer walls of the plasma chamber formed of a dielectric, the accelerating electrode and the inlet cover electrode formed of a metal, and the outlet cover formed of a ceramic.

According to the above-described characteristics, it is preferable that a high voltage of 30 kV is applied to the inlet cover electrode of the plasma ion beam source.

It is preferable that the RF coil of the plasma ion beam source according to the above-described characteristics be placed at the lower part of the outer wall of the plasma chamber.

It is preferable that the plasma exposure area of the accelerating electrode and the entrance cover electrode of the plasma ion beam source according to the above-described characteristics be formed in an uneven shape.

It is preferable that a check valve plug be applied to the gas injection device of the plasma ion beam source according to the above-described characteristics.

The present invention has the effect of providing an ion beam capable of processing a sample in a short period of time, since the insulation is not destroyed even when a high voltage is applied while positioning the RF coil close to the accelerating electrode without installing a Faraday shield, and plasma can be generated close to the outlet.

In addition, the present invention can take advantage of both the vacuum external exposure type accelerating electrode and the vacuum internal placement type accelerating electrode, thereby providing a large amount of ion beams and enabling stable operation of the ion beam source.

In addition, since the shape of the electrode of the present invention is improved to enable stable maintenance of plasma, there is an effect of being able to provide a constant amount of ion beam.

In addition, the present invention applies a check valve plug to a gas injection device, so that not only can the gas supplied through the gas injection device be precisely controlled, but also the internal space of the plasma chamber can be prevented from expanding to the gas injection device and the gas supply line, so that the plasma generation area can be limited to only the internal space of the plasma chamber, and there is an effect of preventing a decrease in vacuum suction efficiency.

In addition, the present invention has the effect of facilitating maintenance since the plasma chamber assembly of the plasma ion beam source is manufactured in a capsule shape and the plasma chamber assembly manufactured in a capsule shape can be modularly replaced on the ion beam source base plate.

Figure 1 is a schematic diagram illustrating a conventional ICP ion beam source.
FIG. 2 is a conceptual diagram illustrating an ICP ion beam source according to a preferred embodiment of the present invention.
Figure 3 is a conceptual diagram explaining beam intensity according to the arrangement of RF coils.
FIG. 4 is a conceptual diagram of a gas injection device to which a check valve plug is applied in an ion beam source according to a preferred embodiment of the present invention.
FIG. 5 is a conceptual diagram for explaining the circulation of an insulating material circulating in the space between the inner and outer walls of a plasma chamber in an ion beam source according to a preferred embodiment of the present invention.
FIG. 6 is a perspective view and a cross-sectional view of an accelerating electrode in an ion beam source according to a preferred embodiment of the present invention.
FIG. 7 is a cross-sectional view of an entrance cover electrode and an accelerating electrode in an ion beam source according to a preferred embodiment of the present invention.
FIG. 8 is a conceptual diagram for explaining the generation of particles in an ion beam source according to a preferred embodiment of the present invention.
FIG. 9 is a cross-sectional view showing the cap-shaped structure of the accelerating electrode in an ion beam source according to a preferred embodiment of the present invention.
FIG. 10 is a conceptual diagram illustrating the inlet and outlet configurations of a double-tube plasma chamber in an ion beam source according to a preferred embodiment of the present invention.
FIG. 11 is a conceptual diagram for explaining the arrangement of an O-ring for maintaining confidentiality in an ion beam source according to a preferred embodiment of the present invention.
FIG. 12 is a conceptual diagram of an accelerating electrode and an extractor electrode arranged on the exit side of a plasma chamber in an ion beam source according to a preferred embodiment of the present invention.
FIG. 13 is a conceptual diagram for explaining the coupling state of a plasma chamber and an accelerating electrode of a capsule-type plasma chamber assembly in an ion beam source according to a preferred embodiment of the present invention.
FIG. 14 is a conceptual diagram for explaining replacement of a capsule-type plasma chamber assembly in an ion beam source according to a preferred embodiment of the present invention.

The above-described object of the present invention can be achieved by forming a plasma chamber assembly of a plasma ion beam source as a double-tubular chamber having an inner wall and an outer wall, circulating an insulating material between the inner wall and the outer wall, arranging an RF coil that provides radio frequency (RF) power to the plasma chamber at the lower part of the outer wall of the plasma chamber, and arranging an accelerating electrode inside the outlet side of the plasma chamber and applying a high voltage of 30 kV to an inlet cover electrode.

Hereinafter, preferred embodiments for achieving the purpose of the present invention will be described with reference to the attached drawings.

However, the present invention can be implemented in various different forms, and therefore is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are given similar drawing reference numerals throughout the specification.

Throughout the specification, when a part is said to be "connected (connected, contacted, coupled)" to another part, this includes not only the case where it is "directly connected" but also the case where it is "indirectly connected" with another member in between. Also, when a part is said to "include" a certain component, this does not mean that other components are excluded unless specifically stated to the contrary, but that other components may be additionally provided. The terms used in this specification are used only to describe specific embodiments and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, the terms "include" or "have" are intended to specify that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but should be understood to not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

FIG. 2 is a conceptual diagram illustrating a plasma source according to a preferred embodiment of the present invention, and FIG. 3 is a conceptual diagram explaining beam intensity according to the arrangement of RF coils.

Referring to FIGS. 2 and 3, the plasma ion beam source according to the present invention is preferably configured to include a capsule-shaped plasma chamber assembly (5) including a plasma chamber including an inner wall (11) and an outer wall (12) made of a dielectric, an inlet cover electrode (21) disposed at an inlet (30) of the plasma chamber, an inlet cover holder (31), an inlet holder mount (33), a gas injection device (32) mounted on the inlet cover electrode (21), an outlet cover (51) disposed at an outlet (50) of the plasma chamber, an accelerating electrode disposed on the outlet cover (51), and an accelerating electrode holder (52) supporting the accelerating electrode, an extractor electrode disposed at a predetermined distance below the accelerating electrode, an RF coil (41) disposed outside the chamber, and an insulating material circulation means (not shown) for circulating an insulating material into a space (13) between the inner and outer walls (11, 12) of the plasma chamber.

The plasma chamber is preferably formed entirely of a dielectric such as quartz, and the inner wall (11) and the outer wall (12) are arranged at a certain distance from each other, and gas is supplied from a gas injection device (32) to the space inside the inner wall (11) of the plasma chamber to generate plasma, and an insulating material supplied from an insulating material circulation means (not shown) is circulated in the space (13) between the inner wall (11) and the outer wall (12) to insulate the plasma chamber from the outside.

Meanwhile, an inlet cover electrode (21) is placed at the inlet (30) of the plasma chamber so as to close the inlet (30) of the plasma chamber. An insulating material inlet (34) and an insulating material outlet (35) are formed at the inlet cover electrode (21), and a gas injection device (32) is mounted thereon.

The inlet cover electrode (21) placed at the inlet (30) of the plasma chamber is formed of metal and a portion thereof may be exposed to the outside so that a high voltage of 30 kV may be directly applied. The reason why the inlet cover electrode (21) is formed of metal and a high voltage is applied in this way will be examined.

Conventional plasma ion beam sources apply high voltage to the accelerating electrode to accelerate ions generated in the plasma chamber with a large potential difference so that the sample can be processed in a short period of time. However, if the high voltage is applied while the accelerating electrode is exposed to the outside of the vacuum, the electrical capacitance overlap between the RF coil and the accelerating electrode in the atmospheric pressure environment increases, which makes it impossible to avoid the problem of insulation breakdown. To avoid this problem, the high voltage must be applied while the accelerating electrode is placed inside a vacuum. In this case, the high voltage cable must be directly connected to the accelerating electrode, and therefore, a feedthru connector for high voltage application must be used. At this time, if a feed-through connector for high voltage application is used, it is difficult to shorten the length of the accelerating electrode in the direction of the length of the plasma chamber, so that the space at the bottom of the plasma chamber must increase, and accordingly, the overall length of the ion beam source becomes longer, which not only acts as an obstacle to obtaining the desired ion beam trajectory and current value, but also causes a problem in that the stable operation of the ion beam source becomes difficult because the high voltage zone also increases as the length of the accelerating electrode becomes longer.

In addition, in order to generate a large amount of ion beams to process a sample in a short period of time, the existing plasma ion beam source must place the RF coil (41) close to the accelerating electrode so that the plasma can be generated near the outlet. However, if the RF coil (41) is placed close to the accelerating electrode in this way, even if the accelerating electrode is placed inside a vacuum, when a high voltage of about 30 kV is applied, the high voltage zone overlaps with the electromagnetic field zone caused by the RF coil (41), which increases electrical capacitive coupling and causes insulation breakdown along with peripheral instability. Therefore, the RF coil (41) cannot be placed close to the accelerating electrode.

In relation to the above-described problem, the present invention solves the problem by applying a high voltage of 30 kV to the inlet cover electrode (21), unlike the existing plasma ion beam source that applies a high voltage of 30 kV to the accelerating electrode. At this time, the plasma ion beam source of the present invention is formed as a double-tubular chamber having inner and outer walls (11, 12), so that an insulating material circulates in the space (13) between the inner and outer walls (11, 12) of the double-tubular chamber, thereby overcoming the problem of insulation breakdown, and since the high voltage of 30 kV is directly applied to the inlet cover electrode (21) exposed to the outside without any element that would cause a potential difference in the surrounding area, a feed-through connector for applying a high voltage does not need to be used.

In addition, since the electrode to which the high voltage is applied is not the accelerating electrode of a conventional ion beam source but the entrance cover electrode (21), even if the RF coil (41) is placed at the bottom of the plasma chamber, the problem of overlapping between the high voltage zone and the electromagnetic field zone caused by the RF coil (41) is solved by the insulating layer, so that the plasma can be generated near the outlet, thereby releasing a large amount of ions that can process the sample in a short period of time and accelerating it with a large potential difference.

The reason why ions can be accelerated with a large potential difference even when a high voltage is applied to the inlet cover electrode (21) as described above can be explained as follows. Even when a high voltage of 30 kV is applied to the inlet cover electrode (21) exposed to the outside, the acceleration electrode positioned on the outlet (50) side of the plasma chamber in a state where gas is not injected or plasma is not generated is positioned on the lower cover formed of an insulating material such as ceramic, so that no voltage is applied, i.e., it is in a 0 kV state, and therefore neither the inlet cover electrode (21) nor the acceleration electrode can perform the function of accelerating ions.

However, when gas is injected into the plasma chamber and the vacuum conditions necessary for plasma generation are met and RF power is applied, plasma is generated. In this state where plasma is generated, if a high voltage of 30 kV is applied to the inlet cover electrode (21), even if the accelerating electrode is not intentionally electrically connected to the high voltage, due to the electrical interaction caused by plasma diffusion between the inlet cover electrode (21) and the accelerating electrode, the accelerating electrode becomes almost at the same potential as the high voltage of 30 kV applied to the inlet cover electrode (21), that is, at about 29.98 kV, so that ions can be accelerated in a similar manner to a state where a high voltage is directly applied to the accelerating electrode, thereby solving a problem occurring in the existing ion beam source.

In addition, as described above, in the plasma ion beam source of the present invention, an RF coil (41) may be placed at the bottom of the plasma chamber so as to generate plasma near the ion beam outlet.

As illustrated in FIG. 3, the RF coil (41) can be placed at the top, middle, and bottom of the plasma chamber. Depending on the placement position of the RF coil (41), the density of the emitted ion beam can vary. As the placement position of the RF coil (41) goes lower, a higher density ion beam can be emitted. Therefore, even if the same RF power is applied to the plasma chamber, if the RF coil (41) is placed lower, the density of the emitted ion beam increases, allowing the sample to be processed in a short period of time.

However, in order to increase the density of the ion beam as described above, if only the RF coil (41) is positioned lower in the plasma chamber of the existing ion beam source, the electromagnetic field zone caused by the RF coil (41) interferes with the high voltage zone caused by the high voltage accelerating electrode, which limits the ability to increase the density of the ion beam. However, in the present invention, since an insulating material is circulated in the space (13) between the inner and outer walls (11, 12) of the plasma chamber and the insulating state can be maintained, the density of the ion beam can be increased by positioning the RF coil (41) lower.

In addition, since an RF coil (41) is arranged outside the plasma chamber of the ICP ion beam source and a current flows through the RF coil (41), a magnetic field is formed by the current flowing through the coil, and an induced electric field is formed from the magnetic field, and particles inside the plasma chamber vibrate and collide due to the induced electric field to form plasma, so that the dielectric existing between the plasma and the RF coil (41) is damaged by the sputtering phenomenon and the contamination inside the plasma chamber is promoted over time. However, in the present invention, as described above, the plasma chamber of the plasma ion beam source is formed as a double-tubular chamber having an inner wall and an outer wall, an insulating material is circulated between the inner wall and the outer wall, and the RF coil is applied to the outside of the outer wall of the plasma chamber. Therefore, since the RF coil is formed in a structure in which it does not come close to the inner wall of the plasma chamber where plasma is generated and maintained and maintains an optimal distance, the self-bias charging effect on the inner wall of the plasma chamber can be reduced. This reduces the electrical capacitive coupling between the inner wall of the plasma chamber and the RF coil, and reduces the damage to the dielectric caused by sputtering, thereby reducing the level of contamination within the plasma chamber. As a means of reducing the electrical capacitive coupling, a Faraday shield, which is a grounded slit-patterned cylindrical metal body, is applied between the RF coil and the dielectric, but when the Faraday shield is applied, there are problems such as a loss of existing input energy occurring, so that a greater RF power must be applied to compensate, and thus the electromagnetic field zone increases further, which may affect peripheral devices. However, in the present invention, the plasma chamber is formed as a double-tube chamber with an inner wall and an outer wall, and an insulating material is circulated inside the chamber, so that the distance between the inner wall of the plasma chamber and the RF coil is sufficiently far and the space between them is reliably insulated, so that the electrical capacitive coupling can be reduced and the structure simplified without the Faraday shield.

FIG. 4 is a conceptual diagram of a gas injection device to which a check valve plug is applied in an ion beam source according to a preferred embodiment of the present invention.

Referring to Fig. 4, the gas required for plasma generation is supplied through a gas injection device (32) mounted on the inlet cover electrode (21). At this time, a check valve plug (38), which is a component of a check valve plug assembly (37), is applied to the gas injection port (36) of the gas injection device (32).

The check valve plug (38) constituting the above check valve plug assembly (37) is applied for the purpose of completely separating the internal space of the plasma chamber from the gas injection device (32) rather than for the purpose of preventing the backflow of gas. To explain this in more detail, the inside of the plasma chamber required for generating an ion beam must be maintained in a vacuum state of about 10-2 Torr, and in order to create the above vacuum state, the pressure of the internal space of the plasma is exhausted through the beam outlet of the accelerating electrode described later. Therefore, the more clearly the internal space of the plasma chamber is divided, the more accurately it is possible to express the vacuum degree value, which is the standard for the conditions for generating and maintaining plasma.

However, in the case of the existing plasma ion beam source, not only is the gas injection port (36) of the gas injection device (32) that supplies gas into the inside of the plasma chamber formed in a structure having one or more holes, but also there is no means for separating the internal space of the plasma chamber from the gas injection device (32), so that the internal space of the plasma chamber easily expands to the gas injection device (32) and the gas supply line, resulting in the same result as the internal space of the plasma chamber expanding. In other words, in the case of the existing plasma ion beam source, the internal space of the plasma chamber, which has a significant effect on the generation of the ion beam, expands to the gas injection device (32) and the gas supply line, which lowers the vacuum suction efficiency and makes it impossible to limit the plasma generation area to only the internal space of the plasma chamber. In order to solve this problem, the present invention applies a check valve plug (38) that can separate the internal space of the plasma chamber from the gas injection device (32).

The above check valve plug assembly (37) is an assembly installed in a gas injection device (32), and is configured to include a check valve plug (38) having a conical tip so that it can be easily inserted into a gas injection port (36) to seal gas, a spring (39) arranged below the check valve plug (38) so that the check valve plug (38) can be elastically supported, and a headless bolt (40) that can adjust the elasticity of the spring. In the check valve plug assembly (37), the headless bolt (40) is arranged below the spring (39) and rotates left and right to adjust the elasticity of the spring (39) by adjusting the length of the spring (39), and the spring (39) pressurizes the check valve plug (38) installed above by the elasticity, thereby suitably adjusting the gas supply pressure supplied into the plasma chamber through the gas injection port (36).

After the check valve assembly (37) of the above-described structure is mounted on the gas injection device (32), the head bolt (40) is rotated to adjust the operating pressure of the spring (39), so that the gas supplied through the gas injection port (36) can be supplied with a precision of 0.1 sccm (standard cubic centimeter per minute) or less, and as described above, the internal space of the plasma chamber can be prevented from expanding to the gas injection device (32) and the gas supply line, so that the plasma generation area can be limited to only the internal space of the plasma chamber, and the problem of reduced vacuum suction efficiency can also be prevented.

FIG. 5 is a conceptual diagram illustrating the circulation of an insulating material circulating in the space between the inner and outer walls of a plasma chamber in an ion beam source according to a preferred embodiment of the present invention, FIG. 6 is a perspective view and a cross-sectional view of an accelerating electrode in an ion beam source according to a preferred embodiment of the present invention, FIG. 7 is a cross-sectional view of an entrance cover electrode and an accelerating electrode in an ion beam source according to a preferred embodiment of the present invention, FIG. 8 is a conceptual diagram illustrating the generation of particles in an ion beam source according to a preferred embodiment of the present invention, and FIG. 9 is a cross-sectional view showing a cap-shaped structure of an accelerating electrode in an ion beam source according to a preferred embodiment of the present invention.

Referring to FIG. 5, an insulating material inlet (34) and an insulating material outlet (35) are formed in an inlet cover electrode (21) disposed at an inlet (30) of a plasma chamber, so that the insulating material can be circulated into a space (13) between the inner and outer walls (11, 12) of the plasma chamber. The reason for circulating the insulating material is that if heat caused by plasma generation is continuously applied to the insulating material through the inner wall of the plasma chamber, the function of the insulating material can be affected, and thus, by circulating the insulating material, the problem of continuous exposure to heat can be solved.

As the insulating material, insulating oil having a specific gravity greater than that of water is used. Since this insulating oil has a specific gravity greater than that of water, even when injected at a low speed through the insulating material inlet (34), it easily descends to the lower part of the space (13) between the inner and outer walls (11, 12) of the plasma chamber, thereby pushing up the insulating oil near the insulating material outlet (35) and allowing the insulating oil to circulate.

At this time, expansion pressure is generated in the plasma chamber due to the insulating material circulating in the space (13) between the inner and outer walls (11, 12), but the vacuum pressure inside the plasma chamber can offset the expansion pressure at the center. In addition, the upper and lower sides are reinforced with holder mounts (33, 53) each having an O-ring (42) interposed between the outer wall (12) of the plasma chamber and the inlet cover holder (31) and the outlet cover holder (54) of the plasma chamber, which will be described later. The holder mount is formed in the shape of an inclined surface on the surface that comes into contact with the outer wall (12) of the plasma chamber and the inlet cover holder (31) or the outlet cover holder (54) of the plasma chamber, thereby strongly pressing the O-ring (42) and resisting the expansion pressure generated by the insulating material circulating in the space (13) between the inner and outer walls (11, 12).

Referring to FIGS. 6 to 8, the acceleration electrode is formed in a cap shape as a whole, but the upper part is formed in a rough shape in order to increase the surface area of the plasma exposure portion (22). Since gas molecules collide with electrons and are ionized, and the electrons are recombined and separated repeatedly to generate and maintain plasma, the unevenness is formed in the plasma exposure portion of the electrode so that more electrons can be continuously supplied as plasma fuel. At this time, electrons move by a sheath in the same potential space up to the uneven surface of the acceleration electrode, and ions are accelerated only after passing through the outlet of the acceleration electrode. Therefore, even if the unevenness is formed in the acceleration electrode, the effect of increasing electrons and increasing plasma fuel can be obtained without affecting other elements. The unevenness can be modified and used in any shape that can increase the surface area of the plasma exposure portion (22), including a waveform, and like the acceleration electrode, the inlet cover electrode (21) can also form the plasma exposure portion (24) in a rough shape.

As described above, the present invention improves the shape of the electrode to enable more stable generation and maintenance of plasma, thereby enabling emission of a constant amount of ion beam.

Referring to FIG. 9, it is preferable that the overall shape of the acceleration electrode be formed in a cap shape so as to prevent insulation breakdown. That is, when an ion beam is emitted from a plasma ion beam source, a part of the emitted beam may hit the extractor electrode (25) placed near the acceleration electrode, and the electrons generated at this time are accumulated on the ceramic plasma chamber outlet cover (51) and prevented from escaping to the ground. If the electrons continue to accumulate in this way, a potential is formed, and over time, a potential difference is generated with the acceleration electrode, which may lead to insulation breakdown. Therefore, it is preferable that the ceramic outlet cover (51) be formed in a cap shape that surrounds the extractor electrode so that it is not exposed to the electrons.

FIG. 10 is a conceptual diagram illustrating the inlet and outlet configurations of a double-tube plasma chamber in an ion beam source according to a preferred embodiment of the present invention, and FIG. 11 is a conceptual diagram explaining the arrangement of an O-ring for maintaining confidentiality in an ion beam source according to a preferred embodiment of the present invention.

Referring to FIG. 10, an inlet cover electrode (21), an inlet holder mount (33), and an inlet cover holder (31) are arranged on the inlet (30) side of the double-tube plasma chamber, and an outlet cover (51), an acceleration electrode holder (52), an outlet holder mount (53), an outlet cover holder (54), and an ion beam source base plate (55) are arranged on the outlet (50) side of the double-tube plasma chamber.

That is, on the inlet (30) side of the double-tube plasma chamber, an inlet cover electrode (21), an inlet holder mount (33), and an inlet cover holder (31) are arranged. As described above, an insulating material inlet (34) and an insulating material outlet (35) are formed in the inlet cover electrode (21), and a gas injection device (32) is also mounted. It is preferable that the inlet cover holder (31) be installed in combination with an inlet holder mount (33) that accommodates the inlet cover electrode (21) and resists expansion pressure generated by an insulating material circulating in the space (13) between the inner and outer walls (11, 12) of the plasma chamber.

In addition, an outlet cover (51), an outlet holder mount (53), and an outlet cover holder (54) are arranged on the outlet (50) side of the double-tubular plasma chamber. The outlet cover (51) accommodates a plasma chamber and an accelerating electrode, and the accelerating electrode is preferably configured to be supported by the accelerating electrode holder (52) while being coupled to an ion beam source base plate (55) that maintains a vacuum in the double-tubular plasma chamber by the outlet cover holder (54). The outlet cover holder (54) is preferably installed in combination with an outlet holder mount (53) that is installed to resist expansion pressure generated by an insulating material circulating in the space (13) between the inner and outer walls (11, 12) of the plasma chamber.

It is preferable that the above inlet cover holder (31), inlet holder mount (33), outlet cover (51), acceleration electrode holder (52), ion beam source base plate (55), outlet holder mount (53), and outlet cover holder (54) be formed of a ceramic material to enhance the insulating effect, and further, as shown in Fig. 11, it is preferable to add an O-ring (42) to necessary locations to prevent leakage of the insulating material, maintain the airtightness of the plasma chamber, and enhance the insulating effect.

Meanwhile, as illustrated in FIG. 12, an extractor electrode (25) is arranged below the accelerating electrode located on the exit (50) side of the plasma chamber. The extractor electrode (25) is an electrode for accelerating an ion beam by a potential difference with respect to the accelerating electrode and at the same time controlling the degree of convergence and divergence of the ion beam. In other words, if the potential difference between the extractor electrode (25) and the accelerating electrode is reduced, the divergence angle is reduced and the resolution is reduced, and if the potential difference is increased, the divergence angle is increased and the resolution is improved. However, since the amount of ion beam reaching the processing sample and whether or not insulation breakdown occurs must also be considered, the shape and the distance between the surrounding electrodes can be considered when arranged.

On the other hand, conventional plasma ion beam sources are not devices that can be used permanently by simply injecting gas. There are problems such as contamination of the plasma chamber, requiring the ion beam source to be disassembled to remove the insulating material and periodically cleaning the inside of the plasma chamber, or replacing the plasma chamber itself. Therefore, there is a need for easy maintenance.

Referring to FIG. 13, the capsule-type plasma chamber assembly (5) constituting the plasma ion beam source of the present invention comprises a plasma chamber including an inner wall (11) and an outer wall (12) made of a dielectric, an inlet cover electrode (21) positioned at the inlet (30) of the plasma chamber, an inlet cover holder (31), an inlet holder mount (33), a gas injection device (32) mounted on the inlet cover electrode (21), an outlet cover (51) positioned at the outlet (50) of the plasma chamber, an acceleration electrode (23) positioned on the outlet cover (51), and an acceleration electrode holder (52) supporting the acceleration electrode (23). When the plasma ion beam source of the present invention configured as described above needs to clean the inside of the plasma chamber, the capsule-type plasma chamber assembly (5) is separated from the ion beam source base plate (55), and only the acceleration electrode (23) and the acceleration electrode holder (52) are disassembled from the capsule-type plasma chamber assembly (5). The interior is easy to maintain.

Referring to FIG. 14, the plasma ion beam source of the present invention comprises a capsule-type plasma chamber assembly (5), an RF coil (41), an outlet holder mount (53), an outlet cover holder (54), and an ion beam source base plate (55) arranged outside the capsule-type plasma chamber assembly (5). The plasma ion beam source of the present invention configured as described above can be simply replaced with a new capsule-type plasma chamber assembly (5) by removing the capsule-type plasma chamber assembly (5) from the ion beam source base plate (55), if necessary. At this time, it is preferable to add an O-ring (42) to a necessary location so that the sealing of the plasma chamber can be maintained while the insulation effect can be strengthened.

Below, the usage state of the present invention is described.

By means of the ion beam generator of the present invention, an insulating material is circulated between the space (13) between the inner and outer walls (11, 12) of the plasma chamber, and a vacuum pressure of about 10-2 Torr is formed inside the plasma chamber. Then, an inert gas is injected into the inside of the plasma generation chamber through the gas injection device (32), and RF power is applied to the RF coil (41) arranged on the lower outer side of the plasma generation chamber. However, voltage is not yet applied to the inlet cover electrode (21). The inert gas injected into the plasma generation chamber by the RF power is ionized, and neutral plasma is generated. At this time, when a high voltage of 30 kV is applied to the inlet cover electrode (21), the accelerating electrode (23) becomes at the same potential as the inlet cover electrode (21) due to the plasma generated in the plasma generation chamber, and the emitted ions are accelerated by the potential difference between the accelerating electrode (23) and the extractor electrode (25), thereby generating an ion beam.

As described above, according to the ion beam generator of the present invention, even if a high voltage is applied while the RF coil is positioned close to the accelerating electrode without installing a Faraday shield, the RF coil is formed in a structure in which the RF coil does not come close to the inner wall of the plasma chamber where plasma is generated and maintained, but maintains an optimal distance and is separated by an insulating layer, so that damage to the dielectric due to the sputtering phenomenon is reduced, thereby obtaining the effect of reducing the level of contamination within the plasma chamber.

In addition, even if a high voltage is applied while the RF coil is positioned close to the accelerating electrode, the insulation is not destroyed, so plasma can be generated close to the outlet, thereby providing an ion beam that can process a sample in a short period of time.

In addition, the present invention can take advantage of both the vacuum external exposure type accelerating electrode and the vacuum internal placement type accelerating electrode, thereby providing a large amount of ion beams and enabling stable operation of the ion beam source.

In addition, the present invention has the effect of facilitating maintenance since the plasma chamber assembly of the plasma ion beam source is formed in a capsule shape and can be modularly replaced with the ion beam source base plate.

The above description of the present invention is for illustrative purposes, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential characteristics of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. For example, each component described as a single component may be implemented in a distributed manner, and likewise, components described as distributed may be implemented in a combined manner.

The scope of the present invention is indicated by the claims described below, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

1: ICP ion beam source 5: Plasma chamber assembly
10: Plasma chamber 11: Inner wall
12: Exterior wall 13: Space between inner and outer walls
20: Electrode 21: Inlet cover electrode
22: Plasma exposure area of the inlet cover electrode
23: Accelerating electrode 24: Plasma exposure part of the accelerating electrode
25: Extractor electrode
30: Inlet of plasma chamber 31: Inlet cover holder
32: Gas injection device 33: Inlet holder mount
34: Insulating material inlet 35: Insulating material outlet
36: Gas inlet 37: Check valve plug assembly
38: Check valve plug 39: Spring
40: Head bolt 41: RF coil
42: O-ring
50: Exit of plasma chamber 51: Exit cover
52: Accelerating electrode holder 53: Exit holder mount
54: Exit cover holder 55: Ion beam source base plate

Claims (7)

A capsule-shaped plasma chamber assembly comprising a plasma chamber having an inlet and an outlet and inner and outer walls for generating and maintaining plasma using gas introduced through the inlet, an inlet cover electrode positioned at the inlet of the plasma chamber and having an insulating material inlet and an insulating material outlet formed therein, a gas injection device mounted on the inlet cover electrode, an outlet cover positioned at the outlet of the plasma chamber, an accelerating electrode positioned on the outlet cover, and an accelerating electrode holder supporting the accelerating electrode; an extractor electrode positioned a predetermined distance below the accelerating electrode; an RF coil positioned outside the outer wall of the plasma chamber and providing RF power; and an insulating material circulation means for circulating an insulating material between the inner and outer walls of the plasma chamber; A high-voltage application and modular replaceable inductively coupled plasma ion beam source
In claim 1,
The plasma chamber is an inductively coupled plasma ion beam source capable of high voltage application and modular replacement, in which the inner and outer walls are formed of a dielectric, the accelerating electrode and the inlet cover electrode are formed of a metal, and the outlet cover is formed of a ceramic.
In claim 2,
The above ion beam source is a high voltage application and modular replaceable inductively coupled plasma ion beam source in which a high voltage of 30 kV is applied to the inlet cover electrode.
In any one of claims 1 to 3,
The RF coil of the above ion beam source is an inductively coupled plasma ion beam source that is placed on the lower part of the outer wall of the plasma chamber and is capable of being applied with a high voltage and being modularly replaced.
In any one of claims 1 to 3,
A high-voltage application and modularly replaceable inductively coupled plasma ion beam source in which the plasma exposure area of the accelerating electrode and the entrance cover electrode of the ion beam source is formed in a convex shape
In any one of claims 1 to 3,
A high-voltage, modularly replaceable inductively coupled plasma ion beam source with a check valve plug applied to the gas injection device of the above ion beam source.
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