阅读说明：本技术 离子枪 (Ion gun ) 是由 汤濑琢巳 于 2020-07-21 设计创作，主要内容包括：本发明的离子枪包括：阳极；磁极,具有与所述阳极相对的内表面、设置在与所述阳极对应的位置上的狭缝和从所述内表面的一端向所述狭缝延伸且形成所述狭缝的一部分的内倾斜面；和罩,至少包覆所述内表面及所述内倾斜面且由具有导电性和非磁性的材料构造,所述罩相对于所述磁极能够拆卸。(The ion gun of the present invention includes: an anode; a magnetic pole having an inner surface opposed to the anode, a slit provided at a position corresponding to the anode, and an inner inclined surface extending from one end of the inner surface to the slit and forming a part of the slit; and a cover that covers at least the inner surface and the inner inclined surface and is made of a material having conductivity and non-magnetism, the cover being detachable with respect to the magnetic pole.)

1. An ion gun, comprising:

an anode;

a magnetic pole having an inner surface opposed to the anode, a slit provided at a position corresponding to the anode, and an inner inclined surface extending from one end of the inner surface to the slit and forming a part of the slit; and

a cover that covers at least the inner surface and the inner inclined surface and is configured of a material having conductivity and non-magnetism, the cover being detachable with respect to the magnetic pole.

2. The ion gun of claim 1,

the cover includes: a first covering portion for covering the inner surface of the magnetic pole; and the second coating part is connected with the first coating part and coats the inner inclined plane.

3. The ion gun of claim 2,

the second coating portion of the cover has a vertical surface extending in a vertical direction with respect to the anode,

the vertical planes facing each other in the slit are parallel to each other.

4. The ion gun of claim 3,

the inner inclined surface of the magnetic pole has an inner front end located on a side of the inner inclined surface opposite to the one end of the inner surface,

the inner front end and the vertical face of the cover are aligned in a top view of the ion gun.

5. The ion gun of claim 2 or 3,

the inner inclined surface of the magnetic pole has an inner front end located on a side of the inner inclined surface opposite to the one end of the inner surface,

in a plan view of the ion gun, the cover has a protrusion protruding from the inner tip toward the slit.

6. The ion gun of any one of claims 1 to 5,

the magnetic pole has: an outer surface on an opposite side of the pole from the inner surface; and an outer inclined surface extending from one end of the outer surface toward the slit and forming a part of the slit,

the cover covers the inner surface, the inner inclined surface, the outer surface and the outer inclined surface.

7. The ion gun of any of claims 1 to 6,

the material from which the shield is constructed is selected from the group consisting of carbon, titanium and copper.

8. The ion gun of claim 7,

the material from which the shroud is constructed is carbon.

Technical Field

The invention relates to an ion gun.

The present application claims priority based on patent application No. 2019-163763, filed on 9/2019 sun.

Background

Conventionally, a process using an ion beam extracted from an ion gun is often used, and the ion gun is mounted in various apparatuses. Generally, an ion gun has the following structure (for example, see patent document 1): plasma is generated between a slit formed in a magnetic pole (cathode) and an anode (anode), and an ion beam is extracted to the outside through the slit.

Patent document 1: specification of U.S. patent application publication No. 2012/0187843

In recent years, a process for increasing the etching rate of an object to be processed by increasing the magnetic field strength of an ion gun has been demanded. However, this process has problems in that the magnetic pole is easily consumed by plasma, a slit interval (gap) of the magnetic pole is widened, and a discharge current is decreased. In addition, there is a problem that the frequency of replacing a consumed magnetic pole with a new magnetic pole increases and the maintainability is poor. Further, there is a problem that contamination due to the magnetic pole material is generated along with the consumption of the magnetic pole, and the process using the ion gun is adversely affected.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide an ion gun that can suppress wear of magnetic poles in magnetic pole slits, improve maintainability by reducing the frequency of replacement of magnetic poles, and suppress the occurrence of contamination due to magnetic pole materials.

An ion gun according to an aspect of the present invention includes: an anode; a magnetic pole having an inner surface opposed to the anode, a slit provided at a position corresponding to the anode, and an inner inclined surface extending from one end of the inner surface to the slit and forming a part of the slit; and a cover that covers at least the inner surface and the inner inclined surface and is made of a material having conductivity and non-magnetism, the cover being detachable with respect to the magnetic pole.

In the ion gun according to one aspect of the present invention, the cover may include: a first covering portion for covering the inner surface of the magnetic pole; and the second coating part is connected with the first coating part and coats the inner inclined plane.

In the ion gun according to one aspect of the present invention, the second coating portion of the cover may have vertical surfaces extending in a vertical direction with respect to the anode, and the vertical surfaces facing each other in the slit may be parallel to each other.

In the ion gun according to one aspect of the present invention, the inner inclined surface of the magnetic pole may have an inner tip located on a side of the inner inclined surface opposite to the one end of the inner surface, and the inner tip may be aligned with the vertical surface of the cover in a plan view of the ion gun.

In the ion gun according to the aspect of the present invention, the inner inclined surface of the magnetic pole may have an inner tip located on a side of the inner inclined surface opposite to the one end of the inner surface, and the cover may have a protrusion protruding from the inner tip toward the slit in a plan view of the ion gun.

In the ion gun according to one aspect of the present invention, the magnetic pole may include: an outer surface on an opposite side of the pole from the inner surface; and an outer inclined surface extending from one end of the outer surface toward the slit and forming a part of the slit, the cover covering the inner surface, the inner inclined surface, the outer surface, and the outer inclined surface.

In the ion gun according to one aspect of the present invention, the material constituting the cover may be selected from the group consisting of carbon, titanium, and copper. In particular, the material from which the cover is constructed is preferably carbon.

According to the above aspect of the present invention, it is possible to suppress consumption of the magnetic pole in the magnetic pole slit, improve maintainability by reducing the frequency of replacement of the magnetic pole, and suppress the occurrence of contamination due to the magnetic pole material.

Drawings

Fig. 1 is a perspective view showing a schematic configuration of a linear ion gun according to an embodiment of the present invention.

Fig. 2 is a diagram showing a schematic configuration 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 of a main part of a linear ion gun according to an embodiment of the present invention.

Fig. 4 is an enlarged cross-sectional view showing a main part of a linear ion gun according to modification 1 of the embodiment of the present invention.

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

Fig. 6 is an enlarged cross-sectional view showing a main part of a linear ion gun according to modification 3 of the embodiment of the present invention.

Fig. 7 is a graph for explaining the experimental results of the embodiment of the present invention.

Detailed Description

An ion gun according to an embodiment of the present invention will be described with reference to the drawings. In the drawings for describing the present embodiment, the scale of each member is appropriately changed so that each member can be made recognizable in size.

In the following description, the "plan view" refers to a plane viewed from above the ion gun, and refers to a plane viewed from a vertical direction of the magnetic pole 30 shown in fig. 1 or fig. 2 described later.

In the following embodiments, ordinal numbers such as "first", "second", and the like are added to avoid confusion of constituent elements, and are not limited to the numbers.

(Linear ion gun)

Fig. 1 is a perspective view showing a schematic configuration of a linear ion gun (ion gun) according to an embodiment of the present invention. Fig. 2 is a sectional view taken along line a-a of fig. 1. Fig. 3 is a diagram showing a main part of a linear ion gun according to an embodiment of the present invention, and is an enlarged cross-sectional view showing a peripheral member of a slit formed in a magnetic pole.

As shown in fig. 1, the linear ion gun 10 includes a yoke 20 and a magnetic pole 30. Inside the yoke 20, the anode 40, the magnet 50, the insulating portion 70, and a gas supply device G (described later) are disposed.

In the magnetic pole 30, a cover 60 (described later) is attached to an inner surface 32 of the magnetic pole 30 facing the anode 40.

The linear ion gun 10 has a simple structure that does not require extraction electrodes such as grid electrodes, and can generate plasma P and ion beam BM due to ion acceleration using one DC power supply (direct current). Further, since the linear ion gun 10 does not have a hot wire, it can be operated for a long time even in an oxygen atmosphere, and has low cost and high reliability.

Although only the linear ion gun 10 is shown in fig. 1, a moving device for moving or swinging the linear ion gun 10 may be connected to the linear ion gun 10. The structure of the moving means may be appropriately selected depending on the apparatus using the linear ion gun 10.

As shown in fig. 1, the linear ion gun 10 has a race track-shaped opening 11, and the opening 11 has a linear portion and a curved portion. The curved portion (corner portion) of the opening 11 has a radius of curvature of, for example, 25mm in a plan view.

(magnet yoke)

The yoke 20 is an iron frame-shaped member surrounding the anode 40, the magnet 50, the insulating portion 70, and the gas supply device G. The region surrounded by the yoke 20 is covered by the magnetic pole 30.

(magnetic pole)

The magnetic pole 30 (cathode) has a size of, for example, 400mm in total length, 100mm in width, and 10mm in height in plan view. As a material constituting the magnetic pole 30, a ferromagnetic material, for example, steel such as SS400, stainless steel such as SUS430, or the like is preferably 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.

The magnetic pole 30 is fixed to the yoke 20 by a fastening member. By releasing the fastening member from the fixing, the magnetic pole 30 can be detached from the yoke 20. Specifically, the magnetic pole 30 includes an inner magnetic pole 30I located inside the opening 11 and an outer magnetic pole 30E located outside the opening 11.

The inner magnetic pole 30I is fixed to the yoke 20 in advance. On the other hand, the outer magnetic pole 30E can be detached from the yoke 20. By releasing the fastening member from the fixed state while maintaining the fixation of inner magnetic pole 30I, outer magnetic pole 30E can be detached.

Further, as the structure of the magnetic pole 30, the inner magnetic pole 30I and the outer magnetic pole 30E may be independently detachable from the yoke 20.

In addition, fig. 1 shows that the outer magnetic pole 30E is one plate member, but the outer magnetic pole 30E may be configured by a plurality of plate members. In this case, each of the plurality of plate members can be independently detached from the yoke 20 by releasing the fixing of the fastening member.

The pole piece 30 has an inner surface 32 opposite the anode 40 and an outer surface 33 on the opposite side of the pole piece 30 from the inner surface 32. Further, the magnetic pole 30 has: an inner inclined surface 38 extending from one end of the inner surface 32 toward the slit 31 and forming a part of the slit 31; and an outer inclined surface 35 extending from one end of the outer surface 33 toward the slit 31 and forming a part of the slit.

The inner inclined surface 38 is an inclined surface extending obliquely upward from an end 39 (one end, lower end) of the inner surface 32 adjacent to the slit 31 toward the center of the slit 31, and the inner inclined surface 38 forms a part of the slit 31.

The outer inclined surface 35 is an inclined surface extending obliquely downward from an end 34 (one end, upper end) of the outer surface 33 adjacent to the slit 31 toward the center of the slit 31, and the outer inclined surface 35 forms a part of the slit 31.

The inner inclined surface 38 of the pole 30 has an inner front end 36 located on the opposite side of the inner inclined surface 38 from the end 39 (one end) of the inner surface 32. In other words, the outer inclined surface 35 of the magnetic pole 30 has an inner tip 36 located on the opposite side of the outer inclined surface 35 from the end 34 (one end) of the outer surface 33. That is, the inner front end 36 is a connecting end connecting the inner inclined surface 38 and the outer inclined surface 35.

The distance between the inner front ends 36 facing each other, i.e., the width of the slit 31, is about 3 mm. The width of the slit 31 is not limited to this value.

(Anode)

The anode 40(anode) is disposed apart from the back surface of the magnetic pole 30, and generates an electric field in a direction substantially perpendicular to the magnetic field generated by the magnet 50. A DC power supply, not shown, is connected to the anode 40.

As a material constituting the anode 40, a nonmagnetic material is preferably used.

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

(magnet)

The magnet 50 is constructed of SmCo (samarium cobalt) alloy for generating a magnetic field in the width direction of the slit 31. NdFe (neodymium iron) may be used as magnet 50.

(gas supply device)

A gas supply device G for supplying Ar and O to the inside of the yoke 20₂Etc. are supplied into the yoke 20. The gas of the gas supply device G for generating plasma between the slit 31 of the magnetic pole 30 and the anode 40 flows toward the opening 11 through the inside of the yoke 20.

Water cooling tubes, not shown, connected to a cooling water circulation device are provided on the outer peripheries of the yoke 20 and the anode 40. By flowing the cooling medium through the water-cooled tube, the linear ion gun 10 can be stably driven without depending on the temperature while preventing the magnetic pole 30 and the anode 40 from being deformed.

(cover)

The cover 60 is made of a conductive and nonmagnetic material, and covers the inner surface 32 and the inner inclined surface 38 of the magnetic pole 30. The cover 60 is separate from the magnetic pole 30 and is fixed to the magnetic pole 30 by a fastening member. By releasing the fastening member from the fixing, the cover 60 can be detached from the magnetic pole 30.

The cover 60 includes: a first coating portion 61 for coating the inner surface 32 of the magnetic pole 30; and a second coating portion 62 connected to the first coating portion 61 and coating the inner inclined surface 38. That is, the first cover 61 and the second cover 62 are integrated.

In the present embodiment, the second coating portion 62 has a vertical surface 63 extending in the vertical direction with respect to the anode 40. The vertical surfaces 63 facing each other in the slit 31 are parallel to each other. The lead straight surface 63 is exposed to the opening 11 in the slit 31.

In addition, in a plan view of the linear ion gun 10, the inner tip 36 of the magnetic pole 30 is aligned with the vertical surface 63 of the cover 60.

The cover 60 is preferably made of a material that is less susceptible to erosion than the material of the magnetic pole. The cap 60 is constructed of a material having electrical conductivity and non-magnetic properties, and specifically, the material of which the cap 60 is constructed is selected from the group consisting of carbon, titanium, and copper. In particular, carbon is preferably used as the material.

Regarding the characteristics of carbon suitable for use as the cap 60, the bending strength is preferably 34MPa to 74MPa, the tensile strength is preferably 22MPa to 48MPa, the specific resistance is preferably 11 [ mu ] Ω · m to 17.5 [ mu ] Ω · m, and the Shore hardness is preferably 53 to 87. By using carbon having such characteristics, the cover 60 suitable for the present 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 maintained in a reduced pressure atmosphere. In the linear ion gun 10, a high-frequency voltage is applied between the anode 40 and the magnetic pole 30 by a DC power supply in a state where a gas is supplied from the gas supply device G to the space between the anode 40 and the magnetic pole 30. 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 extracted from the opening 11.

According to the present embodiment, since the inner inclined surface 38 of the magnetic pole 30 configuring the slit 31 in the opening 11 is covered with the cover 60, the inner inclined surface 38 of the magnetic pole 30 is not exposed inside the slit 31. Therefore, it is possible to suppress consumption of the inner inclined surfaces 38 due to exposure of the inner inclined surfaces 38 to plasma in the slit 31, and to prevent an increase in the interval of the slit 31 (the distance between the two inner front ends 36) due to consumption of the inner inclined surfaces 38. As a result, a predetermined gap can be maintained in the slit 31, and a drop in discharge current can be prevented. In addition, the life of the magnetic pole 30 can be extended, the frequency of replacing the used magnetic pole with a new one can be reduced, and the maintainability can be improved. Further, by suppressing the consumption of the magnetic pole 30, contamination due to the material of the magnetic pole 30 can be suppressed, and the process using the ion gun is not adversely affected.

In the present embodiment, the cover 60 is made of a material less susceptible to erosion than the magnetic pole material, and is made of carbon. Carbon is suitable as a material for the cap 60 because its sputtering efficiency is about 1/3 times that of a typical magnetic pole material.

Further, even if the operation time of the linear ion gun 10 elapses, the effect of suppressing the consumption of the magnetic pole 30 can be obtained, but the sacrificial consumption of the cover 60 is caused. However, the cover 60 can be easily detached from the magnetic pole 30, so that the cover 60 can be replaced.

(replacement of cover)

When replacing old and new cover 60 with magnetic pole 30, first, outer magnetic pole 30E is detached from yoke 20. In this state, cover 60 can be detached from inner surface 32 of outer magnetic pole 30E. Further, in a state where outer magnetic pole 30E is detached from yoke 20, the operator can insert the operator's finger between inner magnetic pole 30I and anode 40. Therefore, cover 60 can be detached from inner surface 32 of inner pole 30I.

Therefore, the used cover 60 can be easily detached from the outer magnetic pole 30E and the inner magnetic pole 30I. Then, new cover 60 before use can be easily attached to outer magnetic pole 30E and inner magnetic pole 30I.

Further, since the magnetic force (magnetic flux) of the outer magnetic pole 30E is smaller than the magnetic force (magnetic flux) of the inner magnetic pole 30I, the work of detaching the outer magnetic pole 30E from the yoke 20 can be easily performed.

(modification of embodiment)

Next, a linear ion gun according to a modification of the embodiment of the present invention will be described with reference to fig. 4 to 6. In fig. 4 to 6, the same reference numerals are given to the same components as those of the above-described embodiment, and the description thereof will be omitted or simplified. The modification described below is different from the above-described embodiment in the structure of the cover 60.

(modification 1)

Fig. 4 is an enlarged cross-sectional view showing a main part of a linear ion gun according to modification 1 of the embodiment of the present invention.

In the above-described embodiment, the structure in which the inner tip 36 of the magnetic pole 30 is aligned with the vertical surface 63 of the second coating portion 62 in the plan view of the linear ion gun 10 has been described, but the inner tip 36 may not be aligned with the vertical surface 63.

Specifically, in modification 1, the cover 60 has a protruding portion 64, and the protruding portion 64 protrudes from the inner tip 36 into the opening 11 in a plan view of the linear ion gun 10.

According to modification 1, since the protruding portion 64 is disposed between the inner tip 36 of the magnetic pole 30 and the plasma generation region, the inner tip 36 is less likely to be exposed to plasma, and the effect of suppressing the consumption of the magnetic pole 30 can be further improved. This can prevent the gap between the slits 31 from increasing due to consumption of the magnetic pole 30. As a result, the slits 31 can maintain a predetermined interval to prevent a drop in discharge current, thereby extending the life of the magnetic pole 30.

The amount of protrusion of the protrusion 64, that is, the distance between the inner tip 36 and the vertical surface 63 (the tip of the protrusion 64) can be determined appropriately according to the frequency of replacement of the cover 60 during maintenance of the linear ion gun 10 and the flow rate of the gas flowing to the outside of the linear ion gun 10 through the opening 11.

Specifically, when the amount of projection of the projection 64 is increased, the frequency of replacement of the cover 60 can be reduced, but on the other hand, the opening area of the opening 11 is reduced, the electrical conductivity is reduced, and the flow rate of the gas flowing through the opening 11 is reduced. On the other hand, when the amount of projection of the projection 64 is reduced, the frequency of replacement of the cover 60 is increased, but the opening area of the opening 11 is increased, the electrical conductivity is increased, and the flow rate of the gas flowing through the opening 11 is increased.

That is, the amount of protrusion of the protrusion 64 and the gas flow rate required by the linear ion gun 10 are in a trade-off relationship. By taking this relationship into consideration, the amount of protrusion of the protrusion 64 is determined.

(modification 2)

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

In the above-described embodiment and modification 1, the case where the cover 60 has the straight surface 63 is described, but the cover 60 does not necessarily have the straight surface 63.

As shown in fig. 5, the second coating portion 62 of the cover 60 may have a protrusion 64 protruding from the inner tip 36 into the opening 11 in a plan view of the linear ion gun 10, and may have an inclined surface parallel to the inner inclined surface 38. In this case, the inclined surface of the second coating portion 62 is exposed to the opening 11 in the slit 31.

According to modification 2, since the protruding portion 64 is disposed between the inner tip 36 of the magnetic pole 30 and the plasma generation region, the inner tip 36 is less likely to be exposed to plasma, and the effect of suppressing the consumption of the magnetic pole 30 can be further improved. This can prevent the gap between the slits 31 from increasing due to consumption of the magnetic pole 30. As a result, the slits 31 can maintain a predetermined interval to prevent a drop in discharge current, thereby extending the life of the magnetic pole 30.

Further, similarly to modification 1, since the projection amount of the projection 64 and the gas flow rate required for the linear ion gun 10 are in a trade-off relationship, the projection amount of the projection 64 is determined by considering this relationship.

(modification 3)

Fig. 6 is an enlarged cross-sectional view showing a main part of a linear ion gun according to modification 3 of the embodiment of the present invention.

In the above-described embodiment and modifications 1 and 2, the structure in which the inner surface 32 of the magnetic pole 30 is covered with the first covering portion 61 and the inner inclined surface 38 is covered with the second covering portion 62 has been described, but the cover 60 may cover at least the inner surface 32 and the inner inclined surface 38, and the cover 60 may cover the outer surface 33 and the outer inclined surface 35.

As shown in fig. 6, the cover 60 includes: a first coating portion 61 coating the inner surface 32; a second coating portion 62 that coats the inner inclined surface 38; a third coating portion 66 coating the outer surface 33; and a fourth coating portion 67 coating the outer inclined surface 35. The fourth coating portion 67 is connected to the third coating portion 66. The third cover 66 and the fourth cover 67 are integrated and fixed to the magnetic pole 30 by a fastening member. By releasing the fastening member from the fixing, the third cover 66 and the fourth cover 67 can be detached from the magnetic pole 30.

The first cover 61 and the second cover 62 constitute a lower cover. The third cover 66 and the fourth cover 67 constitute an upper cover. The lower cover and the upper cover are separated from each other, and each of the lower cover and the upper cover is fixed to the magnetic pole 30.

According to modification 3, not only the same effects as those of the above-described embodiment can be obtained, but also the consumption of the magnetic pole 30 in the outer surface 33 and the outer inclined surface 35 can be suppressed.

In the configuration shown in fig. 6, the protrusion 64 may be provided on the vertical surface 63, or the protrusion may be provided on the vertical surface of the fourth coating portion 67. The projection 64 shown in modification 2 can also be applied to modification 3.

However, as described above, the projection amount of the projection 64 and the gas flow rate required by the linear ion gun 10 are in a trade-off relationship, and therefore the projection amount of the projection 64 is determined by considering this relationship.

In the above-described embodiment and modifications 1 to 3, the two inner inclined surfaces 38 and the two outer inclined surfaces 35 facing each other and arranged in line symmetry (line symmetry with respect to the slit center line) are provided inside the slit 31. In other words, in this structure, two corners facing each other with the inner tip 36 as a vertex are located inside the slit 31.

In such a line-symmetric structure, even if the magnetic pole 30 is consumed inside the slit 31, since the line-symmetric shape is maintained (the similarity relationship), the discharge current does not decrease, and a stable transition (temporal change) of the discharge current is maintained.

The meaning of the similarity relationship of the holding shapes is substantially the same as the meaning that the state (change) of the magnetic flux density generated inside the slits 31 depends only on the intervals of the slits 31. This means that no variation in the magnetic flux distribution due to the change in the surface shape of the magnetic pole 30 inside the slit 31 occurs.

The inventors confirmed evaluation of the degree of contribution of the gap between the slits 31 and the change in the surface shape of the magnetic pole 30 inside the slit 31 by simulation.

As a result, the following results were obtained: in order to stabilize the ion current, it is a main factor in stabilizing the ion current to maintain the similarity in the shape of the magnetic poles 30 facing each other inside the slit 31 as compared with the change in the interval of the slit 31. The evaluation results were confirmed to match the examples (experimental results) described later.

Examples

Next, the effects of the present invention will be described in further detail with reference to fig. 7 and examples.

Fig. 7 is a graph showing a comparison example of a conventional linear ion gun and an example of a linear ion gun using the cover of the above embodiment, and shows a change with time of a discharge current with the passage of an operating time (operating time). In fig. 7, the horizontal axis shows the operating time of the linear ion gun, and the vertical axis shows the change in discharge current. Specifically, the change in the discharge current is a relative change in the discharge current based on (1, 100%) the operation time of 0 hour.

Comparative example

In the linear ion gun of the comparative example, a structure in which no cover is provided in the slit of the magnetic pole, that is, a structure in which the structural member of the magnetic pole is exposed in the slit, is applied.

In the comparative example, the discharge current significantly decreased immediately after the start of operation. Then, until the operation time reached 7.5 hours, the discharge current was gradually decreased. After 7.5 hours of operation, the discharge current decreased continuously. When the operation time reached 17 hours, the change amount of the discharge current was 0.8, and the discharge current decreased by about 20% from that before the start of the operation. After the operating time reached 17 hours, it was confirmed that the magnetic poles in the linear ion gun of the comparative example were worn out, and it was confirmed that a shape change due to wear occurred in the portion corresponding to the inner tip 36 of the magnetic pole 30 of the present embodiment.

(examples)

The structure shown in the above embodiment (fig. 3) is applied to the linear ion gun of this example.

In the present example, the discharge current gradually decreased from the start of operation until the operation time reached 5 hours, but no significant decrease in discharge current was observed as in the comparative example. When the operating time exceeded 5 hours, no decrease in discharge current was observed, and the discharge current was stable. When the operation time reached 17 hours, the change amount of the discharge current was 0.9, and the discharge current was reduced by about 10% compared to that before the operation was started.

Comparing the comparative examples with the examples, it is clear that the examples can suppress the decrease in discharge current by about 10% with respect to the comparative examples after 17 hours has elapsed during operation. That is, the structure in which the cover 60 is provided on the magnetic pole 30 as in the above embodiment contributes to suppressing a decrease in discharge current.

While the preferred embodiments of the present invention have been described above, it should be understood that these embodiments are illustrative of the present invention and are not to be construed as limiting the invention, as described above. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the present invention. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Industrial applicability

The present invention can be widely applied to an ion gun that suppresses consumption of magnetic poles in magnetic pole slits, improves maintainability by reducing the frequency of replacement of magnetic poles, and suppresses the occurrence of contamination caused by magnetic pole materials.

Description of the reference numerals

10 linear ion gun (ion gun) 11 opening

20 magnetic yoke and 30 magnetic pole

30E outer magnetic pole (magnetic pole) 30I inner magnetic pole (magnetic pole)

31 inner surface of slit 32

33 outer surfaces 34, 39 end

35 outer inclined plane 36 inner front end

38 inner inclined plane 40 anode

50 magnet 60 cover

61 first cover part (cover) 62 second cover part (cover)

63 vertical surface 64 projection

66 third cladding (cover) 67 fourth cladding (cover)

70 insulating part BM ion Beam

G gas supply device P plasma