JPH0612660B2 - High voltage ion implanter - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an ion implanting device, and particularly to several 100 keV.
The present invention relates to a high-voltage ion implantation apparatus suitable for high-current beam implantation with energy of several MeV.

[Background of the Invention]

When obtaining high-energy ions with a conventional ion implanter used industrially and implanting them on a substrate, the beam extracted from the ion source is once sorted by the mass separator into the desired ion species, and then this A high energy was used by using an accelerating tube with an accelerating electrode ring and the like. In this case, the high voltage application causes discharge between the acceleration electrodes and so-called corona discharge, and the energy that can be practically achieved is several hundreds at most.
It was about keV. (For example Springer Series in Ele
ctrophsics Volume 10, "Ion Implantation Techvique
s ”, Springer-Verlog Publishing, 1982, p.351)
In addition, the length of the accelerating tube for accelerating to the order of several hundred keV is several meters, which is a huge ion implanter. Further, in the latter-stage accelerating tube in which the conventional accelerating rings are arranged, there is no focusing action for concentrating the beam on the central axis, so that the beam generally spreads, and beam loss and a small-diameter beam cannot be obtained due to the sample substrate. In addition, a magnetic field type mass separator is generally used as a mass separator, but in order to focus the beam on the central axis, unless a special entrance / exit angle setting or another converging lens is used, the convergence is stronger than the efficiency. No effect was obtained.

[Object of the Invention]

It is an object of the invention to RF the beam extracted from the ion source.
An object is to provide a high-voltage ion implanter using an ion beam of several hundred keV to several MeV, which efficiently performs mass separation, acceleration, and convergence simultaneously by using an accelerator Q.

[Outline of Invention]

According to the present invention, a high frequency quadrupole accelerator is provided between an ion source and a sample substrate, and mass separation and ion acceleration are performed simultaneously by this high frequency quadrupole accelerator, whereby several hundred keV to several Me.
This is to realize high-energy ion implantation of V.

Example of Invention

An embodiment of the present invention will be described below with reference to FIG. First
In the figure, the implanting apparatus of the present invention is composed of an ion source 1, an RFQ tank 2 containing a high-frequency quadrupole accelerator (RFQ),
And the implantation chamber 3 containing the sample substrate 5. The structure of the high frequency quadrupole accelerator is shown in FIG. In FIG. 2, the RFQ tank 2 has four electrodes 2 having a wavy shape.
a, 2b, 2c, and 2d, and in a portion where two opposing electrodes protrude, the remaining two sets of electrodes have a periodic wavy shape so as to be dented. This RFQ tank 2
Consists of one type of cavity resonator, and when a high-frequency voltage having a frequency of several tens to several hundreds MHZ is applied to this, an accelerating electric field in the axial direction is generated in the central orbital portion, and ions are efficiently accelerated to several MeV. It In FIG. 1, the ion beam extracted from the ion source generally contains various ion species, but one that is accelerated in the RFQ tank 2 depends on the waved period of the RFQ tank 2 and the applied high frequency voltage. It is only one kind of ion, and other ion species diverge and cannot penetrate. Further, since the RFQ constitutes a kind of converging lens, the beams that can be transmitted are subjected to a converging action of concentrating on the central axis. That is, the use of the RFQ tank 2 enables mass separation, acceleration, and convergence at the same time. Further, since the beam emitted from the ion source 1 may have a height of several 10 keV, the burden on the DC high-voltage power source of the ion source 1 can be lightened and the apparatus can be downsized. In the embodiment shown in FIG. 1, an RFQ tank 2 having different shapes and high-frequency voltages for each ion species is used to generate an ion beam of several MeV such as B ⁺ , N ⁺ , O ⁺ , As ⁺ , P ⁺ , He ^+. It was possible to obtain in pulse form. As the ion source, Japanese Patent Sho 57
The microwave ion sources described in JP-A-4056, JP-A-57-11094, JP-A-57-11093 and JP-A-57-41059 were used. Beam current is several meters in DC conversion
MeV ions in the order of A were obtained.

Next, in FIG. 1, it was necessary to change the structure of the RFQ tank 2 each time the ion species and the final energy were changed. For this reason, when an external resonance type RFQ was used as the RFQ tank 2, it was possible to accelerate various ion species with one RFQ and implant ions into the substrate.

Next, another embodiment will be described with reference to FIG. In the implanter of FIG. 1, the final energy of the beam is the ion species and the RFQ.
It depends on the structure of. Therefore, it is difficult to easily obtain arbitrary energy. In FIG. 3, the beam 1 ′ emitted from RFQ is put into a single-gap resonator 6 which is also a kind of cavity resonator, and the deceleration electric field generated according to the applied high-frequency voltage is used to make the implantation energy variable. It is a thing. As a result, using the same RFQ tank 2, it is possible to implant ions of one kind with arbitrary energy.

For deceleration, instead of the single gap, the cylindrical ring electrode or the flat plate ring electrode 6'used conventionally is used.
A plurality of electrodes, the first electrode on the RFQ side is set to the ground potential,
Similar effects were obtained with a deceleration electrode system in which a positive voltage was applied to the electrodes as it went to the sample side. This embodiment is shown in FIG.

Next, another embodiment according to the present invention is shown in FIG. Generally, in ion implantation, it is required to uniformly implant a prescribed amount of ions onto the entire surface of various substrates including silicon wafers. In FIG. 5, for this reason, a large number of sample substrates 5 are attached to the surface of the rotating disc 13 and the discs 13 themselves are mechanically moved in the radial direction with respect to the beam 1 ′ so that the substrate 5 can be uniformly driven. Is going. In this case, there is a particular problem due to the use of RFQ. That is, in RFQ, even if the beam 1 ′ emitted from the ion source 1 is direct current,
Along with the passage of the FQ2, a pulsed beam becomes a lump, and the pulse cycle is synchronized with the cycle of the high frequency voltage applied to the RFQ2. Therefore, disk 13 rotation frequency ₁ and R
If the ratio of the frequency ₂ of the high frequency applied to FQ2 is the number of Risato,
Depending on the value, the irradiation location is a discrete location on the rotating disk 13. Therefore, in the present invention, for the rotation frequency ₁ , the distance between the two closest points of the discrete point group is smaller than the beam diameter, and uniform ion implantation can be performed along the circumferential direction. . In one embodiment of FIG. 5, numeral 10 is a numerical value generator for generating a finite number of irrational numbers, which is input to the differential amplifier 9 together with the output from the encoder 8. Differential amplifier 9
Is designed to output an electric output in accordance with the difference between the two values, control the rotation speed of the disk rotation motor 7, and make the difference between the two zero.

Another embodiment according to the present invention is shown in FIG. In FIG. 6, a beam scanning electrode system 11 for scanning a beam in the XY directions is provided between the RFQ 2 and the implantation substrate 5, and uniform implantation is performed on the substrate 5. In this case, as shown in FIG. 5, X, Y
The scanning frequency in the direction was smaller than the RFQ frequency. In this case, the distance between the two irradiation spots on the substrate 5 depends on the X and Y electrode voltages and their frequencies. In this embodiment, the irradiation position between the two closest points is smaller than the beam diameter. Although an example using an electric field is shown in the figure, the same uniform implantation can be realized by an XY scanning system using a magnetic field coil.

Next, another embodiment based on the present invention is shown in FIG. 7th
In the figure, two-stage magnetic quadrupole lenses 12a and 12b for focusing the beam are mounted between the ion source 1 and the RFQ tank 2. Generally, the beam cross section of a high current ion source is a rectangular cross section. On the other hand, the beam passing part of RFQ is several mm to several mm.
A circular part with a radius of cm. Therefore, in order to effectively accelerate the beam extracted from the ion source without beam loss, it is necessary to convert the beam cross section into a shape suitable for the RFQ incident part. In this embodiment, a two-stage magnetic quadrupole lens is used,
A high current beam was effectively introduced into RFQ2, and the driving current was also improved to 1 mA or more.

〔The invention's effect〕

According to the high-voltage ion implantation apparatus of the present invention described above, a high-frequency quadrupole accelerator is provided between the ion source and the sample substrate, and mass separation and ion acceleration are performed simultaneously with this high-frequency quadrupole accelerator. Because it was done, several hundred K
It becomes possible to efficiently implant various high-current ion beams in the eV to several MeV range, which is put to practical use, and the effect is extremely large.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the high voltage ion implantation apparatus of the present invention, and FIG. 2 is a perspective view showing the details of the RFQ tank used in FIG. FIG. 7 is a diagram showing different embodiments of the high voltage ion implantation apparatus of the present invention. DESCRIPTION OF SYMBOLS 1 ... Ion source, 1 '... Ion beam, 2 ... High frequency quadrupole accelerator, 3 ... Implanting chamber, 4 ... Faraday cup for current measurement, 5 ... Implanted sample substrate, 6 ... Single gap resonator, 7 ... Rotation Motor, 8 ... Encoder, 9 ... Differential amplifier, 10 ... Numerical value generator, 11 ... Beam scanning electrode system,
12 ... Magnetic quadrupole lens, 6 ″ ... deceleration electrode.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hidemi Koike 1-280 Higashi Koigakubo, Kokubunji, Tokyo Inside Hitachi Central Research Laboratory (72) Inventor Tokuro Saito 1-280 Higashi Koigakubo, Kokubunji, Tokyo Hitachi Ltd. Central Research Laboratory (72) Inventor Susumu Kosasa 1-280, Higashikoigakubo, Kokubunji, Tokyo Hitachi Research Laboratory, Hitachi Ltd.

Claims (5)

[Claims] 1. An ion implanting apparatus for mass-separating a beam of ions extracted from an ion source and mixing the beam into a target ion sample substrate by a predetermined amount, wherein a high frequency quadruple is provided between the ion source and the sample substrate. A high-voltage ion implanting device, which is provided with a polar accelerator, and performs mass separation and ion acceleration at the same time by the high-frequency quadrupole accelerator. 2. A single gap type speed reducer for decelerating ions between the high frequency quadrupole accelerator and the sample substrate, or a flat plate or cylindrical electrode system for speed reduction, wherein the single gap type speed reducer, or The high-voltage ion implantation apparatus according to claim 1, wherein the energy of the implanted ions is variable by the deceleration electrode system. 3. A plurality of said sample substrates are mounted on the surface of a rotating disk, and the disk itself is driven in the radial direction with respect to the beam to provide an implantation chamber capable of uniformly implanting ions on the entire sample substrate. The rotation frequency of the disk is made smaller than the frequency of the high-frequency voltage applied to the high-frequency quadrupole accelerator, and the rotation frequency is such that the beam is regularly and intermittently irradiated along the rotation circumferential direction. The frequency value is selected so that the distance between the two points closest to each other in the group is smaller than the beam diameter, so that uniform implantation can be performed on the substrate. Alternatively, the high-voltage ion implantation apparatus according to item 2. 4. An electric field, a magnetic field, or a beam scanning means combining them is provided between the high frequency quadrupole accelerator and the sample substrate, and the beam scanning frequency is smaller than the frequency applied to the high frequency quadrupole accelerator. As for the scanning voltage and the frequency, the distance between the two closest points in the X and Y directions of the point group that receives the beam irradiation regularly on the substrate is smaller than the beam diameter. The high-voltage ion implantation device according to claim 1 or 2, wherein a voltage value and a frequency value are selected. 5. A multi-stage magnetic quadrupole lens is provided between the ion source and the high frequency quadrupole accelerator to efficiently introduce an ion beam emitted from the ion source into the high frequency quadrupole accelerator. The high-voltage ion implantation apparatus according to claim 1 or 2, characterized in that.