JPH0374037A - Focused ion beam device - Google Patents

Abstract

PURPOSE:To improve functions and structure by inserting an ion species and beam energy analysis component in a drift space in an interval between the surfaces of an objective collimator disposed right on the downstream of an accelerator and a quadruple electromagnetic lens. CONSTITUTION:An objective collimator 5 is disposed right on the downstream of an accelerator 3, and an ion species and beam energy analysis component is inserted in a drift space in an interval between the surfaces of the objective collimator 5 and a quadrupole electromagnetic lens 12. Beam passages in a line from the accelerator 3 through a polarization analysis electromagnet to the objective collimator 5 are eliminated by this, the size of a whole device is contracted by more than 40% to be compact, and because the device is miniaturized, frames can be integrated. The constitution of the focused ion beam device can be integral, and a precise alignment of the components is facilitated to improve the vibration-proof performance, and the beam spot diameter is reduced to improve the analysis function.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is applicable to the fields of semiconductor technology, medical care, biotechnology, etc., using a high-energy charged beam to analyze the physical properties, composition analysis, microfabrication, etc. of minute regions. This article relates to improved technology for improving the functionality and structure of equipment that performs surface modification, etc.

(Prior Art) In the field of semiconductor technology, computers process vast amounts of information, so there is a demand for increased storage capacity and faster information processing speed.

Therefore, the development of highly integrated ICs is progressing from LSI to VLSI and also to three-dimensional ICs. Along with this, individual elements, their wiring, etc. are becoming extremely miniaturized, multilayered, and extremely shallow regions from the surface are being used. In such IC and process research, an ion beam focused to a ξ-crore size becomes an extremely effective means.

For example, in manufacturing, maskless ion implantation can be performed using a focused ion beam accelerated to several hundred to several MeV, which can greatly simplify the manufacturing process. On the other hand, in analysis, it is extremely important to analyze the atomic distribution in the microscopic region, and for this purpose, high energy (MeV)
The Rutherford backscattering method (RBS), which uses a focused ion beam with a resolution of less than 1 μm, and the particle-excited X-ray method (
The effectiveness of analysis methods such as PIXI has been recognized, and efforts are being made to improve the functionality of such devices.

FIG. 4 shows a typical example of the configuration of a conventional high-energy focused ion beam device used as an analysis device.

In this example, a high-energy ion beam (do) generated in the ion source (b) of the accelerator (a) and accelerated in the accelerator tube (C) first passes through the deflection analysis electromagnet (e). The ions are swung at an angle of 15 degrees or more, during which the ion species and energy are selected, and then narrowed down to several tens of μm by an objective collimator (0), and then passed through a 2-5 m drift space to be separated into two or three quadruple stacks. A target (
i) i.e. aligning the beam spot on the measurement sample, 0)
is the detector in the chamber (b), and (2) shows the coil of the deflection analysis electromagnet (e).

The distance in the drift space from the objective collimator (f) to the quadruple electromagnetic lens (2) is called the object surface distance, and the distance from the lens (8) to the target lens (i) is called the image surface distance. It has the function of focusing the aperture of the objective collimator (f) with a reduction ratio approximately equal to the ratio of the two distances and projecting it onto the target (i).
), etc., which requires storage space of about 100 to 200 meters, so in order to make the beam spot smaller and the current density higher, the object surface distance should be made larger to improve the performance of the system. We are trying to

(Problems to be Solved by the Invention) In the configuration of the conventional high-energy ion beam focusing device described above, the distance from the accelerator (0 to the deflection analysis electromagnet (ei) and the distance from the electromagnet to the sample chamber (b) The beam path including the distance must be at least 7 m.

Moreover, in order to select ion species using the deflection analysis electromagnet (e), the deflection angle of the ion beam must be 15 degrees or more, so it spreads laterally, and in an actual device, it requires a space of about 7 m x 3 m or more, so it is more than a device. 1 with in-plane expansion
The facility will occupy two rooms.

Moreover, increasing the size of the device has the disadvantage of focusing the ion beam to a spot size of approximately 1 μm. It is necessary to maintain precise alignment. At this time, 1
It is even more difficult to adjust the alignment between components placed along a beamline that is deflected by 5@ or more. Furthermore, since the device is large, it is almost impossible to integrate a stand for vibration isolation.

(Means for Solving the Problems) The present invention has been made to solve the above-mentioned problems of the prior art. In addition, in order to enable reduced spot focusing of the beam, an objective collimator is installed immediately downstream of the accelerator, and the ion species and beam energy are distributed in the drift space (object surface distance) between the objective collimator and the quadruple electromagnetic lens. A configuration arrangement that inserts the analysis component of In particular, when a Wien (E×B) type mass spectrometer is used as an analysis component, the beam line can be made linear and shortened.

That is, the basic configuration of the focused ion beam device of the present invention is to use a high-energy ion beam in which a high-energy ion beam from an accelerator passes through an ion species selector, an objective collimator, and a beam focuser and is incident on a sample as a spot. In equipment for surface modification of reduced areas, physical properties, composition analysis, etc., an objective collimator is placed immediately downstream of the accelerator, and ion species are collected in the drift space within the object surface distance between the objective collimator and the quadruple electromagnetic lens.・It is characterized by a configuration in which a beam energy analysis component is inserted.

(effect) According to the present invention, the following effects are achieved.

(1) The beam path of the system from the accelerator (a) to the objective collimator (f) via the deflection analysis electromagnet (e) in the conventional device shown in Fig. 4 is omitted. Since the analysis components are installed using the drift space between the objective collimator and the quadruple electromagnetic lens, the overall size of the device is reduced by more than 40%, resulting in a compact device.

(n) Since the device can be miniaturized and the frame can be integrated, precise alignment between components is facilitated, and vibration isolation performance is improved.

These factors are directly linked to the ability to reduce the minimum beam spot diameter that reaches the target.

(III) In particular, when a Wien (E×B) type mass spectrometer is employed as a component for analyzing ion species and beam energy, the beam line becomes straight and alignment work becomes easy.

In addition, the deflection electrode of the Wien mass spectrometer can act as a type of steerer, so it can be used to finely adjust the beam alignment within the quadrupole electromagnetic lens, and also to adjust the beam spot on the measurement sample. It can also be used for scanning.

(Example) Hereinafter, examples will be described in detail regarding the case where the focused ion beam device of the present invention is used as an analysis device with reference to FIGS. 1 to 3. FIG. 1 shows an example in which a Vienna (E×B) type mass spectrometer is used.

In Fig. 1, the electrostatic accelerator (1) has an ion source (
For example, when helium gas is used in 2), ions containing He"He"+ are created, and when an acceleration voltage of, for example, IMV is applied to the acceleration tube (3), they are accelerated and He" becomes I MeV.
, He"+ comes out as a high-energy ion beam (4) with an energy of 2 MeV at high speed and high energy. They are directly supplied to an objective collimator (5) and focused to a diameter of more than ten μm. Also, Vienna (E×
In the B) type mass spectrometer (6), the Wien type mass spectrometer (6) has an electromagnetic coil (7), a window wall electromagnetic yoke (
8) and the magnetic field B created by the analysis electrode (9) on the side wall (
9), under certain conditions of an electric field E created at an electrode distance d by applying voltages +V/2 and -V/2, respectively, only He'' ions travel straight, while other ions are deflected. analysis electrode (9) or exit side ion selection slit) (I
It collides with I, neutralizes its charge, and is emitted as exhaust gas. 00 is the deflection electrode of the He+ beam. Only the He'' ions that have traveled straight enter the quadrupole electromagnetic lens 02) and are focused, and are incident on the target (measurement sample'>04) in the sample chamber 0m as a beam spot.

He" ions interact with the measurement sample 04) and the scattered ions or excited fluorescent X-rays are transferred to the chamber 03.
Energy analysis is performed by the detector 05) in the sample, and data on the physical properties of the sample can be obtained. Also, deflection electrode 01)
By applying a voltage to the spot position, the spot position can be scanned, making two-dimensional analysis possible.

The configuration of this embodiment device has been explained above along with the function and examples of ion species, but in the present invention, the objective collimator (
5) and the quadrupole electromagnetic lens 021 as an analyzer for ion species and beam energy.
The following analysis and examples prove that the ×B) type mass spectrometer is applicable and appropriate.

The Wien (E x B) type mass spectrometer (6) uses the deflection effect of the magnetic field B (proportional to the momentum of the ions) and the deflection effect of the electric field E (
It has a structure in which an electromagnet and parallel electrodes are arranged so that the ions (proportional to ion energy) act in opposite directions.
Ion beads in this EXB field act as a filter that allows only ion species that cancel each other out to proceed straight.
x z t where m: ion mass (for He, y* He -4X1.67X10-" kg) e: ion charge (for He", e He" ml, 6X10-19C coulombs) V: ion velocity - (2eVo /s) ""vo; Accelerating voltage Now, assuming that the total length of the analyzer (6) is L, the amount of deflection ΔX when the ions exit the analyzer is determined by solving the above equation, and the following equation is obtained. Approximate as Δx<<L.

For example, the condition of ΔX=O for He+ ions to travel straight is (magnetic flux density unit of magnetic field B: Teala, l Tesla
gIO'Gauss) Electric field E17) Intensity unit: V/m, IV/se-10
-"V/cm) In Figure 2, the units are Gauss and V/ell.
This relationship is illustrated instead of .

Next, assuming L-2m, He'' under this condition,
The amount of deflection ΔX (unit: knee) of “He” is expressed by the magnetic field B (unit: t
The relationship with es la) is determined as follows.

For He+ Δx ~ 6.9 B For Heh Δx ~ 2.8 B Now, let us assume that the width of the ion selection slit is about 5 - the Bohr diameter of this type of quadruple electromagnetic lens, and He! + is part 1
If we impose the requirement that the beams be deflected so as to be separated by a factor of 0, a magnetic field B of 180 Gauss and, as shown in FIG. 2, an electric field E of approximately 1230 V/ell will be required. Since these values are easily obtained with conventional electromagnetic and electric field configurations, a Wien (ExB) type mass spectrometer can be employed and is suitable for this purpose.

FIG. 3 shows another embodiment of the focused ion beam apparatus of the present invention. Each part equivalent to the embodiment of FIG.

In this example, a deflecting electromagnet 901 is inserted between the objective collimator (5) and the quadruple electromagnetic lens 02) as an analysis component for ion species and beam energy.
Set θ. The deflection angle of the deflection electromagnet 0ω is 45” to 1
You can choose from a range of 80@. Deflection electrodes may be used instead of deflection electromagnets.

An embodiment in which the focused ion beam device of the present invention is used as an analysis device has been described above, but the hard tank bottom of this embodiment can also be used as an ion implantation device as it is. However, when used in this way, the detector Oo may not be provided.

(Effects of the Invention) As described above, according to the present invention, the configuration of the focused ion beam device can be made centralized, precision alignment of each component is facilitated, and vibration isolation performance is improved. Analysis functionality can be improved by reducing the beam spot diameter.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of the first embodiment of the focused ion beam analyzer of the present invention, and FIG.
s) and the electric field strength (V/c1) on the vertical axis; FIG. 3 is a configuration diagram of the second embodiment of the device of the present invention;
FIG. 4 is a structural layout diagram of a conventional device. (1)... Electrostatic accelerator, (2)... Ion source, (
3) Accelerator tube, (4) Ion beam, (5)
...Objective collimator, (6)...Vienna (ExB
) type mass spectrometer, (7)...electromagnetic coil, (8)...
・・Window type electromagnet yoke, (9) ・・Analysis electrode, 0 (D
...Ion selection slit, (10... Deflection electrode, 0
2)...Quadruple contact electromagnetic lens, 0■...Sample chamber 04...Target (measurement sample), 051...
Detector, Q6)...9V bending electromagnet, (B)...Magnetic field, magnetic flux density, (E)...Electric field, electric field strength, (V)
... Applied voltage, (d) ... Distance between poles, (L) ... Total length of analyzer, (a) ... Accelerator, (b) ... Ion source, (C) ... Accelerator tube , (d゛〉...Ion beam,
(e)... Deflection analysis electromagnet, (f)... Objective collimator, (O... Quadruple electromagnetic lens, (b)... Sample chamber (i)... Target, (j)... ...detector, (b)...coil.

Claims (6)

[Claims] (1) A high-energy ion beam from an accelerator passes through an ion species selector, an objective collimator, and a beam focuser and is incident on the sample as a spot. Surface modification of a micro area or physical property/composition analysis using a high-energy charged beam, etc. In this system, an objective collimator is placed immediately downstream of the accelerator, and an analysis component for ion species and beam energy is inserted into the drift space in the object distance between the objective collimator and the quadrupole electromagnetic lens. A focused ion beam device featuring: (2) Vienna (Ex
The focused ion beam device according to claim 1, which uses a type B) mass spectrometer. (3) The focused ion beam device according to claim 1, wherein either a 45° to 180° deflection electromagnet or a deflection electrode is used as the analysis component. (4) A high-energy ion beam from an accelerator passes through an ion species selector, an objective collimator, and a beam focuser and is spot-injected onto a measurement sample. It is characterized by a configuration in which an objective collimator is placed immediately downstream of the accelerator, and an ion species/beam energy analysis component is inserted into the drift space in the object surface distance between the objective collimator and the quadrupole electromagnetic lens. Focused ion beam analyzer. (5) Vienna (Ex
A focused ion beam analysis device according to claim 4, which uses a type B) mass spectrometer. (6) The focused ion beam analyzer according to claim 4, wherein either a 45° to 180° deflection electromagnet or a deflection electrode is used as the analysis component.