JPH0640477B2 - Focused ion beam device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is used in the fields of semiconductor technology, medical care, biotechnology, etc., for physical properties of minute regions, composition analysis, microfabrication, using high-energy charged beams. The present invention relates to an improved technique for improving the function and structure of a device for surface modification and the like.

(Prior Art) In the field of semiconductor technology, since a huge amount of information is processed by a computer, it is required to increase a storage capacity and an information processing speed. Therefore, the high integration of ICs is being developed from LSIs to VLSIs and to three-dimensional ICs. Along with this, individual elements, wirings thereof, and the like are becoming extremely small, multi-layered, and extremely shallow regions from the surface are being used. In such IC and process research, a micro-sized focused ion beam is an extremely effective means. For example, in manufacturing, a focused ion beam accelerated to several hundred to several MeV is used,
Maskless ion implantation is possible and the manufacturing process can be greatly simplified. On the other hand, in the analysis, it is extremely important to analyze the atomic distribution in the microscopic region. For that purpose, a high-energy (MeV) focused ion beam was used.
Raza-Forward Backscattering (RBS) with sub-μm resolution
The effectiveness of analytical methods such as particle excitation X-ray method (PIXE) has been recognized, and the function of the apparatus is being improved.

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

In this example, the accelerator tube generated by the ion source (b) of the accelerator (a)
The high-energy ion beam (d ') accelerated by (c) is normally 15 while it first passes through the deflection analysis electromagnet (e).
It is swung by an angle of more than ° and the ion species and energy are selected during this period, then it is narrowed down to several tens of μm by the objective collimator (f), and then it passes through a drift space of 2 to 5 m, and then double or triple quadrupoles. A beam spot is formed on the target (i), that is, the measurement sample, which is focused by entering the electromagnet lens (g) and is accommodated in the sample chamber (h). (j) is chamber (h)
(K) indicates the coil of the deflection analysis electromagnet (e).

The distance in the drift space from the objective collimator (f) to the quadrupole magnet lens (g) is called the object plane distance, and the distance from the lens (g) to the target (i) is called the image plane distance. It has a function of focusing the diameter of the objective collimator (f) and projecting it onto the target (i) at a reduction ratio approximately equal to the distance ratio. By the way, the image plane distance is about 100 to 200 mm because a storage space such as the detector (j) is required.Therefore, in order to make the beam spot smaller and the current density higher, the object plane distance should be smaller. The size is increased to improve the system performance.

(Problems to be Solved by the Invention) In the configuration arrangement of the conventional high-energy ion beam focusing device, the distance from the accelerator (a) to the deflection analysis electromagnet (e) and the electromagnet to the sample chamber (h) The beam path combined with the distance is required to be at least 7 m or more. Moreover, in order to select the ion species with the deflection analysis electromagnet (e), the deflection angle of the ion beam is set to 15 ° or more, so the ion beam also spreads laterally,
An actual device requires a space of about 7 m x 3 m or more, and it becomes a facility that occupies one room with a planar spread rather than a device.

On the other hand, the size of the device becomes large, but on the other hand, there is a disadvantage. In order to focus the ion beam to a spot size of about 1 μm, the initial adjustment is strictly performed, and the center and axis of each component are aligned even for maintenance work. Precise alignment is required. At this time, 15
Alignment work between components arranged along a beamline that is deflected by more than 0 ° is more difficult. Furthermore, since the device is large, it is almost impossible to integrate a stand for vibration isolation.

(Means for Solving Problems) The present invention has been made to solve the above problems of the prior art, in which the path of a high energy ion beam is shortened to perform ion species selection in the meantime. In addition, in order to enable focused spot focusing of the beam, an objective collimator is installed just downstream of the accelerator, and ion species and beam energy are added to the drift space (object plane distance) between the objective collimator and the quadrupole magnet lens. The configuration arrangement is to insert the analysis component of. Especially when a Wien (E × B) type mass analyzer is used as the analysis component, the beam line can be shortened to be linear.

That is, the focused ion beam apparatus of the present invention uses, as a basic configuration, a high energy ion beam in which a high energy ion beam from an accelerator is spot-incident on a sample through an ion species selector, an objective collimator, and a beam concentrator. In an apparatus such as surface modification of the reduced area, or physical properties and composition analysis, an objective collimator is placed immediately downstream of the accelerator, and ion species are present in the drift space in the physical distance between the objective collimator and the quadrupole electromagnet lens. -Characterized by insertion of beam energy analysis component.

(Operation) According to the present invention, the following various operations are exhibited.

(I) The beam path of the system from the accelerator (a) of the prior art device of FIG. 4 to the objective collimator (f) via the deflection analysis electromagnet (e) is omitted. In the present invention, since the ion species / beam energy analysis component is installed by using the drift space between the objective collimator and the quadrupole electromagnet lens, the size of the entire device is reduced by 40% or more, and the compact device is provided. Is obtained.

(II) Since the gantry can be integrated by miniaturizing the device, precise alignment between the components is facilitated and vibration isolation performance is improved. These are directly linked to the fact that the minimum beam spot diameter reaching the target can be made smaller.

(III) In particular, when a Wien (E × B) mass analyzer is used as an ion species / beam energy analysis component, the beam line becomes linear, and the alignment work becomes easy. The deflection electrode of the Wien mass spectrometer can act as a kind of Steerer, which can be used for fine adjustment of the beam alignment in the quadrupole magnet lens, and scanning of the beam spot on the measurement sample. It can also be used for.

(Example) Hereinafter, an example in which the focused ion beam device of the present invention is used as an analyzer will be described in detail with reference to FIGS. FIG. 1 shows an embodiment in which a Wien (E × B) type mass spectrometer is used.

In FIG. 1, in the electrostatic accelerator (1), for example, when helium gas is used as the ion source (2), ions containing He ⁺ and He ²⁺ are produced, and the acceleration tube (3) has an accelerating voltage of 1 MV, for example. When applied, the ^ions are accelerated and He ⁺ becomes a high energy ion beam (4) with an energy of 1 MeV and He 2 ⁺ of 2 MeV, and emerges at high speed and high energy. They are direct, objective collimator (5)
Is supplied to and is narrowed down to ten and several μm. After that, ion species
A Wien (E × B) type mass analyzer (6) is used as a beam energy analysis component. In the Wien mass spectrometer (6), the electromagnet coil (7), the window electromagnet yoke
A constant condition of the electric field E created under the electrode distance d by applying the voltage + V / 2, -V / 2 to the magnetic field B created in (8) and the side wall analysis electrodes (9) and (9), respectively. He ⁺ ions go straight, and other ions are deflected and collide with the analysis electrode (9) or the ion selection slit (10) on the outlet side, the charge is neutralized, and it is discharged as exhaust gas. It (11) is a deflection electrode for the He ⁺ beam. Only the straight He ⁺ ions enter the quadrupole electromagnet lens (12), are focused, and enter the target (measurement sample) (14) in the sample chamber (13) as a beam spot. The ions scattered by the interaction of He ⁺ ions with the measurement sample (14) or the excited X-ray fluorescence are energy-analyzed by the detector (15) in the chamber (13) to obtain the physical property data of the sample. it can. Further, by applying a voltage to the deflection electrode (11), the spot position can be scanned and two-dimensional analysis can be performed.

The configuration of the apparatus of this embodiment has been described above along with the action and the example of the ion species.
As an ion species / beam energy analyzer installed between the (5) and the quadrupole magnet lens (12), the Vienna (EX
The fact that the B) type mass spectrometer can be adopted and is suitable by analysis and exemplification is as follows.

The Wien (E × B) mass spectrometer (6) is an electromagnet so that the deflection action of the magnetic field B (proportional to the momentum of ions) and the deflection action of the electric field E (proportional to the ion energy) work in opposite directions. And the parallel electrodes are arranged, and the equation of motion of the ion beam on this E × B plate acts as a filter that allows only the ion species that cancel each other to go straight. Z is the direction in which Where m: ion mass (for He, m He = 4 x 1.67 x 10 ^-27 kg) e: ion charge (for He ⁺ , e He ⁺ = 1.6 x 10 ^-19 C coulomb) v: ion velocity = (2eVo / m) ^1/2 Vo: Accelerating voltage Now, letting the total length of the analyzer (6) be L, the deflection amount Δx when the ions leave the analyzer is obtained by solving the above equation, and the following equation is obtained. This is approximated as Δx << L.

For example, the condition for Δx = 0 that He ⁺ ions go straight ahead is (Unit of magnetic flux density of magnetic field B: Tesla, 1 Tesla = 10 ⁴ Gauss) Strength unit of electric field E: V / m, 1 V / m = 10 ^-2 V / cm) Figure 2 shows Gauss and V / cm as units. Instead, this relationship is illustrated.

Next, assuming L = 2m, He ⁺ , He ^{2+ under} this condition
The deflection amount Δx (unit: m) of is calculated as the relationship with the magnetic field B (unit: tesla) as follows.

The width of Derutaekkusu2.8 B Well ion selection slit per Δx6.9 B He ²⁺ per the He ^+, the Bohr diameter of such quadrupole electromagnet lens is about 5 mm, as the He ²⁺ leaves its 10 times When the requirement to deflect the light is applied, a magnetic field B of 180 Gauss and an electric field E of about 1230 V / cm are required from FIG. Since these values can be easily obtained by usual electromagnetic and electric field arrangements, the Vienna (E
A × B) type mass spectrometer is applicable and suitable for this purpose.

FIG. 3 shows another embodiment of the focused ion beam apparatus of the present invention. The same parts as those in the embodiment of FIG. 1 are designated by the same reference numerals in FIG.

In this embodiment, a 90 ° deflection electromagnet (16) is installed as an ion species / beam energy analysis component inserted between the objective collimator (5) and the quadrupole electromagnet lens (12). The deflection angle of the deflection electromagnet (16) can be selected in the range of 45 ° to 180 °. A deflection electrode may be used instead of the deflection electromagnet.

The embodiment in which the focused ion beam device of the present invention is used as an analyzer has been described above, but the hardware configuration of this embodiment can be used as it is as an ion implanter. However, in such a case, the detector (15) may be omitted.

(Effects of the Invention) As described above, according to the present invention, the configuration of the focused ion beam device can be made centralized, the precise alignment of each component is facilitated, and the vibration isolation performance is also improved. The beam spot diameter can be reduced to improve the analysis function.

[Brief description of drawings]

FIG. 1 is a structural layout view of a focused ion beam analyzer according to a first embodiment of the present invention, and FIG. 2 shows various ion beam straight-ahead conditions of the Wien type mass analyzer in which magnetic flux density (Gauss) on the horizontal axis and vertical axis on the vertical axis. Is a diagram showing the relationship of the electric field strength (V / cm) in FIG. 3, FIG. 3 is a structural layout of a second embodiment of the device of the present invention, and FIG. 4 is a structural layout of a conventional device. (1) …… electrostatic accelerator, (2) …… ion source, (3) …… accelerating tube, (4) …… ion beam, (5) …… objective collimator,
(6) …… Wien (E × B) type mass spectrometer, (7) …… electromagnetic coil, (8) …… window electromagnet yoke, (9) …… analyzing electrode, (10) …… ion selection slit , (11) …… Deflecting electrodes,
(12) …… Quadrupole electromagnet lens, (13) …… Sample chamber, (14) …… Target (measurement sample), (15) …… Detector, (16) …… 90 ° deflection 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) …… accelerating tube, (d ′) …… ion beam, (e) …… deflecting analysis electromagnet, (f) …… objective collimator, (g) …… quadrupole electromagnet lens, (h) …… Sample chamber, (i) …… Target, (j) …… Detector, (k) …… Coil.

Front Page Continuation (72) Inventor Koji Inoue 2-3-1, Noboru Shinohara, Nada-ku, Kobe-shi, Hyogo (56) References JP-A-62-82634 (JP, A) JP-A-47-31686 (JP) , A)

Claims (6)

[Claims] 1. Surface modification of a minute region using a high-energy charged beam in which a high-energy ion beam from an accelerator is spot-incident on a sample through an ion species selector, objective collimator, and beam concentrator, or physical properties / composition. In an instrument such as an analyzer, an objective collimator is placed just downstream of the accelerator, and the ion species / beam energy analysis component is inserted in the drift space in the object plane distance between the objective collimator and the quadrupole electromagnet lens. A focused ion beam device characterized in that a magnetic field type mass spectrometer is used as the analysis component. 2. The analysis component comprises 45 ° to 180 °
The focused ion beam device according to claim 1, wherein a deflection electromagnet is used. 3. Surface modification of a minute area using a high-energy charged beam in which a high-energy ion beam from an accelerator is incident on a sample through an ion species selector, an objective collimator, and a beam concentrator, or physical properties and composition. In an instrument such as an analyzer, an objective collimator is placed just downstream of the accelerator, and the ion species / beam energy analysis component is inserted in the drift space in the object plane distance between the objective collimator and the quadrupole electromagnet lens. In addition, the focused ion beam device is characterized in that a Wien (E × B) type mass analyzer is used as the analysis component. 4. An apparatus for analyzing physical properties / composition of a minute region using a high-energy charged beam in which a high-energy ion beam from an accelerator is spot-incident on a measurement sample through an ion species selector, an objective collimator, and a beam concentrator. In the above, the objective collimator is arranged immediately downstream of the accelerator, and the ion species / beam energy analysis component is inserted into the drift space in the object plane distance between the objective collimator and the quadrupole electromagnet lens. A focused ion beam analyzer characterized by using a magnetic field type mass spectrometer as an analysis component. 5. The analysis component comprises 45 ° to 180 °
The focused ion beam analyzer according to claim 4, wherein a deflection electromagnet is used. 6. An apparatus for analyzing physical properties and composition in a minute region using a high energy charged beam in which a high energy ion beam from an accelerator is spot-incident on a measurement sample through an ion species selector, an objective collimator and a beam concentrator. In the above, the objective collimator is arranged immediately downstream of the accelerator, and the ion species / beam energy analysis component is inserted into the drift space in the object plane distance between the objective collimator and the quadrupole electromagnet lens. A focused ion beam analyzer characterized by using a Wien (ExB) type mass analyzer as an analysis component.