TWI470662B - Ion gun - Google Patents

Description

Ion gun

This invention relates to ion guns, and more particularly to improvements in filaments that are cathodes of ion guns.

The ion gun is generally used for a frequency adjusting device of a piezoelectric element or the like. The principle is that plasma is generated inside the ion gun, and ions are extracted from the plasma to accelerate, thereby forming an ion beam.

Patent Document 1 discloses an ion gun in which a plurality of ion beam extraction holes are disposed for emitting an ion beam having a corresponding current density peak.

Patent Document 2 discloses a configuration in which a plurality of filaments are arranged in the longitudinal direction. According to this configuration, as long as the heat generation amount of each of the filaments is the same, the heat distribution of the cathode, that is, the cathode, is uniform, and the current density of the ion beam to be emitted is also expected to be uniform.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-100205

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2007-311118

However, as in the configuration of Patent Document 2, it is necessary to provide a plurality of power sources corresponding to the plurality of filaments, and the configuration of the ion gun is complicated and large, and there is a problem that the cost is high.

Therefore, in the ion gun in which the plurality of ion beam extraction holes are arranged neatly in the above manner, the problem that the ion beam current density becomes uneven (especially, the current density at the end side becomes small) is simple and convenient. It is solved as a problem.

A first aspect of the present invention is an ion gun comprising: a plasma generating means comprising a cathode (10) and an anode (20); and a grid (30) for generating electricity from a plasma generating means The slurry extracts an ion beam; the cathode is composed of a filament (12) disposed between a pair of filament electrodes (13), and the gate has a plurality of ion beam extraction holes (31) arranged in parallel with the filament, including the ends of the filament The amount of heat generated per unit space of the portion (12a) is greater than the amount of heat generated per unit space including the central portion (12b) of the filament.

In addition, the both ends of the filament may be configured to be wound into a coil shape, and the both end portions may be curved.

A second aspect of the invention is an ion gun comprising: a plasma generating means comprising a cathode (10) and an anode (20); and a grid (30) for generating electricity from the plasma generating means The slurry extracts an ion beam; the cathode system is composed of a filament (12) spanned between a pair of filament electrodes, and the gate has a plurality of ion beam extraction holes (31) arranged in parallel with the filament, with respect to the central portion of the filament, two The end side is densely wound.

With respect to the ion gun in which a plurality of ion beam extraction holes are arranged neatly, the current density of the ion beam can be made uniform by a simple and inexpensive configuration, and the current density of the ion beam can be made uniform.

The ion gun 100 of Fig. 1 includes a filament 11 (cathode 10) spanned between a pair of filament electrodes 13, an anode 20 disposed in parallel with the filament 11, and a gate having a plurality of ion beam extraction holes 31. 30. The body 40 in which the cathode 10 and the anode 20 are sealed inside and the plurality of ion beam extraction holes 31 are exposed. The cathode 10 and the anode 20 constitute a plasma generating means and are connected to respective power sources (not shown). Further, the main body 40 includes a gas introduction port 41 for introducing a discharge gas, and a shielding plate 42 for preventing unnecessary discharge between the cathode 10 and the anode 20.

As shown in FIGS. 2A and 2B, the plurality of ion beam extraction holes 31 of the gate electrode 30 are arranged inside the region partitioned by the annular anode 20, and are aligned in the same direction as the filament 11.

The operation of the ion gun first introduces a discharge gas such as argon into the inside of the body 40 from the gas introduction port 41. A negative voltage is applied to the cathode 10, a positive voltage is applied to the anode 20, and discharge is generated by the potential difference to generate a plasma. When a voltage is applied to the gate electrode 30, ions are extracted from the plasma by a plurality of ion beam extraction holes 31 to form an ion beam.

Among them, the anode 20 is supplemented. Fig. 9 (a) to (d) show changes in the shape of the anode (both in plan view). Fig. 9(a) is a ring type shown in Fig. 2, but others are also divided in the long side direction as in (b), as in (c) The shape, such as (d) is divided in the wide direction, and so on. Further, it is not limited to a square shape, and may be an elliptical shape. Further, the body 40 itself may be used as an anode without providing the anode 20.

Further, a plurality of ion beam extraction holes 31 are supplemented. Fig. 10 (a) to (e) show changes in a plurality of ion beam extraction holes 31. Thus, except as shown in Figure 2 (ie, Figure 10 (d)) The ion beam extraction hole 31 can be obtained in various forms. The "plurality of ion beam extraction holes" as used in the specification and claims refers to all aspects of the above-described examples and the like.

In short, the ion gun as shown in Fig. 1 is also resistant to practical use, but the temperature of the hot cathode, that is, the end of the filament 11 is still lower than that of the filament electrode 13, so that the ion emitted from the ion beam extraction hole 31 on the end side The current density of the beam will be reduced.

Fig. 3 is a view showing a position in the configuration of 25 mm from the gate surface, that is, a current density of an ion beam in a position where the substrate is processed. As shown in the figure, each peak line corresponds to each ion beam extraction hole 31, and the peak value of the current density on the end side is slightly decreased with respect to the current density peak near the center. As described above, in the configuration of Fig. 1, the ion beam current density may become uneven.

Thus, Figure 4A shows a further improved ion gun 200 of the present invention. The configuration of the anode 20, the gate electrode 30, and the body 40 of the ion gun 200 is the same as that of the first, second, ninth, and ninth drawings, and therefore the same reference numerals will be given thereto, and the description thereof will be omitted.

In Fig. 4A, the hot cathode, i.e., the cathode 10, is composed of a pair of filaments 12 spanned between the filament electrodes 13. Further, in Fig. 4A, the cathode 10 and the anode 20 also constitute a plasma generating means, and are connected to respective power sources (not shown).

For convenience of explanation, as shown in Fig. 4B, the filament 12 is constituted by the end portion 12a and the central portion 12b. The end portion 12a is wound in a coil shape, and the amount of heat generated at the end portion is increased as compared with the conventional filament 11. Thereby, even if the filament 12 is dissipated by the filament electrode 13, the temperature of the end portion 12a can be maintained at a predetermined high temperature.

Fig. 5 is a view showing the position of the ion gun 200 of Fig. 4A which is 25 mm from the gate surface, that is, the current density of the ion beam in the position where the substrate is processed. Also in Fig. 5, the peak of the current density corresponds to each ion beam extraction hole 31. As can be seen from comparison with Fig. 3, the peak of the current density at the end side is reduced with respect to the peak of the current density near the center of the ion beam, and the ion beam current density can be made to be substantially uniform in the longitudinal direction.

Further, the distribution of the ion beam current density can be adjusted by adjusting the number of windings or the winding density at the end portion 12a.

For example, as shown in Fig. 6A, the filament 12 wound in a coil shape can be made thick in winding, or the winding near the end side can be made dense, and the winding near the center portion can be made thin. Further, as shown in Fig. 6B, the winding diameter of the end portion of the filament may be made larger than the winding diameter of the central portion of the filament. Further, as shown in Fig. 6C, the filament 12 wound in a coil shape can be inclined in the winding diameter, and the winding diameter near the end portion can be increased, and the winding diameter close to the center portion can be made small.

As shown in Fig. 7, the core of the present invention is that the amount of heat generated per unit space A including the filament end portion 12a is larger than the amount of heat generated per unit space B including the filament center portion 12b. Therefore, the embodiment is not limited to the configuration of Fig. 4B, and the following modifications are also included in the present invention.

For example, as shown in Figs. 8A and 8B, the filament end portion 12a may be bent to increase the amount of heat generation at the end side. In addition, the figures do not have to follow the dimensions shown.

Moreover, the impedance value curve of the filament 12 can be inclined, and the impedance value at the end portion side is higher than the impedance value at the center portion side, and the amount of heat generation at the end portion side is increased.

10. . . cathode

11,12. . . filament

12a. . . Filament end

12b. . . Central part of the filament

13. . . Filament electrode

20. . . anode

30. . . Gate

31. . . Ion beam extraction hole

40. . . Ontology

41. . . Gas inlet

42. . . Masking board

100, 200. . . Ion gun

Fig. 1 is a view showing the ion gun of the present invention.

Fig. 2A is an explanatory view showing the configuration of the gate.

Fig. 2B is an explanatory view showing the configuration of the gate.

Figure 3 is an explanatory view of the present invention.

Fig. 4A is a view showing the ion gun of the present invention.

Figure 4B is a diagram showing the filament of the present invention.

Figure 5 is an explanatory view of the present invention.

Fig. 6A is a view showing a modification of the filament of the present invention.

Fig. 6B is a view showing a modification of the filament of the present invention.

Fig. 6C is a view showing a modification of the filament of the present invention.

Figure 7 is an explanatory view of the present invention.

Fig. 8A is a view showing a modification of the filament of the present invention.

Fig. 8B is a view showing a modification of the filament of the present invention.

Figure 9 is a supplementary diagram of the present invention.

Figure 10 is a supplementary diagram of the present invention.

10. . . cathode

12. . . filament

13. . . Filament electrode

20. . . anode

30. . . Gate

40. . . Ontology

41. . . Gas inlet

42. . . Masking board

200. . . Ion gun

Claims (4)

An ion gun comprising: a plasma generating means comprising a cathode (10) and an anode (20); and a grid (30) for extracting an ion beam from the plasma generated by the plasma generating means; The cathode system is composed of a filament (12) spanned between a pair of filament electrodes, the grid having a plurality of ion beam extraction holes (31) arranged in parallel with the filament, comprising each of the two ends (12a) of the filament The amount of heat generated per unit space is greater than the amount of heat generated per unit space including the central portion (12b) of the filament. An ion gun according to claim 1, wherein both ends of the filament are wound into a coil shape. The ion gun of claim 1, wherein the ends of the filament are bent. An ion gun comprising: a plasma generating means comprising a cathode (10) and an anode (20); and a grid (30) for extracting an ion beam from the plasma generated by the plasma generating means; The cathode system is composed of a filament (12) spanned between a pair of filament electrodes, the gate having a plurality of ion beam extraction holes (31) arranged in parallel with the filament, and the two ends are opposite to the central portion of the filament Wrapped densely.