TWI697932B - Ion gun - Google Patents

Abstract

An ion gun includes: an anode; a magnetic pole that has an inner surface facing the anode, an outer surface located on the opposite side of the inner surface, a slit provided at a position corresponding to the anode, and an outer inclined surface extending from one end of the outer surface toward a center of the slit and forming part of the slit; and a cover that covers at least the outer surface and the outer inclined surface and is formed of a non-magnetic material.

Description

Ion gun

The present invention relates to an ion gun.

Previously, the process of using ion beams drawn from ion guns was mostly adopted, and ion guns were mounted on various devices. Generally speaking, an ion gun has a structure that generates plasma between a slit formed in a magnetic pole (cathode) and an anode (anode), and leads the ion beam to the outside through the slit (for example, refer to US Patent Application Publication No. 2012/0187843 No. manual).

In recent years, it is required to increase the magnetic field intensity of the ion gun, and seek to increase the etching rate of the processed body. However, in this manufacturing process, there are the following problems: the magnetic poles are easily consumed by plasma, the gap between the magnetic poles is widened, and the discharge current is reduced. In addition, there are also the following problems: the frequency of replacing the consumed magnetic poles with new ones increases, and the maintenance is poor. Furthermore, there are the following problems: with the consumption of the magnetic poles, pollution caused by the material of the magnetic poles is generated, which has a bad influence on the manufacturing process of the ion gun.

The present invention was completed in consideration of this situation, and its purpose is to provide an ion gun that can suppress the abrasion of the slits formed in the magnetic poles, improve maintenance by reducing the frequency of replacement of the magnetic poles, and can suppress the damage caused by the material of the magnetic poles. The production of pollution.

An ion gun of one aspect of the present invention includes: an anode; a magnetic pole having an inner surface opposed to the anode, an outer surface located on the opposite side of the inner surface, a slit provided at a position corresponding to the anode, and Extending from one end of the outer surface toward the center of the slit and forming a part of the outer inclined surface of the slit; and an outer cover that covers at least the outer surface and the outer inclined surface and includes a non-magnetic material.

In the ion gun according to an aspect of the present invention, the magnetic poles may have vertical surfaces parallel to each other, which extend from one end of the outer inclined surface toward the inner surface and form part of the slit; and the outer cover is covered The above vertical plane.

In the ion gun according to an aspect of the present invention, the magnetic pole may also have an inner inclined surface, which extends from an end of the inner surface toward the center of the slit and forms a part of the slit.

In the ion gun according to an aspect of the present invention, the outer cover may also include: a first covering portion that covers the outer surface of the magnetic pole; and a second covering portion that is connected to the first covering portion and covers the outer surface Inclined surface.

In the ion gun according to an aspect of the present invention, the outer cover may be provided with a third covering part connected to the second covering part, and the third covering part is connected to the first covering part and the second covering part. The connected part is the part on the opposite side extending toward the anode.

In the ion gun according to one aspect of the present invention, the non-magnetic material constituting the outer cover may also include a material selected from the group consisting of carbon, titanium, and copper. The non-magnetic material constituting the outer cover is particularly preferably carbon. [Effects of Invention]

According to the above aspect of the present invention, the abrasion of the slit formed in the magnetic pole can be suppressed, the maintenance performance can be improved by reducing the frequency of replacement of the magnetic pole, and the pollution caused by the material of the magnetic pole can be suppressed.

The ion gun of the embodiment of the present invention will be described with reference to the drawings. In the drawings used in the description of this embodiment, the reduction ratio of each member is appropriately changed in order to make each member a recognizable size.

(Linear ion gun) Fig. 1 is a perspective view showing a schematic structure of a linear ion gun (ion gun) according to an embodiment of the present invention. Fig. 2 is a cross-sectional view taken along the line A-A of Fig. 1; Fig. 3 is an enlarged cross-sectional view of the main part of the linear ion gun showing the embodiment of the present invention.

As shown in FIG. 1, the linear ion gun 10 includes a yoke 20, a magnetic pole 30, an anode 40, a magnet 50, a cover 60, and an insulating part 70.

The linear ion gun 10 has a simple structure that does not require extraction electrodes such as grid electrodes, and can use a high-frequency power source to generate plasma P and ion beam BM by ion acceleration. In addition, the linear ion gun 10 does not have a hot filament, so it can operate for a long time even in an oxygen environment, has low cost, and has high reliability.

Furthermore, FIG. 1 only shows the linear ion gun 10, and a moving device that moves or shakes the linear ion gun 10 can also be connected to the linear ion gun 10. The structure of the moving device is appropriately selected according to the device using the linear ion gun 10.

As shown in FIG. 1, the linear ion gun 10 has an opening 11 in the shape of a track including a straight portion and a curved portion. In the opening 11, a slit 31 of the magnetic pole 30 described below is arranged to cover the surface of the magnetic pole 30 and an outer cover 60. In other words, at the opening 11, the outer cover 60 is exposed. The curved portion (corner portion) of the opening 11 has a radius of curvature of, for example, 25 mm in a plan view.

(Yoke) The yoke 20 is a frame-shaped member made of iron surrounding the magnet 50 and the anode 40. The area surrounded by the yoke 20 is covered by the magnetic pole 30.

(magnetic pole) The magnetic pole 30 (cathode) has a size of 400 mm in total length×100 mm in width×10 mm in height when viewed from above. As the material constituting the magnetic pole 30, a ferromagnetic material can be preferably used, for example, steel such as SS400, and stainless steel such as SUS430.

As shown in FIG. 3, the magnetic pole 30 has a slit 31 provided at a position corresponding to the anode 40. The slit 31 is provided at a position corresponding to the opening 11.

Furthermore, the magnetic pole 30 has an inner surface 32 facing the anode 40, an outer surface 33 on the opposite side of the inner surface 32, and an outer inclined surface 35. The outer inclined surface 35 is an inclined surface extending obliquely downward from the end 34 (one end, upper end) of the outer surface 33 adjacent to the slit 31 toward the center of the slit 31 and forms a part of the slit 31.

Furthermore, in this embodiment, the magnetic pole 30 has two perpendicular surfaces 37 parallel to each other. The vertical surface 37 extends downward from the end 36 (one end, center end) of the outer inclined surface 35 toward the inner surface 32 to form a part of the slit 31.

(anode) The anode 40 (anode) is arranged separately from the back surface of the magnetic pole 30 so as to generate an electric field in a direction substantially perpendicular to the magnetic field generated by the magnet 50. A high-frequency power supply (not shown) is connected to the anode 40.

As the material constituting the anode 40, a non-magnetic body is preferably used.

The anode 40 is supported by the insulating part 70 inside the yoke 20.

(magnet) The magnet 50 includes SmCo (Samarium Cobalt) alloy, and generates a magnetic field in the width direction of the slit 31. In addition, NdFe (neodymium iron) can also be used for the magnet 50.

On the outer periphery of the yoke 20 or the anode 40, a water-cooling pipe (not shown) connected to a cooling water circulation device is provided. By flowing the cooling medium in the water-cooled tube, deformation of the magnetic pole 30 or the anode 40 can be prevented, and the linear ion gun 10 can be stably driven regardless of temperature.

(Housing) The outer cover 60 covers the outer surface 33 of the magnetic pole 30, the outer inclined surface 35 of the magnetic pole 30, and the surface (vertical surface 37) of the magnetic pole 30 in the slit 31.

The cover 60 has a first covering portion 61, a second covering portion 62, and a third covering portion 63.

The first covering portion 61 covers the outer surface 33 of the magnetic pole 30. The second covering portion 62 is connected to the first covering portion 61 and covers the outer inclined surface 35. The third covering portion 63 is connected to the second covering portion 62, and extends toward the anode 40 from the portion A connected to the first covering portion 61 and the second covering portion 62 on the opposite side. The third covering portion 63 covers the vertical surface 37.

In a state where the second covering portion 62 and the third covering portion 63 are fitted into the slit 31, the cover 60 is fixed to the magnetic pole 30 by a fastening member not shown.

The outer cover 60 preferably includes a material that is less corroded than the magnetic pole material. The outer cover 60 includes a non-magnetic material. Specifically, the non-magnetic material is selected from the group consisting of carbon, titanium, and copper. In particular, it is best to use carbon as a non-magnetic material.

Regarding the characteristics of carbon preferably used as the outer cover 60, the bending strength is preferably 34 MPa～74 MPa, the tensile strength is preferably 22 MPa～48 MPa, and the intrinsic resistance is preferably 11 μΩ∙m～17.5 μΩ∙m , Shore hardness is preferably 53-87. By using carbon having such characteristics, the cover 60 suitable for this embodiment can be formed.

Next, the function of the linear ion gun 10 constructed as above will be described.

The linear ion gun 10 is arranged in a chamber that maintains a reduced pressure environment. In the linear ion gun 10, in a state where Ar, O ₂ and other gases are supplied between the anode 40 and the magnetic pole 30 from a gas supply device not shown, a high-frequency power supply is applied between the anode 40 and the magnetic pole 30 High frequency voltage. Thereby, as shown in FIG. 2, plasma P is generated between the magnetic pole 30 and the anode 40, and the ion beam BM is drawn from the opening 11.

According to this embodiment, in the opening 11, the inclined surface 35 and the vertical surface 37 outside the slit 31 are covered by the cover 60, so the magnetic pole 30 is not exposed inside the slit 31. Therefore, it is possible to suppress the consumption of the magnetic pole 30 caused by the exposure of the magnetic pole 30 to the plasma in the slit 31, thereby preventing the gap between the slit 31 (the distance between the two ends 36) caused by the consumption of the magnetic pole 30 increase. As a result, a specified interval in the slit 31 can be maintained, thereby preventing a decrease in the discharge current. In addition, the life of the magnetic pole 30 can be prolonged, and the frequency of replacing the used magnetic pole with a new one can be reduced, thereby improving maintenance. Furthermore, by suppressing the consumption of the magnetic pole 30, the pollution caused by the material of the magnetic pole 30 can be suppressed, and the production process using the ion gun will not be adversely affected.

In this embodiment, the outer cover 60 includes a material that is less corroded than the magnetic pole material, and includes carbon. Carbon has a sputtering efficiency of about 1/3 compared with ordinary magnetic pole materials, so it can be better used as the material of the outer cover 60.

(Examples of changes in implementation) Next, referring to Figs. 4 to 6, a linear ion gun of a modification of the embodiment of the present invention will be described. In FIGS. 4 to 6, the same reference numerals are given to the same members as the above-mentioned embodiment, and the description thereof is omitted or simplified. With regard to the structure of the slit of the magnetic pole 30 or the structure of the cover 60, the modified example described below is different from the above-mentioned embodiment.

(Variation example 1) Fig. 4 is an enlarged cross-sectional view showing the main part of the linear ion gun of Modification 1 of the embodiment of the present invention.

The magnetic pole 30 has an inner inclined surface 38 instead of the vertical surface 37 described in the above embodiment. The inner inclined surface 38 is an inclined surface extending obliquely upward from the end 39 (one end, lower end) of the inner surface 32 toward the center of the slit 31 and forms a part of the slit 31. The inner inclined surface 38 is connected to the outer inclined surface 35 at the end 36.

In Modification 1, the outer cover 60 does not cover the inner inclined surface 38 and the inner inclined surface 38 is exposed in the opening 11.

Specifically, the outer cover 60 has the first covering portion 61 and the second covering portion 62 and does not have the above-mentioned third covering portion 63. The first covering portion 61 covers the outer surface 33 of the magnetic pole 30. The second covering portion 62 is connected to the first covering portion 61 and covers the outer inclined surface 35.

According to this modification 1, in the opening 11, the outer inclined surface 35 forming the slit 31 is covered by the outer cover 60, so the outer inclined surface 35 is not exposed inside the slit 31. Therefore, the consumption of the magnetic pole 30 caused by the outer inclined surface 35 being exposed to the plasma in the slit 31 can be suppressed, and the increase of the interval between the slits 31 caused by the consumption of the magnetic pole 30 can be prevented. As a result, the specified interval in the slit 31 can be maintained, thereby preventing a decrease in the discharge current and extending the life of the magnetic pole 30. Therefore, the same effect as the above-mentioned embodiment can be obtained.

(Variation 2) Fig. 5 is an enlarged cross-sectional view showing the main part of the linear ion gun of Modification 2 of the embodiment of the present invention.

Modification 2 shows that the outer cover 60 shown in FIG. 3 (the outer cover 60 provided with the first covering portion 61, the second covering portion 62, and the third covering portion 63) shown in FIG. 3 is fitted to the magnetic pole provided with the inner inclined surface 38 30 (variation 2, refer to Figure 4).

(Variation 3) Fig. 6 is an enlarged cross-sectional view of the main part of the linear ion gun showing the modification 3 of the embodiment of the present invention.

Modification 3 shows that the outer cover 60 shown in FIG. 4 (modification 1, the outer cover 60 provided with the first covering portion 61 and the second covering portion 62) is fitted to the magnetic pole 30 provided with the vertical surface 37 (embodiment, see FIG. 3 ) Situation.

In any of the modification examples 2 and 3, the outer inclined surface 35 forming the slit 31 is covered by the outer cover 60 in the opening 11, so the outer inclined surface 35 is not exposed inside the slit 31. Therefore, the consumption of the magnetic pole 30 caused by the outer inclined surface 35 being exposed to the plasma in the slit 31 can be suppressed, and the increase of the interval between the slits 31 caused by the consumption of the magnetic pole 30 can be prevented. As a result, the specified interval in the slit 31 can be maintained, thereby preventing a decrease in the discharge current and extending the life of the magnetic pole 30. Therefore, the same effect as the above-mentioned embodiment can be obtained.

In the above-mentioned embodiment and modified examples 1 to 3, the two outer inclined surfaces 35 arranged in line symmetry (line symmetry with respect to the center line of the slit) facing each other are provided inside the slit 31. In other words, in this structure, two corners facing each other with the end 36 as the apex are located inside the slit 31.

In addition, in FIG. 3 and FIG. 6, two vertical surfaces 37 that are opposed to each other and arranged line symmetrically are provided inside the slit 31. In this structure, the vertical surface 37 is connected to the end 36 which becomes the apex.

In addition, in FIG. 4 and FIG. 5, two inner inclined surfaces 38 that are arranged line-symmetrically opposite to each other are provided inside the slit 31. In this structure, the inner inclined surface 38 is connected to the end 36 which becomes the apex.

In this line-symmetrical structure, even if the magnetic pole 30 is consumed inside the slit 31, the line-symmetrical shape (similar relationship) is still maintained, so the discharge current will not decrease, and the discharge current can be kept stable (with time Variety).

The reason is that when it is assumed that the parts not covered by the outer cover in Figs. 4, 5, and 6 are equally consumed, it is obvious that the similar relationship of the shapes described above can be maintained.

The so-called similar relationship of the shape that can be maintained is substantially the same as the state (change) of the magnetic flux density generated inside the slit 31 only depending on the interval of the slit 31. It means that the magnetic flux distribution will not change due to the change of the surface shape of the magnetic pole 30 inside the slit 31.

The inventors of the present invention conducted simulations to evaluate the contribution of both the interval between the slits 31 and the change in the surface shape of the magnetic pole 30 inside the slit 31.

The following results are obtained: when the aim is to stabilize the ion current, compared with the change in the interval of the slit 31, maintaining the similar relationship of the shape of the mutually opposed magnetic poles 30 inside the slit 31 is essential for achieving the stability of the ion current Generally speaking, it is the dominant factor. It has been confirmed that this evaluation result matches the following example (experiment result).

Example Next, referring to FIG. 7 and embodiments, the effects of the present invention will be explained more specifically.

FIG. 7 is a graph comparing the previous comparative example of the linear ion gun with the example of the linear ion gun using the outer cover of the above embodiment, which shows the time-dependent change of the discharge current with the passage of the operating time. In Figure 7, the horizontal axis represents the operating time of the linear ion gun, and the vertical axis represents the change in the discharge current. Specifically, the so-called change in discharge current refers to the relative change in discharge current based on the operating time of 0 hours (1, 100%).

(Comparative example) In the linear ion gun of the comparative example, it is applied to the structure where the slit of the magnetic pole is not provided with a cover, that is, the structure where the constituent member of the magnetic pole is exposed in the slit.

In the comparative example, the discharge current is significantly reduced since the start of operation. Thereafter, until the operation time reached 7.5 hours, the discharge current gradually decreased. After 7.5 hours of operation, the decrease in discharge current continues. When the operating time reaches 50 hours, the amount of change in the discharge current becomes 0.71, and the discharge current is reduced by about 29% compared to before starting the operation. In addition, after the operation time reached 50 hours, the consumption of the magnetic pole in the linear ion gun of the comparative example was confirmed. As a result, it was confirmed that the shape due to the consumption occurred in the part corresponding to the end 36 of the magnetic pole 30 of this embodiment. Variety.

(Example) In the linear ion gun of this embodiment, the structure shown in the above embodiment (FIG. 3) is applied.

In this example, the discharge current was stable from the start of operation until the operation time reached 15 hours, and no significant decrease in the discharge current as shown in the comparative example was seen. After 15 hours of running time, the discharge current gradually decreases. The decrease in discharge current continues until the operating time reaches 35 hours. On the other hand, when the operation time exceeds 35 hours, no decrease in the discharge current is seen, and the discharge current is stable. When the operating time reaches 50 hours, the amount of change in the discharge current becomes 0.90, which is about 10% lower than the discharge current before the start of operation.

After comparing the comparative example with the example, it is clear that after 50 hours of operation time, the example can suppress the decrease of the discharge current by about 19% compared with the comparative example. That is, the structure in which the outer cover 60 shown in the above-mentioned embodiment is provided on the magnetic pole 30 helps to suppress the decrease in the discharge current.

Above, the preferred embodiments of the present invention have been described. Although the description has been made above, it should be understood that these are examples of the present invention and should not be considered as limiting. Additions, omissions, substitutions, and other changes can be made without departing from the scope of the present invention. Therefore, the present invention should not be regarded as limited by the above description, but by the scope of the patent application.

[Industrial availability] The present invention can be widely applied to ion guns that can suppress the abrasion of the slits formed in the magnetic poles, improve maintenance by reducing the frequency of replacement of the magnetic poles, and can suppress pollution caused by the material of the magnetic poles.

10‧‧‧Linear ion gun (ion gun) 11‧‧‧Open 20‧‧‧Yoke 30‧‧‧Magnetic pole 31‧‧‧Slit 32‧‧‧Inner surface 33‧‧‧Outer surface 34‧‧‧End 35‧‧‧Outer inclined surface 36‧‧‧End 37‧‧‧Vertical plane 38‧‧‧Inside inclined surface 39‧‧‧End 40‧‧‧Anode 50‧‧‧Magnet 60‧‧‧Cover 61‧‧‧First Covered Section 62‧‧‧Second Covered Section 63‧‧‧The third covered part 70‧‧‧Insulation Part A‧‧‧ Part B‧‧‧ BM‧‧‧Ion beam P‧‧‧Plasma

Fig. 1 is a perspective view showing a schematic structure of a linear ion gun according to an embodiment of the present invention. 2 is a diagram showing the schematic structure of the linear ion gun of the embodiment of the present invention, and is a cross-sectional view taken along the line A-A shown in FIG. 1. Fig. 3 is an enlarged cross-sectional view of the main part of the linear ion gun showing the embodiment of the present invention. Fig. 4 is an enlarged cross-sectional view showing the main part of the linear ion gun of Modification 1 of the embodiment of the present invention. Fig. 5 is an enlarged cross-sectional view of the main part of the linear ion gun showing the modification 2 of the embodiment of the present invention. Fig. 6 is an enlarged cross-sectional view of the main part of the linear ion gun showing the modification 3 of the embodiment of the present invention. Fig. 7 is a graph showing experimental results of an embodiment of the present invention.

10‧‧‧Linear ion gun (ion gun)

11‧‧‧Open

20‧‧‧Yoke

30‧‧‧Magnetic pole

31‧‧‧Slit

32‧‧‧Inner surface

40‧‧‧Anode

50‧‧‧Magnet

60‧‧‧Cover

70‧‧‧Insulation

BM‧‧‧Ion beam

P‧‧‧Plasma

Claims (5)

An ion gun comprising: an anode; a magnetic pole having an inner surface facing the anode, an outer surface on the opposite side of the inner surface, a slit provided at a position corresponding to the anode, and a magnetic pole from the outer surface One end extends toward the center of the slit and forms a part of the outer inclined surface of the slit; and an outer cover that covers at least the outer surface and the outer inclined surface and includes a non-magnetic material, wherein the outer cover includes: a first covering Part, which covers the outer surface of the magnetic pole; a second cover part which is connected to the first cover part and covers the outer inclined surface; a third cover part which is connected to the second cover part and is free from the first 1 The part where the covering part and the second covering part are connected is the part on the opposite side extending toward the anode; wherein, in the state where the second covering part and the third covering part are fitted into the slit, the outer cover is tightly The solid member is fixed to the above-mentioned magnetic pole. The ion gun of claim 1, wherein the magnetic poles have vertical surfaces parallel to each other, which extend from an end of the outer inclined surface toward the inner surface and form a part of the slit; and the outer cover covers the vertical surface. Such as the ion gun of claim 1, where The magnetic pole has an inner inclined surface extending from one end of the inner surface toward the center of the slit and forming a part of the slit. The ion gun of claim 1, wherein the non-magnetic material constituting the outer cover is selected from the group consisting of carbon, titanium, and copper. The ion gun of claim 4, wherein the non-magnetic material constituting the outer cover is carbon.

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