JP7325597B2 - Ion generator and ion implanter - Google Patents

Description

The present invention relates to an ion generator and an ion implanter including the same.

2. Description of the Related Art In a semiconductor manufacturing process, a process of implanting ions into a semiconductor wafer is standardly performed for the purpose of changing the conductivity of the semiconductor, changing the crystal structure of the semiconductor, and the like. The equipment used in this process is commonly called an ion implanter. In such an ion implanter, ions are generated by an ion generator having an indirectly heated cathode structure and an arc chamber. The generated ions are drawn out of the arc chamber through the extraction electrode.

JP-A-8-227688

In recent years, there has been a desire to generate high energy ion beams to implant ions deeper into the wafer surface. In order to generate a high-energy ion beam, it is necessary to generate multiply-charged ions in an ion generator and accelerate the multiply-charged ions using a DC acceleration mechanism or a high-frequency acceleration mechanism (for example, a linear acceleration mechanism). . In order to generate a sufficient amount of multiply-charged ions in the ion generator, it is necessary to increase the arc voltage and arc current. sell. Under such conditions, problems such as contamination due to wear of the arc chamber and damage to the apparatus due to electrical discharge can occur.

The present invention has been made in view of such circumstances, and an object thereof is to provide an ion generator capable of suppressing damage due to contamination and discharge under conditions that generate more multiply charged ions.

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

Another aspect of the invention is an ion implanter. This ion implanter comprises an ion generator of a certain mode, a beam accelerator that accelerates an ion beam extracted from the ion generator to an energy of 1 MeV or more, and a wafer that is irradiated with the ion beam emitted from the beam accelerator. and an injection process chamber.

It should be noted that arbitrary combinations of the above-described constituent elements and mutual replacement of the constituent elements and expressions of the present invention in methods, devices, systems, etc. are also effective as aspects of the present invention.

ADVANTAGE OF THE INVENTION According to this invention, the ion generator which can produce|generate highly pure multiply charged ion stably can be provided.

1 is a top view showing a schematic configuration of an ion implanter according to an embodiment; FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows schematic structure of the ion generator which concerns on embodiment. FIG. 4 is a plan view showing a schematic configuration of the outer surface side of the slit member; FIG. 4 is a plan view showing a schematic configuration of the inner surface side of the slit member; It is a sectional view showing a schematic structure of an arc chamber. It is a sectional view showing a schematic structure of an arc chamber. It is a sectional view showing a schematic structure of an arc chamber. FIG. 4 is a side view schematically showing a method of fixing the slit member; FIG. 4 is a side view schematically showing a method of fixing the slit member;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and overlapping descriptions are omitted as appropriate. Moreover, the configuration described below is an example and does not limit the scope of the present invention.

FIG. 1 is a top view showing a schematic configuration of an ion implanter 100 according to an embodiment. The ion implanter 100 is a so-called high energy ion implanter. The ion implanter 100 extracts and accelerates ions generated by the ion generator 10 to generate an ion beam IB, and transports the ion beam IB along the beam line to an object to be processed (eg, substrate or wafer W). and implant ions into the object to be processed.

The ion implanter 100 includes a beam generation unit 12 that generates and mass separates ions, a beam acceleration unit 14 that further accelerates the ion beam IB into a high energy ion beam, energy analysis and energy dispersion of the high energy ion beam. A beam deflection unit 16 for controlling and trajectory correction, a beam transport unit 18 for transporting the analyzed high-energy ion beam to the wafer W, and a substrate transport processing unit 20 for implanting the transported high-energy ion beam into a semiconductor wafer. and

The beam generation unit 12 has an ion generator 10 , an extraction electrode 11 and a mass spectrometer 22 . In the beam generation unit 12 , ions are extracted from the ion generator 10 through the extraction electrode 11 and accelerated at the same time. The mass spectrometer 22 has a mass analysis magnet 22a and a mass analysis slit 22b. As a result of mass analysis by the mass spectrometer 22 , ion species necessary for implantation are selected, and ion beams of the selected ion species are guided to the next beam acceleration unit 14 .

The beam acceleration unit 14 comprises a plurality of linear accelerators, ie one or more high frequency resonators, for accelerating ion beams. The beam acceleration unit 14 is a radio frequency acceleration mechanism that accelerates ions by the action of radio frequency (RF) electric fields. The beam acceleration unit 14 comprises a first linear accelerator 15a with a basic multi-stage radio frequency resonator and a second linear accelerator 15b with an additional multi-stage radio frequency resonator for high energy ion implantation. The ion beam accelerated by the beam acceleration unit 14 is redirected by the beam deflection unit 16 .

A high-energy ion beam emitted from the beam acceleration unit 14 has a certain range of energy distribution. Therefore, in order to reciprocate and parallelize the high-energy ion beam downstream of the beam acceleration unit 14 to irradiate the wafer, high-precision energy analysis, trajectory correction, and beam convergence/divergence adjustment are required in advance. must be implemented.

The beam deflection unit 16 performs energy analysis of the high-energy ion beam, energy dispersion control, and trajectory correction. The beam deflection unit 16 comprises at least two precision deflection magnets, at least one energy width limiting slit, at least one energy analysis slit and at least one transverse focusing device. A plurality of bending magnets are configured for energy analysis of the high energy ion beam and precise correction of the ion implantation angle.

The beam deflection unit 16 has an energy analyzing electromagnet 24, a transverse focusing quadrupole lens 26 that suppresses energy dispersion, an energy analyzing slit 28, and a deflection electromagnet 30 that provides steering (trajectory correction of the ion beam). Note that the energy analyzing electromagnet 24 is sometimes called an energy filtering electromagnet (EFM). The high-energy ion beam is redirected by the beam deflection unit 16 towards the wafer W. FIG.

The beam transport unit 18 is a beamline device that transports the ion beam IB emitted from the beam deflection unit 16, and includes a beam shaper 32 composed of a converging/diverging lens group, a beam scanner 34, and 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 total 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 as a whole. do.

A substrate transfer processing unit 20 is provided at the downstream end of the beam transport unit 18 . The substrate transport processing unit 20 includes an implant processing chamber 42 and a substrate transport section 44 . The implantation processing chamber 42 is provided with a platen driving device 40 that holds the wafer W being ion-implanted and moves the wafer W in a direction perpendicular to the beam scanning direction. The substrate transfer unit 44 is provided with a wafer transfer mechanism such as a transfer robot for transferring the wafer W before ion implantation into the implantation processing chamber 42 and for carrying out the ion-implanted wafer W from the implantation processing chamber 42 .

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 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. Accelerating multiply charged ions (eg, divalent, trivalent, quadrivalent or higher) can produce a high energy ion beam more efficiently than accelerating singly charged ions.

The beam acceleration unit 14 may be configured as one linear accelerator as a whole instead of a two-stage linear accelerator as shown, or may be divided into three or more stages of linear accelerators and mounted. . The beam acceleration unit 14 may also consist of any other type of acceleration device, for example it may comprise a DC acceleration mechanism. This embodiment is not limited to a specific ion acceleration method, and any beam accelerator capable of generating a high-energy ion beam of 1 MeV or more or 4 MeV or more can be adopted.

High-energy ion implantation implants desired impurity ions into the wafer surface with higher energy than ion implantation with an energy of less than 1 MeV. impurities can be implanted. An application of high-energy ion implantation is, for example, the formation of P-type and/or N-type regions in the manufacture of semiconductor devices such as modern image sensors.

The ion generator 10 according to the present embodiment is of a type using a so-called indirectly heated cathode (IHC), and generates arc discharge in an arc chamber to generate multiply charged ions. In order 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 worn away, and there is a high possibility that some of the members forming the inner wall of the arc chamber are also ionized and pulled out of the arc chamber. As a result, the ion beam IB mixed with the constituent members of the arc chamber as contaminants is injected into the wafer W, which may affect the characteristics of the semiconductor devices formed on the wafer W.

Also, under conditions where the arc voltage and arc current are high, the amount of ions extracted from the arc chamber increases, and discharge is likely to occur between the arc chamber and the extraction electrode. Depending on how the discharge occurs, the arc chamber may be damaged. Frequent occurrence of discharge or damage shortens the life of the arc chamber, necessitating frequent maintenance of the apparatus. As a result, the operating rate of the ion implanter 100 is lowered, and the production efficiency of semiconductor devices is lowered.

Therefore, the present embodiment provides an ion generator capable of suppressing contamination of the ion beam and damage to the arc chamber due to discharge even when generating a larger number of multiply charged ions. In order to prevent contaminants from entering the ion beam, it is important to increase the purity of the members constituting the arc chamber. From the viewpoint of contaminant suppression, high-purity, high-melting graphite is suitable. On the other hand, graphite is a material that is easily worn out by the plasma generated in the arc chamber, and carbon compounds generated by reacting with the plasma deposit on the surfaces of the components of the ion generator, causing contamination. give rise to Graphite is more likely to cause discharge than high-melting-point metal materials, and is more likely to be damaged when discharge occurs. Therefore, the present embodiment provides an ion generator capable of suppressing damage due to contamination and discharge by appropriately combining graphite and a high-melting-point metal material based on the difference in material properties.

FIG. 2 is a diagram showing a schematic configuration of the ion generator 10 according to the 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 supplies.

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

The arc chamber 50 has a substantially rectangular parallelepiped box shape. The arc chamber 50 defines a plasma generation space S in which plasma is generated. In the drawing, a plasma formation region P where high-concentration plasma is formed is schematically indicated by a dashed line. The arc chamber 50 has a box-shaped body portion 52 with an open front surface 52g and a slit member 54 attached to the front surface 52g of the body portion 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 the direction (also referred to as the axial direction) from the cathode 56 toward the repeller 58 . A positive extraction voltage is applied to the arc chamber 50 with respect to the ground 64g by the extraction power supply 64d.

The body portion 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. A gas introduction port 62 for introducing a source gas is provided in the rear wall 52b. Four side walls including the first side wall 52c and the second side wall 52d are provided so as to define a rectangular opening in the front surface 52g of the body portion 52. As shown in FIG. 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 opening 52e extending in the axial direction, and the cathode 56 is arranged in the cathode insertion opening 52e. The second side wall 52d has a repeller insertion opening 52f extending in the axial direction, and a repeller 58 is arranged in the repeller insertion opening 52f.

The inner surface 52a of the main body 52 exposed to the plasma generation space S is made of a refractory metal material. be done. The body portion 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 body portion 52 can be made of, for example, tungsten with a high melting point (approximately 3400° C.). The purity of the refractory metal material used for the body portion 52 may be a standard purity lower than that of other members (for example, the cathode 56 described later), for example, the content of the refractory metal element is less than 99.99% by weight. is. An example of the content of the refractory metal element in the material used for the body portion 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-like member provided with the front slit 60 . The slit member 54 is attached to the front surface 52g of the main body 52 so as to block the opening of the front surface 52g. The slit member 54 has an inner surface 54a exposed to the plasma generating 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. . The outer member 80, like the body portion 52, may be constructed of a standard purity refractory metal material, such as tungsten.

The inner member 70 has an inner surface 54a exposed to the plasma generation space S. As shown in FIG. The inner member 70 has an inner opening 72 for forming the front slit 60 and has a protrusion 74 protruding toward the outside of the arc chamber 50 near or around the inner opening 72 . The thickness direction position of the outer surface 74b of the projecting portion 74 (the direction from the inside to the outside of the arc chamber 50) coincides with the thickness direction position of the outer surface 54b of the slit member 54 (or the outer member 80). A slit concave portion 76 is formed inside the projecting portion 74 so that the inner surface 54 a of the inner opening 72 is separated from the plasma forming region P in the vicinity of the inner opening 72 . The inner member 70 has a tapered surface 72a provided at the edge of the inner opening 72 so that the opening size increases from the inside of the arc chamber 50 toward the outside. By tapering the edge of the inner opening 72, the front slit 60 can be formed so that the flow of the ion beam IB extracted from the inside to the outside of the arc chamber 50 is less likely to be obstructed.

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 outer side of the inner member 70, and has a role of supporting the inner member 70 made of graphite, which has low mechanical strength, and increasing its strength. Outer member 80 has an outer opening 82 for forming 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 circumference 74 a of the projection 74 . The opening size of the outer opening 82 may be similar to the size of the outer circumference 74a of the protrusion 74, for example, the outer opening 82 may be spaced so that the outer circumference 74a of the protrusion 74 is provided with a rim of the outer opening 82. Configured.

Outer member 80 is preferably configured so as not to interfere with extraction of ion beam IB through inner aperture 72 . Specifically, the outer member is arranged such that the edge of the outer opening 82 is positioned farther from the center 60c of the front slit 60 than the virtual surface 72b formed by extending the tapered surface 72a of the inner opening 72 to the outside of the arc chamber 50. 80 is preferably configured. As a result, the opening shape of the front slit 60 can be defined 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 thermal electrons into the plasma generation space S. The cathode 56 is inserted through the cathode insertion opening 52e and fixed to the arc chamber 50 in an electrically insulated state. 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 columnar member, the tip of which is exposed to the plasma generation space S. As shown in FIG. The thermal break 56c is a cylindrical member that supports the cathode head 56b and extends axially from the outside of the arc chamber 50 toward the inside. The thermal break 56c desirably has a shape with high thermal insulation in order to maintain the cathode head 56b at a high temperature, and has a thin shape. The thermal reflector 56d is a cylindrical member provided so as to surround the outer circumferences 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 cathode head 56b and the thermal break 56c are maintained at high temperatures. The filament 56a is arranged inside the thermal break 56c so as to face the cathode head 56b.

The filament 56a is heated by a filament power source 64a to generate thermal electrons at its tip. The primary thermoelectrons generated by the filament 56a are accelerated by a cathode voltage (for example, 300 to 600 V) from the cathode power supply 64b, collide with the cathode head 56b, and heat the cathode head 56b by the heat generated by the collision. The heated cathode head 56b generates secondary thermoelectrons that are accelerated by an arc voltage (eg, 70-150 V) applied between the cathode head 56b and the arc chamber 50 by the arc power supply 64c. be done. The accelerated secondary thermoelectrons ionize the source gas introduced from the gas introduction port 62 and are emitted into the plasma generation space S as beam electrons having sufficient energy to generate plasma containing multiply charged ions. be. The beam electrons emitted into the plasma generation space S are constrained by the magnetic field B applied axially to the plasma generation space S, and spirally move along the magnetic field B. FIG. By spirally moving the electrons in the plasma generating space S, the movement of the electrons can be restricted to the plasma generating region P and the plasma generating efficiency can be enhanced.

The cathode head 56b is made of a refractory metal material, such as tungsten. The cathode head 56b may be made of a refractory metal material with a higher purity than the standard purity, and the content of the refractory metal element may be 99.99% by weight or more. An example of the content of the refractory metal element in 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 being exposed to high-concentration plasma, and is a member that easily causes contaminants to be mixed into the ion beam IB. By increasing the purity of the refractory metal material forming the cathode head 56b, it is possible to reduce the influence of contaminants mixed into the ion beam IB due to plasmatization of the material forming the cathode head 56b. At least one of the thermal break 56c and the thermal reflector 56d may be made of a standard purity high melting point metal material, or may be made of a high purity high melting point metal material like the cathode head 56b.

The repeller 58 repels electrons in the arc chamber 50 and causes the electrons to stay in the plasma generation region P to increase plasma generation efficiency. The repeller 58 is inserted through the repeller insertion opening 52f and fixed to the arc chamber 50 in an electrically insulated state. A repeller voltage (for example, 120 to 200 V) is applied between the repeller 58 and the arc chamber 50 by a repeller power supply 64e, and configured to repel electrons toward the plasma generation region P. FIG.

The repeller 58 has a repeller head 58a, a repeller shaft 58b, and a repeller support portion 58c. The repeller head 58a is provided inside the arc chamber 50 and is provided at a position facing the cathode head 56b in the axial direction with the plasma generation space S interposed therebetween. The repeller support 58c is provided outside the arc chamber 50 and fixed to a support structure (not shown). The repeller shaft 58b is a cylindrical member inserted through the repeller insertion opening 52f, and connects the repeller head 58a and the repeller support portion 58c. For example, the repeller shaft 58b is internally threaded, the repeller head 58a and the repeller support portion 58c are externally threaded, and the repeller head 58a, the repeller shaft 58b and the repeller support portion 58c are connected to each other by a threaded structure.

The repeller head 58a is made of a refractory metal material, such as tungsten. The repeller head 58a, like the cathode head 56b, may be constructed of a high-purity refractory metal material. Like the cathode head 56b, the repeller head 58a is a member that is easily worn out by being exposed to high-concentration plasma. can be reduced. If the repeller head 58a is made of a refractory metal material, the repeller shaft 58b is preferably made of graphite. As a result, seizing of the repeller head 58a and the repeller shaft 58b, which are connected by a screw structure, can be prevented. Note that the repeller head 58a may be made of graphite.

3 is a plan view showing a schematic configuration of the slit member 54 on the side of the outer surface 54b, and shows a front view when the front slit 60 is viewed from the extraction electrode 11. FIG. FIG. 2 corresponds to a cross section taken along the line AA in FIG. The outer member 80 has a substantially rectangular outer shape that is elongated in the axial direction. In addition, the inner member 70 indicated by the dashed line also has a substantially rectangular outer shape elongated in the axial direction. The front slit 60 is provided in the center of the slit member 54, and its opening shape is defined by an inner opening 72 that is elongated in the axial direction and has a substantially rectangular shape. The outer circumference 74a of the projecting portion 74 is also substantially rectangular, and the edge of the outer opening 82 is also substantially rectangular. Outer member 80 is configured to completely cover inner member 70 except for protrusion 74 near or around front slit 60 . Accordingly, the outer member 80 has a larger outer size than the inner member 70 indicated by the dashed line. Four outer engaging portions 86 a , 86 b , 86 c , 86 d for fixing the outer member 80 are provided on the outer periphery of the outer member 80 . The outer engaging portions 86a to 86d are provided two by two along the two long sides of the outer circumference of the outer member 80. As shown in FIG.

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. FIG. FIG. 2 corresponds to a cross section taken along the line AA in FIG. The inner surface 54a of the inner member 70 is provided with a cathode housing recess 78a, a repeller housing recess 78b and a central recess 78c. The cathode housing recess 78 a is provided at a position facing the cathode 56 , and the repeller housing recess 78 b is provided at a position facing the repeller 58 . The central recess 78c extends axially along the front slit 60 and is provided to connect between the cathode accommodating recess 78a and the repeller accommodating recess 78b. The cathode housing recess 78a and the repeller housing recess 78b are configured such that the inner surfaces facing the cathode 56 and the repeller housing recess 78b, respectively, are flat surfaces or cylindrical curved surfaces. The central recessed portion 78c is configured such that the inner surface exposed to the plasma generation space S is a substantially cylindrical 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. wear of the inner surface 54a can be reduced.

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

The inner surface 54a of the inner member 70 is provided with inner engaging portions 78p and 78q. The inner engaging portions 78p and 78q engage with body-side engaging portions provided on the main body portion 52 of the arc chamber 50 to regulate the position of the inner member 70 with respect to the main body portion 52. As shown in FIG. The inner engaging portions 78p and 78q are recesses provided on the inner surface 54a of the inner member 70, and body-side engaging portions protruding from the main body portion 52 are inserted thereinto. 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 the size in the axial direction and the size in the lateral direction orthogonal to the axial direction are substantially the same. On the other hand, the second inner engaging portion 78q is formed to have a long shape in the axial direction, and the size in the axial direction is larger than the size in the lateral direction. The shapes of the first inner engaging portion 78p and the second inner engaging portion 78q are not limited to those shown in the drawings, and other shapes may be used as long as they can be engaged with the main body side engaging portion to regulate the position. good.

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 recessed portion 88 a is provided at a position facing the cathode 56 on the outer periphery of the outer member 80 and is configured with a cylindrical curved surface corresponding to the cylindrical cathode 56 . The first outer peripheral recess 88 a is spaced apart from the cathode 56 to ensure electrical insulation between the cathode 56 and the slit member 54 . The second outer peripheral recessed portion 88 b 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 the outer member 80 is configured to have a vertically symmetrical shape. Therefore, the outer member 80 can be used upside down, and can be mounted so that the first outer peripheral recess 88a faces the repeller 58 and the second outer peripheral recess 88b faces the cathode 56. Note that the outer member 80 may not be provided with the second outer peripheral recessed portion 88b. Since the repeller shaft 58b that can face the second outer peripheral recess 88b has a smaller radial size (that is, thinner) than the repeller head 58a, the repeller 58 and the slit member 54 do not need to be provided with the second outer peripheral recess 88b. sufficient electrical insulation between

FIG. 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. As shown in FIG. FIG. 5 corresponds to the CC line cross section of FIG. 4 and shows a cross section when the repeller 58 is viewed from the cathode 56. FIG. As illustrated, the repeller 58 is arranged to protrude from the front surface 52g of the main body 52, and a portion of the repeller 58 overlaps the slit member 54 in the axial direction. Incidentally, the cathode 56 is similarly arranged so as to protrude from the front surface 52g of the main body 52, and a part of the cathode 56 overlaps the slit member 54 in the axial direction. A protrusion 74 protrudes toward the outside of the arc chamber 50 around the inner opening 72 , and a slit recess 76 is provided inside the protrusion 74 . The slit recess 76 is configured to be spaced apart from the cathode 56 and the repeller 58 in the radial direction orthogonal to the axial direction so as not to overlap the cathode 56 and the repeller 58 in the axial direction.

FIG. 6 is a cross-sectional view showing a schematic configuration of the arc chamber 50, and corresponds to the DD line cross-section of FIG. FIG. 6 shows a cross section orthogonal to the axial direction at a position corresponding to the cathode housing recess 78a and the first inner engaging portion 78p. As illustrated, the cathode 56 is arranged to protrude from the front surface 52g of the main body 52, and part of the cathode 56 is arranged inside the cathode housing recess 78a. Further, the body portion 52 is provided with a first body-side engaging portion 52p protruding from the front surface 52g. The first body-side engaging portion 52p regulates the position of the inner member 70 by engaging with the corresponding first inner engaging portion 78p.

FIG. 7 is a cross-sectional view showing a schematic configuration of the arc chamber 50, and corresponds to the EE line cross-section of FIG. FIG. 7 shows a cross section orthogonal to the axial direction at a position corresponding to the repeller housing recess 78b and the second inner engaging portion 78q. As illustrated, the repeller 58 is arranged to protrude outward from the front surface 52g of the body portion 52, and a portion of the repeller 58 is arranged inside the repeller housing recess 78b. Further, the main body portion 52 is provided with a second main body side engaging portion 52q projecting from the front surface 52g. The second body-side engaging portion 52q regulates the position of the inner member 70 by engaging with the corresponding second inner engaging portion 78q.

8 and 9 are side views schematically showing how the slit member 54 is fixed. 8 shows a state in which the slit member 54 is removed from the body portion 52, and FIG. 9 shows a state in which the slit member 54 is fixed to the body portion 52. As shown in FIG. Arc chamber 50 is fixed relative to structure 90 . The structure 90 includes an accommodation recess 92 that accommodates and supports the body portion 52, and locking structures 94a and 94b for fixing the slit member 54. As shown in FIG. The locking structures 94a, 94b engage with outer engaging portions 86a, 86b provided on the outer member 80, and apply a pulling force to the outer member 80 toward the main body portion 52, thereby moving the slit member 54 to the main body portion 52. fixed against. 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 tensile force applied to the first rod 96a. and a first spring 98a for applying the The first rod 96a is configured to be displaceable in the longitudinal direction and in the direction orthogonal to the longitudinal direction with the first bearing portion 97a as a fulcrum. It is configured so that the angle is variable.

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 engaging portion 86b to fix the slit member 54 to the body portion 52. As shown in FIG. The structure 90 is provided with a third locking structure and a fourth locking structure (not shown). The third locking structure engages the third outer engaging portion 86c shown in FIG. 3 and the fourth locking structure engages the fourth outer engaging portion 86d shown in FIG. The slit member 54 is pulled toward the body portion 52 by four locking structures and fixed to the body portion 52 . At this time, the first body side engaging portion 52p and the first inner side engaging portion 78p are engaged, and the second body side engaging portion 52q and the second inner side engaging portion 78q are engaged. The inner member 70 is precisely positioned with respect to.

Next, the operational effects of the ion generator 10 will be described. According to the present embodiment, the inner surface 54a of the slit member 54 is made of graphite, and the front slit 60 is defined by the inner opening 72 made of graphite, thereby minimizing contamination of the ion beam IB. . The inner surface 54a of the slit member 54 is a portion that is exposed to high-concentration plasma in the plasma generation region P, and can be said to be a portion that contributes the most to the contamination of the ion beam IB extracted from the front slit 60 with contaminants. By using graphite in such a portion, it is possible to suitably suppress the contamination of the ion beam IB. Mixing can be effectively suppressed.

According to the present embodiment, by constructing the cathode head 56b and the repeller head 58a from a high-melting-point metal material, the damage caused by the plasma is reduced compared to the case where these members are constructed from graphite, and the inside of the arc chamber 50 is reduced. reduce the amount of dirt that can accumulate on Also, 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 contamination of the plasma generated in the plasma generation region P with contaminants. In addition, by forming the inner surface 52a of the main body 52, which is less likely to be damaged by plasma, from a high-melting-point metal material of standard purity, the cost increase due to high purity can be suppressed, and the plasma generated in the plasma generation region P can be improved. contamination can be suitably suppressed.

According to this embodiment, by attaching the 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 electric discharge that may occur between the slit member 54 and the extraction electrode 11. Also, damage due to discharge can be suppressed. In particular, by minimizing the exposed area of the outer surface 74b of the projecting portion 74 around the inner opening 72, the effect of suppressing the discharge caused by the exposure of the graphite to the extraction electrode 11 and the damage caused by the discharge can be enhanced. Further, by providing 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 imaginary surface 72b of the inner opening 72, the ion beam IB extracted from the front slit 60 Inclusion of contaminants caused by the outer member 80 of is suppressed.

According to the present embodiment, the inner member 70 is provided with the cathode housing recess 78a, the repeller housing recess 78b, and the central recess 78c. and the repeller 58 can be positioned 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 multiply charged ions generated in the vicinity of the center of the plasma generation region P can be increased. can. Thereby, more multiply charged ions can be supplied to the downstream side of the ion generator 10 . In addition, if the supply amount of multiply-charged ions is about the same, by adopting the configuration of the present embodiment, it is possible to relatively reduce the arc voltage and arc current. Discharge between the arc chamber and the extraction electrode can be suppressed.

Although the present invention has been described with reference to the above-described embodiments, the present invention is not limited to the above-described embodiments, and can be applied to any suitable combination or replacement of the configurations of the embodiments. It is included in the present invention. Further, it is also possible to appropriately rearrange the combinations and the order of processing in the embodiments based on the knowledge of a person skilled in the art, and to add modifications such as various design changes to the embodiments. Embodiments described may also fall within the scope of the present invention.

DESCRIPTION OF SYMBOLS 10... Ion generator, 50... Arc chamber, 52... Main-body part, 54... Slit member, 56... Cathode, 58... Repeller, 60... Front slit, 70... Inner member, 80... Outer member, 100... Ion implantation apparatus.

Claims (12)

an arc chamber defining a plasma generation space;
a cathode that emits thermal electrons toward the plasma generation space;
The arc chamber is provided with a slit for extracting ions,
The inner surface of the arc chamber exposed to the plasma generation space includes a portion made of a high melting point metal material,
The cathode has a cathode head exposed to the plasma generating space, and the cathode head is made of a refractory metal material having a higher purity than the refractory metal material forming the inner surface of the arc chamber. An ion generator characterized by: 2. The ion generator according to claim 1, further comprising a repeller facing said cathode across said plasma generation space. The repeller has a repeller head exposed to the plasma generation space, and the repeller head is made of a high-melting-point metal material having a higher purity than the high-melting-point metal material forming the inner surface of the arc chamber. The ion generator according to claim 2. 4. The ion generator according to claim 2, wherein said slit extends in an axial direction in which said cathode and said repeller face each other. 5. The ion according to any one of claims 1 to 4, wherein the refractory metal material constituting the inner surface of the arc chamber has a refractory metal element content of less than 99.99% by weight. generator. 6. The ion generator according to claim 5, wherein the refractory metal material forming the inner surface of the arc chamber has a refractory metal element content of less than 99.95% by weight. 7. The ion generator according to claim 6, wherein the refractory metal material forming the inner surface of the arc chamber has a refractory metal element content of less than 99.9% by weight. 8. The ion generator according to claim 7, wherein the refractory metal material forming the inner surface of the arc chamber has a refractory metal element content of less than 99.8% by weight. The ion generator according to any one of claims 1 to 8, wherein the refractory metal material contains at least one of tungsten, molybdenum and tantalum. 10. The ion generator according to any one of claims 1 to 9, wherein the ion generator generates multiply charged ions of boron, phosphorus or arsenic. An ion generator according to any one of claims 1 to 10;
a beam accelerator that accelerates an ion beam extracted from the ion generator to an energy of 1 MeV or more;
and an ion implantation chamber in which an ion beam emitted from the beam accelerator is irradiated onto an object to be processed. 12. The ion implanter according to claim 11, wherein said beam accelerator accelerates the ion beam extracted from said ion generator to energy of 4 MeV or more.

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