JPH06302293A - Microwave ion source - Google Patents

Abstract

PURPOSE:To provide a microwave ion source for obtaining a large current of ion beams by canceling magnetic field dispersion at the slit position of an ion beam outlet and in front of the slit of the ion beam outlet. CONSTITUTION:In a microwave ion source for generating plasma in a discharging box 7 by microwave discharge in a magnetic field and for pulling out ion beams through a slit 8a' by means of pulling out electrodes 8a, 8b pole pieces 21, 22 for correcting at least a pair of magnetic fields formed of a magnetic substance are installed on the sides of the discharging box 7 in such a way that the discharging box 7 may be sandwiched. Thus, magnetic force components at the slit position and in the narrow slit width direction in front of the slit position are canceled to parallel pulling out ion beams, obtaining a large current of ion beams.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave ion source used in an ion implantation apparatus, and relates to improvement of magnetic field distribution near the slit and increase of ion extraction current.

[0002]

2. Description of the Related Art FIG. 6 is a diagram for explaining a conventional microwave ion source. In FIG. 6, 1 is a magnetron for generating microwaves, 2 is a choke flange, 3 is a waveguide, 4 is an introduction window made of an insulating material, 5 is a dielectric filling material, 6
Is a coil for magnetic field generation, 7 is a discharge box, 8a 'is a slit,
Reference numerals 8a, 8b, 9a and 9b are extraction electrodes, 10 is an ion beam, 11 is a waveguide, 12 is a pole piece for efficiently collecting a magnetic field, 13 is a gas inlet, and 14 is a magnetic path.
Here, a power supply control device that supplies and controls current and voltage to each coil and electrode is omitted.

A high-frequency (for example, 2.45 GHz) microwave generated in the magnetron 1 is introduced through the choke flange 2 and the waveguide 3, and further through the introduction window 4 made of an insulating material. This microwave further passes through the dielectric filler 5 and the waveguide 11 and is guided to the discharge box 7. In the discharge box 7, the magnetic field generated by the coil 6 is efficiently collected by using the pole piece 12, and the sample gas is introduced into the magnetic field through the gas introduction port 13 to generate plasma. This plasma passes through the slit 8a ', and the extraction electrode 8
The ion beam 10 is obtained by using a, 8b, 9a, and 9b.

Here, the extraction electrode 8b is made of a magnetic material,
The magnetic field and the magnetic path 14 are prevented from leaking to the extraction electrodes 9a and 9b. At this time, the change in the extraction direction of the ion beam 10 between the magnetic force component (Bz) in the extraction direction of the ion beam 10 on the central axis of the discharge box 7 and the magnetic force component (Bx) in the narrow direction of the slit 8a ′ is shown. It shows in FIG. Here, the position of the slit 8a 'is at a position of 2.4 cm.

[0005]

However, as shown in FIG. 7, in the prior art ion source, the magnetic force component Bx in the direction in which the width of the slit is narrow is located at and before the position of the slit 8a 'for extracting ions. Was not 0 and was finite. In other words, because the magnetic field there was diverging,
The ions moving along the lines of magnetic force cannot pass through the slit to the outside of the ion source, collide with the slit, disappear, or become a divergent beam even if extracted. As a result, there is a problem that it is difficult to increase the extracted ionic current.

An object of the present invention is to eliminate the magnetic field divergence at the slit position at the exit of the ion beam and in front of it, without causing magnetic field leakage to the extraction electrode, so that a large current ion beam can be obtained. It is to provide a microwave ion source.

[0007]

The above object is achieved by mounting at least one pair of magnetic field correcting members made of a magnetic material on the side surface of the discharge box of the microwave ion source so that the discharge box is in between. it can. A pole piece or a permanent magnet can be used as the magnetic field correction member.

[0008]

According to the present invention, the pole piece for magnetic field correction is attached to the slit position and in front of the slit position to absorb and deflect the magnetic lines of force to separate the magnetic path from the slit, thereby separating the slit position and the slit in front of it. The magnetic force component in the direction of narrow width can be made extremely small. Similarly, a permanent magnet is attached instead of the pole piece for magnetic field correction, and magnetic force components in the narrow slit width direction in that region can be canceled by combining those magnetic force lines.

Therefore, in the discharge box, the magnetic field at the slit position and in front of it does not diverge, and the charged particles moving along the magnetic field lines of the magnetic field are extracted as a parallel beam without colliding with the slit. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. First, FIG. 1 shows a structure near the discharge box of the ion source according to the present invention, which is different from the conventional technique.

FIG. 1 shows a discharge box 7 as a magnetic field correction member.
An example in which the pole pieces 21 and 22 are attached to the above is shown. Here, 11 is a waveguide attached so as to surround the discharge box 7, 8a 'is a slit, 8a and 8b are extraction electrodes,
12 is a pole piece. In FIG. 1, the magnetron 1, the choke flange 2, the waveguide 3, the introduction window 4, the dielectric filling 5, the coil 6, the extraction electrodes 9a and 9b, the ion beam 10, the gas introduction port 13, and the magnetic path 14 are shown. Illustration is omitted. These structures are the same as shown in FIG. There is also a voltage control device (not shown) that controls the voltage of each electrode.

The extraction electrode 8b is made of a magnetic material and efficiently generates a magnetic field in the discharge box 7 together with the pole piece 12. Further, the magnetic field correcting pole pieces 21, 22
So as to sandwich the discharge box 7 between each pair,
The slits are arranged so as to face each other in the direction in which the slit width is narrow, and one is placed near the slit 8a ′ and the other is placed near the pole piece 12. Here, two pairs of pole pieces are used because the gradient of the magnetic field distribution generated by disposing only one pair of pole pieces near the slit 8a 'is made uniform. Further, the extraction electrode 8a is
It is a non-magnetic material.

The simulation result of the magnetic field distribution in the discharge box 7 is shown in FIG. Horizontal axis Z in FIG.
Indicates the position on the central axis of the discharge box 7 when the extraction direction of the ion beam 10 is positive, and the upper end of the slit 8a 'is at a position of 2.4 cm. Here, Bz is the magnetic force component in the Z direction on the central axis, and Bx is the slit 8
It is the magnetic force component in the direction of the narrow width of a '. As described above, in the regions before and after the slit position, the magnetic field Bx in the X direction is extremely small, and the magnetic force lines are parallel to the Z direction.

Next, the permanent magnet 2 is used as a magnetic field correcting member.
An example in which 3 is attached is shown in FIGS. 3 and 4. In FIG. 3, the magnetic field correction pole pieces 21 and 2 in FIG.
Instead of 2, the structure around the discharge box 7 with the permanent magnet 23 attached is shown.

In FIG. 3, the permanent magnets 23 are mounted so that the same pole faces face each other. Here, when the direction of the magnetic force lines is from the pole piece 12 to the extraction electrode 8b, the permanent magnet 23 has N poles on both side surfaces thereof and an S pole on the opposite surface thereof so as to sandwich the central axis of the discharge box 7. The poles are mounted so that they are arranged.

The simulation result of the magnetic field distribution at this time is shown in FIG. The Z on the horizontal axis in FIG. 4 indicates the position on the central axis of the discharge box 7 when the extraction direction of the ion beam 10 is positive, and the lower end of the slit 8a 'is 2.4 cm.
Is the position. Here, Bz is Z in the central axis.
In the magnetic force component in the direction, Bx is the magnetic force component in the direction in which the width of the slit 8a 'is narrow. As described above, Bx is extremely small in the area inside the discharge box 7 including the position of the slit 8a ′, and the magnetic force lines are substantially parallel to the Z axis.

In the above two embodiments, the pole piece or the permanent magnet is used as the magnetic field correcting member, or
It is also possible to use an electromagnet capable of adjusting the magnetic field.

Next, an ion implantation apparatus using the microwave ion source of these embodiments will be described with reference to FIG. The ion implantation apparatus shown in FIG. 5 includes a magnetron 1 for generating microwaves, a choke flange 2 for introducing microwaves from a low potential portion to a high potential portion,
A microwave ion source 31 for generating ions, extraction electrodes 9a, 9b for extracting the ion beam 10 from the microwave ion source 31 and made of a metal plate having a rectangular hole in the center, The ion beam 10
A mass separator 32 including an electromagnet, disposed in the passage of
A downstream accelerating electrode 33, which is arranged on the downstream side and is composed of a plurality of metal plate materials having a rectangular hole in the center, and a deflection magnet 34, which is arranged on the downstream side and is made of an electromagnet. And a rotating disk 35 on the downstream side of the deflection magnet 34, on which a sample is placed. Here, although not shown, there is a power supply device that is connected to each of the electrodes and the electromagnet and controls their voltage and current.

In this embodiment, ions are generated by the microwave ion source 31 according to the present invention, and the ions pass through the extraction electrodes 9a and 9b to generate the ion beam 10. Since the magnetic field component Bx near the slit of the ion source 31 is very small, the extracted ion beam 10 becomes a parallel beam having a uniform ion density distribution in the X direction. The ion beam 10 is sent to the mass separator 32, where only the necessary ions are separated, and thereafter, the post-acceleration electrode 33 accelerates the ion beam to a predetermined energy, for example, several tens of kV. The accelerated ion beam 10 is deflected by a deflection magnet 34 attached for removing impurities. Finally, the ion beam 10 is driven while being rotated to a sample such as a semiconductor attached to a rotating disk 35 that is scanned in a direction perpendicular to the ion beam 10. Since the ion beam 10 is a parallel beam having a uniform ion density distribution, uniform beam irradiation can be performed.

[0020]

According to the present invention, in the microwave ion source, since the magnetic force component in the direction perpendicular to the beam extraction direction can be canceled out, the extracted ion beam becomes parallel and the beam in the direction perpendicular to the beam extraction direction. The density distribution becomes uniform. Therefore, the ions generated in the discharge box of the ion source are extracted without waste, and the ion beam can have a large current.

When this ion source is used, the extracted ion beam is a parallel beam with a large current and a uniform ion density, so that uniform and rapid beam implantation is possible, and the throughput of the ion implantation apparatus is increased. It is possible to greatly improve.

[0022]

[Brief description of drawings]

FIG. 1 is a detailed cross-sectional view of the vicinity of a discharge box to which a pole piece for magnetic field correction is attached as one embodiment of the present invention.

FIG. 2 is obtained by a magnetic field distribution simulation,
2 is a graph showing distributions of magnetic field components in X and Z directions, where the ion beam extraction direction is the positive Z direction on the central axis of the discharge box according to the embodiment of FIG. 1.

FIG. 3 is a detailed cross-sectional view of the vicinity of a discharge box to which a permanent magnet is attached for magnetic field correction, as an embodiment of the present invention.

FIG. 4 is obtained by a magnetic field distribution simulation,
4 is a graph showing distributions of magnetic field components in the X and Z directions, where the ion beam extraction direction is the positive Z direction on the central axis of the discharge box according to the embodiment of FIG. 3.

FIG. 5 is an explanatory diagram of an embodiment of an ion implantation apparatus equipped with the ion source of the present invention.

FIG. 6 is an illustration of a microwave ion source according to the prior art.

FIG. 7: Obtained by magnetic field distribution simulation,
7 is a graph showing magnetic field component distributions in the X and Z directions, where the ion beam extraction direction is the positive Z direction on the central axis of the discharge box according to the conventional technique of FIG. 6.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetron, 2 ... Choke flange, 3 ... Waveguide, 4 ... Introduction window, 5 ... Dielectric filling, 6 ... Coil, 7 ... Discharge box, 8a, 8
b, 9a, 9b ... Extraction electrode, 8a '... Slit,
10 ... Ion beam, 11 ... Waveguide,
12 ... Pole piece, 13 ... Gas inlet, 14 ... Magnetic path, 21, 22 ...
Magnetic field correcting pole piece, 23 ... Permanent magnet, 31 ... Microwave ion source, 32 ... Mass separator, 33 ...
Rear accelerating electrode, 34 ... Deflection magnet, 35 ... Rotating disk.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 21/265

Claims (7)

[Claims] 1. A microwave ion source in which a plasma is generated in a discharge box by a microwave discharge in a magnetic field, and the plasma is extracted from a slit by using an extraction electrode to be an ion beam. At least one pair of magnetic field correction members are arranged so as to face each other so that the box is in between, and the magnetic field correction member cancels the divergent magnetic force component in the direction perpendicular to the ion extraction direction in the slit position and the region in front of it. A microwave ion source, which is characterized in that it is arranged as follows. 2. The magnetic field correction member according to claim 1,
A microwave ion source, which is a pole piece for canceling the divergent magnetic force component by changing the magnetic path of the magnetic field. 3. The magnetic field correction member according to claim 1,
A microwave ion source, which is a permanent magnet for canceling the divergent magnetic force component by superposing the magnetic force line of the magnetic field and the magnetic force line generated by itself. 4. A microwave ion source in which a plasma is generated in a discharge box by a microwave discharge in a magnetic field, and the plasma is extracted from a rectangular slit by using an extraction electrode to form an ion beam, which is made of a magnetic material. , At least one pair of magnetic field correction members disposed so as to face each other so that the discharge box is in between, and the magnetic field correction member cancels the magnetic force component Bx in the direction of the narrow slit width in the slit position and the area in front of it. A microwave ion source, which is characterized in that the microwave ion source is arranged at. 5. The magnetic field correction member according to claim 4,
A microwave ion source, which is a pole piece for canceling the Bx by changing the magnetic path of the magnetic field. 6. The magnetic field correction member according to claim 4,
A microwave ion source, which is a permanent magnet for canceling the Bx by superimposing a magnetic force line of the magnetic field and a magnetic force line generated by itself. 7. An ion source for generating ions and extracting the ions by an extraction electrode, a mass separator for separating the mass of the extracted ions, and further accelerating or decelerating the ions separated by the mass separator. An ion implantation apparatus comprising: an electrode for forming an ion beam; a deflection magnet for deflecting an accelerated or decelerated ion beam; and a disk to which an object to be implanted into which the ion beam is attached is attached. 7. An ion implanting device, which is the microwave ion source according to any one of 6 and 6.