JPH08212963A - Energy dispersing x-ray detecting device - Google Patents

Abstract

PURPOSE: To provide an energy dispersing X-ray detecting device which can perform X-ray analysis of high sensitivity without worsening resolution, in a scanning electron microscope of system arranging a sample in an objective lens magnetic field. CONSTITUTION: An EDX detector device, provided with a detector element 12 and a collimator 13 positioned before this detector element, is used to detect an X-ray by arranging at least partly the collimator 13 in a leakage field of a field type objective lens. The collimator 13, in a cylindrical shape formed of non-magnetic material, has an irregular structure in the internal wall. A material of small generating a secondary electron due to electron irradiation, is applied to the internal wall of the collimator, or the collimator itself is made of material small generating an electron.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energy dispersive X-ray analysis apparatus, and more particularly to an apparatus which can be mounted on a high resolution scanning electron microscope equipped with an in-lens type objective lens or a magnetic field leakage type objective lens. Without affecting the resolution
The present invention relates to an energy dispersive X-ray analyzer suitable for detecting X-rays with high sensitivity and performing high-precision X-ray analysis.

[0002]

2. Description of the Related Art In order to perform highly accurate X-ray analysis in an energy dispersive X-ray analyzer (EDX) using an energy dispersive X-ray detector such as a silicon semiconductor detector, the X-ray from a sample must be highly sensitive. In addition to detection, it is necessary to remove scattered electrons (reflected electrons) incidentally generated from the sample by the primary electron beam. The scattered electrons become background noise in the X-ray spectrum and affect the accuracy of quantitative analysis and the like.

As shown in FIG. 3, the conventional EDX detection apparatus includes an E as an X-ray detector together with the X-ray 14 from the sample 7.
In order to remove the scattered electrons that jump into the DX element 12, a ring-shaped permanent magnet 17 is provided at the tip of the EDX element 12 as an electron trap, and the trajectory of the scattered electrons 10 is bent by the magnetic field generated by this magnet. It prevented scattered electrons from entering the EDX element.

[0004]

In order to perform high-resolution observation of a sample, a scanning electron microscope of the type (in-lens type or magnetic field leakage type) in which the sample is placed in the magnetic field of the objective lens is often used. In a scanning electron microscope, the sample is placed in the magnetic field of the objective lens. There is a problem that the magnetic field of the objective lens is disturbed by the magnetic field generated from the above, and high resolution observation cannot be performed.
Therefore, in such a high resolution electron microscope, EDX
Since the detector could not be brought close to the sample, it was not possible to achieve both high-sensitivity X-ray analysis and high-resolution observation.

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to impair the lens performance (resolution) of a scanning electron microscope even when combined with a scanning electron microscope having an in-lens type objective lens or a leakage magnetic field type objective lens. An object of the present invention is to provide an energy dispersive X-ray analyzer capable of performing highly sensitive X-ray analysis without any need.

[0006]

In order to achieve the above object, in the present invention, a cylindrical collimator made of a non-magnetic material such as aluminum that does not affect the magnetic field of the objective lens is attached to the tip of the X-ray detector. Using the EDX detector, place part or all of the collimator in the magnetic field of the objective lens,
The trajectory of the scattered electrons is bent by the magnetic field of the objective lens, and the scattered electrons become X.
Prevented from getting into the line detector.

Further, by providing the concavo-convex structure on the inner wall of the X-ray passage hole of the collimator, even if scattered electrons bent by the magnetic field of the objective lens collide with the inner wall of the X-ray passage hole of the collimator, the collision scattered electrons are generated. The electrons generated in 1 above did not proceed to the X-ray detection section. The concavo-convex structure can be formed, for example, by cutting a screw on the inner surface of the collimator, or may be formed by roughening the surface. A height of 0.1 mm is sufficient.

Further, in order to reduce the electrons generated when the scattered electrons collide with the X-ray passing hole of the collimator,
The inner wall of the X-ray passing hole of the collimator is coated with a material (for example, carbon) that hardly generates electrons, or
The collimator itself is made of a material such as aluminum which does not generate electrons.

Further, in order to prevent scattered electrons from entering the EDX element as much as possible, the entrance of the X-ray of the collimator is made narrower than the exit of the X-ray, that is, the side on which the EDX element is arranged.

With the above-mentioned structure, the trajectory of scattered electrons generated from the sample by the electron beam irradiation is bent by the magnetic field of the objective lens and prevented from entering the EDX detector. Even if the scattered electrons bent by the magnetic field of the objective lens collide with the inner wall of the X-ray passage hole of the collimator, the inner wall of the X-ray passage hole of the collimator is affected by the collision of scattered electrons.
Since it is composed of a material that generates less secondary electrons,
The number of secondary electrons generated from the X-ray passage hole due to the collision of scattered electrons is attenuated each time the collision is repeated. further,
Since the inner wall of the X-ray passage hole of the collimator has a concavo-convex structure, even if scattered electrons that collide with the inner wall of the X-ray passage hole generate secondary electrons, they have a concavo-convex structure of the inner wall of the X-ray passage hole. Do not enter the X-ray detector because it is blocked by.

On the other hand, the X-ray generated from the sample travels straight even if the magnetic field of the objective lens is present, and is detected by the EDX detector. As described above, according to the present invention, even when the sample is attached to the scanning electron microscope in which the sample is placed in the magnetic field of the objective lens, the X-ray analysis is performed with high sensitivity without affecting the resolution of the scanning electron microscope. be able to.

By narrowing the X-ray entrance of the collimator, it becomes possible to make it difficult for scattered electrons to enter. This configuration simply makes the inner diameter of the collimator a narrow tubular shape, while the EDX element can be made large, so X
It also improves the efficiency of line detection. Further, the shape is suitable for disposing the collimator in the leakage magnetic field generated by the objective lens without being disturbed by the objective lens.

Further, by forming the collimator with a material having a low X-ray transmittance, it is possible to prevent the generation of secondary X-rays that are excited and generated by irradiating the outer wall of the collimator. It is also possible to prevent the generation of X-rays that are excited and generated by the collision of reflected electrons with the collimator. If the collimator is sharpened as in the present invention, a lot of backscattered electrons will hit the outer wall of the collimator, which is an effective configuration.

[0014]

1 is a schematic sectional view of an embodiment of the present invention. Voltage V1 applied to cathode 1 and first anode 2
As a result, the primary electron beam 4 emitted from the cathode 1 is accelerated to the voltage Vacc applied to the second anode 3 and advances to the lens system in the subsequent stage. The primary electron beam 4 is supplied to the lens control power source 15
Sample 7 by focusing lens 5 and objective lens 6 controlled by
Is focused as a minute spot on the sample, and the sample is two-dimensionally scanned by the two-stage deflection coil 8. The scanning signal of the deflection coil 8 is controlled by the deflection control device 16 according to the observation magnification. The objective lens magnetic field 9 of the objective lens 6 is generated on the sample side, and the sample 7 is arranged in the objective lens magnetic field.

The EDX detector 11 comprises a detector element 12 and a collimator 13 arranged in front of it. The collimator 13 is, for example, a cylindrical body made of non-magnetic aluminum, and has a screw having a height of about 0.1 mm cut on the inner surface. The EDX detector 11 is arranged so that its collimator 13 is located in the objective lens magnetic field 9 of the objective lens 6.

The X-ray 14 generated from the sample 7 passes through the X-ray passage hole of the collimator 13 and is detected by the detector element 12 in the EDX detector 11. On the other hand, the scattered electrons 10 generated from the sample 7 are bent by the objective lens magnetic field 9 of the objective lens 6 as shown in FIG.
It cannot pass through the line passage hole and collides with its inner wall. The scattered electrons that collide with the inner wall generate secondary electrons on the collision surface of the inner wall, but cannot travel to the detector element 12 because of the uneven structure on the inner wall. Further, since the inner wall surface is made of a material that does not easily generate secondary electrons due to the collision of the scattered electrons 10, the probability that the scattered electrons 10 enter the detector element 12 is synergistic with the uneven structure. Very small

Further, the collimator 13 is made of a material having a low X-ray transmittance, for example, tantalum or tungsten, so that the secondary wall of the secondary X-ray which is excited by the irradiation of the outer wall of the collimator 13 is generated. It can prevent the occurrence. It is also possible to prevent the generation of X-rays that are excited and generated by the collision of reflected electrons with the collimator 13. Particularly, when the collimator 13 is sharpened as in the present invention, many reflected electrons come into contact with the outer wall of the collimator, which is an effective configuration.

In the present invention, the collimator 1 as shown in FIG.
Since 3 is sharpened toward the sample, the objective lens 2
The collimator 13 can easily be brought close to the leak magnetic field of the objective lens 20 without being blocked by zero. Further, by sharpening, the X-ray entrance becomes narrower than the X-ray exit. That is, invasion of reflected electrons can be reduced. This configuration requirement differs from that of simply narrowing the inner diameter of the cylindrical collimator to form a thin cylinder in the following points.

That is, sharpening has the effect of not only narrowing the entrance of the collimator 13 but also increasing the size of the detector element 12. Generally, the X-rays obtained by irradiating the sample 7 with the primary electron beam 4 radiately diverge around the irradiation point of the primary electron beam of the sample. That is, if it is attempted to obtain the same entrance diameter as that of the collimator 13 of the present invention by simply narrowing the entire inner diameter of the collimator, the detection efficiency of the present invention is equal to that of the X-rays that collide with the inner wall of the collimator between the EDX element and the collimator entrance. drop down.

By sharpening the collimator as described above, it becomes possible to easily arrange the collimator in the leakage magnetic field of the objective lens, and it is possible to reduce the penetration of backscattered electrons into the collimator.

The collimator 13 has a collimator along a straight line connecting the irradiation point of the primary electron beam of the sample 7 and the end of the detector element 12 in consideration of the efficiency of preventing backscattered electrons from entering and the efficiency of detecting X-rays. If the inner wall of 13 is formed, the detector element 1
It is possible to provide the collimator 13 capable of maximizing the detection efficiency of No. 2 and minimizing the penetration of backscattered electrons while maintaining the detection efficiency.

Here, an example in which the EDX detection device 11 is mounted on a scanning electron microscope equipped with a magnetic field leakage type objective lens has been described, but the same applies when mounted on a scanning electron microscope equipped with an in-lens type objective lens. It is possible to exert an effect.

[0023]

According to the present invention, scattered electrons generated from a sample can be removed without affecting the magnetic field of the objective lens and X-rays can be efficiently detected. In the X-ray analysis combined with the resolution scanning electron microscope, there is an effect that a highly sensitive X-ray analysis can be performed without deteriorating the resolution of the scanning electron microscope.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a collimator section.

FIG. 3 is a schematic configuration diagram of a conventional EDX detection device.

FIG. 4 is a layout view of a collimator of the present invention.

[Explanation of symbols]

1 ... Cathode, 2 ... First anode, 3 ... Second anode, 4 ... Primary electron beam, 5 ... Focusing lens, 6, 20 ... Objective lens, 7 ... Sample, 8 ... Deflection coil, 9 ... Objective lens magnetic field, 10 ... scattered electrons, 11 ... EDX detection device, 12 ... detector element, 13
... Collimator, 14 ... X-ray, 15 ... Lens control power supply, 1
6 ... Deflection control device, 17 ... Permanent magnet.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsugu Sato 882 Ichige, Ichima, Hitachinaka City, Ibaraki Prefecture Hitachi Ltd. Measuring Instruments Division, Ltd. (72) Naomasa Suzuki, 882 Ichige, Ichige, Hitachinaka, Ibaraki Prefecture Hitachi, Ltd. Measuring Instruments Division

Claims (16)

[Claims] 1. An electron beam generating means, an electron beam converging lens,
Magnetic field type objective lens, energy dispersive X-ray detector,
In the energy dispersive X-ray analyzer, the energy dispersive X-ray analyzer detects X-rays emitted from a sample placed in a leakage magnetic field of the magnetic field type objective lens by electron beam irradiation, by the energy dispersive X-ray detector. An energy dispersive X-ray analyzer characterized in that a collimator made of a non-magnetic material is provided between a detector and a sample, and at least a part of the collimator is arranged in a leakage magnetic field of the magnetic field type objective lens. 2. The energy dispersive X-ray analyzer according to claim 1, wherein the collimator has an uneven structure on its inner wall. 3. The energy dispersive X-ray analyzer according to claim 1, wherein the collimator is sharpened toward the sample. 4. The energy dispersive X-ray detection device according to claim 1, wherein the collimator is made of a material in which secondary electrons are less likely to be generated by electron irradiation. 5. The energy dispersive X-ray detection device according to claim 1, wherein the collimator is made of a material having a low X-ray transmittance. 6. An electron beam generating means, an electron beam converging lens,
Magnetic field type objective lens, energy dispersive X-ray detector,
In the energy dispersive X-ray analyzer, the energy dispersive X-ray analyzer detects X-rays emitted from a sample placed in a leakage magnetic field of the magnetic field type objective lens by electron beam irradiation, by the energy dispersive X-ray detector. An energy dispersive X-ray analyzer characterized in that a collimator made of a non-magnetic material and sharpened toward the sample is provided between the detector and the sample. 7. The energy dispersive X-ray analyzer according to claim 6, wherein at least a part of the collimator is located in a leakage magnetic field of the magnetic field type objective lens. 8. The energy dispersive X-ray analyzer according to claim 6, wherein the collimator has an uneven structure on its inner wall. 9. The energy dispersive X-ray detection device according to claim 6, wherein the collimator is made of a material that is less likely to generate secondary electrons due to electron irradiation. 10. The collimator according to claim 6, wherein the collimator is X.
An energy dispersive X-ray detection device characterized by being made of a material having a low ray transmittance. 11. An electron beam generating means, an electron beam converging lens, a magnetic field type objective lens, an energy dispersive X-ray detector, and a sample placed in a leakage magnetic field of the magnetic field type objective lens by electron beam irradiation. In an energy dispersive X-ray analyzer for detecting X-rays emitted from the energy dispersive X-ray detector, a non-magnetic material is used between the energy dispersive X-ray detector and the sample, and unevenness is formed on the inner wall. An energy dispersive X-ray analyzer characterized in that a collimator having a structure is provided. 12. The energy dispersive X-ray analyzer according to claim 11, wherein at least a part of the collimator is located in a leakage magnetic field of the magnetic field type objective lens. 13. The energy dispersive X-ray detection device according to claim 11, wherein the collimator is made of a material in which secondary electrons are less likely to be generated by electron irradiation. 14. The energy dispersive X-ray detector according to claim 11, wherein the collimator is sharpened toward the sample. 15. The energy dispersive X-ray detection device according to claim 11, wherein the collimator is made of a material having a low X-ray transmittance. 16. An electron beam generating means, an electron beam converging lens, a magnetic field type objective lens, an energy dispersive X-ray detector, and a sample placed in a leakage magnetic field of the magnetic field type objective lens by electron beam irradiation. In the energy dispersive X-ray analyzer for detecting the X-rays emitted from the energy dispersive X-ray detector, the energy dispersive X-ray detector is made of a non-magnetic material and is placed between the sample and the energy dispersive X-ray detector. An energy dispersive X-ray analyzer comprising a collimator having an opening on the sample side that is smaller than the opening on the dispersive X-ray detector side.