Ion gun and vacuum processing equipment

Abstract

An ion gun includes: an anode; a cathode having a first part and a second part facing the anode; and a magnet forming a spatial magnetic field between the first part and the second part. An annular gap including a straight portion and a curved portion is provided between the first part and the second part of the cathode. Between the first part and the second part of the curved portion, the magnet forms magnetic force lines having a bottom closer to the inside than the cross-sectional center line of the gap.

Description

Technical Field

[0001] The present invention relates to an ion gun and a vacuum processing apparatus. Background Art

[0002] An ion gun is a device for ejecting generated ions as an ion beam, and is used in vacuum processing equipment for manufacturing semiconductor devices, etc. Among them, an ion gun called a closed drift ion source has an ejection port for an ion beam that literally forms a closed loop, and is used in various fields by utilizing the feature that the area of ​​the ion gun can be easily increased.

[0003] Although the closed drift type ion gun has the advantage that plasma generation and ion acceleration can be performed simultaneously, due to its structure, some accelerated ions inevitably collide with the magnetic poles that constitute the ejection port. As a result, the magnetic poles are eroded over time, the discharge stability gradually decreases, and eventually the discharge cannot be maintained. In addition to the erosion of the magnetic poles, this also leads to problems such as contamination of the processed object due to the eroded magnetic pole material, heating of the magnetic poles, and a reduction in etching rate due to ion beam loss.

[0004] As a method for solving such a problem, Patent Document 1 discloses an ion gun in which the image ratio near the ejection port is increased. In addition, Patent Document 2 discloses an ion gun in which a magnetic pole is coated with a member having high sputtering resistance.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: U.S. Patent Application Publication No. 2005 / 0247885

[0008] Patent Document 2: U.S. Patent Application Publication No. 2004 / 0016640 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] As a closed drift type ion gun, there is known an ion gun having an annular ejection port in which a straight line portion and a curved line portion are combined in shape. However, the inventors have clearly discovered for the first time that in such an ion gun, if the straight line portion and the curved line portion are designed in the same manner, the amount of ions colliding with the magnetic pole is small in the straight line portion but very large in the curved line portion. In Patent Documents 1 and 2, no special consideration is given to the shape of the ejection port.

[0011] An object of the present invention is to provide an ion gun capable of improving the ejection efficiency and uniformity of an ion beam and stably operating over a long period of time, and a vacuum processing apparatus using the ion gun.

[0012] Solutions for solving problems

[0013] According to one aspect of the present disclosure, an ion gun is provided, comprising: an anode; a cathode, which is opposite to the anode and has a first part and a second part; and a magnet, which is configured to form a magnetic field space between the first part and the second part, wherein an annular gap including a straight portion and a curved portion is provided between the first part and the second part of the cathode, and the magnet is configured to form magnetic lines of force between the first part and the second part of the curved portion, and the bottom of the magnetic lines of force is inside the cross-sectional centerline of the gap.

[0014] According to another aspect of the present disclosure, an ion gun is provided, comprising: an anode; a cathode, which is opposite to the anode and has a first part and a second part; and a magnet, which is configured to form a magnetic field space between the first part and the second part, wherein an annular gap including a straight portion and a curved portion is provided between the first part and the second part of the cathode, the first part is arranged on the inner side relative to the gap, and the second part is arranged on the outer side relative to the gap, the magnet is configured to form magnetic lines of force in a direction from the second part to the first part in the space between the first part, the second part and the anode, and in the curved portion, the magnetic field vector at the point where the magnetic lines of force intersect the cross-sectional center line of the gap is inclined relative to a plane orthogonal to the cross-sectional center line at a first angle that is less than 1.5 degrees with respect to the side where the first part and the second part are located and greater than 0 degrees with respect to the side where the anode is located.

[0015] According to another aspect of the present disclosure, there is provided an ion beam adjustment method, which adjusts an ion beam emitted from a gap of an ion gun, the ion gun comprising an anode, a cathode opposite to the anode and having a first part and a second part, and a magnet constructed to form a magnetic field space between the first part and the second part, wherein the gap is an annular gap comprising a straight portion and a curved portion and arranged between the first part and the second part of the cathode, the method comprising: adjusting the center position of the ion beam emitted from the gap by shifting the position of the bottom of the magnetic field lines formed between the first part and the second part of the curved portion toward the inside of the cross-sectional center line of the gap.

[0016] According to another aspect of the present disclosure, there is provided an ion beam adjustment method for adjusting an ion beam emitted from a gap of an ion gun, the ion gun comprising an anode, a cathode opposite to the anode and having a first part and a second part, and a magnet configured to form a magnetic field space between the first part and the second part, wherein the gap is an annular gap including a straight portion and a curved portion and arranged between the first part and the second part of the cathode, wherein the first part is configured on the inner side relative to the gap and the second part is configured on the outer side relative to the gap, and the magnet is configured to form magnetic lines of force in a direction from the second part to the first part in the space between the first part and the second part and the anode, the method comprising: adjusting the center position of the ion beam emitted from the gap by tilting the magnetic field vector at a point where the magnetic lines of force intersect a cross-sectional center line of the gap in the curved portion relative to a plane orthogonal to the cross-sectional center line toward the side where the anode is located.

[0017] Effects of the Invention

[0018] According to the present invention, the ion beam ejection efficiency and uniformity can be improved. In addition, the collision of the ion beam with the magnetic pole can be suppressed, and excellent effects such as reducing the time variation, improving the maintenance cycle, and reducing the running cost can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] [ Figure 1 ] Figure 1 1 is a perspective view showing the structure of an ion gun according to a first embodiment of the present invention.

[0020] [ Figure 2 ] Figure 2 is a plan view showing the structure of an ion gun according to a first embodiment of the present invention.

[0021] [ Figure 3A ] Figure 3A is a schematic cross-sectional view showing the structure of an ion gun according to a first embodiment of the present invention (part 1).

[0022] [ Figure 3B ] Figure 3B is a schematic cross-sectional view showing the structure of the ion gun according to the first embodiment of the present invention (part 2).

[0023] [ Figure 4 ] Figure 4 1 is an enlarged schematic cross-sectional view showing the structure near the emission outlet of the ion gun according to the first embodiment of the present invention.

[0024] [ Figure 5A ] Figure 5Ais a diagram showing the operation of the ion gun according to the first embodiment of the present invention (part 1).

[0025] [ Figure 5B ] Figure 5B is a diagram showing the operation of the ion gun according to the first embodiment of the present invention (part 2).

[0026] [ Figure 6 ] Figure 6 is a schematic diagram showing the magnetic mirror force generated by the magnetic mirror field.

[0027] [ Fig. 7A ] Fig. 7A is a diagram showing the structure and operation of an ion gun according to a reference example (part 1).

[0028] [ Figure 7B ] Figure 7B is a diagram showing the structure and operation of an ion gun according to a reference example (part 2).

[0029] [ Figure 8 ] Figure 8 Schematic diagram showing the magnetic mirror force generated in the curved portion of the ejection port.

[0030] [ Fig. 9 ] Fig. 9 Schematic diagram showing the electrical relationship between the plasma, the anode, and the magnetic pole plate in the curved portion of the ejection port.

[0031] [ Fig.10 ] Fig.10 Schematic diagram showing the direction of the magnetic field vector on the cross-sectional center line of the ejection port.

[0032] [ Fig.11 ] Fig.11 is a schematic diagram showing the movement of electrons in the space between the pole plate and the anode.

[0033] [ Fig.12 ] Fig.12 : is a graph showing the simulation results of the erosion amount of the magnetic pole plate when the bottom position of the magnetic field line is changed.

[0034] [ Fig.13 ] Fig.13 : is a graph showing the simulation results of the relationship between the distance under the magnet and the bottom position of the magnetic field line.

[0035] [ Fig.14 ] Fig.14 : is a graph showing the relationship between the inclination angle of the magnetic field lines obtained by simulation and the distance from the anode on the cross-sectional center line of the injection port.

[0036] [ Fig.15 ] Fig.15is a schematic diagram showing a vacuum processing apparatus according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0037] (First Embodiment)

[0038] Reference Figures 1 to 3B The structure of the ion gun according to the first embodiment of the present invention will be described. Figure 1 It is a perspective view showing the structure of the ion gun according to the present embodiment. Figure 2 is a plan view showing the structure of an ion gun according to the present embodiment. Figure 3A and Figure 3B is a schematic cross-sectional view showing the structure of an ion gun according to the present embodiment. Figure 3A It is along Figure 2 A cross-sectional view taken along line AA' of Figure 3B It is along Figure 2 A cross-sectional view taken along line BB'.

[0039] like Figures 1 to 3B As shown, the ion gun 10 according to the present embodiment includes magnetic pole plates 20A and 20B, a magnet 32, a yoke 34, and an anode 40, and has a substantially rectangular parallelepiped appearance. Figure 1 As shown, an ejection port 22 for ejecting an ion beam is provided on one main surface of the ion gun 10 .

[0040] The pole plate 20A and the pole plate 20B are plate-like bodies made of a high-permeability magnetic material having electrical conductivity. The pole plate 20B is a ring-shaped plate-like body having an opening corresponding to the outer peripheral shape of the pole plate 20A. The pole plate 20A is arranged inside the opening of the pole plate 20B in a manner to ensure a predetermined gap between the pole plate 20A and the pole plate 20B. The pole plate 20A and the pole plate 20B can be used as a magnetic pole that forms a magnetic field space by arranging a predetermined gap between the pole plate 20A and the pole plate 20B. The pole plate 20A and the pole plate 20B are also used as a cathode opposite to the anode 40. The pole plate 20A constitutes a first part of the cathode, and the pole plate 20B constitutes a second part of the cathode.

[0041] The gap between the magnetic pole plate 20A and the magnetic pole plate 20B forms an annular opening along the outer periphery of the magnetic pole plate 20A and the inner periphery of the magnetic pole plate 20B. The annular opening formed in this way constitutes the ion beam ejection port 22. For example, Figure 1 and Figure 2As shown, the ejection port 22 may include a straight portion 22a and a semicircular curved portion 22b. In order to maintain discharge, the ejection port 22 is preferably annular, but the shape of the ejection port 22 is not particularly limited. Any shape such as a portion of a perfect circle or a portion of an ellipse may be applied to the curved portion 22b. The curvature of the curved shape may be constant or non-constant.

[0042] When viewed from the center of the ejection port 22 in a plan view, Figure 2 As shown, the pole plate 20A is located on the inner side of the annular ejection port 22, and the pole plate 20B is located on the outer side of the annular ejection port 22. In this specification, the expression "inner side" of the ejection port 22 means the side of the pole plate 20A relative to the ejection port 22, and the expression "outer side" of the ejection port 22 means the side of the pole plate 20B relative to the ejection port 22.

[0043] The magnetic pole plates 20A and 20B are not particularly limited as long as they are made of a high-permeability magnetic material having electrical conductivity, and may be composed of, for example, ferromagnetic stainless steel such as SUS430, SmCo alloy, NdFe alloy, or the like.

[0044] like Figure 2 As shown in FIG. 3 , the magnet 32 ​​and the yoke 34 constitute a structure 30 having an annular recess 36. The pole plate 20A and the pole plate 20B are bonded to the surface of the structure 30 provided with the recess 36 in such a manner that the ejection port 22 is located above the recess 36 along the recess 36. The yoke 34 is magnetically coupled to the magnet 32 ​​and the pole plates 20A and 20B, and serves as a magnetic conductor for guiding the magnetic flux generated by the magnet 32 ​​to the pole plates 20A and 20B. The magnet 32 ​​and the yoke 34 are configured so that the recess 36 is located inside the magnetic circuit (magnetic path) formed by the pole plates 20A and 20B, the magnet 32 ​​and the yoke 34. The magnet 32 ​​forms a magnetic field space between the pole plates 20A and 20B via the yoke 34. The yoke 34 and the magnet 32 ​​can be electrically connected to the pole plates 20A and 20B.

[0045] The yoke 34 is not particularly limited as long as it is a high-permeability magnetic material with conductivity, and can be composed of, for example, ferromagnetic stainless steel such as SUS430, SmCo alloy, NdFe alloy, etc. The magnet 32 ​​can be a permanent magnet or an electromagnet. The maximum magnetic flux density of the magnet 32 ​​in the magnetic field formed between the magnetic pole plate 20A and the magnetic pole plate 20B is preferably about 1000 [Gauss].

[0046] The yoke 34 is provided with an air inlet 38 communicating with the recessed portion 36 from the outside of the structure 30. Figure 3A and Figure 3BA plurality of air inlets 38 are shown provided at the bottom of the structure 30 , but the number and arrangement of the air inlets 38 are not particularly limited.

[0047] like Figure 3A As shown, in the straight portion 22a of the ejection port 22, the magnet 32 ​​is located on the cross-sectional center line 24 of the ejection port 22. That is, the distance between the magnet 32 ​​and the magnetic pole plate 20B is substantially equal to the distance between the magnet 32 ​​and the magnetic pole plate 20A. Alternatively, the magnetic path length between the magnet 32 ​​and the magnetic pole plate 20B is substantially equal to the magnetic path length between the magnet 32 ​​and the magnetic pole plate 20A. In this specification, the cross-sectional center line 24 of the ejection port 22 refers to a straight line parallel to the ejection direction (Z direction) of the ion beam passing through the center of the width direction of the ejection port 22.

[0048] like Figure 3B As shown, in the curved portion 22b of the ejection port 22, the magnet 32 ​​is located outside the cross-sectional centerline 24 of the ejection port 22. That is, the distance between the magnet 32 ​​and the magnetic pole plate 20B is shorter than the distance between the magnet 32 ​​and the magnetic pole plate 20A. Alternatively, the magnetic path length between the magnet 32 ​​and the magnetic pole plate 20B is shorter than the magnetic path length between the magnet 32 ​​and the magnetic pole plate 20A.

[0049] The anode 40 is an annular structure corresponding to the shape of the recessed portion 36, and is housed in the recessed portion 36 away from the magnetic pole plates 20A, 20B, the magnet 32, and the yoke 34. The anode 40 is opposite to the magnetic pole plates 20A and 20B as cathodes, and serves as an accelerating electrode that accelerates ions in the plasma generated in the space between the magnetic pole plates 20A and 20B and the anode 40 together with the magnetic pole plates 20A and 20B. The anode 40 is not particularly limited, but, for example, may be fixed to the structure 30 by a spacer (not shown) made of an insulating material. The anode 40 may be conductive and does not need to consider magnetic properties, and may be composed of non-magnetic stainless steel, for example.

[0050] Next, we will refer to Figure 4 The specific shape of the portion of the magnetic pole plates 20A and 20B facing the anode 40 will be described. Figure 4 This is a cross-sectional view conceptually illustrating the shape of the portion of the magnetic pole plates 20A and 20B facing the anode 40 .

[0051] The characteristics of the ion beam emitted from the emission port 22 vary greatly depending on the shape of the ends of the magnetic pole plates 20A and 20B, the positional relationship between the magnetic pole plates 20A and 20B and the anode 40, etc. Therefore, the shape of the ends of the magnetic pole plates 20A and 20B, the positional relationship between the magnetic pole plates 20A and 20B and the anode 40, etc. are appropriately set according to the characteristics required for the ion beam, and are typically set as follows: Figure 4 The relationship shown.

[0052] For example, Figure 4 As shown, the ends of the pole plates 20A and 20B can be formed into a cone with a chamfered portion on the side facing the anode 40. When the width of the ejection port 22 is G, the thickness of the thinnest part of the pole plates 20A and 20B is T1, the thickness of the cone portion is T2, and the gap between the pole plates 20A and 20B and the anode 40 is S, all of which can be set to a size of about several millimeters. The cone angle θ can be set to about 45 degrees. The shape of the ends of the pole plates 20A and 20B and the sizes of the various parts are merely examples and are not particularly limited. Depending on the ion gun, the corners of the pole plates 20A and 20B on the side opposite to the anode 40 can be chamfered.

[0053] Next, we will refer to Figure 5A and Figure 5B The operation of the ion gun according to this embodiment will be described. Figure 5A and Figure 5B The operation of the ion gun according to the present embodiment is shown. Figure 5A Corresponding to along Figure 2 A cross-sectional view taken along line AA' of Figure 5B Corresponding to along Figure 2 The cross-sectional view is taken along the line BB'. Assume Figure 5A and Figure 5B The cross section shown is a surface that appears when the ion gun 10 is cut along a direction in which the width of the ejection port 22 becomes the smallest.

[0054] First, a discharge gas such as argon (Ar) is supplied to the recess 36 through the gas inlet 38 to adjust the pressure inside the ion gun 10 to about 0.1 Pa. When the pressure in the use environment (for example, the pressure in the chamber of the vacuum processing equipment where the ion gun 10 is installed) is already about 0.1 Pa and discharge is possible in this state, the gas supply operation can be omitted.

[0055] Next, the magnetic pole plates 20A and 20B and the magnetic yoke 34 serving as cathodes are set to a ground potential (0 V), and a voltage of, for example, about 1000 V to 4000 V is applied from a power supply (not shown) to the anode 40. Thus, an electric field is generated between the anode 40 and the magnetic pole plates 20A and 20B, and the gas introduced into the ion gun 10 is excited, dissociated, and ionized by the electric field, thereby generating plasma 50.

[0056] On the other hand, the magnetic flux (magnetic field lines 60) emitted from the N pole of the magnet 32 ​​passes through the yoke 34 and the pole plate 20B, and is emitted from the end of the pole plate 20B. The magnetic field lines 60 emitted from the end of the pole plate 20B are diffused by the repulsive force and then sucked into the pole plate 20A. As a result, in the gap space between the pole plates 20A and 20B, as shown in FIG. Figure 5A and Figure 5BAs shown, the magnetic field lines 60 are convex up and down. The magnetic field space with this shape is called a magnetic mirror field. The magnetic mirror field plays a role in confining charged particles therein.

[0057] Figure 6 is a schematic diagram showing the magnetic mirror force generated by the magnetic mirror field. Figure 6 As shown, when the magnetic field lines 60 have a dense portion and a sparse portion, the charged particles in the magnetic mirror field receive a magnetic mirror force 64 in the direction from the dense portion of the magnetic field lines 60 to the sparse portion of the magnetic field lines. Therefore, the charged particles are confined in the magnetic mirror field. In addition, when the plasma 50 is generated in the magnetic mirror field, the density of the plasma 50 is higher than when there is no magnetic field.

[0058] The electrons in the plasma 50 are pulled into the anode 40 by the electric field between the pole plates 20A and 20B and the anode 40. The positive ions in the plasma 50 are accelerated by the potential difference between the pole plates 20A and 20B and the anode 40 to form an ion beam 52.

[0059] As described above, the ion gun 10 according to the present embodiment is characterized in that the magnet 32 ​​is arranged outside the cross-sectional center line 24 of the ejection port 22 in the curved portion 22b of the ejection port 22. The reason why the ion gun 10 of the present embodiment is constructed in this manner will be described below while comparing with the ion gun of the reference example.

[0060] Fig. 7A and Figure 7B is a schematic cross-sectional view showing the structure and operation of an ion gun according to a reference example. Fig. 7A Corresponding to along Figure 1 A cross-sectional view taken along line AA' of Figure 7B Corresponding to along Figure 1 In addition to the different configurations of the magnet 32, according to Fig. 7A and Figure 7B The ion gun of the reference example shown is the same as the ion gun 10 according to the present embodiment. That is, in the ion gun according to the reference example, the magnet 32 ​​is arranged at a position opposite to the ejection port 22, wherein the anode 40 is interposed between the ejection port 22 and the magnet 32. That is, in both the straight portion 22a and the curved portion 22b of the ejection port 22, the magnet 32 ​​is located on the cross-sectional center line 24 of the ejection port 22.

[0061] In a conventional ion gun, the magnetic field is designed so that the magnetic field is symmetrical with respect to the cross-sectional center line 24 of the ejection port 22. By designing the magnetic field in this way, the center of the generated plasma 50 is located on the cross-sectional center line 24 of the ejection port 22, so that the collision of the ion beam 52 with the magnetic pole plates 20A and 20B can be minimized, and the ion beam 52 can be efficiently ejected. For this purpose, for example, as in the case of Fig. 7A and Figure 7B As in the ion gun of the reference example shown, the magnet 32 ​​is often arranged at a position opposite to the ejection port 22 , with the anode 40 interposed between the ejection port 22 and the magnet 32 ​​.

[0062] However, when the magnetic field is designed in the curved portion 22b of the ejection port 22 in the same manner as in the straight portion 22a, as shown in FIG. Figure 7B As shown, the center of the generated plasma 50 is shifted to the outside of the cross-sectional center line 24 of the ejection port 22, and the ion beam 52 colliding with the magnetic pole plate 20B increases. Therefore, the ion beam 52 cannot be ejected from the ejection port 22 efficiently.

[0063] In addition, the magnetic pole plates 20A and 20B are eroded over time by the sputtering effect of the ion beam 52 that collides with the magnetic pole plates 20A and 20B, and the discharge stability gradually decreases, and eventually the discharge cannot be maintained. Therefore, the magnetic pole plates 20A and 20B need to be replaced regularly, but when the colliding ion beam 52 increases, the amount of erosion of the magnetic pole plates 20A and 20B increases, and the maintenance cycle is shortened. In addition, since the particles generated by the sputtering magnetic pole plates 20A and 20B cause contamination of the processing equipment, it is desirable that the amount of the ion beam 52 that collides with the magnetic pole plates 20A and 20B is as small as possible.

[0064] Reference Figure 8 and Fig. 9 The reason why the center of the plasma 50 is shifted to the outside from the center of the cross section of the ejection port 22 in the curved portion 22 b of the ejection port 22 will be described. Figure 8 2 is a schematic diagram showing a magnetic mirror force generated in the curved portion 22 b of the ejection port 22 . Fig. 9 2 is a schematic diagram showing the electrical relationship between the plasma 50 in the curved portion 22 b of the ejection port 22 , the anode 40 , and the magnetic pole plates 20A and 20B.

[0065] like Figure 8 As shown in FIG. 1 , in a plane (XY plane) parallel to the magnetic pole plates 20A and 20B, the intervals between the magnetic lines of force 60 of the curved portion 22b gradually spread from the magnetic pole plate 20A toward the magnetic pole plate 20B. That is, the magnetic lines of force 60 are dense on the magnetic pole plate 20A side (inside the ejection port 22) and sparse on the magnetic pole plate 20B side (outside the ejection port 22). As a result, as shown in FIG. Figure 7B As shown, the plasma 50 receives the magnetic mirror force 64 directed outwardly through the magnetic mirror effect, and moves toward the magnetic pole plate 20B side (outside the cross-sectional centerline 24 of the ejection port 22 ).

[0066] When comparing the areas of the magnetic pole plates 20A and 20B in contact with the plasma 50 in the curve portion 22b, the area of ​​the magnetic pole plate 20B in contact with the plasma 50 (electrode area) is larger than the area of ​​the magnetic pole plate 20A in contact with the plasma 50 (electrode area). Therefore, when comparing the impedance R between the plasma 50 and the magnetic pole plate 20A A and the impedance R between the plasma 50 and the magnetic pole plate 20B B When the magnetic pole plate 20B having a larger electrode area than the magnetic pole plate 20A and the plasma 50 becomes smaller (R A >R B ). That is, the magnetic pole plate 20B functions more strongly as a cathode than the magnetic pole plate 20A. As a result, a larger amount of current flows toward the magnetic pole plate 20B side, and more plasma 50 is generated on the magnetic pole plate 20B side.

[0067] Due to these two effects, the center of the plasma 50 is shifted outward from the cross-sectional center line 24 of the ejection port 22 in the curved portion 22 b of the ejection port 22 .

[0068] From this point of view, in the ion gun 10 according to the present embodiment, the magnetic field is designed so that the bottom 62 of the magnetic field line 60 in the curved portion 22b of the ejection port 22 is located closer to the magnetic pole plate 20A than the cross-sectional center line 24 of the ejection port 22 (see Figure 5B ). That is, the center position of the ion beam 52 ejected from the ejection port 22 is adjusted so that the bottom 62 of the magnetic force line 60 formed between the magnetic pole plate 20A and the magnetic pole plate 20B of the curved portion 22b is shifted to the inside from the cross-sectional center line 24 of the ejection port 11. In this specification, the bottom 62 of the magnetic force line 60 means a point on the magnetic force line 60 in the space between the magnetic pole plates 20A and 20B and the anode 40, at which point the tangent direction of the magnetic force line 60 is parallel to the surface of the anode 40 facing the ejection port 22.

[0069] From another point of view, in the space between the magnetic pole plates 20A, 20B and the anode 40 in the curved portion 22b, the direction of the magnetic force lines 60 (magnetic field vector) from the magnetic pole plate 20B toward the magnetic pole plate 20A is inclined toward the anode 40 side relative to the plane 66 orthogonal to the cross-sectional center line 24 at the point where the cross-sectional center line 24 of the ejection port 22 and the magnetic force lines 60 intersect each other (see Fig.10 That is, in the curved portion 22b, the center position of the ion beam 52 ejected from the ejection port 22 is adjusted so that the magnetic field vector at the point where the magnetic field line 60 intersects the cross-sectional center line 24 of the ejection port 22 is inclined toward the anode 40 side relative to the plane orthogonal to the cross-sectional center line 24.

[0070] Fig.112 is a schematic diagram showing the movement of electrons in the space between the magnetic pole plates 20A and 20B and the anode 40. In the plasma, electrons and ions are continuously generated by ionization. The generated electron e is attracted to the anode 40 by the potential difference between the magnetic pole plates 20A and 20B and the anode 40, but is also subjected to the magnetic field force (Lorentz force), and thus moves along the magnetic field lines 60 in a manner entangled with the magnetic field lines 60, and reciprocates with the bottom 62 as the center. The reciprocating electron e gradually loses energy due to collision with the gas and is eventually collected by the anode 40. When the electron e is located at the bottom 62 of the magnetic field lines 60, the kinetic energy of the electron e is the highest during the reciprocating motion. Therefore, the frequency of occurrence of ionization, that is, the density of the plasma 50 is the highest near the bottom 62 of the magnetic field lines 60. Therefore, if the magnetic field is designed so that the position of the bottom 62 of the magnetic field lines 60 is transferred from the cross-sectional center line 24 of the ejection port 22, the center of the plasma 50 and the ion beam 52 can also be transferred from the cross-sectional center line 24 of the ejection port 22.

[0071] Therefore, by shifting the position of the bottom 62 of the magnetic field line 60 toward the inside of the cross-sectional center line 24 of the ejection port 22 so as to offset the movement of the plasma 50 toward the outside due to the magnetic mirror effect, the center of the plasma 50 can be shifted to the vicinity of the cross-sectional center line 24 of the ejection port 22. Thus, in the curved portion 22b of the ejection port 22 and in the straight portion 22a, the collision of the ion beam 52 with the magnetic pole plates 20A and 20B can be minimized, and the ion beam 52 can be efficiently ejected.

[0072] Since the magnetic lines 60 exist in an infinite number, the bottoms 62 of the magnetic lines 60 also exist in an infinite number. What is important in the present invention is that, as can be seen from the mechanism, the position of the bottoms 62 of the magnetic lines 60 is at a height where the plasma 50 is generated. In many cases, the plasma 50 is generated at a height of about 1 mm from the surface of the anode 40. Therefore, in one example, the position of the bottoms 62 of the magnetic lines 60 can be defined as the position of the bottoms 62 of the magnetic lines 60 at a height of 1 mm from the surface of the anode 40.

[0073] Next, the amount of the position of the bottom 62 of the magnetic field line 60 shifting inward from the cross-sectional center line 24 of the ejection port 22 will be described. The shift amount of the bottom 62 was simulated and detected by using ELF / MAGIC, which is a general magnetic field analysis software, and PEGASUS, which is a general plasma analysis software. As simulation conditions, the gas used to generate plasma was Ar, the pressure in the chamber was 0.07 Pa, and the voltage applied to the anode 40 was 3000 V.

[0074] Fig.1220A and 20B when the position of the bottom 62 of the magnetic line of force 60 is changed. The vertical axis represents the ratio of the erosion amount of the magnetic pole plate 20A to the erosion amount of the magnetic pole plate 20B (the inside-outside ratio of the erosion). The vertical axis represents the value obtained by dividing the larger value of the erosion amount of the magnetic pole plate 20A and the erosion amount of the magnetic pole plate 20B by the smaller value. When the erosion amount of the magnetic pole plate 20B is greater than the erosion amount of the magnetic pole plate 20A, the vertical axis represents a positive value, and when the erosion amount of the magnetic pole plate 20A is greater than the erosion amount of the magnetic pole plate 20B, the vertical axis represents a negative value. The horizontal axis represents the distance from the cross-sectional center line of the ejection port 22 to the bottom 62 of the magnetic line of force 60 (the position of the bottom of the magnetic line of force). The horizontal axis represents the amount of displacement of the bottom 62 when the position is displaced outward relative to the cross-sectional centerline 24 of the ejection port 22 as positive values, and represents the amount of displacement of the bottom 62 when the position is displaced inward relative to the cross-sectional centerline 24 of the ejection port 22 as negative values.

[0075] like Fig.12 As shown, the inside-outside ratio of erosion of the pole plates 20A and 20B is roughly proportional to the position of the bottom 62 of the magnetic flux 60. As the position of the bottom 62 of the magnetic flux 60 moves in the outer direction, the inside-outside ratio of erosion increases in the positive direction, and as the position of the bottom 62 of the magnetic flux 60 moves in the inner direction, the inside-outside ratio of erosion increases in the negative direction.

[0076] For example, when the bottom 62 of the magnetic field lines 60 in the curved portion 22b of the ejection port 22 is located on the cross-sectional center line 24 of the ejection port 22 (shift amount = 0 mm), the center of the plasma 50 and the ion beam 52 shifts outward from the cross-sectional center line 24 of the ejection port 22 as described above. In this case, the erosion amount of the magnetic pole plate 20B is approximately 2.1 times the erosion amount of the magnetic pole plate 20A.

[0077] In order to evenly transfer the erosion amount of the magnetic pole plates 20A and 20B, that is, to transfer the center of the plasma 50 and the ion beam 52 to the vicinity of the cross-sectional center line 24 of the ejection port 22, the bottom 62 of the magnetic field line 60 can be transferred toward the inside of the cross-sectional center line 24 of the ejection port 22. Fig.12 In the example, it has been found that the position of the bottom 62 of the magnetic line 60 is preferably shifted from the cross-sectional center of the ejection port 22 toward the inner side by about 0.1 mm to 0.4 mm, and most preferably shifted from the cross-sectional center of the ejection port 22 toward the inner side by 0.25 mm.

[0078] At a position where the inside-outside ratio of erosion is equal, the absolute erosion amount of the pole plates 20A and 20B tends to be small. In the inventor's research, by setting the transfer amount of the bottom 62 to 0.1 mm to 0.4 mm, the erosion amount of the pole plates 20A and 20B can be reduced by about 20% at most compared to the case where the transfer amount of the bottom 62 is set to 0 mm. This means that the heat generation of the pole plates 20A and 20B, the contamination of the processed object, the ion beam loss, etc. can be reduced by about 20% at most.

[0079] In addition, in the research of the present inventors, by setting the transfer amount of the bottom 62 to 0.1 mm to 0.4 mm, the peak erosion rate can be reduced from about 1 / 1.3 to about 1 / 1.8 of the case where the transfer amount of the bottom 62 is set to 0 mm. This is equivalent to increasing the life and maintenance cycle of the component by about 1.3 to 1.8 times.

[0080] Note that the appropriate shift amount of the position of the bottom 62 of the magnetic force line 60 varies depending on the structure of the ion gun 10, discharge conditions, etc. For example, when the size of the ion gun 10 or the curvature of the curved portion 22b of the ejection port 22 increases, it is considered that the optimal shift amount is greater than the above value. Depending on the structure of the ion gun 10, discharge conditions, etc., it is preferred to appropriately set the shift amount of the position of the bottom 62 of the magnetic force line 60.

[0081] Although there is no particular limitation on the method for shifting the position of the bottom 62 of the magnetic flux 60 in the curved portion 22b of the ejection port 22, one example is a method of changing the position of the magnet 32 ​​as described in the present embodiment. Shifting the position of the bottom 62 of the magnetic flux 60 is to destroy the symmetry of the magnetic field with respect to the cross-sectional center line 24 of the ejection port 22, and it can be said that moving the position of the magnet 32 ​​is the most direct method.

[0082] Fig.13 3 is a graph showing the simulation results of the relationship between the distance under the magnet and the bottom position of the magnetic field line. The "distance under the magnet" on the vertical axis represents the distance x from the bottom surface of the structure 30 to the bottom surface of the magnet 32 ​​(see Figure 5B ). In the "bottom position of the magnetic field line" on the horizontal axis, when the bottom 62 is located on the cross-sectional center line 24 of the ejection port 22, it is represented as 0, the position inside the cross-sectional center line 24 is represented by a negative sign, and the position outside the cross-sectional center line 24 is represented by a positive sign. In the simulation, the distance x under the magnet 32 ​​is changed without changing the size of the magnet 32.

[0083] like Fig.13As shown, the distance x under the magnet and the position of the bottom 62 of the magnetic field line 60 are roughly proportional to each other. By changing the distance x under the magnet, the inner and outer balance of the magnetic field near the magnetic pole changes, and the position of the bottom 62 of the magnetic field line 60 changes. By increasing the distance x under the magnet, the position of the bottom 62 of the magnetic field line 60 can be shifted toward the inner side of the ejection port 22. According to the simulation results, by setting the distance x under the magnet to Y, the position of the bottom 62 of the magnetic field line 60 can be shifted inward by 0.25 mm. The size of Y can be set to several tens of millimeters.

[0084] Fig.14 Graph 2 is a graph showing the relationship between the distance from the anode 40 on the cross-sectional center line 24 of the injection port 22 and the inclination angle of the magnetic force lines 60 . Fig.14 The simulation results are shown when the position of the bottom 62 of the magnetic force line 60 is set to -0.1 mm, -0.4 mm, and -0.56 mm, respectively. The negative sign indicates that the position of the bottom 62 of the magnetic force line 60 is at the position inside the cross-sectional center line 24 of the ejection port 22, and the positive sign indicates that the position of the bottom 62 of the magnetic force line 60 is at the position outside the cross-sectional center line 24 of the ejection port 22. When the magnetic force line 60 is parallel to the plane 66 ( Fig.10 ), the inclination angle of the magnetic lines of force 60 is 0 degrees, which is indicated by a minus sign when the magnetic lines of force 60 are inclined toward the anode 40, and by a plus sign when the magnetic lines of force 60 are inclined toward the magnetic pole plates 20A and 20B.

[0085] like Fig.14 As shown, as the magnetic force lines 60 approach the anode 40, the inclination angle of the magnetic force lines 60 at the point where they intersect the cross-sectional center line 24 of the ejection port 22 becomes larger. In addition, as the transfer amount at the bottom 62 position of the magnetic force lines 60 increases in the inner direction, the inclination angle at the point where they intersect the cross-sectional center line 24 of the ejection port 22 toward the anode 40 increases. According to the simulation results, it was found that the inclination angle of the magnetic force lines 60 in the transfer amount range of -0.1 mm to -0.4 mm was in the range of 1.5 degrees to -3.5 degrees, and in the transfer amount range of -0.1 mm to -0.4 mm, the absolute erosion amount and erosion rate peak of the magnetic pole plates 20A and 20B were improved.

[0086] That is, in the curved portion 22b, it is desirable that the magnetic field vector at the point where the magnetic force line 60 and the cross-sectional center line 24 of the ejection port 22 intersect is inclined at a first angle relative to a plane 66 orthogonal to the cross-sectional center line 24, the first angle being inclined toward the magnetic pole plates 20A and 20B sides within a range of 0 to 1.5 degrees, and being inclined toward the anode 40 side within a range of 0 to 3.5 degrees. In addition, in the straight portion 22a, it is desirable that the magnetic field vector at the point where the magnetic force line 60 and the cross-sectional center line 24 of the ejection port 22 intersect each other forms a second angle smaller than the first angle relative to the plane 66 orthogonal to the cross-sectional center line 24. In the case where the magnetic field vector is parallel to the plane 66, the optimal value of the second angle is 0 degrees.

[0087] The method of shifting the position of the bottom 62 of the magnetic field lines 60 by breaking the symmetry of the magnetic field is not limited to the method of moving the position of the magnet 32. Other methods include, for example, a method of controlling an applied current when an electromagnet is used as the magnet 32.

[0088] As described above, according to this embodiment, the ejection efficiency and uniformity of the ion beam can be improved. In addition, the collision of the ion beam with the magnetic pole can be suppressed, achieving excellent effects such as reducing the time variation, improving the maintenance cycle and reducing the running cost.

[0089] (Second Embodiment)

[0090] Reference Fig.15 A vacuum processing apparatus according to a second embodiment of the present invention will be described. Fig.15 2 is a schematic diagram of a vacuum processing apparatus according to the present embodiment. The same components as those of the ion gun according to the first embodiment are denoted by the same reference numerals, and description thereof will be omitted or simplified.

[0091] In this embodiment, as an example of an apparatus to which the ion gun 10 according to the first embodiment is applied, an ion beam etching apparatus as a vacuum processing apparatus for manufacturing a semiconductor device or the like will be described. The application example of the ion gun according to the first embodiment is not limited to the ion beam etching apparatus, and may be a film forming apparatus such as an ion beam sputtering apparatus. In addition, the application example of the ion gun according to the first embodiment is not limited to the vacuum processing apparatus, but may be other apparatus including the ion gun.

[0092] like Fig.15 As shown, the vacuum processing apparatus 100 according to the present embodiment may include a vacuum chamber 110, a vacuum pump 120, a holder 130 holding a substrate 132 to be processed, and an ion gun 140 as main components. The vacuum pump 120 is connected to the vacuum chamber 110. The holder 130 and the ion gun 140 are installed in the vacuum chamber 110.

[0093] The vacuum chamber 110 is a processing chamber, the inside of which may be maintained in a vacuum state, and various processes such as etching, surface modification, and surface cleaning may be performed inside the vacuum chamber 110 .

[0094] The vacuum pump 120 is an exhaust device for exhausting the gas in the vacuum chamber 110 and making the interior of the vacuum chamber 110 enter a vacuum state. By exhausting the gas in the vacuum chamber 110 by the vacuum pump 120, the interior of the vacuum chamber can enter a vacuum state of about 10 -3 Up to 10 - 6 pa high vacuum state.

[0095] The holder 130 is a member for holding a processed object (processed substrate 132) made of, for example, Si, Ga, carbon or the like. The holder 130 may include a swing mechanism. Since the holder 130 includes a swing mechanism, the processed substrate 132 can be subjected to high planar uniformity processing. The holder 130 may also have other functions, for example, a heating function for heating the processed substrate 132.

[0096] The ion gun 140 is the ion gun described in the first embodiment, and is arranged at a position opposite to the processed substrate 132 held by the holder 130. The ion gun 140 irradiates the positive ion beam 52 toward the processed substrate 132. The ion beam 52 emitted from the ion gun 140 collides with the processed substrate 132 with high kinetic energy. Thereby, the surface of the processed substrate 132 can be subjected to a predetermined process such as etching.

[0097] By constructing the vacuum processing apparatus 100 using the ion gun 10 according to the first embodiment, the substrate 132 to be processed can be irradiated with the ion beam 52 with high uniformity, thereby improving the processing quality. In addition, since the collision between the ion beam 52 and the magnetic pole plates 20A and 20B can be reduced, the maintenance cycle can be extended. Thus, the production cost can be improved, and the processing capacity of the substrate 132 to be processed can be improved. In addition, the contamination of the inside of the vacuum chamber 110 and the substrate 132 to be processed by particles generated by the ion beam 52 sputtering the magnetic pole plates 20A and 20B can be suppressed.

[0098] (Variant Implementation)

[0099] The present invention is not limited to the above-described embodiment, and various modifications may be made.

[0100] For example, the example that a part of the structure of any embodiment is added to another embodiment or a part of the structure of another embodiment is replaced is also an embodiment of the present invention. In addition, known techniques or well-known techniques in the technical field can be appropriately applied to parts not shown in specific descriptions or embodiments.

[0101] In addition, in the above-mentioned embodiment, although the magnet 32 ​​is arranged on the cross-sectional center line 24 of the ejection port 22 in the straight portion 22a of the ejection port 22, if the magnetic field is symmetrical with respect to the cross-sectional center line 24 of the ejection port 22, it is not necessary to arrange the magnet 32 ​​on the cross-sectional center line 24.

[0102] Although argon is exemplified as the discharge gas in the above embodiment, the discharge gas is not limited to a rare gas such as argon, and may be a reactive gas represented by oxygen or nitrogen. The discharge gas may be appropriately selected depending on the purpose of use of the ion gun 10 and the like.

[0103] [Explanation of Reference Numerals]

[0104] 10…Ion Gun

[0105] 20A, 20B…Magnetic pole plate

[0106] 22…Ejection port

[0107] 22a…Straight line

[0108] 22b…curve

[0109] 24…Centerline of section

[0110] 30…Structure

[0111] 32…Magnet

[0112] 34…Yoke

[0113] 36…Depression

[0114] 38…Air Inlet

[0115] 40…Anode

[0116] 42…Magnetic board

[0117] 50…Plasma

[0118] 52…Ion beam

[0119] 60…Magnetic lines of force

[0120] 62…Bottom

[0121] 64…Magnetic mirror force

[0122] 66…Plane perpendicular to the centerline of the section

[0123] 100…Vacuum treatment equipment

[0124] 110…Vacuum chamber

[0125] 120…Vacuum pump

[0126] 130…Retaining parts

[0127] 132…Processed substrate

[0128] 140…Ion gun

Claims

1. An ion gun, comprising: anode; a cathode opposite to the anode and having a first portion and a second portion; as well as a magnet configured to form a magnetic field space between the first portion and the second portion, wherein an annular gap including a straight portion and a curved portion is provided between the first portion and the second portion of the cathode, and The magnet is configured to form magnetic lines of force between the first portion and the second portion of the curved portion, with the bottom of the magnetic lines of force being inside a cross-sectional centerline of the gap.

2. The ion gun according to claim 1, characterized in that The magnet is configured to form magnetic lines of force between the first portion and the second portion of the straight portion, and the bottom of the magnetic lines of force is located outside the curved portion relative to a cross-sectional center line of the gap.

3. The ion gun according to claim 2, characterized in that The magnet is configured to form magnetic lines of force between the first portion and the second portion of the straight portion, with the bottoms of the magnetic lines of force being on the cross-sectional center line.

4. The ion gun according to claim 1, characterized in that By applying an electric field between the anode and the cathode, plasma is generated at the bottom location.

5. The ion gun according to claim 1, characterized in that The height of the bottom from the surface of the anode is 1 mm.

6. The ion gun according to claim 1, characterized in that The distance between the center line of the cross section and the bottom is in the range of 0.1 mm to 0.4 mm.

7. The ion gun according to claim 1, characterized in that In the curved portion, the magnet is arranged outside a cross-sectional center line of the gap.

8. The ion gun according to claim 1, characterized in that In the straight portion, the magnet is arranged on a cross-sectional center line of the gap.

9. The ion gun according to claim 1, characterized in that: In the curved portion, a minimum value of a length of a magnetic path between the second portion and the magnet is smaller than a minimum value of a length of a magnetic path between the first portion and the magnet.

10. The ion gun according to claim 1, characterized in that The gap is an ejection port for ejecting an ion beam.

11. The ion gun according to any one of claims 1 to 10, characterized in that The magnet, together with a yoke for magnetically coupling the magnet to the first portion and the second portion, constitutes a structure having an annular recess for accommodating the anode, and The first portion and the second portion of the cathode are bonded to the surface of the structure body provided with the annular recessed portion such that the gap is located above the annular recessed portion along the annular recessed portion.

12. A vacuum processing device comprising: a processing chamber capable of maintaining a vacuum state; a holding member disposed in the processing chamber and holding an object to be processed; as well as The ion gun according to any one of claims 1 to 11, which is arranged in the processing chamber and performs a predetermined process on the object to be processed by using an ion beam.

13. An ion gun comprising: anode; a cathode opposite to the anode and having a first portion and a second portion; as well as a magnet configured to form a magnetic field space between the first portion and the second portion, wherein an annular gap including a straight portion and a curved portion is provided between the first portion and the second portion of the cathode, The first portion is arranged inside the gap, and the second portion is arranged outside the gap. The magnet is configured to form magnetic lines of force in a direction from the second portion to the first portion in a space between the first portion and the second portion and the anode, and In the curved portion, the magnetic field vector at the point where the magnetic lines of force intersect the cross-sectional centerline of the gap is inclined relative to a plane orthogonal to the cross-sectional centerline at a first angle that is less than 1.5 degrees on the side where the first part and the second part are located and greater than 0 degrees on the side where the anode is located.

14. The ion gun according to claim 13, characterized in that In the straight portion, a magnetic field vector at a point where the magnetic force lines intersect a cross-sectional centerline of the gap forms a second angle smaller than the first angle on the anode side relative to a plane orthogonal to the cross-sectional centerline.

15. The ion gun according to claim 13, characterized in that The first angle is an angle within a range of 0 degrees to 3.5 degrees relative to the side where the anode is located.

16. The ion gun according to claim 13, characterized in that In the curved portion, a point where the magnetic field vector of the magnetic lines of force is parallel to a plane orthogonal to the cross-sectional centerline is located closer to the second portion than the cross-sectional centerline and is within a range of 0.1 mm to 0.4 mm from the cross-sectional centerline.

17. The ion gun according to claim 13, characterized in that In the curved portion, the magnet is arranged outside a cross-sectional center line of the gap.

18. The ion gun according to claim 13, characterized in that In the straight portion, the magnet is arranged on a cross-sectional center line of the gap.

19. The ion gun according to claim 13, characterized in that In the curved portion, a minimum value of a length of a magnetic path between the second portion and the magnet is smaller than a minimum value of a length of a magnetic path between the first portion and the magnet.

20. The ion gun according to claim 13, characterized in that The gap is an ejection port for ejecting an ion beam.

21. An ion gun according to any one of claims 13 to 20, characterized in that The magnet, together with a yoke for magnetically coupling the magnet to the first portion and the second portion, constitutes a structure having an annular recess for accommodating the anode, and The first portion and the second portion of the cathode are bonded to the surface of the structure body provided with the annular recessed portion such that the gap is located above the annular recessed portion along the annular recessed portion.

22. A vacuum processing device comprising: a processing chamber capable of maintaining a vacuum state; a holding member disposed in the processing chamber and holding an object to be processed; as well as The ion gun according to any one of claims 13 to 21, which is arranged in the processing chamber and performs a predetermined process on the object to be processed by using an ion beam.

23. An ion beam adjustment method, which adjusts an ion beam emitted from a gap of an ion gun, the ion gun comprising an anode, a cathode opposite to the anode and having a first portion and a second portion, and a magnet configured to form a magnetic field space between the first portion and the second portion, wherein the gap is an annular gap including a straight portion and a curved portion and disposed between the first portion and the second portion of the cathode, The method comprises: The center position of the ion beam emitted from the gap is adjusted by shifting the position of the bottom of the magnetic force line formed between the first portion and the second portion of the curved portion toward the inside of the cross-sectional center line of the gap.

24. An ion beam adjustment method, which adjusts an ion beam emitted from a gap of an ion gun, the ion gun comprising an anode, a cathode opposite to the anode and having a first portion and a second portion, and a magnet configured to form a magnetic field space between the first portion and the second portion, wherein the gap is an annular gap including a straight portion and a curved portion and disposed between the first portion and the second portion of the cathode, wherein: the first portion is arranged inside with respect to the gap and the second portion is arranged outside with respect to the gap, and the magnet is configured to form magnetic lines of force in a direction from the second portion to the first portion in a space between the first portion and the second portion and the anode, The method comprises: The center position of the ion beam emitted from the gap is adjusted by inclining the magnetic field vector at the point where the magnetic force lines intersect the cross-sectional center line of the gap in the curved portion toward the anode relative to a plane orthogonal to the cross-sectional center line.

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