JPH02284342A - Ion implanting device - Google Patents

Abstract

PURPOSE:To place ions with optional energy over the whole electric current range to the maximum ion electric current which an ion placing device can produce by composing an ion implanting device in which high voltage to ground is applicable to a target formed in an insulation condition to the ground. CONSTITUTION:An ion implanting device has structure in which a target 7 to which ions are implanted is insulated from the ground, and voltage of optical magnitude is applicable. As a result, placing energy of the ions drawn out from a plasma chamber 101 can be given as a difference between positive electrode voltage Vac to ground and negative electrode voltage Vt given to the target 7. Since ion current drawn out from a plasma chamber is determined with a difference between the positive polarity voltage Vac given to the plasma chamber and draw-out voltage Vs of negative polarity to the ground given to a draw-out electrode 102, the positive polarity voltage Vac to the ground given to the plasma chamber can be set optionally high even when placing energy of the ions is desired to be set low, and the ions can be placed to the target with optional energy up to the maximum ion current which the device can produce.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the configuration of an ion implantation device for controlling ion implantation energy in an ion implantation device used in material surface modification and semiconductor manufacturing processes.

(vl technology) FIG. 9 shows an outline of a conventional ion implantation device.

This ion implantation device has an ion source 1. Vacuum vessel at ground potential 2. 3. A process chamber coupled to the same potential as the vacuum vessel. Vacuum exhaust system 4. It consists of ancillary equipment such as a high-voltage DC power supply. In the ion source 1, the target gas 5 introduced into the plasma chamber lot is turned into plasma by an appropriate means such as low-pressure discharge, and the effect of the electric field formed between the plasma chamber 101 and the extraction electrode 102 is generated from this plasma. The ion beam 6 is extracted by the reference numeral 103, where reference numeral 103 indicates a ground electrode.

The extracted ions travel within the vacuum vessel 2 forming an ion beam travel channel at ground potential with the energy represented by the ground voltage, that is, the acceleration voltage vMc supplied from the power supply 8 to the plasma chamber 101, and then pass through the process chamber 3.
It is fired into target 7 placed inside. If the purity of the implanted ions is required, an electromagnet for mass spectrometry may be installed upstream of the process chamber 3.

Here, when the plasma is made to have a high density, the upper limit of the extracted ion current is usually limited by the space charge limiting current, and below the space charge limiting current, it is proportional to the extraction voltage to the 372nd power. Therefore, in order to increase productivity, the drawer power supply 15
kV is used for the extraction electrode 102.

[Problem to be solved by the invention]

However, the energy of ions is closely related to the subsequent crystal growth on the surface of the ion-implanted material, depending on the depth of ion penetration into the target, the sputtering of atoms on the target surface, and so on. For this reason, for example, when attempting to perform low-energy, high-current ion implantation, the acceleration voltages v and c are reduced, and
It is necessary to increase the difference between the reduced positive polarity accelerating voltage V ac and the negative polarity extraction voltage ■ so that the desired large current can be obtained. It became necessary to increase the extraction voltage to the negative side beyond the output voltage limit, which caused difficulties due to equipment constraints such as the capacity of the extraction power supply and the insulation strength of the extraction part for extracting the extraction electrode to the outside of the vacuum vessel. ,For this reason,
When reducing the implantation energy, there is a problem in that the implantation ion current must also be reduced.

The purpose of this invention is to provide an ion implantation device that can implant ions at any energy up to the maximum ion current that existing ion implantation devices can produce, without having to strengthen the ion implantation device in terms of voltage, such as by increasing the capacity of the extraction power source. The purpose is to provide the following configuration.

[Means to solve the problem]

In order to solve the above ms, in this invention, target gas or metal vapor is turned into plasma by means such as low-pressure discharge, ions are extracted from the plasma by the action of an electric field, and ions are extracted into a traveling channel at ground potential. An ion implantation device for driving an ion beam as an ion beam and implanting it into a target is configured so that the target can be installed in an insulated state with respect to the ground, and a high voltage to the ground can be applied to the target. In addition, when applying a positive voltage to the target, a ring-shaped electrode that circumferentially surrounds the ion beam traveling path or a pair of plate-shaped electrodes that sandwich the ion beam is connected to the ground on the upstream side of the target in the ion beam traveling path. It is preferable to include a suppression electrode to which a negative voltage is applied. Further, when applying a negative voltage to the target, it is preferable to provide means for forming a magnetic field in a direction perpendicular to the ion beam travel path on the front side of the target.

[Effect]

When the ion implantation device is formed in this way, the energy of the ions implanted into the target is uniquely determined by the difference between the voltage to ground V ac supplied to the plasma chamber and the voltage to ground applied to the target. The ion current extracted from the ground voltage V, and the extraction voltage V
Since it is determined by the difference between .

(Example) A first example of the configuration of an ion implantation apparatus according to the present invention is shown in FIG. 1. In FIG. 0, the same members as in FIG. , to insulate the target from the ground, the process chamber 3, which is at the same potential as the target, is insulated from the vacuum vessel 2 using an insulator 9;
A high voltage (2) is applied to the target 7 from the high voltage power supply 10. By configuring the ion implantation device in this way,
The potential and ion energy of each part are as shown in Figure 2. In Figure 2, the horizontal axis indicates the position of each member in Figure 1.
The ions are accelerated by the ion source l to energies v and c, and travel in the vacuum container 2 at a speed corresponding to this energy,
Further, it is decelerated toward the target by the ground potential v1 of the target, and is finally driven into the target with energy of V, c-Vt. Voltage V applied to target
By changing , ions can be implanted into the target with arbitrary energy. In addition, the code 10 in the figure
0 is process chamber 3. Therefore, a resistance is shown to eliminate floating of the ground potential of the target 7.

FIG. 3 shows a modification of the above embodiment. In this example, an insulator 3c is used instead of the conductive support member 3a in the conventional device configuration (FIG. 9) to insulate the target 7 from the ground. , and a sample stage 3d made of an insulator or a metal plate. The configuration uses an insulating stand 3b.

FIG. 4 shows a second embodiment of the invention. The power supply connected to the plasma chamber 101 (11th P11) is formed by connecting a plurality of power supplies in series, and the mutual connection points of the power supplies are connected to the target 7. When trying to set the ion implantation energy to several tens of eV to several tens of QeV, this value is less than a percent level of the extraction voltage value, so taking the difference in the output voltages of the two power supplies is likely to cause an error from the desired value (and may affect stability). Although it is poor, if the configuration shown in Fig. 3 is used, the implantation energy is determined by V□., so the accuracy is good (
Moreover, a desired value can be stably secured.

FIG. 5 shows a third embodiment of the present invention, in which a ring-shaped suppression electrode 11 is provided near the process chamber 3 of the vacuum vessel 2 so as to pass inside the ion beam 6, and a ground voltage of about several 100 volts to 10 kV is applied. Negative voltage is applied.

The ion beam 6 traveling inside the vacuum container 2 contains floating electrons 1
However, when a positive voltage is applied to the target 7, these floating electrons are attracted and the electrical neutrality of the ion beam is broken, and the ion beam is The beam may diverge and the ion beam cannot be used effectively. Further, thermal damage may be caused to the target 7. If a negative voltage is applied to the sublensing electrode 11, the suppression electrode 11 becomes a barrier to floating electrons, so that the above-mentioned problem does not occur.

A fourth embodiment of the present invention is shown in FIGS. 6 to 8. In this embodiment, in the apparatus configuration shown in FIG.
A magnetic field 14 of 0.00 Gauss is generated. When a negative voltage is applied to the target 7, secondary electrons 13 generated when ions hit the target are accelerated toward the vacuum chamber and collide with the inner wall surface of the vacuum chamber. This may cause thermal damage to the vacuum container and generate X-rays at the same time. If a magnetic field is formed as shown in FIG. 6, the secondary electrons will be restrained by the action of the Lorentz force and will return to the target 7, so that the above-mentioned problem will not occur.

To form a magnetic field with a component perpendicular to the ion beam 6,
For example, as shown in Fig. 7.8, a permanent magnet 18 or an electromagnetic coil 20 may be used.
9 indicates a yoke forming a magnetic path.

Although the present invention has been described above under the condition that there is no mass spectrometer electromagnet, the same functions as the ion implantation device can be obtained even when there is a mass spectrometer electromagnet.

〔Effect of the invention〕

As described above, according to the present invention, the ion implantation apparatus has a structure in which the target into which ions are implanted is insulated from the earth, and a voltage of an arbitrary positive or negative polarity can be applied to the earth. , the implantation energy of ions extracted from the plasma chamber can be given as the difference between the positive voltage to the ground (V, c) applied to the plasma chamber and the positive or negative voltage to the ground (V, ) applied to the target, On the other hand, the ion current drawn from the plasma chamber is determined by the positive polarity voltage to the ground (V, ) applied to the plasma chamber and the negative polarity extraction voltage to the ground (V, ) applied to the extraction electrode.
), so even if you want to lower the ion implantation energy, it is possible to set the ground positive polarity voltage (Vac) applied to the plasma chamber arbitrarily high, so it is necessary to increase the capacity of the extraction power supply. This makes it easy to supply the extraction voltage to obtain the maximum ion current that the device can produce, and the voltage applied to the target (
By changing v1), it is possible to bombard the target with any energy up to the maximum ion current that the device can produce. In the ion implantation apparatus configured as described above, a suppression electrode consisting of a ring cane electrode surrounding the ion beam path or a pair of plate-shaped electrodes sandwiching the ion beam is arranged on the upstream side of the target in the ion beam path. By applying a negative voltage to the ground to the target, it is possible to implant the ion beam while keeping the electrons in the ion beam even if a positive voltage to the ground is applied to the target, preventing the ion beam from dispersing and damaging the target. It can be prevented. In addition, by attaching a means to form a magnetic field in the direction perpendicular to the ion beam on the front side of the target, when a negative polarity voltage to the ground is applied to the target, ions are generated when they hit the target and are accelerated toward the vacuum vessel side. Since the secondary electrons that are about to be ejected are deflected in their traveling direction by the magnetic field and returned to the target, thermal damage to the vacuum container and generation of X-rays can be prevented.

In this way, according to the present invention, over the entire current range up to the maximum ion current that the device can produce, the ion beam can be used without divergence or damage to the device or target.
It becomes possible to implant ions with arbitrary energy.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing a first embodiment of the ion implantation device configuration according to the present invention, FIG. 2 is a diagram showing the potential of each part of the ion implantation device and the energy of ions in FIG. 1, and FIG. 5 is a sectional view showing a modification of the first embodiment of the ion implantation device configuration shown in FIG. 1; FIG. 4 is a partially sectional side view showing a second embodiment of the ion implantation device configuration according to the present invention;
The figure is a cross-sectional view of the main part showing the third embodiment, FIG. 6 is an explanatory diagram illustrating the functions of the device configuration according to the fourth embodiment of the present invention, and FIGS. 7 and 8 are respectively the fourth embodiment. FIG. 9 is a longitudinal sectional view showing an example of the configuration of a conventional ion implantation device. 1: Ion source, 2: Vacuum container (travel channel), 3:
Process chamber, 3b: Insulation table, 5: Gas, 6: Ion beam, 7: Target, 9: Insulator, 10: High voltage power supply, 11? Sub-ledge four electrodes, 15: Extraction power supply, 1
8: Permanent magnet, 20: Electromagnetic coil, 101 plasma chamber,
102: Extraction electrode. Figure 1 Figure 2

Claims (1)

[Claims] 1) A target gas or metal vapor is turned into plasma by means such as low-pressure discharge, ions are extracted from the plasma by the action of an electric field, and the ions travel as an ion beam in a travel channel at ground potential. An ion implantation apparatus for implanting ions into a target, wherein the target is formed so as to be installed in an insulated state with respect to the ground, and a high voltage to the ground can be applied to the target. 2) In the ion implantation apparatus according to claim 1,
A suppression electrode is provided on the upstream side of the target in the ion beam travel path, and is made of a ring-shaped electrode that circumferentially surrounds the ion beam travel path or a pair of plate-shaped electrodes that sandwich the ion beam, and to which a negative voltage is applied to the ground. An ion implantation device characterized by: 3) In the ion implantation apparatus according to claim 1,
An ion implantation device characterized by comprising means for forming a magnetic field in a direction perpendicular to an ion beam travel path on the front side of a target.