JPS60121656A - Latter step acceleration type ion implantation device - Google Patents

Abstract

PURPOSE:To drive high energy ions without increasing the size of the captioned device while reducing the load on an operating power source by using a high- frequency quadruplex accelerator as an acceleration tube for the latter step acceleration of an ion implantation device. CONSTITUTION:An ion implantation device is formed of an ion source 1, a mass separator 2, a high-frequency quadruplex accelerator 10 and a driving chamber 5 with a sample 6 enclosed therein, while the high-frequency quadruplex accelerator 10 is formed of four electrodes having the periodically corrugated shape so that the two remaining electrodes may be concave at the part where the two opposing electrodes are convex. Further, the former step of the quadruplex accelerator 10 is provided with a two-step magnetic quadruplex lens 12 for converting a beam section in order to enable a driving current to be increased. Accordingly, the high-frequency quadruplex accelerator 10 makes it possible to accelerate with extremely good efficiency, thus making it possible to simply realize driving an mA class beam of 100KeV- several MeV with a light load on power source.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an ion implantation device for doping a sample with a predetermined amount of specific ions having a predetermined energy.
The present invention relates to a post-acceleration type ion implantation apparatus suitable for implanting mA class beams with energies of 00 keV to several M e V.

[Background of the invention]

A conventional example will be explained using FIG. When obtaining a high energy beam of 100 keV or more with a conventional ion implantation device,
A post-acceleration method is used in which the mass-separated beam is accelerated by an acceleration tube arranged with acceleration rings 3. However, the practical energy that could be achieved in the conventional example was around 400 keV. This is because as the energy increases, the length of the accelerating tube becomes enormous, and at 400 keV or higher, discharge between electrode rings, corona discharge, etc. occur, making it impossible to create a stable ion implantation device for practical use. . Also, in conventional implant devices, the mass separator is typically large. This dimension increases with increasing beam energy. For this reason, a method is usually used to extract a beam from an ion source with an energy of several tens of keV, separate the beams by mass, and accelerate the beams. Therefore, in the conventional example, the mass separator 2. The potential of the ion source 1 had to be maintained at the maximum voltage of the accelerating tube.

For this reason, these drive power supplies 7 and 8 must also be operated at a high voltage, and the power required by the high voltage power supply 7 is enormous, placing a heavy burden on the power supply. For the above reasons, with conventional ion implantation equipment, the acquired energy is several hundred at most.
keV, and the burden on the high voltage power supply is the beam energy,
Since the beam current increases as the beam current increases, the beam current was several tens of micrometers at most.

[Purpose of the invention]

The purpose of the present invention is to use an accelerator using a high-frequency quadrupole resonator instead of a post-acceleration tube, and to
It is an object of the present invention to provide a small-sized post-acceleration type ion implantation device that realizes a large current ion beam of V and has a small burden on a power source.

[Summary of the invention]

The present invention focuses on a radio frequency quadrupole (RFQ) accelerator with excellent acceleration efficiency and beam convergence, and uses it as an acceleration tube for the latter stage acceleration of an ion implanter.
The feature is that a multi-stage magnetic quadrupole lens is installed between the accelerators.

[Embodiments of the invention]

The present invention will be explained in detail below. FIG. 2 is an embodiment of a post-acceleration type ion implantation apparatus using an RFQ accelerator based on the present invention.

The apparatus shown in FIG. 2 has a high frequency quadruple transverse accelerator IO between the mass separator 2 and the implantation chamber 5, and efficiently performs acceleration up to several MeV. A detailed diagram of the high frequency quadruple transverse accelerator 10 is shown in FIG. In Figure 3, a high-frequency quadrupole resonator (
The RFQ (hereinafter abbreviated as RFQ) consists of four electrodes with a wavy shape, and is configured such that where two opposing electrodes protrude, the remaining two electrodes are recessed.

This accelerator constitutes a kind of cavity resonator, and when a high frequency voltage with a frequency of several tens to several hundred MI (2) is applied to this, an axial accelerating electric field is generated in the central orbit, and the ions are efficiently The ion source is accelerated to several MeV.In this case, since the RFQ operates at ground potential in terms of direct current, the ion source in the preceding stage.

The mass separator does not need to be raised to a high voltage, and the burden on the power source is extremely light. Furthermore, in RFQ, the maximum applied voltage is only several tens of keV, so there is no practical acceleration limit limit due to discharge generation or the like. According to this embodiment, several MeV
ion beam can be efficiently realized, and there is no need for a large-capacity, high-voltage power supply as in the conventional example. In the actual experiment, the ion source was
B+ was mass-separated to around 40 keV using the microwave ion source described in No. 11094 and Japanese Patent Publication No. 57-41059.

0” HN” HP” HAs 10th grade ion beam R
The beam was input into an FQ resonator, and a mA-class beam of several M e V was implanted into the silicon substrate. However, in the embodiment shown in FIG. 2, the proportion of the beam current reaching the sample substrate in the beam emitted from the ion source tended to be small.

Generally, when mass-separating an ion beam, the resolution varies depending on the beam width, so in order to obtain high resolution, the beam cross section of the ion beam source is usually made vertically long. Therefore, the ion beam cross section after mass separation also generally has a vertically elongated cross-sectional shape. On the other hand, the beam-passable portion of the entrance cross section of the RFQ resonator is a circular portion with a diameter of several holes. For this reason,
The ion beam utilization efficiency could not be increased. Therefore, it has been experimentally revealed that it is necessary to change the beam cross section in order to reduce the loss of beam current. FIG. 4 is a diagram illustrating another embodiment based on the present invention. Fourth
In the figure, a two-stage magnetic quadrupole lens (direct current operation) 12 is used to convert the beam cross section, and a rectangular cross-sectional beam can be converted into a circular beam that can be introduced into RFQ, and the implantation current is more than doubled.

〔Effect of the invention〕

According to the present invention described above, when obtaining a high-energy beam using the post-acceleration method, it is possible to experiment with a mA-class beam of several 100 keV to several M eV with a light power supply burden, and it is possible to easily realize high-energy ion implantation. , the effect is extremely large when put into practical use.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining a conventional example, FIG. 2 is a diagram explaining an embodiment based on the present invention using an RFQ accelerator, FIG. 3 is a diagram explaining the structure of a high frequency quadrupole resonator, FIG. 4 is a diagram illustrating another embodiment based on the present invention. ■...Ion source, 1'...Ion beam, 2...
Mass separator, 3... Acceleration ring electrode, 4... Resistor, 5... Implanting chamber, 6... Sample substrate, 7... High voltage current, 8... Mass separator, 9 ...Ion source operating power supply, IO...RFQ resonator, 11...High frequency voltage power supply, ]2...Magnetic quadrupole lens. Section 1 Figure Z Continuation of Figure 1 Page ■ Inventor: Saito Tokube 0 Inventor: Kosasa Susumu 1-28 Hata, Higashikoigakubo, Kokubunji City Hitachi, Ltd. Central Research Laboratory

Claims (1)

[Scope of Claims] 1. An ion source that extracts a large current beam, a mass separator that mass-separates the ion beam and selects only the target ion species, and a mass separator that accelerates the mass-separated ions to the target energy. In an ion implantation device consisting of an accelerator and an implantation chamber for implanting the ions into a sample substrate, a radio frequency quadrupole (RF Q + Ra) is used as the acceleration tube.
1do -Frequency Quadrupole
)Using an accelerator, it does not increase the size of the device and reduces the burden on the power source for operating the device.
A post-acceleration ion implantation device that can implant high-energy ions of V to several MeV. 2. In the invention described in claim 1, a multi-stage magnetic quadrupole lens is installed between the mass separator and the RFQ accelerator, and the ion beam cross section coming out of the mass separator is
A post-acceleration type ion implantation device that has a cross-sectional shape that can be introduced into a Q accelerator, thereby reducing beam current loss and increasing the implantation beam current.