JP7464781B2 - Ion generating device and ion implantation device - Google Patents

Description

The present invention relates to an ion generating device and an ion implantation device including the same.

In the semiconductor manufacturing process, a standard process is to implant ions into semiconductor wafers in order to change the conductivity or crystal structure of the semiconductor. The equipment used in this process is generally called an ion implanter. In such an ion implanter, ions are generated by an ion generator equipped with an indirectly heated cathode structure and an arc chamber. The generated ions are extracted to the outside of the arc chamber through an extraction electrode.

Japanese Patent Application Laid-Open No. 8-227688

In recent years, there has been a demand for generating high-energy ion beams in order to implant ions deeper into the wafer surface. To generate a high-energy ion beam, it is necessary to generate multicharged ions in an ion generator and accelerate the multicharged ions using a DC acceleration mechanism or a radio frequency acceleration mechanism (e.g., a linear acceleration mechanism). To generate a sufficient amount of multicharged ions in the ion generator, the arc voltage and arc current must be increased, which can lead to more significant wear of the arc chamber and discharge between the arc chamber and the extraction electrode. Under these conditions, problems such as contamination due to wear of the arc chamber and damage to the device due to discharge can occur.

The present invention was made in consideration of these circumstances, and aims to provide an ion generating device that can suppress the intrusion of contaminants and damage caused by discharge under conditions that generate a larger number of multicharged ions.

An ion generating device according to one embodiment of the present invention comprises an arc chamber that defines a plasma generating space, a cathode that emits thermoelectrons toward the plasma generating space, and a repeller that faces the cathode across the plasma generating space. The arc chamber has a box-shaped main body with an open front, and a slit member that is attached to the front of the main body and has a front slit for drawing out ions. The inner surface of the main body that is exposed to the plasma generating space is made of a high-melting point metal material, and the inner surface of the slit member that is exposed to the plasma generating space is made of graphite.

Another aspect of the present invention is an ion implantation device. This ion implantation device includes an ion generation device of a certain aspect, a beam acceleration device that accelerates an ion beam extracted from the ion generation device to an energy of 1 MeV or more, and an implantation processing chamber in which the ion beam emitted from the beam acceleration device is irradiated onto a wafer.

In addition, any combination of the above components or mutual substitution of the components or expressions of the present invention between methods, devices, systems, etc. are also valid aspects of the present invention.

The present invention provides an ion generator capable of stably generating high-purity multiply-charged ions.

1 is a top view showing a schematic configuration of an ion implantation apparatus according to an embodiment; 1 is a cross-sectional view showing a schematic configuration of an ion generating device according to an embodiment. FIG. 4 is a plan view showing a schematic configuration of an outer surface side of a slit member. 4 is a plan view showing a schematic configuration of an inner surface side of a slit member. FIG. FIG. 2 is a cross-sectional view showing a schematic configuration of an arc chamber. FIG. 2 is a cross-sectional view showing a schematic configuration of an arc chamber. FIG. 2 is a cross-sectional view showing a schematic configuration of an arc chamber. 11 is a side view illustrating a method for fixing the slit member. FIG. 11 is a side view illustrating a method for fixing the slit member. FIG.

Below, the embodiments for carrying out the present invention will be described in detail with reference to the drawings. Note that in the description of the drawings, the same elements are given the same reference numerals, and duplicate descriptions will be omitted as appropriate. Also, the configurations described below are examples, and do not limit the scope of the present invention in any way.

Figure 1 is a top view showing a schematic configuration of an ion implantation device 100 according to an embodiment. The ion implantation device 100 is a so-called high-energy ion implantation device. The ion implantation device 100 generates an ion beam IB by extracting and accelerating ions generated by an ion generation device 10, transports the ion beam IB along a beamline to a workpiece (e.g., a substrate or wafer W), and implants ions into the workpiece.

The ion implantation device 100 includes a beam generation unit 12 that generates ions and separates them by mass, a beam acceleration unit 14 that further accelerates the ion beam IB to form a high-energy ion beam, a beam deflection unit 16 that performs energy analysis of the high-energy ion beam, controls the energy dispersion, and corrects the trajectory, a beam transport unit 18 that transports the analyzed high-energy ion beam to the wafer W, and a substrate transport processing unit 20 that implants the transported high-energy ion beam into a semiconductor wafer.

The beam generating unit 12 has an ion generating device 10, an extraction electrode 11, and a mass analyzing device 22. In the beam generating unit 12, ions are extracted from the ion generating device 10 through the extraction electrode 11 and accelerated at the same time, and the extracted and accelerated ion beam is mass analyzed by the mass analyzing device 22. The mass analyzing device 22 has a mass analyzing magnet 22a and a mass analyzing slit 22b. As a result of the mass analysis by the mass analyzing device 22, the ion species required for injection is selected, and the ion beam of the selected ion species is guided to the next beam acceleration unit 14.

The beam acceleration unit 14 includes multiple linear accelerators, i.e., one or more radio frequency resonators, for accelerating the ion beam. The beam acceleration unit 14 is a radio frequency acceleration mechanism that accelerates ions by the action of a radio frequency (RF) electric field. The beam acceleration unit 14 includes a first linear accelerator 15a that includes a basic multi-stage radio frequency resonator, and a second linear accelerator 15b that includes an additional multi-stage radio frequency resonator for high energy ion implantation. The direction of the ion beam accelerated by the beam acceleration unit 14 is changed by the beam deflection unit 16.

The high-energy ion beam emitted from the beam acceleration unit 14 has a certain range of energy distribution. Therefore, in order to perform reciprocating scanning and parallelization of the high-energy ion beam downstream of the beam acceleration unit 14 and irradiate the wafer, it is necessary to perform highly accurate energy analysis in advance, as well as trajectory correction and adjustment of the beam convergence/divergence.

The beam deflection unit 16 performs energy analysis of the high-energy ion beam, controls the energy dispersion, and corrects the trajectory. The beam deflection unit 16 includes at least two high-precision deflection electromagnets, at least one energy width limiting slit, at least one energy analysis slit, and at least one lateral focusing device. The multiple deflection electromagnets are configured to perform energy analysis of the high-energy ion beam and precise correction of the ion implantation angle.

The beam deflection unit 16 includes an energy analysis electromagnet 24, a transverse focusing quadrupole lens 26 that suppresses energy dispersion, an energy analysis slit 28, and a deflection electromagnet 30 that provides steering (trajectory correction of the ion beam). The energy analysis electromagnet 24 is sometimes called an energy filter electromagnet (EFM). The high-energy ion beam is redirected by the beam deflection unit 16 and directed toward the wafer W.

The beam transport unit 18 is a beamline device that transports the ion beam IB output from the beam deflection unit 16, and includes a beam shaper 32 consisting of a group of converging/diverging lenses, a beam scanner 34, a beam collimator 36, and a final energy filter 38 (including a final energy separation slit). The length of the beam transport unit 18 is designed to match the combined length of the beam generation unit 12 and the beam acceleration unit 14, and is connected by the beam deflection unit 16 to form a U-shaped layout overall.

A substrate transport processing unit 20 is provided at the downstream end of the beam transport unit 18. The substrate transport processing unit 20 includes an implantation processing chamber 42 and a substrate transport section 44. The implantation processing chamber 42 is provided with a platen drive device 40 that holds the wafer W undergoing ion implantation and moves the wafer W in a direction perpendicular to the beam scanning direction. The substrate transport section 44 is provided with a wafer transport mechanism such as a transport robot for transporting the wafer W before ion implantation into the implantation processing chamber 42 and transporting the wafer W after ion implantation out of the implantation processing chamber 42.

The ion generator 10 is configured to generate multiply charged ions of, for example, boron (B), phosphorus (P) or arsenic (As). The beam acceleration unit 14 accelerates the multiply charged ions extracted from the ion generator 10 to generate a high energy ion beam of 1 MeV or more or 4 MeV or more. By accelerating multiply charged ions (e.g., divalent, trivalent, quadruple or more), a high energy ion beam can be generated more efficiently than when accelerating monovalent ions.

The beam acceleration unit 14 may be configured as a single linear accelerator as a whole, rather than as a two-stage linear accelerator as shown, or may be implemented as a separate linear accelerator having three or more stages. The beam acceleration unit 14 may also be configured as any other type of accelerator, for example, it may include a DC acceleration mechanism. This embodiment is not limited to a specific ion acceleration method, and any beam acceleration device may be used as long as it is capable of generating a high-energy ion beam of 1 MeV or more or 4 MeV or more.

High energy ion implantation allows the desired impurity ions to be implanted into the wafer surface at higher energies than ion implantation with energies less than 1 MeV, allowing the desired impurity to be implanted deeper into the wafer surface (e.g., to a depth of 5 μm or more). Applications of high energy ion implantation include, for example, the formation of P-type and/or N-type regions in the manufacture of semiconductor devices such as advanced image sensors.

The ion generating device 10 according to the present embodiment uses a so-called indirectly heated cathode (IHC) and generates multiply charged ions by generating an arc discharge in the arc chamber. To generate multiply charged ions, it is necessary to increase the arc voltage and arc current in order to strip more electrons from the atoms. Under such arc conditions, the inside of the arc chamber is subject to severe wear, and it is highly likely that a part of the material constituting the inner wall of the arc chamber will be ionized and drawn out of the arc chamber. As a result, the ion beam IB containing the contaminants of the arc chamber may be implanted into the wafer W, which may affect the characteristics of the semiconductor element formed on the wafer W.

In addition, under conditions of high arc voltage and arc current, the amount of ions extracted from the arc chamber increases, making it easier for discharge to occur between the arc chamber and the extraction electrode. Depending on the manner in which the discharge occurs, the arc chamber may be damaged, and frequent discharges and damage shorten the life of the arc chamber, making it necessary to frequently maintain the device. This reduces the operating rate of the ion implantation device 100 and reduces the production efficiency of semiconductor devices.

Therefore, in this embodiment, an ion generating device is provided that can suppress contamination of the ion beam and damage to the arc chamber due to discharge, even when a larger number of multivalent ions are generated. In order to prevent contamination of the ion beam, it is important to increase the purity of the members constituting the arc chamber, and from the viewpoint of suppressing contamination, graphite with high purity and high melting point is suitable. On the other hand, graphite is a material that is easily worn by plasma generated in the arc chamber, and carbon compounds generated by reacting with plasma are deposited on the surfaces of the members constituting the ion generating device, causing dirt. In addition, graphite is more likely to cause discharge than high-melting point metal materials, and is easily damaged when discharge occurs. Therefore, in this embodiment, an ion generating device is provided that can suppress contamination and damage due to discharge by appropriately combining graphite and high-melting point metal materials based on the difference in the properties of the materials.

Figure 2 is a diagram showing the schematic configuration of an ion generator 10 according to an embodiment. The ion generator 10 is an indirectly heated ion source, and includes an arc chamber 50, a cathode 56, a repeller 58, and various power sources.

An extraction electrode 11 is arranged near the ion generator 10 to extract the ion beam IB through the front slit 60 of the arc chamber 50. The extraction electrode 11 includes a suppression electrode 66 and a ground electrode 68. A suppression power supply 64f is connected to the suppression electrode 66, and a negative suppression voltage is applied to the suppression electrode 66. The ground electrode 68 is connected to the ground 64g.

The arc chamber 50 has a substantially rectangular box shape. The arc chamber 50 defines a plasma generation space S in which plasma is generated. In the drawing, a plasma generation region P in which high-density plasma is generated is shown by a dashed line. The arc chamber 50 has a box-shaped main body 52 with an opening at the front surface 52g, and a slit member 54 attached to the front surface 52g of the main body 52. The slit member 54 is provided with a front slit 60 for extracting the ion beam IB. The front slit 60 has an elongated shape extending in a direction (also called the axial direction) from the cathode 56 toward the repeller 58. A positive extraction voltage is applied to the arc chamber 50 by an extraction power supply 64d with respect to ground 64g.

The main body 52 has a rear wall 52b and four side walls including a first side wall 52c and a second side wall 52d. The rear wall 52b is provided at a position facing the front slit 60 across the plasma generation space S, and is arranged to extend in the axial direction. The rear wall 52b is provided with a gas inlet 62 for introducing a source gas. The four side walls including the first side wall 52c and the second side wall 52d are provided to define a rectangular opening on the front surface 52g of the main body 52. The first side wall 52c and the second side wall 52d are arranged to face each other in the axial direction. The first side wall 52c has a cathode insertion port 52e extending in the axial direction, and a cathode 56 is arranged in the cathode insertion port 52e. The second side wall 52d has a repeller insertion port 52f extending in the axial direction, and a repeller 58 is arranged in the repeller insertion port 52f.

The inner surface 52a of the main body 52 exposed to the plasma generation space S is made of a high-melting point metal material, for example, tungsten (W), molybdenum (Mo), tantalum (Ta), or other high-melting point metals or alloys thereof. The main body 52 may be entirely made of a high-melting point metal material, or only the inner surface 52a may be selectively made of a high-melting point metal material. The main body 52 may be made of, for example, tungsten with a high melting point (about 3400°C). The purity of the high-melting point metal material used in the main body 52 may be a standard purity lower than that of other members (for example, the cathode 56 described later), and for example, the content of the high-melting point metal element is less than 99.99% by weight. An example of the content of the high-melting point metal element in the material used in the main body 52 is less than 99.8% by weight, less than 99.9% by weight, or less than 99.95% by weight.

The slit member 54 is a plate-shaped member in which a front slit 60 is provided. The slit member 54 is attached to the front surface 52g of the main body 52 so as to close the opening of the front surface 52g. The slit member 54 has an inner surface 54a exposed to the plasma generation space S made of graphite, and an outer surface 54b exposed to the outside of the arc chamber 50 made of a high-melting point metal material. The slit member 54 has an inner member 70 made of graphite and an outer member 80 made of a high-melting point metal material, and has a double structure in which the inner member 70 and the outer member 80 are overlapped. The outer member 80 can be made of a high-melting point metal material of standard purity, like the main body 52, and is made of tungsten, for example.

The inner member 70 has an inner surface 54a exposed to the plasma generation space S. The inner member 70 has an inner opening 72 for forming the front slit 60, and a protruding portion 74 protruding toward the outside of the arc chamber 50 in the vicinity or periphery of the inner opening 72. The position of the outer surface 74b of the protruding portion 74 in the thickness direction (direction from the inside to the outside of the arc chamber 50) coincides with the position of the outer surface 54b of the slit member 54 (or the outer member 80) in the thickness direction. A slit recess 76 is formed on the inside of the protruding portion 74, so that the inner surface 54a of the inner opening 72 is separated from the plasma generation region P in the vicinity of the inner opening 72. The inner member 70 has a tapered surface 72a provided on the edge of the inner opening 72 so that the opening size increases from the inside to the outside of the arc chamber 50. By making the edge of the inner opening 72 tapered, the front slit 60 can be made to be less likely to obstruct the flow of the ion beam IB drawn from the inside to the outside of the arc chamber 50.

The outer member 80 has an outer surface 54b exposed to the outside of the arc chamber 50, and is provided so as to face the extraction electrode 11 (suppression electrode 66). The outer member 80 is a cover that covers the outside of the inner member 70, and plays a role in supporting the inner member 70 made of graphite, which has low mechanical strength, to increase its strength. The outer member 80 has an outer opening 82 for forming the front slit 60. The opening size of the outer opening 82 is larger than the opening size of the inner opening 72. The opening size of the outer opening 82 is larger than the size of the outer periphery 74a of the protrusion 74. The opening size of the outer opening 82 may be approximately the same as the size of the outer periphery 74a of the protrusion 74, and for example, the outer opening 82 is configured so that the edge of the outer opening 82 is provided along the outer periphery 74a of the protrusion 74.

The outer member 80 is preferably configured so as not to impede the extraction of the ion beam IB through the inner opening 72. Specifically, the outer member 80 is preferably configured so that the edge of the outer opening 82 is located at a position farther from the center 60c of the front slit 60 than an imaginary plane 72b that is an extension of the tapered surface 72a of the inner opening 72 to the outside of the arc chamber 50. As a result, the opening shape of the front slit 60 can be determined only by the inner opening 72, and the outer member 80 can be prevented from being exposed to the ion beam IB extracted from the arc chamber 50.

The cathode 56 emits thermoelectrons into the plasma generation space S. The cathode 56 is inserted into the cathode insertion port 52e and fixed in a state in which it is electrically insulated from the arc chamber 50. The cathode 56 has a filament 56a, a cathode head 56b, a thermal break 56c, and a thermal reflector 56d.

The cathode head 56b is a solid cylindrical member, the tip of which is exposed to the plasma generation space S. The thermal break 56c is a cylindrical member that supports the cathode head 56b and extends axially from the outside to the inside of the arc chamber 50. The thermal break 56c is preferably of a highly thermally insulating shape in order to maintain the high temperature state of the cathode head 56b, and has a thin wall shape. The thermal reflector 56d is a cylindrical member that is provided to surround the outer periphery of the cathode head 56b and the thermal break 56c. The thermal reflector 56d reflects radiant heat from the cathode head 56b and the thermal break 56c, which are in a high temperature state, so that the high temperatures of the cathode head 56b and the thermal break 56c are maintained. The filament 56a is arranged to face the cathode head 56b inside the thermal break 56c.

The filament 56a is heated by the filament power supply 64a, generating thermoelectrons at its tip. The primary thermoelectrons generated by the filament 56a are accelerated by the cathode voltage (e.g., 300 to 600 V) from the cathode power supply 64b, collide with the cathode head 56b, and heat the cathode head 56b with the heat generated by the collision. The heated cathode head 56b generates secondary thermoelectrons, which are accelerated by the arc voltage (e.g., 70 to 150 V) applied between the cathode head 56b and the arc chamber 50 by the arc power supply 64c. The accelerated secondary thermoelectrons ionize the source gas introduced from the gas inlet 62 and are emitted into the plasma generation space S as beam electrons with sufficient energy to generate plasma containing multivalent ions. The beam electrons emitted into the plasma generation space S are bound by the magnetic field B applied axially to the plasma generation space S, and move in a spiral shape along the magnetic field B. By making the electrons move in a spiral manner in the plasma generation space S, the electron movement can be restricted to the plasma generation region P, thereby increasing the plasma generation efficiency.

The cathode head 56b is made of a high melting point metal material, for example, tungsten. The cathode head 56b may be made of a high melting point metal material with a purity higher than the standard purity, and the content of the high melting point metal element may be 99.99% by weight or more. An example of the content of the high melting point metal element of the material used for the cathode head 56b is 99.995% by weight or more, 99.9995% by weight or more, or 99.9999% by weight or more. The cathode head 56b is a member that is easily worn out by exposure to high concentration plasma, and is a member that is likely to cause contamination of the ion beam IB. By increasing the purity of the high melting point metal material that constitutes the cathode head 56b, the influence of contamination of the ion beam IB due to the plasmatization of the material that constitutes the cathode head 56b can be reduced. At least one of the thermal break 56c and the thermal reflector 56d may be made of a high-melting-point metal material of standard purity, or may be made of a high-melting-point metal material of high purity, like the cathode head 56b.

The repeller 58 repels electrons in the arc chamber 50, retaining the electrons in the plasma generation region P and increasing plasma generation efficiency. The repeller 58 is inserted into the repeller insertion port 52f and fixed in a state in which it is electrically insulated from the arc chamber 50. A repeller voltage (e.g., 120 to 200 V) is applied between the repeller 58 and the arc chamber 50 by the repeller power supply 64e, and is configured to repel electrons toward the plasma generation region P.

The repeller 58 has a repeller head 58a, a repeller shaft 58b, and a repeller support 58c. The repeller head 58a is provided inside the arc chamber 50, and is provided at a position axially opposite the cathode head 56b across the plasma generation space S. The repeller support 58c is provided outside the arc chamber 50 and is fixed to a support structure (not shown). The repeller shaft 58b is a cylindrical member that is inserted into the repeller insertion port 52f, and connects the repeller head 58a and the repeller support 58c. For example, a female thread is formed on the repeller shaft 58b, and male threads are formed on the repeller head 58a and the repeller support 58c, and the repeller head 58a, the repeller shaft 58b, and the repeller support 58c are connected to each other by a screw structure.

The repeller head 58a is made of a high melting point metal material, for example, tungsten. The repeller head 58a may be made of a high-purity high melting point metal material, like the cathode head 56b. The repeller head 58a is a member that is easily worn out by exposure to high-concentration plasma, like the cathode head 56b, so by increasing the purity of the material that makes up the repeller head 58a, the effect of contamination of the ion beam IB can be reduced. When the repeller head 58a is made of a high melting point metal material, it is preferable that the repeller shaft 58b is made of graphite. This makes it possible to prevent the repeller head 58a and the repeller shaft 58b, which are connected by a screw structure, from burning. The repeller head 58a may also be made of graphite.

3 is a plan view showing a schematic configuration of the outer surface 54b side of the slit member 54, and shows a front view of the front slit 60 as seen from the extraction electrode 11. The cross section of line A-A in FIG. 3 corresponds to FIG. 2. The outer member 80 has an outer shape of a substantially rectangular shape that is long in the axial direction. The inner member 70 shown by the dashed line also has an outer shape of a substantially rectangular shape that is long in the axial direction. The front slit 60 is provided in the center of the slit member 54, and the opening shape is determined by the inner opening 72 that is elongated in the axial direction and is substantially rectangular. The outer periphery 74a of the protrusion 74 is also substantially rectangular, and the edge of the outer opening 82 is also substantially rectangular. The outer member 80 is configured to completely cover the inner member 70, except for the protrusion 74 near or around the front slit 60. Therefore, the outer size of the outer member 80 is larger than the outer size of the inner member 70 shown by the dashed line. Four outer engagement parts 86a, 86b, 86c, and 86d for fixing the outer member 80 are provided on the outer periphery of the outer member 80. The outer engagement portions 86a to 86d are provided in pairs along the two long sides of the outer periphery of the outer member 80.

Figure 4 is a plan view showing a schematic configuration of the inner surface 54a side of the slit member 54, and shows a rear view of the front slit 60 when viewed from the plasma generation space S. The cross section of line A-A in Figure 4 corresponds to Figure 2. The inner surface 54a of the inner member 70 is provided with a cathode accommodating recess 78a, a repeller accommodating recess 78b, and a central recess 78c. The cathode accommodating recess 78a is provided at a position facing the cathode 56, and the repeller accommodating recess 78b is provided at a position facing the repeller 58. The central recess 78c extends in the axial direction along the front slit 60 and is provided so as to connect between the cathode accommodating recess 78a and the repeller accommodating recess 78b. Each of the cathode accommodating recess 78a and the repeller accommodating recess 78b is configured so that the inner surface facing the cathode 56 and the repeller 58 is a flat surface or a cylindrically curved surface. The central recess 78c is configured so that the inner surface exposed to the plasma generation space S is an approximately cylindrically curved surface. By providing the cathode accommodating recess 78a, the repeller accommodating recess 78b, and the central recess 78c, the distance from the plasma generation region P, where high-concentration plasma is generated, to the inner surface 54a of the inner member 70 can be increased, reducing wear on the inner surface 54a of the inner member 70.

A cathode outer periphery recess 78d is provided on the inner surface 54a of the inner member 70. The cathode outer periphery recess 78d is provided at a position facing the cathode 56 on the outer periphery of the inner member 70. The cathode outer periphery recess 78d is composed of a cylindrical curved surface corresponding to the cylindrical cathode 56. The cathode outer periphery recess 78d is spaced from the cathode 56 to ensure electrical insulation between the cathode 56 and the slit member 54.

The inner engaging portions 78p and 78q are provided on the inner surface 54a of the inner member 70. The inner engaging portions 78p and 78q engage with the body side engaging portions provided on the body portion 52 of the arc chamber 50 to regulate the position of the inner member 70 relative to the body portion 52. The inner engaging portions 78p and 78q are recesses provided on the inner surface 54a of the inner member 70, into which the body side engaging portions protruding from the body portion 52 are inserted. The first inner engaging portion 78p is provided near the cathode accommodating recess 78a, and the second inner engaging portion 78q is provided near the repeller accommodating recess 78b. The first inner engaging portion 78p is formed so that its axial size and its lateral size perpendicular to the axial direction are approximately the same. On the other hand, the second inner engaging portion 78q is formed so that its axial size is elongated in the axial direction, and its axial size is larger than its lateral size. The shapes of the first inner engaging portion 78p and the second inner engaging portion 78q are not limited to those shown in the figure, and may be other shapes as long as they can engage with the main body side engaging portion to regulate the position.

The outer member 80 is provided with an inner member accommodating recess 84, a first outer peripheral recess 88a, and a second outer peripheral recess 88b. The inner member accommodating recess 84 has a size corresponding to the outer shape of the inner member 70 and accommodates the inner member 70. The first outer peripheral recess 88a is provided at a position facing the cathode 56 on the outer periphery of the outer member 80, and is composed of a cylindrical curved surface corresponding to the cylindrical cathode 56. The first outer peripheral recess 88a is spaced from the cathode 56 to ensure electrical insulation between the cathode 56 and the slit member 54. The second outer peripheral recess 88b is provided at a position facing the repeller 58 on the outer periphery of the outer member 80. The second outer peripheral recess 88b is configured to have the same shape and size as the first outer peripheral recess 88a, and is configured so that the outer member 80 has a vertically symmetrical shape. Therefore, the outer member 80 can be used upside down, and can also be attached so that the first outer peripheral recess 88a faces the repeller 58, and the second outer peripheral recess 88b faces the cathode 56. The second outer peripheral recess 88b does not have to be provided on the outer member 80. The repeller shaft 58b that can face the second outer peripheral recess 88b has a smaller radial size (i.e., thinner) than the repeller head 58a, so electrical insulation between the repeller 58 and the slit member 54 can be sufficiently ensured even without providing the second outer peripheral recess 88b.

5 is a cross-sectional view showing a schematic configuration of the arc chamber 50, showing a cross section perpendicular to the axial direction at the center 60c of the front slit 60. FIG. 5 corresponds to the cross section of line C-C in FIG. 4, and shows a cross section of the repeller 58 as viewed from the cathode 56. As shown in the figure, the repeller 58 is disposed so as to protrude outward from the front surface 52g of the main body 52, and a part of the repeller 58 overlaps with the slit member 54 in the axial direction. The cathode 56 is also disposed so as to protrude outward from the front surface 52g of the main body 52, and a part of the cathode 56 overlaps with the slit member 54 in the axial direction. The protruding portion 74 protrudes toward the outside of the arc chamber 50 around the inner opening 72, and a slit recess 76 is provided inside the protruding portion 74. The slit recess 76 is configured to be spaced apart from the cathode 56 and the repeller 58 in a radial direction perpendicular to the axial direction so as not to overlap with the cathode 56 and the repeller 58 in the axial direction.

Figure 6 is a cross-sectional view showing the schematic configuration of the arc chamber 50, and corresponds to the cross section taken along line D-D in Figure 4. Figure 6 shows a cross section perpendicular to the axial direction at a position corresponding to the cathode accommodating recess 78a and the first inner engagement portion 78p. As shown in the figure, the cathode 56 is arranged so as to protrude outward from the front surface 52g of the main body portion 52, and a portion of the cathode 56 is arranged inside the cathode accommodating recess 78a. The main body portion 52 is also provided with a first main body side engagement portion 52p that protrudes from the front surface 52g. The first main body side engagement portion 52p engages with the corresponding first inner engagement portion 78p to regulate the position of the inner member 70.

Figure 7 is a cross-sectional view showing the schematic configuration of the arc chamber 50, and corresponds to the cross section taken along line E-E in Figure 4. Figure 7 shows a cross section perpendicular to the axial direction at a position corresponding to the repeller accommodating recess 78b and the second inner engagement portion 78q. As shown in the figure, the repeller 58 is disposed so as to protrude outward from the front surface 52g of the main body portion 52, and a portion of the repeller 58 is disposed inside the repeller accommodating recess 78b. The main body portion 52 is also provided with a second main body side engagement portion 52q that protrudes from the front surface 52g. The second main body side engagement portion 52q engages with the corresponding second inner engagement portion 78q to regulate the position of the inner member 70.

8 and 9 are side views that show a schematic method of fixing the slit member 54. FIG. 8 shows the state in which the slit member 54 is removed from the main body 52, and FIG. 9 shows the state in which the slit member 54 is fixed to the main body 52. The arc chamber 50 is fixed to the structure 90. The structure 90 includes an accommodating recess 92 that accommodates and supports the main body 52, and locking structures 94a and 94b for fixing the slit member 54. The locking structures 94a and 94b engage with the outer engaging portions 86a and 86b provided on the outer member 80, and fix the slit member 54 to the main body 52 by applying a pulling force to the outer member 80 toward the main body 52. The first locking structure 94a includes a first rod 96a having a tip that engages with the first outer engaging portion 86a, a first bearing portion 97a that supports the first rod 96a, and a first spring 98a for applying a tensile force to the first rod 96a. The first rod 96a is configured to be displaceable in the longitudinal direction and in a direction perpendicular to the longitudinal direction with the first bearing portion 97a as a fulcrum, and is configured so that the angle can be changed in the direction away from the arc chamber 50 and in the direction toward the arc chamber 50 when the rod 96a is attached or detached.

The second locking structure 94b is configured similarly to the first locking structure 94a, and has a second rod 96b, a second bearing portion 97b, and a second spring 98b. The second locking structure 94b engages with the second outer engagement portion 86b to fix the slit member 54 to the main body portion 52. The structure 90 is provided with a third locking structure and a fourth locking structure (not shown). The third locking structure engages with the third outer engagement portion 86c shown in FIG. 3, and the fourth locking structure engages with the fourth outer engagement portion 86d shown in FIG. 3. The slit member 54 is pulled toward the main body portion 52 by the four locking structures and fixed to the main body portion 52. At this time, the first main body side engagement portion 52p engages with the first inner engagement portion 78p, and the second main body side engagement portion 52q engages with the second inner engagement portion 78q, so that the inner member 70 is accurately positioned relative to the main body portion 52.

Next, the effects of the ion generating device 10 will be described. According to this embodiment, the inner surface 54a of the slit member 54 is made of graphite, and the front slit 60 is defined by an inner opening 72 made of graphite, thereby minimizing contamination of the ion beam IB. The inner surface 54a of the slit member 54 is the part exposed to the high-concentration plasma in the plasma generation region P, and can be said to be the part that contributes most to contamination of the ion beam IB drawn from the front slit 60. By using graphite in such a part, contamination of the ion beam IB can be suitably suppressed, and in particular contamination of the metal elements of the high-melting point metal material itself and metal elements contained in trace amounts in the high-melting point metal material can be effectively suppressed.

According to this embodiment, by constructing the cathode head 56b and the repeller head 58a from a high-melting point metal material, it is possible to reduce wear caused by plasma and reduce dirt that may accumulate inside the arc chamber 50 compared to when these components are constructed from graphite. In addition, by increasing the purity of the high-melting point metal material that constitutes the cathode head 56b and the repeller head 58a, it is possible to suitably suppress the intrusion of contaminants into the plasma generated in the plasma generation region P. In addition, by constructing the inner surface 52a of the main body 52, which is not easily worn by plasma, from a high-melting point metal material of standard purity, it is possible to suitably suppress the intrusion of contaminants into the plasma generated in the plasma generation region P while suppressing the increase in cost due to high purity.

According to this embodiment, by attaching a cover of the outer member 80 made of a high melting point metal material to the outer surface 54b side of the slit member 54, it is possible to suppress discharge that may occur between the slit member 54 and the extraction electrode 11, and also to suppress damage caused by discharge. In particular, by minimizing the exposed area of the outer surface 74b of the protrusion 74 around the inner opening 72, it is possible to enhance the effect of suppressing discharge and damage caused by discharge due to exposure of graphite to the extraction electrode 11. In addition, by locating the edge of the outer opening 82 of the outer member 80 at a position farther from the center 60c of the front slit 60 than the tapered surface 72a and the virtual surface 72b of the inner opening 72, it is possible to suppress the intrusion of contaminants caused by the outer member 80 into the ion beam IB extracted from the front slit 60.

According to this embodiment, by providing the cathode accommodating recess 78a, the repeller accommodating recess 78b, and the central recess 78c in the inner member 70, the thickness of the outer periphery of the inner member 70 is increased to increase the mechanical strength, while the cathode 56 and the repeller 58 can be arranged closer to the slit member 54. As a result, the distance from the plasma generation region P sandwiched between the cathode 56 and the repeller 58 to the front slit 60 can be shortened, and the extraction efficiency of the multivalent ions generated in greater quantities near the center of the plasma generation region P can be improved. This allows more multivalent ions to be supplied to the downstream side of the ion generating device 10. In addition, under the same conditions of the supply amount of multivalent ions, the configuration of this embodiment can be adopted to relatively reduce the arc voltage and arc current, thereby suppressing wear of the arc chamber and discharge between the arc chamber and the extraction electrode.

Although the present invention has been described above with reference to the above-mentioned embodiment, the present invention is not limited to the above-mentioned embodiment, and suitable combinations or substitutions of the configurations of the embodiments are also included in the present invention. In addition, it is possible to suitably rearrange the combinations and processing order in the embodiments based on the knowledge of those skilled in the art, and to make modifications to the embodiments such as various design changes, and embodiments with such modifications are also included in the scope of the present invention.

10...Ion generating device, 50...Arc chamber, 52...Main body, 54...Slit member, 56...Cathode, 58...Repeller, 60...Front slit, 70...Inner member, 80...Outer member, 100...Ion implantation device.

Claims (15)

an arc chamber defining a plasma generation space;
a cathode that emits thermoelectrons toward the plasma generating space;
The arc chamber is provided with a slit for extracting ions,
an inner surface of the arc chamber exposed to the plasma generating space includes a portion made of a first high melting point metal material;
the cathode includes a portion made of a second high melting point metal material;
The ion generating device according to claim 1, wherein the second high-melting point metal material is made of a high-melting point metal material having a higher purity than the first high-melting point metal material. The ion generating device according to claim 1, characterized in that the cathode is fixed in a state in which it is electrically insulated from the arc chamber. The ion generating device according to claim 1 or 2, characterized in that the cathode comprises a filament that generates primary thermoelectrons, and a cathode head that is heated by collision of the primary thermoelectrons from the filament and emits secondary thermoelectrons toward the plasma generating space. The ion generating device according to claim 3, characterized in that the cathode head is made of the second high melting point metal material. The ion generating device according to any one of claims 1 to 4, characterized in that each of the first high melting point metal material and the second high melting point metal material contains at least one of tungsten, molybdenum, and tantalum. Further, a repeller is provided facing the cathode across the plasma generation space,
The ion generating device according to claim 1 , wherein the repeller includes a portion made of a third high melting point metal material. the repeller has a repeller head exposed to the plasma generation space and made of the third high melting point metal material,
The ion generating device according to claim 6 , wherein the third high-melting point metal material is made of a high-melting point metal material having a higher purity than the first high-melting point metal material. The ion generating device according to claim 6 or 7, characterized in that the third high melting point metal material includes at least one of tungsten, molybdenum, and tantalum. The ion generating device according to any one of claims 1 to 8, characterized in that the first high-melting point metal material has a high-melting point metal element content of less than 99.99% by weight. The ion generating device according to any one of claims 1 to 8, characterized in that the first high-melting point metal material has a high-melting point metal element content of less than 99.95% by weight. The ion generating device according to any one of claims 1 to 8, characterized in that the first high melting point metal material has a high melting point metal element content of less than 99.9% by weight. The ion generating device according to any one of claims 1 to 8, characterized in that the first high melting point metal material has a high melting point metal element content of less than 99.8% by weight. An ion generating device according to any one of claims 1 to 12,
an implantation processing chamber in which an object to be processed is irradiated with the ion beam extracted from the ion generating device. The ion beam generating device further includes a beam accelerator for accelerating the ion beam extracted from the ion generating device to an energy of 1 MeV or more.
14. The ion implantation apparatus according to claim 13, wherein an object to be treated is irradiated with the ion beam emitted from the beam accelerator in the implantation processing chamber. The ion implantation device according to claim 14, characterized in that the beam accelerator accelerates the ion beam extracted from the ion generator to an energy of 4 MeV or more.

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