JP5329941B2 - Ion source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To relax and suppress stress imposed on a filament caused by thermal expansion of a filament holder holding the filament in an ion source, and thereby to prevent malfunction of the filament caused by breaking, deformation or the like of the filament. <P>SOLUTION: An ion source includes: a filament holder for holding the both ends of the filament on the outside of a plasma container; a base for holding and fixing the filament holder; and an interposing member for interposing and connecting between the filament holder and the base. When a first direction is determined to be from a first connection position where the filament holder and the interposing member are connected to a position where the filament of the filament holder is held, and a second direction is determined to be from a second connection position where the interposing member and the base are connected to the first connection position, the second connection position is on a side of the first connection position out of two sides divided by a first surface, and a component obtained by projecting the second direction on the first direction turns in a direction opposite to the first direction. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an ion source that generates a plasma to generate an ion beam.

  An ion implantation apparatus is used for processing a substrate by implanting ions by making an ion beam collide with the substrate. Various ion sources have been conventionally developed as an apparatus for generating an ion beam of such an ion implantation apparatus.

  In the ion source, a filament that is inserted into a plasma container and supplies thermal electrons when energized is used as a cathode, and the plasma container is used as an anode. In the plasma container, arc discharge is induced to turn the raw material gas into plasma. One or more slit openings are provided on the wall surface of the plasma container of the ion source, and charged ions in the plasma are extracted from the slit openings as an ion beam. A magnetic pole for applying a magnetic field orthogonal to the extraction direction of the ion beam is provided outside the plasma container.

8-10 is a figure which shows an example of the conventional ion source. FIG. 8 is a perspective view showing the entire ion source, FIG. 9 is a view for explaining the arrangement of filament clamps of the ion source shown in FIG. 8, and FIG. 10 is a plasma container of the ion source shown in FIG. FIG.
As shown in FIG. 8, a filament 102 is provided in the plasma container 100, and a slit opening 104 through which plasma generated in the plasma container 100 is extracted as an ion beam B is provided on the wall surface of the plasma container 100. As shown in FIG. 9, on the outside of the plasma container 100, as shown in FIG. 9, a filament clamp 106 that holds the filament 102, a base 110 that fixes the filament clamp 106 via an insulating material 108, and the plasma container 100 is a base 108. A support member 112 for supporting and fixing the magnetic poles 114 and 116 for forming a magnetic field in the plasma vessel 100 are provided.
As shown in FIG. 10, the plasma container 100 includes a plate member 116 having a pair of through holes for providing the filament 102 and a plate member 117 having a slit opening 104, and plate members 118 and 119. It is configured in shape.

In such an ion source, the filament 102 is firmly held by the filament clamp 106 so that the filament 102 inserted through the pair of through holes of the plasma vessel 100 does not touch the inner surface of the through hole of the plasma vessel 100. It is fixed on the base 110. Further, the plasma container 100 is also fixed on the base 110 via the support member 112. Thus, the plasma container 100 and the filament 102 are separately fixed on the base 108 in order to prevent the filament 102 and the plasma container 100 from contacting and conducting.
Further, an insulating material is not provided in a portion where the filament 102 passes through the through hole of the plasma container 100. This is due to the following reason. That is, a conductive film is easily deposited on the inner wall surface of the plasma vessel 100, the filament 102, or a member around the plasma vessel 100, and is insulated around the filament (cathode) 102 passing through the through hole of the plasma vessel (anode) 100. This is because when the material is provided, the conductive film covers the surface of the insulating material, and the filament 102 and the plasma container 100 may be electrically connected.

  As shown in FIG. 8, the pair of filament clamps 106 and 106 are provided so that the distance between the filament clamps 106 and 106 increases in a C shape as the distance from the through hole of the filament 102 increases. This is due to design limitations. In such a state, the filament 102 is heated by energizing to 2000 ° C. or higher. By heating by this energization, the filament clamp 106 is also heated by heat conduction and resistance loss, and the filament clamp 106 is thermally expanded along its longitudinal direction. For this reason, the filament 102 held by the filament clamp 106 is subjected to stress in the direction of the interval between the filaments 106 and 106. For example, when the filament clamp 106 is made of molybdenum having a length of 100 mm, it thermally expands by 0.6 mm with a temperature rise of 1000 ° C. This thermal expansion becomes stress on the filament 102. For example, when the angle formed by the filament clamps 106 and 106 shown in FIG. 9 is 30 degrees, the filament 102 is subjected to a compressive stress that is about 0.3 mm and tries to push and narrow the width of the filament 102.

  The filament 102 is elastically deformed by such a compressive stress, but a portion heated to a high temperature by high temperature creep is intensively deformed. When the operation of the ion source is completed, the current heating is finished, the temperature is lowered to room temperature, and the filament clamp 106 is further cooled, the filament 102 is subjected to a tensile stress. Tungsten is often used as the material of the filament 102. In this case, crystal grains grow large and become brittle in the portion heated to a high temperature of the filament 102. The weakened portion is easily broken or deformed by the stress, and as a result, it often fails to fulfill the function of supplying filament thermoelectrons.

  The following Patent Document 1 describes an ion source for use in an ion implanter. The ion source is configured to fix an arm (filament clamp) for holding a filament to a single member and then fix it at a location corresponding to the base of the ion source.

JP 10-199430 A

  However, the ion source does not disclose a fixing method in consideration of thermal expansion caused by heating of the filament for the arm that holds the filament and the single member that fixes the arm.

  Therefore, in order to solve the above problems, the present invention relieves and suppresses the stress applied to the filament by thermal expansion of the filament holder that holds the filament in the ion source, thereby causing breakage and deformation of the filament. An object of the present invention is to provide an ion source capable of preventing filament malfunction.

The above object can be achieved by the following ion source that generates a plasma to generate an ion beam.
That is, the ion source is
(A) a plasma container covered with a wall surface for generating plasma and forming an internal space;
(B) a linear filament that is provided in the internal space through a pair of through holes provided in the plasma vessel and is heated by energization to emit thermoelectrons, with the intermediate portion folded;
(C) A rod-like shape for holding both ends of the filament in a state where a gap is provided between the filament passing through the pair of through-holes and a wall surface of the through-hole, provided outside the plasma vessel. A pair of filament holders having gripping portions;
(D) a base for supporting and fixing each of the pair of filament holders;
An interposition member for interposing and connecting between each of the pair of filament holders and the base.
At this time,
(E) determining a first direction from a first connection position where each of the pair of filament holders and the interposition member are connected to a holding position of the filament of each of the pair of filament holders; A second direction from the second connection position where the interposition member and the base are connected to the first connection position is defined, and the pair of through holes are viewed from the internal space, and the pair of through holes When the first surface that bisects the line connecting the openings on the wall surface of the first substantially bisecting line is defined, the second connection position is the two of the two sides divided by the first surface. The component that is on the side where the first connection position is located and projects the second direction into the first direction is directed in the opposite direction to the first direction.

More specifically, it is set as follows.
The rod-shaped gripping portions of the pair of filament holders are provided so that the interval between the rod-shaped gripping portions spreads in a C shape as the distance from the through hole increases, and the second connection position is the first connection position. Is closer to the first surface than the connection position.
At this time, it is preferable that the distance from the second connection position to the first surface is greater than 0% and equal to or less than 40% of the distance from the first connection position to the first surface.

More specifically, the setting is as follows.
When the pair of through holes are viewed from the internal space, the first connection position is substantially parallel to a line segment connecting openings on the wall surfaces of the pair of through holes, perpendicular to the first surface. The second connection position is provided on the side having the filament holding position in the two regions divided into two by the second surface when the second surface passing through is hypothesized. .

  The pair of filament holders are preferably made of an alloy whose main component is a metal selected from tungsten, molybdenum, and tantalum, and the interposition member is preferably made of a stainless alloy or an aluminum alloy.

  Further, a slit opening for extracting an ion beam is provided on the wall surface of the plasma container, and the wall surface of the slit opening is opposed to the wall surface provided with the pair of through holes through which the filament passes. It has become.

The interposition member may be a pair of members that separately connect the pair of filament holders to the base, or may be a single member that connects the pair of filament holders to the base in common. It may be a member.
The ion source is
A plasma container covered with a wall for generating plasma and forming an internal space;
A linear filament which is provided in the internal space through a pair of through-holes provided in the plasma vessel, and is heated by energization to emit thermoelectrons, with an intermediate portion folded;
A rod-shaped gripping part for holding both ends of the filament in a state where a gap is provided between the filament passing through the pair of through-holes and a wall surface of the through-hole, provided outside the plasma vessel. A first filament holder and a second filament holder having
A base for supporting and fixing each of the first filament holder and the second filament holder;
One interposed member for interposing and connecting between each of the first filament holder and the second filament holder and the base,
When the first surface that bisects the line segment connecting the openings on the wall surfaces of the pair of through holes when the pair of through holes is viewed from the internal space is approximately perpendicularly divided, the first filament holder Holds one end of the filament on the first side of the two sides divided by the first surface, and is connected to the interposition member at the first connection position A1 on the first side. The second filament holder holds the other end of the filament on a second side different from the first side of the two sides, and a first connection position on the second side. Connected to the interposition member at A2,
Wherein the first connecting position A1, the first in the first direction X1 reaches the holding position of the filament of the filament holder, and, from the first connecting position A2, the said second filament holder A first direction X2 to reach the filament holding position is defined, and further, the second connecting position D1 where the interposition member and the base are connected on the first side reaches the first connecting position A1 . A second direction Y1 and a second direction Y2 from the second connection position D2 where the interposition member and the base are connected on the second side to the first connection position A2 are defined. when the components of the second direction Y1 obtained by projecting the second direction Y1 in the first direction X1, together with the first direction X1 and the opposite direction toward Ward, the second direction Y2 Projected in the first direction X2 The components of the second direction Y2 may be characterized in that facing the first direction X2 opposite to the direction.

  In the ion source described above, the second connection position where the interposition member and the base are connected is on the side where the first connection position is located, out of the two sides divided by the first surface, The component obtained by projecting the second direction into the first direction is directed in the opposite direction to the first direction. For this reason, the stress which a filament receives by thermal expansion of the filament holder holding a filament is relieve | moderated and suppressed, By this, the malfunction of the filament by the fracture | rupture or deformation | transformation of a filament can be prevented.

Hereinafter, the ion source of the present invention will be described in detail based on preferred embodiments.
FIG. 1 is a diagram for explaining a plasma generation portion of an ion source 1 which is an embodiment of the ion source of the present invention. The ion source 1 is used as a part of an ion implantation apparatus that generates an ion beam having a uniform or desired current density distribution and implants impurity into a substrate to be processed.
The ion source 1 includes a plasma container 10, a filament 12, a slit opening 14, magnetic poles 24 and 26, a repeller 30, electrodes 38 and 40, and various power sources 32, 34, 42, and 44. In addition, as will be described later, the ion source 1 includes members for fixing and supporting the plasma container 10 and the filament 12 (see FIG. 2).

The plasma container 10 is an elongated container that generates plasma P in a substantially closed and elongated internal space and draws the plasma P as an elongated shape from the slit opening 14 to generate an ion beam B. At least the inner wall surface of the plasma container 10 is made of a conductor. For example, the plasma container 10 itself is made of a conductive material. Alternatively, the plasma container 10 is mainly made of an insulating material, and the inner wall surface facing the inner space is covered with a conductor film.
The pressure in the plasma vessel 10 is directly adjusted by supplying the gas G from the source gas supply unit (not shown) through the gas supply hole. Further, the pressure is indirectly adjusted using a vacuum container (not shown) containing the plasma container 10 and an exhaust device, and is maintained at a constant pressure.

The filament 12 and the repeller 30 are provided in the internal space of the plasma container 10. The repeller 30 is provided at both ends in the longitudinal direction of the internal space of the plasma container 10 having an elongated internal space. The filament 12 is provided on the front surface of one repeller 30.
The plasma container 10 and the repeller 30 are fixed by an insulating material (not shown) at a position isolated from the plasma P. Moreover, the repeller 30 is electrically insulated without contacting the filament 12 while maintaining a certain space. The plasma container 10 and the filament 12 are supported and fixed to a base 20 described later.

  The magnetic poles 24 and 26 are provided so as to form a substantially parallel static magnetic field along the longitudinal direction of the elongated internal space of the plasma vessel 10, that is, to connect two repellers 30 and generate a magnetic force line substantially parallel to a straight line. ing.

The filament 12 is a portion made of a linear wire having a substantially circular cross section, and emits thermoelectrons by energization heating. The filament 12 is wound and folded back so as to rotate 540 degrees at its intermediate portion. The folded back intermediate portion is provided so as to protrude into the internal space of the plasma container 10. The vicinity of both ends of the filament 12 extends substantially in equilibrium, and both ends are provided so as to extend to the outside of the plasma vessel 10 through a pair of through holes provided in the inner wall surface of the plasma vessel 10.
Such a filament 12 is manufactured by bending a linear wire. The manufacturing method of the filament 12 having the above shape is effective in that it can be manufactured at low cost. Since the filament 12 is exposed to the plasma P and wears and becomes thin and breaks, the filament 12 is thickened to extend the operational life of the ion source, but is preferably made thinner than about 3 mm in order to facilitate bending. . A filament structure (a structure in which the rotation direction of the wire is two directions) in which a conventionally known intermediate portion is folded and wound, and further the folded portion is bent at a right angle is complicated, and thus it is difficult to manufacture it compactly. The filament 12 has a simple structure that is wound and turned back so as to rotate 540 degrees, but the dimensional accuracy is still rough. For this reason, it is difficult to install the filament 12 at an accurate position and to fix and support both ends at the accurate position by the filament clamp 16. Therefore, it is necessary to finely adjust the attachment position according to the filament 12 with slightly different dimensions as a product difference. For this reason, as will be described later, the attachment position of the filament 12 can be finely adjusted using the filament clamp 16 as shown in FIG.

  A filament power supply 32 is connected to both ends of the filament 12 outside the plasma vessel 10. In the filament power source 32, the filament power source 32 is adjusted so that the filament 12 is energized and heated to emit thermoelectrons from the filament 12. One repeller 30 located near the filament 12 is connected to the positive electrode of the filament power supply 32. By this connection, one end of the filament 12 and the one repeller 30 are at the same potential. The negative electrode of the arc power supply 34 is connected to the negative electrode of the filament power supply 32, and the positive electrode is connected to a conductor formed on at least the inner wall surface of the plasma container 10.

The thermoelectrons emitted from the filament 12 are accelerated to the center of the plasma vessel 10 by the potential difference between one repeller 30 located near the filament 12 and the filament 12. Further, the plasma is accelerated toward the inner wall surface of the plasma vessel 10 by the potential difference of the arc power supply 34. However, due to the action of the static magnetic field generated by the magnetic poles 24 and 26, the thermoelectrons start a spiral motion and reciprocate between the repellers 30 on both sides.
The thermoelectrons that perform the spiral motion collide with the molecules of the gas G. Thereby, the gas G is ionized, and the ionized ions and thermoelectrons are further accelerated by the electric field in the filament 12, the repeller 30 and the plasma container 10. Thereby, plasma P is generated and maintained.

  The surface 36 of the plasma vessel 10 has a slit opening 14, and electrodes 38 and 40 are provided outside the plasma vessel 10 so as to face the surface 36. The electrodes 38 and 40 have an opening having a shape related to the shape of the slit opening 14. The electrode 38 is connected to the negative electrode of the power source 42, and the electrode 40 is connected to the positive electrode of the power source 42. The positive electrode of the power source 42 is connected to the ground terminal and is fixed at a potential of zero. The negative electrode of the power supply 44 is connected to the positive electrode of the power supply 42, and the positive electrode of the power supply 44 is connected to the plasma container 10. Due to the potential difference between the surface 36 of the plasma vessel 10 and the electrode 38, a potential gradient is generated in the vicinity of the slit opening 14, and ions are separated from the plasma P by this potential gradient, and are further extracted to generate the ion beam B.

  In such an ion source 1, since the plasma container 10 is in contact with the high temperature plasma P, as described above, the filament clamp 16, which will be described later, in the vicinity of the plasma container 10 also becomes high temperature and thermally expands to Trying to give stress. However, by providing a relaxation member (intervening member) 19 as will be described later, the stress received by the filament 12 is relaxed and suppressed. Thereby, the breakage of the filament 12 is suppressed. In addition, fine adjustment due to variations in the product of the filament 12 can be performed, and the thermal stress can be reduced, so that the manufacturing cost can be reduced.

  FIG. 2 is a view for explaining the configuration of each part on the outside of the plasma vessel 10 constituting the ion source 1. FIG. 3 is a view showing a structure for fixing and supporting the filament 12 of the ion source 1 and the plasma vessel 10. FIG. 4 is a diagram for explaining the positional relationship between the connection position A between the filament clamp 16 and the relaxation member 19 and the connection position D between the relaxation member 19 and the base 20. Fig.5 (a) is a top view of the structure shown in FIG. 3, FIG.5 (b) is the front view.

In addition to the magnetic poles 24 and 26, the ion source 1 supports a filament clamp (filament holder) 16, an insulating material 18, a relaxation member (intervening member) 19, a base 20, and a support in addition to the magnetic poles 24 and 26. Member 22.
The filament clamp 16 is connected by being fixed to the relaxation member 19 with a bolt or the like via the insulating member 18, and the relaxation member 19 is connected to the base 20 by being fixed with a bolt or the like.
The filament clamp 16 is a pair of clamp members that are made of a conductive member and hold both ends of the filament 12. The filament clamp 16 includes a rod-shaped gripping portion that holds both ends of the filament 12 that protrudes to the outside of the plasma vessel 10 through a pair of through holes provided in the wall surface of the plasma vessel 10. The rod-shaped gripping portion has a square shape, and the distance between the rod-shaped gripping portions increases as the distance from the pair of through holes through which the filament 12 passes is increased. The filament clamp 16 is fixed to the base 20 via an insulating material 18 and a relaxation member 19.

The insulating material 18 is a member provided so that the filament 12 and the filament clamp 16 are not electrically connected to the base 20. The insulating material 18 is provided at two connection positions between each of the pair of filament clamps 16 and the relaxing member 19 so as to be sandwiched between the filament clamp 16 and the relaxing member 19.
The relaxation member 19 is a member made of a metallic material that functions to relieve and suppress the stress that the filament clamp 16 expands due to the heating of the filament clamp 16 and the filament 12 receives by the expansion of the relaxation member 19 itself. is there. Thus, in order for the relaxation member 19 to function to relieve and suppress the stress acting on the filament 12, the relaxation member 19 and the base 20 are connected to the connection position between the filament clamp 16 and the relaxation member 19. The connection position of is offset. This point will be described in detail later.
The base 20 is in contact with a vacuum vessel (not shown) and the plasma vessel 10, and is mainly used to accurately maintain the relative positional relationship between the electrodes 38 and 40 and the surface 36 of the plasma vessel 10.

  The reason why the plasma container 10 is firmly fixed and supported with respect to the base 20 is to strictly adjust and fix the relative position of the plasma container 10 with respect to the electrodes 38 and 40 in order to generate the ion beam B. The electrodes 38 and 40 are fixed via a vacuum container and a base 20 (not shown). The wall surface where the slit opening 14 is provided is at a position facing the wall surface including a pair of through holes through which the filament 12 passes. In FIG. 2, an opening in which the side surface of the plasma container 10 is greatly cut out is shown. However, the notched opening is for easy understanding of the internal structure of the plasma container 10. There are no cutout openings.

  As shown in FIG. 3, each of the pair of filament clamps 16 has a bar shape in which the gripping portion of the filament 12 is divided into two portions. Hold it separately. The filament 12 becomes a high temperature of 2000 ° C. or higher by energization heating. Since the filament clamp 16 is in direct contact with the filament 12 in a high temperature state, the filament clamp 16 is made of an alloy mainly containing a metal selected from tungsten, molybdenum, and tantalum from the viewpoint of heat resistance. The main component means a component whose weight percentage exceeds 50%. In general, these alloys are easy to break, and therefore, the bar-shaped holding portion divided into two forks needs to be sufficiently long.

Further, both ends of the filament 12 having a circular cross section are clamped by the filament clamp 16 from a direction perpendicular to the direction in which the filament 12 extends in order to secure a large contact portion by the filament clamp 16. It is configured.
In addition, if the filament 12 is elastically deformed according to the individual dimensional difference of the filament 12 and forcibly installed, the filament 12 is heated in a stressed state, so that deformation due to high temperature creep occurs and the function of the filament 12 is increased. May not be demonstrated. For this reason, as described above, the filament clamp 16 is fixed after finely adjusting the positions of both ends of the filament 12 that has come out of the plasma vessel 10 through the pair of through holes. Therefore, in order to enable the filament clamp 16 to be easily fixed after the fine adjustment, the connection position where the relaxation member 19 and the filament clamp 16 are fixed and connected with a bolt is a pair through which the filament 12 passes as shown in FIG. When the wall surface of the plasma container 10 provided with the through-hole is viewed from the front, the plasma container 10 is provided so as to come outside the width of the plasma container 10.

By the way, the connection position between the filament clamp 16 and the relaxation member (interposition member) 19 and the connection position between the relaxation member 19 and the base 19 are set to the following positional relationship.
That is, as shown in FIG. 4, the direction X from the connection position A where each of the pair of filament clamps 16 and the relaxing member 19 are connected to the holding position G of the filament 12 of each of the pair of filament clamps 16 is determined. When the direction Y from the connection position D where the relaxation member 19 and the base 20 are connected to the connection position A is determined, the Y-direction component obtained by projecting the Y direction into the X direction faces the opposite direction to the X direction. ing. Each of the pair of filaments 16 has a positional relationship of the connection positions. In addition, an intermediate position is defined as the connection position when there are two points to be connected. As described above, the positional relationship between the connection position A and the connection position D is determined by the stress caused by thermal expansion that the filament 12 receives by relaxing and suppressing the displacement in the X direction at the holding position of the filament 12 on the filament clamp 16. This is to ease the problem. That is, even if the rod-shaped grip portion of the filament clamp 16 extends in the X direction by thermal expansion starting from the connection position A, the relaxation member 19 also extends in the Y direction by thermal expansion around the connection position D. The displacement in the X direction at the 12 holding positions is alleviated and suppressed.

  More specifically, the bar-shaped gripping portions of the pair of filament clamps 16 are provided so that the interval between the bar-shaped gripping portions spreads in a square shape as the distance from the through hole through which the filament 12 passes. Further, when viewing the pair of through-holes through which the filament 12 passes from the internal space of the plasma container 10, a surface B that virtually bisects the line segment connecting the openings on the wall surfaces of the pair of through-holes is assumed. At this time, the connection position D is on the side where the connection position A is located, and is closer to the surface B than the connection position A.

With such a configuration, the component in the direction orthogonal to the surface B of the stress received by the filament 12 due to the thermal expansion of the filament clamp 16 can be relaxed by the elongation due to the thermal expansion of the relaxation member 19.
The distance to the surface B of the connection position D is more than 0% and 40% or less of the distance to the surface B of the connection position A. That is, when a surface C parallel to the surface B passing through the connection position A is assumed, the distance from the connection position D to the surface C is 60% or more and less than 100% of the distance between the surface B and the surface C. When the thermal conductivity of the insulating material 18 between the filament clamp 16 and the relaxation member 19 is high and the temperature of the relaxation member 19 is high, the temperature of the clamp 16 is decreased. It is preferably about 60% nearby. When the heating of the filament 12 is strong and the ion beam current amount is set to be large, it is preferable that the upper limit range is about 100% near the upper limit.

Further, as shown in FIG. 4, the pair of through holes through which the filament 12 passes are substantially parallel to a line segment connecting the openings on the wall surfaces of the pair of through holes when viewed from the internal space of the plasma container 10. Thus, a plane E that is perpendicular to the plane B that bisects the line segment and that passes through the connection position A is assumed. At this time, the connection position D is provided on the side where the holding position G of the filament 12 is present in the two regions divided in half by the surface E.
With such a configuration, the component in the direction perpendicular to the plane E of the displacement at the both ends of the filament 12 due to the thermal expansion of the filament clamp 16 can be relaxed by the elongation of the relaxation member 19 due to the thermal expansion. . That is, the displacement at the holding position G of each of the pair of filament clamps 16 is suppressed, and the difference in displacement due to the expansion of both ends of the filament 16 is reduced, so that the displacement received by the filament 12 in the direction perpendicular to the plane E is reduced. Can do.

  Heat generated by energization heating of the filament 12 passes through the filament clamp 16, is conducted to the insulating material 18, the relaxation member 19, and the base 20 and moves to the outside. Therefore, the temperature of the relaxation member 19 is lower than that of the filament clamp 16. For this reason, in order for the relaxation member 19 to effectively absorb the elongation due to the thermal expansion of the filament clamp 16 and suppress the stress applied to the filament 12, a stainless alloy or aluminum alloy having a large thermal expansion is used as the material of the relaxation member 19. It is preferable to use it.

FIG. 6 is a diagram showing another embodiment different from the embodiment shown in FIG.
In FIG. 6, the same members as those in the embodiment shown in FIG. Members with the same number have the same function.
In FIG. 6, members different from the embodiment shown in FIG. 3 are a filament clamp 46 and an insulating material 48. As with the insulating material 18, the insulating material 48 is a member provided so that the filament 12, the filament clamp 16, and the base 20 are not electrically connected, and is larger than the insulating material 18. . A conductive film is easily deposited on each member provided around the plasma container as the plasma P is generated. However, as the insulating material 48 is enlarged, the function of the insulating material 48 as an insulating material is reduced. And the function as an insulating material can be maintained for a longer time. Furthermore, in order to cover the surface of the insulating material 48 more effectively, a large base portion of the filament clamp 46 is provided. Even if the large insulating material 48 is used and the angle formed between the pair of filament clamps 46 is increased as in this embodiment, since the relaxation member 19 is used, the stress due to thermal expansion that the filament 12 receives is suppressed. Can do.

  The relaxation member 19 of the embodiment shown in FIGS. 3 and 6 is provided corresponding to both of the pair of filament clamps 16, but in the ion source 1, one of the filament clamps 16 of the pair of filament clamps 16. Even if one relaxation member 19 is provided corresponding to the above, the stress applied to the filament 12 can be relaxed or suppressed as compared with the conventional case.

FIG. 7 is a diagram showing another embodiment different from the embodiment shown in FIGS. 3 and 6.
In the embodiment shown in FIG. 7, the same members as those in the embodiment shown in FIG. Members with the same number have the same function.
In FIG. 7, a member different from the embodiment shown in FIG. The relaxation member 19 in the embodiment shown in FIG. 3 is provided in each of the pair of filament clamps 16, but the relaxation member 59 in the embodiment shown in FIG. One member connected to the base 20. Even in the relaxation member 59, if the connection position A and the connection position D are in the positional relationship as described with reference to FIG. 4, the stress received by the filament 12 is relaxed and suppressed by the thermal expansion of the filament clamp 16. be able to.

  The ion source of the present invention has been described in detail above. However, the present invention is not limited to the above-described embodiment, and various improvements and modifications may be made without departing from the spirit of the present invention. .

It is a figure explaining the plasma production | generation part of one Embodiment of the ion source of this invention. It is a figure explaining the structure of each part of the outer side of a plasma container which comprises the ion source shown in FIG. It is a figure which shows the structure which fixes and supports the filament and plasma container of the ion source shown in FIG. It is a figure which shows the positional relationship of the connection position A between the filament clamp shown in FIG. 3, and the relaxation member, and the connection position D between a relaxation member and a base. (A) is a top view of the structure shown in FIG. 3, (b) is the front view. (A) And (b) is a figure which shows other embodiment different from embodiment shown in FIG. It is a figure which shows other embodiment different from embodiment shown in FIG. 3 and FIG. It is a perspective view which shows the whole conventional ion source. It is a figure explaining arrangement | positioning of the filament clamp of the conventional ion source shown in FIG. It is a disassembled perspective view of the plasma container of the conventional ion source shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ion source 10,100 Plasma container 12,102 Filament 14,104 Slit opening 16,46,106 Filament clamp 18,48,108 Insulation material 19,59 Relaxation member 20,110 Base 22,112 Support member 24,26, 114, 116 Magnetic pole 32 Filament power source 34 Arc power source 36 Surface 38, 40 Electrode 42, 44 Power source 116, 117, 118, 119 Plate member

Claims (13)

An ion source that generates a plasma to generate an ion beam,
A plasma container covered with a wall for generating plasma and forming an internal space;
A linear filament which is provided in the internal space through a pair of through-holes provided in the plasma vessel, and is heated by energization to emit thermoelectrons, with an intermediate portion folded;
A rod-shaped gripping part for holding both ends of the filament in a state where a gap is provided between the filament passing through the pair of through-holes and a wall surface of the through-hole, provided outside the plasma vessel. A pair of filament holders,
A base for supporting and fixing each of the pair of filament holders;
An interposition member for interposing and connecting between each of the pair of filament holders and the base,
A first direction is determined from a first connection position where each of the pair of filament holders and the interposition member is connected to each filament holding position of the pair of filament holders, and the interposition member A second direction from the second connection position to which the base is connected to the first connection position is defined, and the pair of through holes are viewed from the inner space, and the wall surfaces of the pair of through holes are When the first surface that bisects the line segment that connects the openings of the first vertical surface is determined, the second connection position is the first side of the two sides divided by the first surface. An ion on the side where there is a connection position, wherein the component of the second direction obtained by projecting the second direction into the first direction is directed in the direction opposite to the first direction. source. The rod-shaped gripping portions of the pair of filament holders are provided so that the interval between the rod-shaped gripping portions spreads in a C shape as the distance from the through hole increases.
The ion source according to claim 1, wherein the second connection position is closer to the first surface than the first connection position. 3. The ion source according to claim 2, wherein a distance of the second connection position to the first surface is greater than 0% and not more than 40% of a distance of the first connection position to the first surface. . When the pair of through holes are viewed from the internal space, the first connection position is substantially parallel to a line segment connecting openings on the wall surfaces of the pair of through holes, perpendicular to the first surface. When virtualizing the second surface passing through
The said 2nd connection position is provided in the side with the holding position of the said filament among the two area | regions equally divided by the said 2nd surface. Ion source. The pair of filament holders is made of an alloy mainly composed of a metal selected from tungsten, molybdenum, and tantalum,
The ion source according to claim 1, wherein the interposition member is made of a stainless alloy or an aluminum alloy.   The wall surface of the plasma vessel is provided with a slit opening for extracting an ion beam, and the wall surface of the slit opening is at a position facing the wall surface provided with the pair of through holes through which the filament passes. 6. The ion source according to any one of 5 above.   The ion source according to claim 1, wherein the interposition member is a pair of members that separately connect the pair of filament holders to the base. An ion source that generates a plasma to generate an ion beam,
A plasma container covered with a wall for generating plasma and forming an internal space;
A linear filament which is provided in the internal space through a pair of through-holes provided in the plasma vessel, and is heated by energization to emit thermoelectrons, with an intermediate portion folded;
A rod-shaped gripping part for holding both ends of the filament in a state where a gap is provided between the filament passing through the pair of through-holes and a wall surface of the through-hole, provided outside the plasma vessel. A first filament holder and a second filament holder having
A base for supporting and fixing each of the first filament holder and the second filament holder ;
One interposed member for interposing and connecting between each of the first filament holder and the second filament holder and the base,
When the first surface that bisects the line segment connecting the openings on the wall surfaces of the pair of through holes when the pair of through holes is viewed from the internal space is approximately perpendicularly divided, the first filament holder Holds one end of the filament on the first side of the two sides divided by the first surface, and is connected to the interposition member at the first connection position A1 on the first side. The second filament holder holds the other end of the filament on a second side different from the first side of the two sides, and a first connection position on the second side. Connected to the interposition member at A2,
Wherein the first connecting position A1, the first in the first direction X1 reaches the holding position of the filament of the filament holder, and, from the first connecting position A2, the said second filament holder A first direction X2 to reach the filament holding position is defined, and further, the second connecting position D1 where the interposition member and the base are connected on the first side reaches the first connecting position A1 . A second direction Y1 and a second direction Y2 from the second connection position D2 where the interposition member and the base are connected on the second side to the first connection position A2 are defined. when the components of the second direction Y1 obtained by projecting the second direction Y1 in the first direction X1, together with the first direction X1 and the opposite direction toward Ward, the second direction Y2 Projected in the first direction X2 The components of the second direction Y2, the ion source and wherein the facing opposite directions between the first direction X2. The rod-shaped gripping portions of the first filament holder and the second filament holder are provided so as to spread in a letter C shape as the distance between the rod-shaped gripping portions increases from the through hole,
Said second connecting position D1, as compared to the first connecting position A1, the near rather the first surface, the second connecting position D2, as compared to the first connecting position A2, the The ion source according to claim 8 , wherein the ion source is close to the first surface . The distance to the first surface of the second connecting position D1, the Ri first the first der than 40% more than 0% of the distance to the surface of the connection position A1, the second The ion source according to claim 9 , wherein a distance of the connection position D2 to the first surface is greater than 0% and 40% or less of a distance of the first connection position A2 to the first surface . When the pair of through holes are viewed from the internal space, the first connection position is substantially parallel to a line segment connecting openings on the wall surfaces of the pair of through holes, perpendicular to the first surface. When the second surface passing through A1 is assumed, the second connection position D1 is provided on the side where the filament is held in the two regions divided in two by the second surface. ,
When the pair of through holes are viewed from the internal space, the first connection position is substantially parallel to a line segment connecting openings on the wall surfaces of the pair of through holes, perpendicular to the first surface. When imagining the third surface passing through A2, the second connection position D2 is provided on the side where the filament is held in the two regions divided into two by the third surface. and ion source according to any one of claims 8 to 10.. The first filament holder and the second filament holder are made of an alloy mainly containing a metal selected from tungsten, molybdenum, and tantalum,
The interposed member, the ion source according to any one of claims 8-11 comprising a stainless steel alloy or aluminum alloy. Wherein the walls of the plasma vessel, a slit opening is provided for extracting an ion beam, the wall surface of the slit opening, claims 8 to which is positioned to face the wall surfaces of the pair of through-holes through which the filament is provided 13. The ion source according to any one of items 12 .