JPS58102454A - Ion analyzer - Google Patents

Abstract

PURPOSE:To enable a sample to be locally analyzed as well by synchronously operating the scanning system of incident ions and the anti-scanning system of scattered ions, and introducing only specified scattered ions obtained into an energy analyzer. CONSTITUTION:A primary ion beam discharged from an ion source 1, after being restricted by an ion lens 3, becomes incident upon scanners 4 and 4'. The primary ion beam receives a deflection for scanning a sample 5, and becomes incident upon parts X1 and X2 of the sample 5 which have different component elements at the same angle (phi). The scanners 4 and 4' and anti-scanners 6 and 6' are operated synchronously by means of scan control units 13 and 14. Then, only secondary ions which become incident upon the sample 5 at the same incidence angle (phi) and are scattered from the sample 5 at the same scattering angle (theta), are introduced into an energy analyzer through a slit 7. Secondary ions, after passing through the analyzer 8, are detected with a detector 10, and treated with a data processing unit 12. By the means mentioned above, local analysis of the sample 5 as well as measurement of the component element of the sample 5 can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ion analyzer that detects forward scattered ions among secondary ions generated when a primary ion beam is incident on a sample to analyze constituent elements of the sample.

The ion analyzer W makes a primary ion beam incident on a sample, detects secondary ions generated when the beam is incident, and measures the distribution of constituent elements of the sample. As the ion species of the primary ion beam, for example, light element ions such as 1(÷, He÷, Ar, etc.) are used. FIG. 1 is a diagram showing the incident and scattering state of the primary ion beam. When an ion of −1 is incident on the sample S at an angle of The target atoms are pushed out of the sample, and the incident ions themselves are also scattered in the direction of an angle θ with respect to the incident line direction n.Here, the energy of the incident ions (primary ions) before collision is expressed as EO% The energy of the incident ion (secondary ion) after colliding with the target atom is E
Then, E is expressed by the following formula.

E=Eo (m, cosθ±(+!122 @
12 sin 2θ)” )2/(ml +12)2
(1) Conventional devices of this type detect and analyze so-called backscattered ions scattered in the direction of incidence.
Scattering 5pectroLletry
) method is used. As a typical example, the scattering angle θ−
Considering the case of π, equation (1) becomes the following equation.

Ee-x = Eo (13-12/l z + Zenz
)2-(141112/(11+12)2)EO...
...(2) From equation (2), when θ = π, that is, in backscattering in which ions are directly scattered in the direction of incidence, the scattered ions have an energy loss ΔE given by the following equation. I can see that you are receiving it.

ΔF=4m 112/ (If +12
) 2-(3) Therefore, if the mass fat 1 and energy E00 of the incident ion are known in advance, the mass -2 of the target atom can be determined by measuring the energy loss ΔF of the scattered ions. That is, it can be used as an ion analyzer.

However, as is clear from equation (1), if 11≧-2, the energy E becomes a complex number, so backscattering cannot occur. For backscattering to occur, III<1I1
Must be 2. That is, the mass 11 of the incident ion is
Quality of target atom ■ Must be smaller than 12. For this reason, when performing ISS using a conventional device of this kind, light element ions such as protons, hydrogen ions, and helium ions are used as ion species.

However, since light element ions are used as the ion species, their energy is low, and the strength and brightness of the ion source is low, making it impossible to narrow down the ion beam. Therefore, it has the disadvantage that local analysis cannot be performed.

Here, consider the case of forward scattering in which the scattered ions are directly scattered in the traveling direction of the incident ions, as shown in FIG. For example, if θ−〇 is used for simplicity, equation (1) becomes the following equation.

E=Eo (m 1cos±Ill 2 )2/ (I
ll l ten @ 2) 2... (4) As shown in equation (4), 2 does not need to be -l in this case, and -1≧l112 may be true. Therefore, since there are no restrictions on the selection of ion species, it is possible to use relatively heavy elements as ion species. Therefore, the strength and brightness of the ion source can be increased, and the ion beam can be narrowed down. Therefore, local analysis is also possible.

The present invention has been made with attention to these points, and it synchronizes the scanning of incident ions and the anti-scanning system of scattered ions, and calculates the angle of incidence of the incident ion with respect to the sample and the scattering of the scattered ions with respect to the angle of incidence. By configuring the angle so that only the scattered ions that remain constant regardless of the sample scanning of the incident ion beam are guided to the energy analyzer, it is possible to measure not only the distribution of constituent elements of the sample but also the local distribution of only a part of the sample. This is the result of realizing an ion analyzer that makes this possible.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 is a configuration diagram showing an embodiment of the present invention. In the figure, 1 is an ion source, 2 is a primary ion beam emitted from the ion source 1, and 3 is an ion lens for converging the ion beam 2. 4.4' is a scanner that two-dimensionally scans the ion beam narrowed by the ion lens 3 on the sample; 5 is the sample over which the primary ion beam is scanned. The sample 5 is made sufficiently thin in the direction of incidence of the ion beam to prevent the incident ions from being scattered multiple times (multiple scattering) by sample atoms within the sample. The thickness of the sample 5 is selected to be, for example, 1000 Å or less. The incident ions collide with target atoms in the sample 5 to cause scattering, and as described above, the sample 5 can be struck at an angle of θ with respect to the incident direction. Of course, there are also ions that collide with other atoms in the sample 5 and undergo multiple scattering with a certain probability, but these are not used in the apparatus of the present invention.

6.6' is an anti-scanner that corrects the trajectory of scattered ions by returning the deviation of the scanners 4 and 4'. The scanner 4.4' and the anti-scanner 6.6' operate synchronously, so that even when the incident ion beam scans over the sample, a bundle of scattered ions with a specific scattering angle θ is incident on the following slit 7. to work. Also, scanner 4.4' and anti-scanner 6.6
' are each a two-stage deflection system and operate synchronously so as to guide only scattered ions that are incident on the sample surface at a constant angle and have a constant scattering angle θ to the slit 7. 8
is an arc 1 energy analyzer, and 9 is a slit on the exit side of scattered ions.

10 is a detector that detects scattered ions that have passed through the energy analyzer 8 and converts them into electrical signals; 11 is an amplifier that amplifies the output of the detector 10; 12 is increase #i device 1
This is a data processing unit that receives the output of sample n5 and obtains a distribution map of the constituent elements of sample n5. The output is recorded on a recorder and displayed as an analog waveform, or converted into digital data and output to a printer or the like. 13 is a scan control unit that controls scanning of the scanner 4.4', 14 is an anti-scanner 6.6
This is a scan control unit that controls the scanning of . Scan signals from these scan control units 13 and 14 are applied to the data processing unit 12.

The operation of the device configured in this way will be described next.

A primary ion beam emitted from an ion source 1 is focused by an ion lens 3 and enters scanners 4 and 4'. The primary ion beam is deflected to scan the sample 5 while passing through the scanner 4.4'. Scanner 4.4'
The primary ion beam that has passed through is incident on the sample 5. FIG. 3 is a diagram showing the scattering process of the sample and ions at this time. In the figure, 5 is the sample described above. Mass 11
The incident ion beams 11 and 12 have portions Xt each having different constituent elements.

x2 at the same angle φ. Here, φ is the angle between the sample surface and the incident direction. The ion beam 11 is
It enters the s part and collides with a target atom of mass m2 at point A, the target atom is pushed out of the sample, and the incident ions are scattered. At this time, attention is paid to ions scattered at an angle θ to the incident direction behind the forward scattered ions.

On the other hand, the other ion beam 12 enters the NX2 section, collides with a target atom having a mass of 13 at point B, and undergoes similar scattering. At this time, we focus on ions that are scattered in the incident direction and at an angle θ.

The scanner 4°4' and the anti-scanner 6.6', which each constitute a two-stage deflection system, make the light incident on the sample at the same angle of incidence φ, as shown in FIG. Scattering angle θ
Only the secondary ions scattered by the energy analyzer 8 are guided to the energy analyzer 8.

As mentioned above, the difference between the two types of scattering is that the mass of the target atom in which the collision occurred is 12. (3) This difference is measured as a difference in energy loss ΔF of scattered ions as shown in equation (3). That is,
According to the present invention, by discriminating the elements constituting the thin film of the sample using the method described above, it is possible to know the distribution of the constituent elements of the sample.

The secondary scattered ions that have passed through the energy analyzer 8 are detected by the detector 1o. The detector 10 detects a specific energy value, e.g. (W
Only scattered ions with energies from O-Δw/2) to (W o +ΔW/2) are detected. This means that
Quality - (10+Δl/2) to (s o A m /
2 > This means detecting the atomic distribution at Ma. The output of the detector 1o obtained in this way is amplified by the subsequent amplifier 11 and enters the data processing unit 12. A scan signal is input to the data processing unit 12 from a scan control unit 13.14. Therefore, sample 5. , a distribution map of the constituent elements of the sample can be obtained in synchronization with the above scanning. Incidentally, the incident angle φ of the ion beam incident on the sample 5 and the scattering angle θ after the incidence can be selected and measured separately.

Regarding scanning, it is also possible to fix the scanning system and configure the sample to be scanned with respect to the incident ion beam by the sample moving mechanism of the sample device under conditions of specific incident angles and scattering angles. be.

As described in detail above, according to the present invention, it is possible to realize an ion analyzer that is capable of not only measuring the distribution of the constituent elements of a sample but also performing local analysis of only a portion of the sample.

[Brief explanation of the drawing]

FIGS. 1 and 3 are diagrams showing the scattering process of a sample and ions, and FIG. 2 is a configuration diagram showing an embodiment of the present invention. 1... Ion source 2... Primary ion beam 3
...Ian lens 4,4'...Scanner 5...
・Sample 6.6'...Anti-scanner 7.9...Slit 8...Energy analyzer 10...Detector 11...Amplifier 12...
Data processing unit 13.14...Scan control unit Patent applicant: JEOL Co., Ltd. Representative: Patent attorney: Fujiji Tsukishima

Claims (1)

[Claims] By synchronizing the scanning of incident ions and the anti-scanning system of scattered ions, only the scattered ions can be detected so that the incident angle of the incident ions with respect to the sample and the scattering angle of the scattered ions with respect to the incident angle are constant regardless of the sample scanning of the incident ion beam. An ion analyzer characterized in that the ion analyzer is configured to guide the energy to an energy analyzer.