JPH10223553A - Ion-implanting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the beam current of an ion beam by a beam-current meter at the same position as on a substrate, without obstructing ion implanting to the substrate. SOLUTION: This apparatus comprises a vacuum vessel 20, a parallel hexahedral rotary holder 22 housing this vessel, platens 22 disposed at mutually opposite side faces 22a, 22b of the holder 22 for holding a substrate 8, beam-current meters 26 disposed on the remaining two opposite side faces 22c, 22d for measuring the beam currents of an ion beam 6 from an ion source 4, and holder rotation mechanism disposed below the holder 22 for rotating the holder 22, stepwise by 90 deg. with the center at a center shaft 23 parallel to the side face of the holder. The ion source 4 is mounted on one side face of the vessel 20 for irradiating an ion beam in a fixed direction on the substrate 8 held with the platens 24 on the holder 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion implantation apparatus for irradiating a substrate with an ion beam to perform ion implantation. Typically, an ion beam extracted from an ion source passes through a mass separating means and a scanning means. More specifically, the present invention relates to an ion implantation apparatus that irradiates a substrate as it is (this is also referred to as an ion doping apparatus), and more specifically, to an improvement in means for measuring a beam current of an ion beam irradiating the substrate.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional example of this type of ion implantation apparatus.
Shown in This ion implantation apparatus applies an ion beam 6 extracted from an ion source 4 to a substrate (for example, a semiconductor wafer) 8 held on a platen 10 provided in a vacuum vessel 2 which is evacuated to a vacuum. Irradiation is performed without passing through the means, and ion implantation is performed on the substrate 8. In order to perform ion implantation on the entire surface of the substrate 8, the cross-sectional dimension of the ion beam 6 is made larger than the dimension of the substrate 8.

A beam current measuring device (for example, a Faraday cup) 12 is arranged beside the substrate 8 on the platen 10 and does not hinder the ion implantation into the substrate 8, and the beam current measuring device 12 The beam current of the ion beam 6 is measured by receiving a part of the ion beam 6 irradiated to the beam 8. The beam current measured by the beam current measuring device 12 is used, for example, in the dose amount computing device 1.
By integrating at 4, the amount of ion implantation (dose) with respect to the substrate 8 can be measured.

[0004]

The ion beam 6 extracted from the ion source 4 has a non-uniform beam current density distribution in which the beam current density at the periphery is lower than that at the center. Is common.

However, in the above-described ion implantation apparatus, since the substrate 8 and the beam current measuring device 12 cannot be arranged at the same position with each other, the substrate 8 is irradiated due to the non-uniformity of the beam current density distribution. There is an unavoidable difference between the beam current of the ion beam 6 to be measured and the beam current measured by the beam current measuring device 12. Therefore,
Unless the beam current measured by the beam current measuring device 12 is corrected, the dose amount with respect to the substrate 8 cannot be accurately measured, and this correction has conventionally been performed.

However, since the beam current density distribution of the ion beam 6 extracted from the ion source 4 varies depending on the implantation conditions, specifically, the ion species, beam current, beam energy, etc. of the ion beam 6, the implantation conditions must be adjusted. Each time the beam current is changed, the beam current must be corrected again, which requires time and effort. This causes a reduction in the throughput of the ion implantation apparatus (substrate processing capacity per unit time). I was

SUMMARY OF THE INVENTION Accordingly, it is a main object of the present invention to enable a beam current measuring device to measure a beam current of an ion beam at the same position as a substrate without obstructing ion implantation into the substrate. And

[0008]

According to the present invention, there is provided an ion implantation apparatus comprising: a vacuum vessel evacuated to vacuum; a parallelepiped-shaped rotary holder housed in the vacuum vessel; Two platens respectively provided on two sides and holding the substrate, and two beam current measuring devices respectively provided on the remaining two opposite sides of the holder and measuring the beam current of the ion beam, A holder rotation mechanism for rotating the holder in steps of 90 degrees about a central axis parallel to the side surface thereof, and an ion source for irradiating a substrate held on a platen on the holder with an ion beam from a fixed direction. It is characterized by:

According to the above configuration, the holder is rotated stepwise by 90 degrees by the holder rotating mechanism, so that the ion beam is alternately incident on the substrate held on the platen and the beam current measuring device at the same position. be able to. Therefore, the beam current of the ion beam can be measured by the beam current measuring device at the same position as the substrate without obstructing the ion implantation into the substrate.

[0010]

FIG. 1 is a plan view showing an example of an ion implantation apparatus according to the present invention. FIG. 2 is a side view of the ion implantation apparatus of FIG. Parts that are the same as or correspond to those in the conventional example of FIG.

In this embodiment, a vacuum (for example, 10 ^-5 to
A vacuum vessel 20 to be evacuated (to about 10 ⁻⁷ Torr) is provided.

A rotary holder 22 having a parallelepiped shape (for example, a rectangular parallelepiped or a cube) is accommodated in the vacuum vessel 20.

Two opposite side surfaces 22a of the holder 22
And 22b are each provided with a platen 24 for holding the substrate 8 as described above. As means for holding the substrate 8, each platen 24 is provided with, for example, a plurality of claws for gripping the peripheral portion of the substrate 8, an electrostatic chuck for attracting the substrate 8 by static electricity, and the like (all not shown).

The platens 24 are of a rotary type in this example, and are respectively rotated in the rotation directions (that is, the center axis 25 of the platen 24 is rotated by a platen rotating mechanism 40 provided in the holder 22, as shown by an arrow B, for example). (Centered around). Each platen rotation mechanism 40
In this example, a rotating shaft 43 connected to the platen 24,
A motor 42 for rotating the platen 24 via the rotating shaft 43 as described above, and a magnetic seal portion 44 for vacuum-sealing a portion where the rotating shaft 43 passes through the holder 22 are provided.

Although it is not essential to provide the platen rotating mechanism 40, by providing it and rotating the platen 24 and the substrate 8 held thereon during ion implantation, the ion beam 6 irradiated from the ion source 4 can be rotated. By eliminating the non-uniformity of the beam current density distribution, the uniformity of the injection into the substrate 8 can be further improved.

A beam current measuring device 26 for measuring the beam current of the ion beam 6 irradiated from the ion source 4 is provided on each of the other two opposite side surfaces 22c and 22d of the holder 22. In this example, as shown in FIGS. 2 and 3, the beam current measuring devices 26 are arranged in a cross shape, receive the ion beam 6, and measure the beam current of the ion beam 6 at that location. A plurality of Faraday cups 30 are disposed in front of the Faraday cups 30, and a negative voltage is applied from a power supply (not shown) to each Faraday cup 30.
A suppressor electrode 32 for pushing back secondary electrons emitted from the substrate and preventing the secondary electrons from escaping to the ground, and a mask 36 disposed in front of the suppressor electrode 32. The suppressor electrode 32 and the mask 36 are provided with a plurality of holes 34, 38 corresponding to the respective Faraday cups 30, respectively.
Respectively. The Faraday cup 30 is attached to the insulating plate 28.

If each beam current measuring device 26 has a plurality of Faraday cups 30 as in this embodiment, not only the beam current of the ion beam 6 but also the beam current density distribution of the ion beam 6 can be measured. Although it is possible to do so, it is not essential that each beam current meter 26 includes one Faraday cup 30 located near the center of the ion beam 6 when it faces the ion source 4. May be provided.

Further, the distance from the center axis 23 of rotation of the holder 22 to the surface of the substrate 8 on each platen 24 and the surface of each beam current measuring instrument 26 from the center axis 23 (more precisely, the measurement surface Front of each Faraday cup 30)
It is preferable to keep the distance to
By doing so, the ion beam 6 can be measured by the beam current measuring device 26 at substantially the same position as the surface of the substrate 8, so that the beam current of the ion beam 6 applied to the substrate 8 can be measured by the beam current measurement. The measuring device 26 enables more accurate measurement in a state closer to the injection condition.

As shown in FIG. 2, the holder 22 is positioned 90 degrees below the holder 22 about the center axis 23 parallel to the side surfaces 22a to 22d of the holder 22, for example, in a direction indicated by an arrow A. Step rotation (rotation step by step)
A holder rotating mechanism 46 is provided. In this example, the holder rotating mechanism 46 is attached to the bottom surface of the holder 22 and penetrates the bottom surface of the vacuum vessel 20, a bearing function of the rotating shaft 48,
The bearing unit 50 has a function of vacuum-sealing a portion penetrating through zero, and the rotation drive unit 52 for stepwise rotating the holder 22 by 90 degrees via the rotation shaft 48 as described above.

Further, in this example, the above-described ion source 4 for irradiating the substrate 8 held on the platen 24 on the holder 20 with the ion beam 6 from one direction is attached to the side surface of the vacuum vessel 20. However, the ion source 4 may be provided away from the side surface of the vacuum vessel 20, and a vacuum communication pipe may be provided between the two. This ion source is preferably a bucket-type ion source using a cusp magnetic field for confining plasma. According to this, an ion beam 6 having a large area and high uniformity can be easily extracted. The ion beam 6 extracted from the ion source 4 irradiates the substrate 8 on the platen 24 without passing through the mass separating means and the scanning means as in the conventional example.

According to the above ion implantation apparatus, the holder 22
Is rotated in steps of 90 degrees by the holder rotating mechanism 46 so that the substrate 8 held on the platen 24 is rotated.
And the beam current measuring device 26 are alternately directed to the ion source 4, and the ion beam 6 can be incident on the substrate 8 and the beam current measuring device 26 alternately at the same position. That is, the ion implantation and the beam current measurement can be alternately repeated at the same position. Therefore, the beam current measuring device 26 irradiates the substrate 8 (more specifically, immediately before or immediately after the ion implantation) at the same position as the substrate 8 without hindering the ion implantation into the substrate 8. 6 can be measured. As a result, there is no need to correct the measured beam current as in the conventional example. Even if the correction is performed, it is not necessary to perform the correction every time the injection condition is changed unlike the conventional example, so that the throughput does not decrease.

Normally, the holder 22 is rotated 90 degrees each time the ion implantation into one substrate 8 is completed.
Strictly speaking, the time when the beam current is measured by the beam current measuring device 26 is different from the time when the beam is injected into the substrate 8 by the injection time (this is, for example, about several seconds to several tens of seconds). Since the fluctuation of the beam current of the ion beam 6 at the time can be generally ignored,
There is no particular problem.

Further, in this embodiment, although not essential, each platen 24 in the vacuum vessel 20 is promptly exchanged between the injected substrate 8 and the uninjected substrate 8 as follows. The structure is adopted.

That is, a vacuum valve (for example, a gate valve) 54 having a size larger than that of the substrate 8 or a substrate holding portion 62 described later is provided on the side surface of the vacuum container 20 opposite to the ion source 4, and the outside thereof is provided. A detachable air lock chamber (which is also called a vacuum preparatory chamber) 56 is provided. Further, in the vicinity of the outside of the airlock chamber 56, two substrate exchange mechanisms 60 having the same structure in this example are provided.

Each substrate exchange mechanism 60 holds (for example, holds) the substrate 8 on the platen 24.
And put it in the vacuum vessel 20 through the vacuum valve 54 by the arrow C
And a telescopic shaft 66 for attaching and detaching the air lock chamber 56 to and from the outside of the vacuum valve 54 in conjunction with the insertion and removal of the substrate holding portion 62, as shown in FIG.
And an expansion / contraction drive unit 68 that expands / contracts the actuators 66 in conjunction with each other, an arm 70 that supports the expansion / contraction drive unit 68, and an arm 70 that reciprocates as shown by the arrow D to move the substrate holding unit 62 and the air lock chamber 56, A rotation drive unit 72 is provided for turning in the horizontal direction (see FIG. 1) and downward (see FIG. 2). The substrate mounting portion 7 is provided below the downward substrate holding portion 62 and the like.
6 are provided.

For example, while the ions are being implanted into the substrate 8 on one platen 24, the implanted substrate 8 is removed from the other platen 24 by the respective substrate exchange mechanisms 60, and After being moved into the air lock chamber 56 and the inside of the air lock chamber 56 is returned to the atmospheric pressure, the injected substrate 8 is placed on the substrate placing portion 76 with the air lock chamber 56 facing downward. be able to. Further, in the reverse operation, the next uninjected substrate 8 on the substrate mounting portion 76 is held by the substrate holding portion 62, and the substrate holding portion 62 and the air lock chamber 56 are rotated sideways to remove air. The lock chamber 56 is mounted outside the vacuum valve 54, and after evacuating the air lock chamber 56, the vacuum valve 54 is opened, and the substrate holding unit 62 is inserted through the vacuum valve 54 into the vacuum container 20, and the empty platen 24 is An unimplanted substrate 8 can be mounted.

The above operation can be performed alternately and continuously in the two substrate exchange mechanisms 60. Thereby, for example, while ion-implanting the substrate 8 on the platen 24 on the opposite side with respect to each platen 24 in the vacuum vessel 20, the exchange of the implanted substrate 8 with the unimplanted substrate 8 is performed. Can be performed promptly. Therefore, by adopting such a structure, the throughput is further improved. When the implantation and replacement of the substrate 8 are completed, the holder 22 is rotated by 90 degrees, and the beam current of the ion beam 6 is measured by the beam current measuring device 26 described above. Then, the above operation is repeated as appropriate.

[0028]

Since the present invention is configured as described above, it has the following effects.

According to the first aspect of the present invention, the holder is rotated stepwise by 90 degrees by the holder rotating mechanism, so that the substrate and the beam current measuring device, which are held on the platen, are alternately positioned at the same position. A beam can be incident. Therefore, without hindering ion implantation into the substrate, at the same position as the substrate,
The beam current of the ion beam can be measured by the beam current measuring device. As a result, there is no need to correct the measured beam current as in the conventional example. Even if the correction is performed, it is not necessary to perform the correction every time the injection condition is changed unlike the conventional example, so that the throughput does not decrease.

According to the second aspect of the present invention, since the platen rotating mechanism as described above is provided, the non-uniformity of the beam current density distribution of the ion beam irradiated from the ion source is eliminated, and The injection uniformity can be further improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of an ion implantation apparatus according to the present invention.

FIG. 2 is a side view of the ion implantation apparatus of FIG.

FIG. 3 is an enlarged sectional view showing an example of a beam current measuring device in FIG.

FIG. 4 is a cross-sectional view showing an example of a conventional ion implantation apparatus.

[Explanation of symbols]

 Reference Signs List 4 ion source 6 ion beam 8 substrate 20 vacuum vessel 22 holder 24 platen 26 beam current measuring instrument 40 platen rotation mechanism 46 holder rotation mechanism 60 substrate exchange mechanism

Claims (2)

[Claims] A vacuum container evacuated to vacuum, a parallelepiped-shaped rotary holder housed in the vacuum container,
Two platens respectively provided on two opposite side surfaces of the holder and holding the substrate, and two platens respectively provided on the other two opposite side surfaces of the holder for measuring the beam current of the ion beam. A beam current measuring device, a holder rotating mechanism for rotating the holder in steps of 90 degrees around a central axis parallel to the side surface thereof, and irradiating the substrate held by a platen on the holder with an ion beam from a fixed direction. An ion implantation apparatus, comprising: 2. The ion implantation apparatus according to claim 1, wherein a platen rotating mechanism for rotating each of the platens in a rotation direction is provided in the holder.