TW201941241A - 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 invention relates to an ion gun.

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

In recent years, a process for increasing the magnetic field strength of the ion gun and improving the etching rate of the object to be processed is required. However, in this process, there are problems in that the magnetic poles are easily consumed by the plasma, the gap (gap) between the magnetic pole slits is widened, and the discharge current is reduced. In addition, there is a problem that the frequency of replacing a consumed magnetic pole with a new magnetic pole is increased, and maintenance is poor. Furthermore, there is also a problem that contamination caused by the material of the magnetic pole is generated with the consumption of the magnetic pole, which adversely affects the process of using the ion gun.

The present invention was made in consideration of such a situation, and an object thereof is to provide an ion gun that can suppress abrasion of a slit formed in a magnetic pole, improve maintenance by reducing the frequency of replacement of the magnetic pole, and can prevent The generation of pollution.

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

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

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

In the ion gun according to one aspect of the present invention, the outer cover may further 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 portion. Inclined surface.

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

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

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

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

(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 sectional view taken along line AA in FIG. 1. FIG. 3 is an enlarged cross-sectional view showing a main part of a linear ion gun according to an 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 portion 70.

The linear ion gun 10 has a simple structure that does not require a lead electrode such as a grid electrode, and can generate plasma P using one high-frequency power source and ion beam BM by accelerating ions. In addition, the linear ion gun 10 does not have a hot filament, so it can be operated for a long time even in an oxygen environment, the cost is low, and the reliability is high.

In addition, FIG. 1 only shows the linear ion gun 10, and a moving device for moving or shaking the linear ion gun 10 may be connected to the linear ion gun 10. The structure of the mobile device is appropriately selected depending on the device using the linear ion gun 10.

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

(Yoke)
The yoke 20 is an iron frame-shaped member that surrounds 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 total length of 400 mm × width 100 mm × height 10 mm in a plan view. As a material constituting the magnetic pole 30, a ferromagnetic body can be preferably used, for example, steel such as SS400 and stainless steel such as SUS430 are used.

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 to 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 portion 34 (one end, upper end) of the outer surface 33 adjacent to the slit 31 toward the center of the slit 31 to form 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 portion 36 (one end, the 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 is arranged separately from the back surface of the magnetic pole 30 so that an electric field is generated in a direction substantially perpendicular to the magnetic field generated by the magnet 50. A high-frequency power source (not shown) is connected to the anode 40.

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

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

(magnet)
The magnet 50 includes an SmCo (SmCo) alloy, and generates a magnetic field in the width direction of the slit 31. 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 causing the cooling medium to flow 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 driven stably regardless of temperature.

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

The cover 60 includes 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 the portion B on the opposite side from the portion A connected to the first covering portion 61 and the second covering portion 62 extends toward the anode 40. 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 in the slit 31, the cover 60 is fixed to the magnetic pole 30 by a fastening member (not shown).

The cover 60 is preferably made of a material that is less susceptible to corrosion than the magnetic pole material. The cover 60 includes a non-magnetic material. Specifically, the non-magnetic material is selected from the group consisting of carbon, titanium, and copper. Particularly, it is preferable to use carbon as the non-magnetic material.

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

Next, the operation of the linear ion gun 10 configured as described above will be described.

The linear ion gun 10 is disposed in a chamber that maintains a reduced pressure environment. In the linear ion gun 10, when a gas such as Ar, O ₂ is 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. As a result, as shown in FIG. 2, a plasma P is generated between the magnetic pole 30 and the anode 40, and an ion beam BM is drawn from the opening 11.

According to this embodiment, since the inclined surface 35 and the vertical surface 37 outside the slit 31 are covered by the cover 60 in the opening 11, the magnetic pole 30 is not exposed inside the slit 31. Therefore, the consumption of the magnetic pole 30 due to the exposure of the magnetic pole 30 to the plasma in the slit 31 can be suppressed, and the interval between the slits 31 (the distance between the two end portions 36) caused by the consumption of the magnetic pole 30 can be prevented. increase. As a result, a specific interval in the slit 31 can be maintained, and a reduction in the discharge current can be prevented. In addition, the life of the magnetic pole 30 can be extended, and the frequency of replacing the used magnetic pole with a new magnetic pole can be reduced, thereby improving the maintainability. Furthermore, by suppressing the consumption of the magnetic pole 30, it is possible to suppress the generation of contamination caused by the material of the magnetic pole 30, without causing a bad influence on the process using the ion gun.

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

(Modifications of Implementation Mode)
Next, a linear ion gun according to a modified example of the embodiment of the present invention will be described with reference to FIGS. 4 to 6. In FIG. 4 to FIG. 6, the same components as those in the above embodiment are denoted by the same symbols, and descriptions thereof are omitted or simplified. In the structure of the slits of the magnetic pole 30 or the structure of the cover 60, the modification examples described below are different from the above-described embodiment.

(Modification 1)
FIG. 4 is an enlarged sectional view of a main part of a linear ion gun showing a modification example 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 that extends obliquely upward from the end portion 39 (one end, lower end) of the inner surface 32 toward the center of the slit 31 to form a part of the slit 31. The inner inclined surface 38 is connected to the outer inclined surface 35 at an end portion 36.

In the modification 1, the outer cover 60 is not covered with the inner inclined surface 38, and the inner inclined surface 38 is exposed in the opening 11.

Specifically, the cover 60 includes the first covering portion 61 and the second covering portion 62, and does not include the third covering portion 63 described above. 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 the first modification, since the inclined surface 35 outside the slit 31 in the opening 11 is covered by the cover 60, the external inclined surface 35 is not exposed inside the slit 31. Therefore, it is possible to suppress the consumption of the magnetic poles 30 caused by the outer inclined surface 35 being exposed to the plasma in the slits 31, and to prevent an increase in the interval of the slits 31 caused by the consumption of the magnetic poles 30. As a result, a specific 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, it is possible to obtain the same effect as that of the above embodiment.

(Modification 2)
FIG. 5 is an enlarged cross-sectional view showing a main part of a linear ion gun according to a second modification of the embodiment of the present invention.

Variation 2 shows that the outer cover 60 (Embodiment 1 including the first covering portion 61, the second covering portion 62, and the third covering portion 63 of the outer cover 60) shown in FIG. 3 is fitted to the magnetic pole having the inner inclined surface 38 30 (variation 2, see FIG. 4).

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

Variation 3 shows that the outer cover 60 (variation 1 including the first covering portion 61 and the second covering portion 62 including the outer covering 60) shown in FIG. 4 is fitted to a magnetic pole 30 having a vertical surface 37 (for an embodiment, refer to FIG. 3). ).

In any of the modified examples 2 and 3, since the inclined surface 35 outside the slit 31 is covered by the cover 60 at the opening 11, the outer inclined surface 35 is not exposed inside the slit 31. Therefore, it is possible to suppress the consumption of the magnetic poles 30 caused by the outer inclined surface 35 being exposed to the plasma in the slits 31, and to prevent an increase in the interval of the slits 31 caused by the consumption of the magnetic poles 30. As a result, a specific 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, it is possible to obtain the same effect as that of the above embodiment.

In the above-mentioned embodiment and modification examples 1 to 3, two outer inclined surfaces 35 which are arranged opposite to each other and are line-symmetrical (line-symmetrical with respect to the center line of the slit) are provided inside the slit 31. In other words, in this structure, two corner portions facing each other with the end portion 36 as an apex are located inside the slit 31.

In addition, in FIG. 3 and FIG. 2, two vertical planes 37 which are opposite to each other and are arranged symmetrically in a line are provided inside the slit 31. In this structure, the vertical surface 37 is connected to the end portion 36 that becomes a vertex.

In addition, in FIG. 4 and FIG. 2, two inner inclined surfaces 38 which are arranged opposite to each other and are arranged in line symmetry are provided inside the slit 31. In this structure, the inner inclined surface 38 is connected to the end portion 36 which becomes a vertex.

In such a linearly symmetric structure, even if the magnetic pole 30 is consumed inside the slit 31, the linearly symmetric shape is maintained (similar relationship), so the discharge current does not decrease, and the discharge current can be kept stable (over time Variety).

The reason is that if the parts not covered by the cover in FIG. 4, FIG. 5, and FIG. 6 are considered to be consumed equally, it is obvious that the similar relationship of the shapes described above can be maintained.

The similar relationship of the so-called maintainable shape and the condition (change) of the magnetic flux density generated inside the slit 31 have substantially the same meaning depending only on the interval of the slit 31. This means that the magnetic flux distribution does not change due to the change in the surface shape of the magnetic pole 30 inside the slit 31.

The present inventors confirmed the evaluation of 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 by simulation.

The following results were obtained: when the purpose of stabilizing the ion current is to maintain the similar relationship between the shapes of the magnetic poles 30 facing each other in the slit 31 compared to the change in the interval between the slits 31 to stabilize the ion current In terms of transformation, it is the dominant factor. It was confirmed that this evaluation result matches the following examples (experimental results).

EXAMPLES Next, the effects of the present invention will be described more specifically with reference to FIG. 7 and the examples.

FIG. 7 is a graph comparing a comparative example of a conventional linear ion gun with an example of a linear ion gun to which the outer cover of the above embodiment is applied, and it shows a change in the discharge current with the passage of time with time. In FIG. 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 change in the discharge current refers to a relative change in the discharge current based on a case where the operating time is 0 hours as a reference (1, 100%).

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

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

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

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

After comparing the comparative example with the example, it is clearly understood that, after 50 hours of operation time, the example can suppress a decrease in the discharge current by about 19% relative to 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 contributes to suppressing a reduction in the discharge current.

The preferred embodiments of the present invention have been described above. Although it has been described above, it should be understood that these are examples of the present invention and should not be considered as restrictors. Additions, omissions, replacements, 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 limited by the scope of patent application.

[Industrial availability]
The present invention can be widely applied to an ion gun that can suppress abrasion of a slit formed in a magnetic pole, improve maintenance by reducing the frequency of replacing the magnetic pole, and can suppress generation of pollution caused by the material of the magnetic pole.

10‧‧‧ linear ion gun (ion gun)

11‧‧‧ opening

20‧‧‧Yoke

30‧‧‧ magnetic pole

31‧‧‧Slit

32‧‧‧ inner surface

33‧‧‧ outer surface

34‧‧‧ tip

35‧‧‧Outer inclined surface

36‧‧‧ tip

37‧‧‧ vertical plane

38‧‧‧Inner inclined surface

39‧‧‧ tip

40‧‧‧Anode

50‧‧‧magnet

60‧‧‧Cover

61‧‧‧The first covered part

62‧‧‧ 2nd covered section

63‧‧‧ 3rd Covered Department

70‧‧‧Insulation Department

A‧‧‧Part

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.

FIG. 2 is a diagram showing a schematic structure of a linear ion gun according to an embodiment of the present invention, and is a cross-sectional view taken along line A-A shown in FIG. 1.

FIG. 3 is an enlarged cross-sectional view showing a main part of a linear ion gun according to an embodiment of the present invention.

FIG. 4 is an enlarged sectional view of a main part of a linear ion gun showing a modification example 1 of the embodiment of the present invention.

FIG. 5 is an enlarged cross-sectional view of a main part of a linear ion gun showing a modified example 2 of the embodiment of the present invention.

FIG. 6 is an enlarged sectional view of a main part of a linear ion gun showing a modification example 3 of the embodiment of the present invention.

Fig. 7 is a graph showing experimental results illustrating an example of the present invention.

Claims (7)

An ion gun having: anode; A magnetic pole having 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 a magnetic pole extending from one end of the outer surface toward the center of the slit And forming an inclined surface outside a part of the slit; and The outer cover covers at least the outer surface and the outer inclined surface, and includes a non-magnetic material. As claimed in the ion gun of item 1, wherein The magnetic poles have perpendicular planes parallel to each other, which extend from one 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. As claimed in the ion gun of item 1, wherein The magnetic pole has an inner inclined surface that extends from one end of the inner surface toward the center of the slit and forms a part of the slit. If the ion gun of any one of claims 1 to 3, wherein The cover includes: 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 inclined surface. As claimed in the ion gun of item 4, wherein The outer cover includes a third covering portion connected to the second covering portion, and The third coating portion extends from a portion on the opposite side from a portion connected to the first coating portion and the second coating portion toward the anode. As claimed in the ion gun of item 1, wherein The non-magnetic material constituting the cover is selected from the group consisting of carbon, titanium, and copper. As claimed in the ion gun of item 6, wherein The non-magnetic material constituting the cover is carbon.