JPS62229645A - Focusing ion beam device - Google Patents

Abstract

PURPOSE:To realize a highly accurate blanking even in a system not making cross over, by furnishing two phases of blanking plates with the same gain, and a blanking aperature applied with the voltages of the same value and the inverse polarities between the two lens systems. CONSTITUTION:When voltages of the same value and the inverse polarities are applied to blanking plates 21 and 22, the beams are deflected. When the blanking plates 21 and 22 have the same deflecting gain, the deflected beams B' i are parallel to the optical axis Z and become parallel-shifted beams from the initial beams Bi. Therefore, even though the beams are deflected, the latter lens 7 can focus the beams constantly at a point on a target 4. Consequently, by furnishing a blanking aperture 23 between the blanking plates 21 and 22, and the latter phase lens 7, all the beams can be blanked.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a focused ion beam device.

(Prior art) A focused ion beam device ionizes metal atoms, accelerates and focuses the generated ions to form an ion beam, and irradiates this ion beam onto a substrate such as Si to perform maskless ion implantation, etc. It is a device that performs An electromagnetic lens is used as the lens system of this type of device, and there are several focusing lens systems such as a one-stage lens system and a two-stage lens system. FIG. 4(A) shows an example of the configuration of a one-stage lens system, and FIG. 4(B) shows an example of the configuration of a two-stage lens system.

(a) In the figure, 1 is the ion source, Bi is the ion source 1
2 is a focusing lens, 3 is a deflector that deflects (scans) the ion beam Bi in a predetermined direction, and 4 is a target to which the ion beam St is irradiated. (B) In the figure, 5 is a condenser lens (pre-stage lens), 6 is an EX8 (pronounced E-cross B) mass filter that removes unnecessary ions through the interaction of electric and magnetic fields applied at right angles to each other, and 7 is an objective. lens (second stage lens).

When using a focused ion beam device as a mask revealer or etching device, a Ga (gallium) metal ion source (LMIS) is generally used as the liquid metal ion source.
is used. (Since the 3a metal ion source is a single metal ion source, there is no need to use a mass filter. Therefore,
In a two-stage lens system, there is no need to create a lossover (point a in the figure) between the two lenses as shown in FIG. 4(b). The reason is as follows. That is, since the mass filter is an energy filter, it is necessary to place the mass filter at the crossover a to prevent the beam from becoming blurred due to energy division of the ion beam.

Incidentally, in this type of apparatus, ion beam blanking (cutting off ion beam irradiation onto a target) is performed. When performing high-speed blanking, create a crossover between the two-stage lens systems, place a beam blanker at the crossover position, and align the blanking deflection center with the object point of the subsequent lens. .

By adopting such a layout, it is possible to prevent the beam from being irradiated onto unnecessary portions during the time delay until the beam is completely cut.

Furthermore, the shorter the distance from the lens to the target (sample) surface, the smaller the aberration. Therefore, it is desirable to perform the deflection at the front of the rear lens. Furthermore, in order to obtain a large amount of current, it is better to shorten the distance between the ion source and the front lens. Therefore, a focused ion beam device that does not create a lossover as shown in FIG. 5 has been considered.

In FIG. 5, 11 is a first deflector placed after the condenser lens 5, and 12 is a second deflector placed before the objective lens 7. In this way, the two lenses 5 If two deflectors are placed between the two deflectors 11 and 12, and the lenses 5 and 7 are adjusted so as to create a parallel beam BHr between these deflectors 11 and 12, the length of this intermediate portion will be determined by the aberration of the lens system. Therefore, in order to perform high-speed deflection, this portion can be lengthened and a deflector of arbitrary length can be inserted without increasing lens aberration.

(Problems to be Solved by the Invention) In the case of the embodiment shown in FIG. 5, high-speed deflection operation can be performed, but since it is a method that does not create a crossover,
The deflection center of blanking cannot be made to coincide with the object point of the subsequent lens. Therefore, an inconvenience arises in that the beam is irradiated onto an unnecessary portion during the time delay from the start of blanking until the beam is completely cut off.

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 blanking with high accuracy even in a system that does not create a crossover.

(Means for Solving the Problems) The present invention, which solves the above-mentioned problems, provides a focused ion beam device comprising a two-stage lens system. A blanking plate and a blanking aperture are provided, and the voltages applied to the blanking plate are of the same magnitude and opposite in polarity.

(Function) The present invention provides two-stage blanking plates having the same shape and the same gain and a blanking aperture between the two-stage lens system.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing the basic structure of an embodiment of the present invention. Components that are the same as those in FIG. 5 are designated with the same numbers. In the figure, 21.22 is the front lens (condenser lens) 5
A blanking plate 23 having the same shape and the same gain is arranged between the blanking plate 22 and the rear lens (objective lens) 7, and 23 is a blanking aperture arranged between the blanking plate 22 and the rear lens 7. A parallel beam as shown in the figure is created between the lenses 5 and 7, and the rear lens 7 is assumed to maintain the intensity so as to focus this parallel beam on the target 4. . 2 is an optical axis. The operation of the device configured as described above will be explained as follows.

A parallel beam as shown in the figure is created between two lenses 5 and 7, and the intensity is maintained so that the latter lens 7 focuses the beam on one point on the target 4. shall be. In such a state, if the beam incident on the rear lens 7 is parallel to the optical axis 2, all the passing beams will be focused on one point on the target 4. Here, when voltages of the same magnitude and opposite polarity are applied to the blanking plates 2M and 22 from an amplifier (not shown),
The beam is deflected as shown in FIG.

Here, B; is the conventional parallel beam, and B i / is the beam when the blanking plates 21, 22 are activated. Assuming that the blanking plates 21 and 22 have the same deflection gain, the deflected beam B Ht is parallel to the optical axis 2, and is a parallel-shifted version of the conventional beam 3i. Therefore, even if such a deflection is applied, the rear lens 7 always focuses the beam on one point on the target 4.

Therefore, if a blanking aperture 23 as shown in FIG. 1 is arranged between the blanking plate 21, 22 and the rear lens 7, all the beams can be cut (blanked). At this time, the focal position of the leaked beam on the target 4 remains unchanged even during the time delay until blanking is completely completed. Therefore, even with a focused ion beam device that does not create a crossover, highly accurate ion beam writing is possible.

FIG. 3 is a diagram showing a specific configuration example of the present invention.

Components that are the same as those in FIG. 1 are designated by the same numbers.

In the actual device, the beam is transmitted between the blanking aperture 23 and the rear lens 7 on the target 4 in two directions in the XY direction.
Deflectors 31 and 32 for dimensional scanning are arranged.

(Effects of the Invention) As described in detail above, according to the present invention, two blanking plates for blanking having the same shape and the same gain are provided between the front and rear two-stage lens systems, and By providing a blanking aperture between these blanking plates and the subsequent lens, and applying voltages of the same size but different polarities to the blanking plates, if the beam between the two lenses is a parallel beam, the blanking aperture is During the delay W# between the start and complete completion of ranking, the focal position of the leakage beam on the target does not move. Therefore, even with a focused ion beam device that does not create a crossover, accurate ion beam drawing can be performed without irradiating the beam to unnecessary positions during blanking.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the principle of construction of an embodiment of the present invention, Fig. 2 is a diagram showing the trajectory of an ion beam, Fig. 3 is a diagram showing a specific example of the arrangement of the invention, Figs. 4 and 5. 1 is a diagram showing an example of the configuration of a conventional focusing lens system. 1... Ion source 2... Focusing lens 3.11
．． 12.31.32... Deflector 4... Target
5... Front stage lens 6... Mass filter 7.
... Rear lens 21.22...Blanking plate 23...Blanking aperture Fig. 4 (A) (O) Negative etc. 5 Fig. 1; Ion source 4i target 51 Front kill lens 7; Rear lens 11. 12; Kumukiki

Claims (1)

[Claims] In a focused ion beam device consisting of a two-stage lens system,
Two-stage blanking plates having the same shape and the same gain and a blanking aperture are provided between the two lens systems, and the voltages applied to the blanking plates have the same magnitude and opposite polarity. A focused ion beam device characterized in that it is configured to have a voltage of .