JPH03135787A - X-ray detector - Google Patents

Abstract

PURPOSE:To use a light element thin film window and improve pressure resistance performance and to detect X rays with high sensitivity by decreasing the thickness of the X-ray detection window gradually from the outer peripheral part supported on a tube in a vacuum state to the center part of the window. CONSTITUTION:The detector part of an energy dispersion type X-ray spectroscope is arranged nearby a sample 9 between magnetic pole pieces 8 of an objective while penetrating the lens barrel 7 of an electron microscope. Then the lens barrel 7 and a protection barrel 4 are connected by a bellows 5 to attain vacuum sealing and the vacuum in the lens barrel 7 is maintained. The inside of the spectroscope is arranged hermetically in the protection barrel 4 in a vacuum state and a semiconductor detector 1 which is cooled by a cooling tank 2 at all times detects X rays transmitted through a beryllium window 10 from the sample. This window 10 is formed decreasing gradually in thickness from the window outer peripheral part to the detection center part according to the phenomenon that stress applied to the thin film window with uniform thickness decreases toward the center part. Therefore, even if the center part is thin, the pressure resistance performance is good and higher sensitivity is obtained at the center part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a window of an energy dispersive X-ray detector that detects characteristic X-rays generated when a sample is irradiated with an electron beam.

[Prior Art] Conventionally, electromagnetic waves such as X-rays generated from a sample of an electron microscope are detected by a semiconductor detector placed near the sample.

As an X-ray analyzer used for this X-ray detection, an apparatus having a configuration as shown in the seventh example is known.

In FIG. 7, 1 is a semiconductor detector, 2 is a cooling tank for cooling the semiconductor detector 1, 3 is a heat conductive rod for connecting the cooling tank 2 and the semiconductor detector 1, and 4 is a device whose inside is in a vacuum state. 5 is a bellows, 6 is an adjustment screw, 7 is an electron microscope housing, 8 is a magnetic pole piece, 9 is a sample, and 10 is a beryllium window.

The detector portion of the energy dispersive X-ray spectrometer, which consists of the semiconductor detector 1, cooling tank 2, thermally conductive rod 3, and protective tube 4, passes through the housing tube 7 and passes through the sample 9 between the magnetic pole pieces 8 of the objective lens. is located near. At this time, in order to maintain the vacuum inside the housing tube 7, the housing tube 7 and the protection tube 4 are connected by a bellows 5 and vacuum-sealed. The protection tube 4 is fixed by an adjustment screw 6, and the adjustment screw 6 allows the position of the spectrometer (particularly the detector) to be adjusted to the sample 9.
adjusted for.

Further, a window 10 made of a light element film, for example, beryllium, and having an area approximately equal to the effective detection area of the detector 1 is provided at the tip of the protection tube 4 . The protective tube 4 is airtightly attached to the protective tube 4 so as to act as a partition wall that maintains the pressure difference within the housing tube.

[Problem to be solved by the invention] Recently, low-energy X-rays generated from light elements in a sample have been detected by forming the window material into an extremely thin film of about 1 μm. ing. However, such an extremely thin light element film of about 1 μm is used as a window in the protective tube 4.
If the window is attached to the tip of the electron microscope, it is difficult to maintain the pressure difference between the inside of the protective cylinder and the inside of the casing, and if the inside of the casing of the electron microscope leaks to atmospheric pressure, the window may be damaged. This has become a problem.

Therefore, in an X-ray analyzer that uses an ultra-thin light-element film window that can detect low-energy I closed it to protect the window. However, when using this method to prevent window damage, the problem is that components such as valves increase the size of the device, making it impossible to bring the detector close to the sample, and reducing detection sensitivity. Become.

Therefore, a lattice-shaped reinforcing member 1 as shown in FIG.
1 or a slit-shaped reinforcing member to increase pressure resistance.

However, if the window is prevented from being damaged by such a method, it is possible to bring the detector close to the sample;
Characteristics X generated from the sample depending on the width and thickness of the reinforcing grid
The problem is that sufficient detection sensitivity cannot be obtained because the radiation is obstructed and the detection sensitivity is lowered, and a ghost spectrum is generated by secondary X-rays from the elements of the grating member.

The present invention takes the above-mentioned problems into consideration and aims to provide an energy dispersive X-ray detector that uses a light element thin film window and has good pressure resistance (vacuum resistance) and high X-ray detection sensitivity. .

[Means for Solving the Problems] The first aspect of the present invention uses an X-ray detector that is sealed in a tube in a vacuum state and is constantly cooled to detect X-rays generated from a sample.
In an energy dispersive X-ray detector that detects X-rays passing through a radiation detection window, the thickness of the X-ray detection window is gradually thinned from an outer peripheral portion supported by the tube toward a central portion of the detection window. It is characterized by the fact that it was formed.

The second invention uses an X-ray detector that is hermetically placed in a vacuum tube and is constantly cooled to detect the X-rays generated from the sample.
In an energy dispersive X-ray detector that detects X-rays passing through a radiation detection window, the thickness of the X-ray detection window is gradually thinned from an outer peripheral portion supported by the tube toward a central portion of the detection window. The present invention is characterized in that a reinforcing member is provided attached to the window, and the intervals between the reinforcing members are gradually made coarser from the outer peripheral portion supported by the tube toward the center portion of the detection window.

A third aspect of the present invention is that the thickness of the reinforcing member attached to the window is gradually reduced from the outer peripheral portion supported by the tube toward the central portion of the detection window, and the interval between the reinforcing members is adjusted to The energy dispersive X-ray detector is characterized by an energy dispersive X-ray detector that is gradually roughened from the outer periphery supported by the detection window toward the center of the detection window.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. 1st
The figure is an apparatus configuration diagram for explaining one embodiment of the present invention, FIG. 2 is a sectional view of main parts for explaining the first present invention, and
The figure is a cross-sectional view of a main part for explaining the second invention, FIG. 4 is a view taken along the line A-A in FIG. 3, and FIG. Figure 6 is B-B of Figure 5.
”This is a view from the arrow.

First, the configuration of the apparatus according to the present invention will be explained based on FIG.

In FIG. 1, 1 is a semiconductor detector, 2 is a cooling tank for cooling the semiconductor detector 1, 3 is a heat conductive rod for connecting the cooling tank 2 and the semiconductor detector 1, and 4 is a device whose inside is in a vacuum state. 5 is a bellows, 6 is an adjustment screw, 7 is an electron microscope housing, 8 is a magnetic pole piece, 9 is a sample, and 10 is a beryllium window.

The detector part of the energy dispersive X-ray spectrometer, which consists of the semiconductor detector 1, the cooling bath 2, the thermally conductive rod 3, and the protective tube 4, penetrates the housing tube 7 and detects the sample 9 between the magnetic pole pieces 8 of the objective lens. located nearby. At this time, in order to maintain the vacuum inside the housing tube 7, the housing tube 7 and the protection tube 4 are connected by a bellows 5 and vacuum-sealed. Furthermore, a beryllium window 10 is airtightly placed at the tip of the protective tube 4.

Further, the protective tube 4 is fixed by an adjustment screw 6, and the spectrometer (particularly the detector) is adjusted with respect to the sample by the adjustment screw 6.

Here, the structure of the beryllium window 1° according to the first aspect of the present invention is as shown in FIG. ing. This window is formed by pressing or etching the center portion of a beryllium thin film window formed to have a uniform thickness.

The window having the structure described above was formed by paying attention to the phenomenon that the stress applied to a conventional thin film window of uniform thickness decreases toward the center of the window. Therefore, even if the central portion of a conventionally structured thin film window is made into an extremely thin structure by pressing or the like, a window having a structure with good pressure resistance can be obtained. Therefore, an energy dispersive X-ray detector with high sensitivity at the center of the window (detection center) is realized.

Next, the second invention will be explained based on FIGS. 3 and 4. In the second embodiment of the invention shown in FIG.
A reinforcing grid 11 is pasted on a thin film window that is gradually made thinner from the outer periphery of the window 10 toward the detection center (window center), and the eyes of the reinforcing grid are covered with a protective tube as shown in FIG. The detection window is gradually roughened from the outer periphery toward the center of the detection window.

The configuration described above strengthens reinforcement to increase the mechanical strength of the outer periphery of the window, which is subject to greater stress than that which is subject to less stress, and widens the lattice spacing in the center of the thin film window to improve detection sensitivity. This is what was done. This results in
As with conventional detectors with reinforced grids to increase pressure resistance, the width and thickness of the reinforcing grids can interfere with characteristic X-rays generated from the sample, reducing detection sensitivity. In addition, since the occurrence of ghost spectra due to secondary X-rays from the elements of the grating material is reduced, an energy dispersive X-ray detector with high detection sensitivity can be realized.

Next, the third invention will be explained based on FIGS. 5 and 6. In the third embodiment of the present invention shown in FIG.
On one side of the thin film window 10, which is formed gradually thinner from the outer periphery of the window toward the detection center (window center), grid eyes are formed gradually and coarsely from the outer periphery of the protective tube 4 toward the center of the detection window. At the same time, the thickness of the reinforcing grid 11 is gradually reduced from the outer peripheral portion supported by the protection tube toward the center of the detection window.

By adopting the structure of the reinforcing grid as described above, the characteristic X-rays generated from the sample may be obstructed by the width and thickness of the reinforcing grid, reducing the detection sensitivity, or
Since the generation of ghost spectra due to secondary X-rays is reduced, an energy dispersive X-ray detector with better pressure resistance and higher detection sensitivity can be realized.

Note that the above-described embodiment is only one embodiment of the present invention, and the present invention can be implemented with various modifications. For example, in the above-mentioned embodiment, the reinforcing member of the thin film window was a reinforcing lattice with different spacing between the outer periphery and the center of the window, but the reinforcing member was a slit-shaped reinforcing lattice with different spacing between the outer periphery and the center of the window. A honeycomb-shaped reinforcing member may also be used. Further, in the above embodiments, the material of the thin film window is beryllium, but the window may be made of a material other than beryllium.

[Effects of the Invention] As is clear from the above description, according to the first invention, an X-ray detector that is hermetically placed in a vacuum tube and is constantly cooled detects X-rays generated from a sample. In an energy dispersive X-ray detector that detects X-rays passing through a detection window, the thickness of the X-ray detection window is gradually thinned from the outer circumference supported by the tube toward the center of the detection window. As a result, an energy dispersive X-ray detector with higher detection sensitivity than the thin film window of conventional structure can be realized.

Further, according to the second aspect of the present invention, an X-ray detector that is hermetically placed in a vacuum tube and is constantly cooled detects X-rays generated from a sample and transmitted through an X-ray detection window. In the energy dispersive X-ray detector, the thickness of the X-ray detection window is gradually reduced from the outer peripheral portion supported by the tube toward the center of the detection window, and a reinforcing member attached to the window. , and the spacing between the reinforcing members is gradually made coarser from the outer periphery supported by the tube toward the center of the detection window, thereby increasing pressure resistance compared to pasting a uniform reinforcing grid as in the past. An energy dispersive X-ray detector with higher detection sensitivity than a detector configured in this manner can be realized.

Furthermore, according to the third aspect of the present invention, the thickness of the reinforcing member attached to the window is gradually reduced from the outer peripheral portion supported by the tube toward the central portion of the detection window, and the reinforcing member is By gradually increasing the spacing from the outer circumference supported by the tube toward the center of the detection window, an energy dispersive X-ray detector with high detection sensitivity can be achieved while maintaining vacuum resistance. .

[Brief explanation of the drawing]

FIG. 1 is an apparatus configuration diagram for explaining an embodiment of the present invention, FIG. 2 is a sectional view of essential parts for explaining the first present invention,
FIG. 3 is a sectional view of essential parts for explaining the second invention, FIG. 4 is a view taken along the line A-A in FIG. 3, and FIG. 5 is a main part for explaining the third invention. Partial sectional view, Figure 6 is taken along the line B-B in Figure 5.
The arrow view, FIG. 7, and FIG. 8 are diagrams for explaining the conventional example. 1: Semiconductor detector 2: Cooling tank 3: Heat conduction rod 4: Protective tube 5: Bellows 6: Adjusting screw 7 : Electron microscope housing 8: Magnetic pole piece 9: Sample 10: Beryllium window 11: Reinforcement grid drawing (no change in content)

Claims (3)

[Claims] (1) In an energy dispersive X-ray detector that detects X-rays generated from a sample and transmitted through an X-ray detection window using an X-ray detector that is sealed inside a vacuum tube and constantly cooled. An energy dispersive X-ray detector, characterized in that the thickness of the X-ray detection window is gradually thinned from the outer peripheral portion supported by the tube toward the center of the detection window. (2) In an energy dispersive X-ray detector that detects X-rays generated from a sample and transmitted through an X-ray detection window using an X-ray detector that is sealed inside a vacuum tube and constantly cooled. , the thickness of the X-ray detection window is gradually reduced from the outer peripheral portion supported by the tube toward the center of the detection window, and a reinforcing member is provided attached to the window, and the interval between the reinforcing members is set. An energy dispersive X-ray detector characterized in that the detection window is gradually roughened from the outer peripheral portion supported by the tube toward the central portion of the detection window. (3) The thickness of the reinforcing member attached to the window is gradually made thinner from the outer peripheral portion supported by the tube toward the central portion of the detection window, and the intervals between the reinforcing members are adjusted to reduce the thickness of the reinforcing member attached to the window. 3. The energy dispersive X-ray detector according to claim 2, wherein the detection window is formed gradually coarser from the outer circumference toward the center of the detection window.