KR101188604B1 - Ion beam generating device - Google Patents

Abstract

PURPOSE: An ion beam generator is provided to change a cross-sectional area by including a flow route formation part drawing out ion beam and to improve focusing and density of ion by a formed magnetic field structure. CONSTITUTION: A magnetic material(110) generates a magnetic field. A body(120) accepts the magnetic material in inside. The body is grounded with the magnetic material. An anode(130) applies high voltage in discharge gas inside the body. A cathode comprises a flow route formation part. A focusing part is formed at one side of the flow route formation part. The focusing part forms the magnetic field in a direction which is at right angles to an ion beam draw-out direction.

Description

Ion beam generating device

The present invention relates to an ion beam generator, and more particularly, to an ion beam generator to improve the density and focus of the ion beam by specifying the shape of the cathode which is one component of the anode layer type ion beam generator.

The ions generated by electric discharge of the neutral gas are accelerated into the electric field to form an ion beam.

Such an ion beam may have directionality and may be in a high energy state.

In addition, the ion beam may be classified into a focused ion beam and an ion shower according to focusing, sputtering and implanting according to the energy range of the accelerated ions. (implanting), deposition, reactive ion etching, measurement and surface treatment.

That is, the ion beam device using the energy of the ion is a device that generates a large amount of ions such as protons, helium, nitrogen, argon, xenon and the like and accelerates them to several tens of keV or more to inject into the material or irradiate the surface.

Accordingly, ion beams are widely used for surface modification and micromachining of materials such as improving the hardness, wear resistance and corrosion resistance of metal surfaces, improving electrical conductivity of polymer surfaces, blocking UV rays, and controlling light transmittance.

On the other hand, the Anode layer type ion beam generating device induces the rotational movement in the closed loop of the electrons by the magnetic field and the electric field formed between the electrodes, thereby effectively emitting ionized ions with high energy of 500eV or more.

At this time, the current density, energy, and beam spreading characteristics of the ion beam drawn out are determined by the structure of the electrode, the strength and structure of the magnetic field, and the gas distribution in the ion source. Accordingly, various structural improvements are made to develop an ion beam generator suitable for various applications. This has been tried.

In addition, the anode layer type ion beam generator is operated in the form of collimated beam and diffused beam according to the operating pressure range. In the case of the collimated beam type, the high energy ion beam can be drawn out at a low current and used for surface etching and shape control.

On the other hand, in the case of the diffused beam type operating conditions, low energy ion beams can be drawn at a high current and are mainly used for the deposition process.

In various surface treatment processes, the high ion density of the extracted ion beam is required to enable rapid etching and deposition processes, and thus, the ion beam current density needs to be improved, and a high durability ion beam generator for stable ion beam extraction even in a large area for a long time operation is required. Development is required.

1 is a partially enlarged view showing the shape of a cathode, which is one component of an anode layer type ion beam generator according to the prior art, and left and right photographs are computer simulations of electron and ion behavior.

As shown in the figure, the cathode 1 according to the prior art is configured in parallel with each other in the shape of the nearest place in the surface facing each other.

Therefore, there is a problem that the distribution of electrons affects the extraction electric field distortion that accelerates the ions, thereby lowering the collecting speed and the extraction energy of the extracted ion beam.

An object of the present invention for solving the above problems is to provide an ion beam generating device to improve the density and focus of the ion beam by specifying the shape of the cathode, which is one configuration of the anode layer type ion beam generating device.

Another object of the present invention is to specify the shape of the cathode to control the intensity distribution of the magnetic field present in the space between the cathode, and to minimize the collision between the cathode and the electron ion beam to reduce the spread of the ion beam and improve the density The present invention provides a generator.

An ion beam generating apparatus according to the present invention includes a magnetic body generating a magnetic field, a body accommodating the magnetic body therein, a body grounded with the magnetic body, an anode for applying a high voltage to a discharge space inside the body, and an opening inside the body. And a cathode including a flow path forming portion that enables the extraction of the ion beam to the outside of the body by forming an ion extracting flow path. The flow path forming portion is characterized in that the cross-sectional area is changed toward the height direction.

One side of the flow path forming portion, characterized in that the focusing portion having an acute longitudinal section shape.

The surface of the flow path forming portion is characterized in that made of a straight line crossing each other.

The focusing unit may form a magnetic field in a direction orthogonal to the ion beam extraction direction.

The focusing part may be provided in plural in the height direction of the flow path forming part.

The plurality of focusing parts may have different separation distances.

The flow path forming unit may have a symmetrical or asymmetrical shape with respect to the center.

The plurality of focusing portion is characterized by having a separation distance of 1 to 5mm.

In the present invention, the ion beam generating device is provided with a flow path forming portion that enables the extraction of the ion beam on one side of the cathode, but is configured such that the cross sectional area changes in the height direction.

That is, and the flow path forming section was provided with a focusing section having an acute angle of longitudinal section shape.

As a result, a magnetic field orthogonal to the ion beam extraction direction is formed, and the concentration and density of ions can be improved by the formed magnetic field structure, and thus the extraction performance is improved.

In addition, the etching rate is improved due to the focusing and the density of the ions, and there is an advantage that can be stably applied to a high discharge voltage without causing arc generation.

1 is a partially enlarged view showing the shape of a cathode as one configuration in the anode layer type ion beam generator according to the prior art.
Fig. 2 is a schematic diagram showing the configuration of an ion beam generator in which preferred embodiment 1 of the present invention is adopted.
Figure 3 is a result of calculating the discharge behavior characteristics of the ion beam generator adopting a preferred embodiment 1 of the present invention through computer simulation.
Fig. 4 is a partial schematic diagram showing the construction of an ion beam generator in which preferred embodiment 2 of the present invention is adopted.
5 is a result of calculating the discharge behavior characteristics of the ion beam generator adopting a preferred embodiment 2 of the present invention through computer simulation.
Fig. 6 is a partial schematic view showing the construction of an ion beam generator in which preferred embodiment 3 of the present invention is adopted.
7 is a result of calculating the discharge behavior characteristics of the ion beam generator adopting a preferred embodiment 3 of the present invention through computer simulation.
8 is a graph comparing current densities of ion beams measured for ion beam extraction performance evaluation of preferred examples and comparative examples of the present invention.
9 is a graph comparing the etching rate measured for the evaluation of the ion beam extraction performance of the preferred embodiment and the comparative example of the present invention.

Hereinafter, a configuration of an ion beam generator according to the present invention will be described with reference to FIG. 2.

Prior to this, terms and words used in the present specification and claims should not be construed in a conventional and dictionary sense, and the inventor may appropriately define the concept of the term in order to describe its invention in the best possible way It should be construed as meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely preferred embodiments of the present invention, and are not intended to represent all of the technical ideas of the present invention. Therefore, various equivalents It should be understood that water and variations may be present.

2 is a schematic diagram showing the configuration of an ion beam generator in which preferred embodiment 1 of the present invention is adopted.

As shown in the drawing, the ion beam generating apparatus 100 is an apparatus for forming an ion beam by accelerating ions with an electric field. The ion beam generating apparatus 100 accommodates a magnetic body 110 generating a magnetic field and the magnetic body 110 therein, and the magnetic body ( 110 and the grounded body 120, the positive electrode 130 for applying a high voltage to the discharge gas in the body 120, and the ion extracting flow path 142 to open the body 120 to form a body It includes a cathode 140 having a flow path forming portion 144 that allows the extraction of the ion beam to the outside (120).

The magnetic body 110 and the body 120 are made of a magnetic body 110 is grounded to 0V, the anode 130 is made of a non-magnetic material is accommodated in the body 120.

In addition, a gas inflow path (not shown) is formed at one side of the body 120 to allow discharge gas to flow therein.

The magnetic body 110, the body 120, and the anode 130 may be changed to various shapes and positions, and the ion beam generator 100 may control the density of the ion beam by specifying the shape of the cathode 140. Done.

That is, the cathode 140 has an ion extracting passage 142 formed to open the body 120 to the outside to draw the ion beam, and limits the shape of the ion extracting passage 142 to limit the concentration of ions. And to increase the density.

In more detail, the cathode 140 forms the ion extracting passage 142 by the channel forming unit 144, and the channel forming unit 144 is symmetric with respect to the center of the ion extracting channel 142. It has a shape.

Therefore, the ion extracting flow passage 142 has a shape formed by stacking a plurality of concentric circles, and is configured to change the separation distance toward the height direction of the cathode 140.

The flow path forming unit 144 may be configured to have an asymmetrical shape with respect to the center as necessary.

That is, the extraction pattern of the ion beam may be varied by variously changing the shape of the ion extraction channel 142.

In addition, the cross-sectional area of the flow path forming part 144 changes in the thickness direction of the cathode 140. That is, since the surface of the flow path forming part 144 forms the ion extracting flow path 142, the shape corresponding to the outer surface of the flow path forming part 144 corresponds to the inner wall surface of the ion extracting flow path 142. Will have

The cathode 140 may be formed by fastening a plurality of pieces to the body 120 to form the ion extracting flow path 142, or may be formed by processing a single component ion extracting flow path 142 to be perforated.

The flow path forming part 144 is provided with a focusing part 146. The focusing part 146 is configured to be formed in a straight line crossing each other on the surface of the flow path forming portion 144 formed to be inclined in the inner direction of the ion extraction passage 142 so that the cross-sectional shape has an acute angle.

That is, the focusing portions 146 adjacent to each other form a magnetic field in a direction orthogonal to the extraction direction of the ion beam, that is, in a horizontal direction, thereby increasing the focusing rate of the ions.

Figure 3 is a result of calculating the discharge behavior characteristics of the ion beam generator adopting a preferred embodiment 1 of the present invention by computer simulation, the object simulation Oriented Particle in Cell (OOPIC) computer simulation, the calculation conditions are pressure 1 mTorr, discharge Voltage is 3kV.

Looking at comparing the embodiment of FIG. 3 and the comparative example of FIG. 1, it can be seen that in the case of FIG. 3, in which the preferred embodiment of the present invention is adopted, the ion beam focusing speed and the generated ion density are excellent.

As a result, the magnetic force line distribution determines the electron confinement efficiency when the electron is constrained by the magnetic field, and when applied to the ion beam generator 100, the magnetic field distribution in the space between the cathode 140 and the cathode 140 increases the electron confinement efficiency. You can confirm the decision.

In particular, when the intensity distribution of the magnetic field existing in the space between the cathodes 140 is strong near the cathode 140 and weak between the cathode 140 and the cathode 140, the collision between the cathode 140 and the electrons is minimized, It can be seen that the restraint is effective, and it is possible to control the spreading phenomenon of the ion beam drawn out through the restraint position control of electrons.

Accordingly, when the shape of the cathode 140 is performed as in the embodiment, the restraint position of the electrons is distributed between the anode 130 and the cathode 140, which is less affected by the extraction electric field distortion that accelerates the ions. This means that the ion beam focusing speed can be improved.

On the other hand, the cathode 140 can be modified to have a variety of shapes as a way to increase the concentration of ions.

4 is a partial schematic view showing the configuration of an ion beam generator adopting a preferred embodiment 2 of the present invention, Figure 5 is calculated through computer simulation the discharge behavior characteristics of the ion beam generator adopting a preferred embodiment 2 of the present invention As a result, as shown in the accompanying drawings, in the second embodiment, two focusing portions 146 are formed on each of the cathodes 140.

Therefore, the ion extracting passage 142 has a ZIGZAG shape, and as the ions generated between the cathode 140 and the anode 130 pass through the flow path forming unit 144 as shown in FIG. 5, the ion beam spreads. It can be seen that decreases.

That is, as the plurality of focusing units 146 are provided, additional ionization may occur by electrons present in the ion extracting flow path 142 between the focusing units 146, and may be formed between the anode 130 and the cathode 140. By suppressing excessive electron density in the discharge space, inefficient ion acceleration and arcing occurrence of the electric field can be prevented.

 Among the plurality of focusing parts 146, the focusing part 146 located on the upper side has a distance of 2 mm spaced apart in the horizontal direction, and the focusing part 146 located on the lower side is configured to be spaced apart by 4 mm.

In addition, it was confirmed that the cathode 140 of the second embodiment slightly improved the density of the ion beam compared to the cathode 140 of the first embodiment, and the generation of the ion beam with uniform density was possible.

Meanwhile, the cathode 140 may be provided in plural as shown in FIGS. 6 and 7, but the separation distance may be different from that of the second embodiment.

6 is a partial schematic view showing the configuration of an ion beam generator adopting a preferred embodiment 3 of the present invention, Figure 7 is calculated through computer simulation the discharge behavior characteristics of the ion beam generator adopting a preferred embodiment 3 of the present invention As a result, the cathode 140 of the third embodiment is formed so that the separation distance of the focusing unit 146 located on the upper side is closer than the separation distance of the focusing unit 146 located on the lower side.

That is, the horizontal separation distance of the focusing part 146 located on the upper side among the plurality of focusing parts 146 is 4 mm, and the horizontal separation distance of the focusing part 146 located on the lower side is 2 mm. Configured.

As a result, even when the lower side is formed to have a narrow distance in the separation distance of the focusing unit 146, the ion beam focusing characteristics were excellent and the ion beam of uniform density was possible.

As described above, the magnetic field structure and intensity can be controlled by controlling the shape of the cathode 140 and the separation distance of the focusing unit 146, and the spreading characteristics of the ion beam can be controlled using the same.

Hereinafter, with reference to the accompanying Figure 8 will be described by comparing the current density of the Example and Comparative Example.

FIG. 8 is a graph comparing current densities of ion beams measured for ion beam extraction performance evaluation of preferred embodiments of the present invention and comparative examples. FIG.

As shown in FIG. 8, when the simulation results of electrons (left photo) and ions (right photo) are viewed, the focusing portion 146 located above the plurality of focusing portions 146 has a distance of 2 mm in the horizontal direction. , Focusing portion 146 located on the lower side was configured to be spaced apart 4mm.

In addition, it was confirmed that the cathode 140 of the second embodiment slightly improved the density of the ion beam compared to the cathode 140 of the first embodiment, and the generation of the ion beam with uniform density was possible.

According to the embodiment of the present invention, the plasma can be effectively constrained by optimizing the magnetic field of the discharge space between the cathodes 140, and the ion beam extraction performance was confirmed to be improved when compared with the comparative example.

In more detail, the ion beam extraction performance can be evaluated by measuring the current density of the ion beam being drawn out, and the working pressure is 1.3 ± 0.1 mTorr, and the discharge gas is 25 sccm injected with argon (Ar) in both the examples and the comparative examples.

The distance between the cathode 140 and the ion beam current density measuring device is equal to 100 mm, and the ion beam current density measurement was performed through an ion current incident into a faraday cup having a diameter of 3.5 mm.

As a result, it can be seen that the ion beam current density drawn at the same discharge voltage is about 2.5 times higher than that of the comparative example.

This means that the cathode 140 of the embodiment has a structure optimized for electron confinement and thus generates ions more actively than the cathode of the comparative example as the electron density is high in the discharge space between the cathodes 140.

In addition, by effectively constraining the electrons in the space between the cathodes 140, it is possible to stably apply a discharge voltage up to about 3 kV without generating an arc, which is a result of improved device stability compared to the cathode of the comparative example.

Hereinafter, the etch rate was compared with reference to FIG. 9.

9 is a graph comparing the etching rate measured for the evaluation of the ion beam extraction performance of the preferred embodiment and the comparative example of the present invention, the result of measuring the etching rate for the silicon (Si) substrate.

The pressure was 1.3 ± 0.1 mTorr, the discharge gas was injected in the same amount of argon (Ar) 25 sccm, the distance between the cathode and the etching specimen in both Comparative Examples and Examples was set to 50mm.

Then, the etching specimen was positioned to be orthogonal to the opening direction of the ion extraction channel 142, and then the etching rate was measured after ion beam etching for 5 minutes.

At this time, as the discharge voltage, the maximum applied voltage to the cathode of the comparative example and the example was applied.

That is, 2.5 kV was applied to the negative electrode of the comparative example and 3.0 kV was applied to the negative electrode 140 of the example.

As a result, the etching rate of the embodiment showed an etching rate of about 4 times or more compared with the etching rate of the comparative example, and as a result, the focusing rate of the ion beam through the cathode 140 according to the embodiment showed an improved current density than the comparative example. Can be.

The scope of the present invention is not limited to the above-described embodiments, and many other modifications based on the present invention will be possible to those skilled in the art within the scope of the present invention.

100. Ion beam generator 110. Magnetic material
120.Body 130.Anode
140. Cathode 142. Ion Withdrawal Channel
144. Flow path forming section 146. Focusing section

Claims (8)

Magnetic material generating a magnetic field,
A body which accommodates the magnetic material therein and is grounded with the magnetic material;
An anode for applying a high voltage to the discharge gas inside the body;
It comprises a cathode having a flow path forming portion for forming the ion extracting passage to open the inside of the body to enable the extraction of the ion beam to the outside of the body,
The flow path forming unit is an ion beam generator, characterized in that the cross-sectional area is changed toward the extraction direction of the ion beam. The ion beam generating apparatus of claim 1, wherein a side of the flow path forming unit includes a focusing unit having an acute angle in a longitudinal cross-sectional shape. The ion beam generating apparatus of claim 2, wherein surfaces of the flow path forming unit are formed in a straight line crossing each other. The ion beam generating apparatus of claim 3, wherein the focusing unit forms a magnetic field in a direction orthogonal to the ion beam extraction direction. The ion beam generating device according to any one of claims 2 to 4, wherein the focusing part is provided in a number of directions in a height direction of the flow path forming part. The ion beam generator of claim 5, wherein the plurality of focusing portions have different separation distances. The ion beam generating apparatus of claim 6, wherein the flow path forming unit has a symmetrical or asymmetrical shape with respect to a center thereof. 8. The ion beam generator of claim 7, wherein the plurality of focusing portions have a separation distance of 1 to 5 mm.

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