JPH0266844A - Focussed ion beam generator - Google Patents

Abstract

PURPOSE:To reduce the aberration of a filter by making the surface of a pole piece for magnetic field generation to compose an EXB filter opposing to the optic axis practically as a blanking electrode surface, and applying a blanking voltage to the electrode surface. CONSTITUTION:A voltage and a current are fed to an EXB filter to radiat only ion beams IB on a target, and as a result, the intensities of the magnetic field and the electrode are deflected into a specific type of ion beams, which strike on an aperture plate 19. In this case, since blanking electrodes 17 and 18 are formed of a non-magnetic material, the magnetic field of the EXB filter is never disturbed. In this case, when ion beams advancing to the target is blanked, a blanking voltage is applied to the electrodes 17 and 18, the beams are deflected and struck to the plate 19. Furthermore, the crossover is to be positioned at the center of the electrodes 17 and 18, and an ideal blanking can be carried out.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a focused ion beam device that irradiates a target with a narrowly focused ion beam, and in particular to a focused ion beam device suitable for use in maskless ion implantation. Regarding beam equipment.

(Prior Art) Ions such as boron (B), beryllium (Be), silicon (S i ), phosphorus < P, and zinc (7n) are obtained by a liquid metal ion source. By implanting these ions into silicon wafers or wafers made of elements of group 1-v, P-type or N-type dopants and other impurities can be obtained for these wafers. Therefore, a focused ion beam device using this ion source is attracting attention because it enables maskless impurity implantation. With this liquid metal ion source, it is difficult to obtain ions from substances with a high melting point or high vapor pressure.
It is used as a eutectic alloy with a lower melting point.

For example, if you want to obtain 5iPRe ions, gold (A
A ternary alloy of u), S (and Be) is used.

The melting point of this alloy is quite low, about 350° C., and therefore it is possible to obtain ions of each substance.

When this alloy is ionized, ions of a plurality of elements constituting the alloy are obtained, and an ExB filter is used to obtain the specific ions needed.

FIG. 4 shows a conventional focused ion beam device using an ExB filter. In the figure, 1 is a liquid metal ion source. An ion beam emitted from an ion source 1 and accelerated by 4" is focused on a target 40 such as a silicon wafer by a converging lens 2 and an objective lens 3. 5 is Ex
B filter, and the center of this E×B filter 5 is located at the crossover point IC formed by the converging lens 2.
has been affected by Blanking electrodes 6.7 are arranged before and after this ExB filter 5.

To explain the operation of such a configuration, first, ions of a plurality of elements generated from a liquid metal ion source are focused at a crossover point C by a converging lens 2. Among these ions of a plurality of elements, ions of a specific element travel straight through the ExB filter 5 and are focused onto the target 4 by the objective lens 3 . On the other hand, ions of elements other than the specific element are bent in their traveling direction by the ExB filter 5, collide with the aperture A7 plate 8, and are prevented from irradiating the target 4. The reason why this E×B filter is placed at the crossover position of the ion beam rB is as follows.
This is to reduce the chromatic aberration of the ExB filter due to the energy width of the ion beam.

(Problem to be Solved by the Invention) The ion beam traveling straight through the ExB filter 5 is focused on the target 4, but in maskless ion implantation, the irradiation position of the ion beam on the target is controlled by a deflector (Fig. (not shown) and by drawing the desired pattern. Also, in this drawing, the ion beam must be blanked, and the blanking electrode must be placed at the crossover position C to eliminate tailing caused by the ion beam on the target. be. However, since the ExB filter 5 is arranged at the crossover position C, two stages of blanking electrodes 6 and 7 are provided before and after the ExB filter, as shown in the figure, and the solid line in the figure As shown, the ion beam is deflected so that blanking is performed at crossover position C, which appears to be earth. However, in this method, two stages of blanking electrodes 6.
7 have exactly the same shape and apply the same voltage, desired blanking can be performed.

However, blanking needs to be performed on the order of nanoseconds, and if there is a large difference in the length of the lead wires for supplying voltage to the two blanking electrodes 6°7, the voltage cannot be applied to the two electrodes. The timing will be off and tilling will occur.

The present invention has been made in view of these points, and
The purpose is to realize a focused ion beam device that can perform ion beam blanking without causing day ringing.

<Means for Solving the Problems> A focused ion beam device according to claim 1 of the present invention includes an ion source and an ExB filter that selects specific ion species from the ion beam generated from the ion source. , an ion beam apparatus comprising means for focusing an ion beam so that the ion beam forms a crossover at the center of an E×B filter, and a focusing lens for focusing ions selected by the E×B filter. A feature is that the surface of the magnetic field generating pole piece constituting the ×B filter that substantially faces the optical axis is a blanking electrode surface, and a blanking voltage is applied to this blanking electrode surface. .

A focused ion beam device according to claim 2 of the present invention includes an ion source, an ExB filter that selects specific ion species from the ion beam generated from the ion source, and an ion beam located at the center of the ExB filter. In an ion beam device having means for focusing an ion beam so as to form a crossover with the ion beam, and a focusing lens for focusing ions selected by an ExB filter, a pole piece for generating a magnetic field constituting the ExB filter. A blanking electrode is disposed on a surface facing the optical axis of the lens via an insulator, and a blanking voltage is applied to the blanking electrode.

A focused ion beam device according to claim 3 of the present invention includes an ion source, an ExB filter that selects specific ion species from the ion beam generated from the ion source, and an ion beam located at the center of the ExB filter. In an ion beam device having means for focusing an ion beam so as to form a crossover with the ion beam, and a focusing lens for focusing ions selected by an ExB filter, a pole piece for generating a magnetic field constituting the ExB filter. It is characterized in that it is configured such that a blanking voltage is applied to J-.

(Function) In the invention of claim 1, the surface of the vA magnetic field generating pole piece constituting the ExB filter that substantially faces the optical axis is used as a blanking electrode, and the gap between the ExB filter and the blanking electrode is Both are placed at the ion beam crossover position.

In the invention according to claim 2, a blanking electrode is attached via an insulator to face the optical axis of the magnetic field generating pole piece constituting the ExB filter.

In the third aspect of the present invention, a blanking voltage is directly applied to the magnetic field generating pole piece constituting the ExB filter.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. 1 and 2 show an embodiment of the E×B filter and blanking electrode portion of a focused ion beam device based on the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. . In the figure, reference numerals 11 and 12 indicate pole pieces for generating the magnetic field of the ExB filter, which are made of iron, cobal, or the like. 13 and 14 are electrodes for generating the electric field of the ExB filter. Blanking electrodes 17 and 18 made of a non-magnetic conductive material such as aluminum plus are attached to the surfaces of the pole pieces 11 and 12 facing the optical axis O, respectively, via insulators 15 and 16. ing. This blanking electrode 17.18
A blanking voltage is applied from a blanking power supply (not shown) to the blanking voltage. 19 is an average plate, and E
Ions deflected by the xB filter and ion beams deflected by blanking are prevented from advancing toward a target (not shown) by this aperture plate 19.

The operation in such a configuration is as follows.

Voltage and current are supplied to the ExB filter so that the target is irradiated with only the ion beam IB of a predetermined ion type among the multiple ion types generated from the ion source, and as a result, the strength of the magnetic and electric fields is An ion beam of a predetermined ion species travels straight along the optical axis, and ion beams of other ion species are deflected and collide with the aperture plate 19 . At this time, since the blanking electrodes 17 and 18 are made of a non-magnetic material, the magnetic field of the ExB filter is not disturbed in any way. Here, when blanking the ion beam heading toward the target, a blanking voltage is applied to the blanking electrodes 17 and 18, and as a result, the ion beam is deflected and impinges on the aperture plate 19.

In this way, the ion beam crossover C is located at the center of the ExB filter, and this crossover C
is also located at the center of the blanking electrodes 17, 18, allowing ideal blanking.

In this embodiment, the blanking N pole is attached to the pole piece through an insulator, but a non-magnetic metal may be deposited on the insulator.

FIG. 3 shows another embodiment of the invention. In this embodiment, the magnetic field generating pole piece 21.22 of the ExB filter is attached to the base body 23.24 via an insulator 25.26.

The ExB filter magnetic field is generated by passing an excitation current through the coils 27,28. Blanking voltage source 2
The blanking voltage from 9 is configured such that it can be applied directly to the pole piece 21.22 itself via an amplifier 30.31.

In this example, the magnetic field generation pole piece of the ExB filter also serves as the blanking electrode, so the ExB filter and the blanking electrode are placed at the ion beam crossover position, similar to the first example. It can be placed in @C.

(Effect of the invention) As explained above, in the inventions of claims 1 to 3,
Since the surface substantially facing the optical axis of the magnetic field generating pole piece constituting the filter is used as the blanking electrode, both the ExB filter and the blanking electrode can be placed at the ion beam crossover position. I can do it,
It is possible to reduce the aberration of the ExB filter and to perform blanking of the ion beam without causing the Erling phenomenon.

−11=

[Brief explanation of the drawing]

1 and 2 are views showing one embodiment of the present invention, FIG. 3 is a view showing another embodiment of the present invention, and FIG. 4 is a conventional ion beam device using an ExB filter. FIG. 1...Ion source 2...Converging lens 3...
・Objective lens 4...Target 5...Ex
B filter 6... Objective lens 6.7... Blanking electrode 8... Aperture plate 11.12... Pole piece 13.14... Electrode 15.16... Insulator 17.18... ...Blanking electrode 19...Aperture plate 20...Target 21
．． 22...Pole piece 23,. 24...Base 25.26...Insulator 2
7.28...Coil 29...Blanking voltage source 30.31...Amplifier B

Claims (3)

[Claims] (1) An ion source and an ExB filter that selects specific ion species from the ion beam generated from the ion source;
means for focusing the ion beam so that the ion beam forms a crossover at the center of the E×B filter;
In an ion beam device having a focusing lens that focuses ions selected by an ×B filter,
A focused ion device characterized in that the surface of the magnetic field generating pole piece constituting the filter that substantially faces the optical axis is a blanking electrode surface, and a blanking voltage is applied to the blanking electrode surface. Beam device. (2) an ion source and an ExB filter that selects specific ion species from the ion beam generated from the ion source;
means for focusing the ion beam so that the ion beam forms a crossover at the center of the E×B filter;
In an ion beam device having a focusing lens that focuses ions selected by an ×B filter,
A focusing device characterized in that a blanking electrode is arranged on the surface facing the optical axis of a magnetic field generating pole piece constituting the filter with an insulator interposed therebetween, and a blanking voltage is applied to the blanking electrode. Ion beam device. (3) an ion source and an ExB filter that selects specific ion species from the ion beam generated from the ion source;
means for focusing the ion beam so that the ion beam forms a crossover at the center of the E×B filter;
In an ion beam device having a focusing lens that focuses ions selected by an ×B filter,
A focused ion beam device characterized in that it is configured to apply a blanking voltage to a magnetic field generating pole piece that constitutes a filter.