JPH08138613A - X-ray micro analyzer - Google Patents

Abstract

PURPOSE: To perform X-ray analysis without decreasing detection sensitivity of low energy X ray. CONSTITUTION: A window 9 of an X-ray detector 7 is indirectly heated by installing a heater in a collimeter 13 to raise a temperature to the same as a sample chamber or higher and prevent contamination from sticking to the window 9 of the X-ray detector 7. A heater is thus installed in a collimeter so that a detection element can be cooled without decreasing temperature of the window of the X-ray detector.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an X-ray microanalyzer.

[0002]

2. Description of the Related Art An X-ray microanalyzer detects an X-ray generated from a sample by a detector when an electron beam narrowed down by an electron lens is applied to a minute area on the surface of the sample and performs elemental analysis of the sample. To do. The detection element is cooled by liquid nitrogen or the like to improve the S / N ratio. The detector is provided with a thin film window through which X-rays can pass in order to protect the detection element. This window is also cooled by cooling the detection element and is lower than the temperature inside the sample chamber. .
Further, the collimator for preventing the electron beam from entering the detector is also cooled.

[0003]

In the prior art, since the window and the collimator are lower than the temperature in the sample chamber, there is a problem that contamination in the sample chamber adheres to the window. Therefore, the detection sensitivity of low-energy X-rays, particularly X-rays of light elements, is lowered, which has a great influence on the quantitative analysis result.

An object of the present invention is that contamination is X
An object of the present invention is to provide an X-ray microanalyzer capable of performing X-ray analysis by preventing the X-ray from adhering to the window of the X-ray detector, without lowering the detection sensitivity of low energy X-rays.

[0005]

Prevention of contamination from adhering to the window of an X-ray detector is important in X-ray analysis. Contamination adheres to places with low temperature,
It tends to adhere to the window of the detector that has become lower than the sample chamber temperature.
In an electron microscope, a trap plate is provided in the sample chamber and cooled to prevent contamination from adhering to the sample.

In order to achieve the above object, in the present invention, X
In order to raise the temperature of the window of the line detector, the collimator for preventing the electron beam from entering the detector is provided with a heater for indirectly heating the window.

[0007]

[Operation] By passing an electric current through the heater equipped in the collimator, the window of the detector is indirectly heated, and the temperature of the sample chamber is made equal to or higher than the temperature inside the sample chamber to prevent contamination from adhering to the window. However, the detection sensitivity of low energy X-rays is prevented from decreasing.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an explanatory diagram showing the configuration of an apparatus which is an embodiment of the present invention. Electron beam 2 emitted from electron gun 1
Is narrowed down by the converging lens 3 and the objective lens 4,
The minute area on the surface of the sample 5 is irradiated. The X-ray 6 generated from the sample 5 by the irradiation of the electron beam 2 passes through the window 9 for protecting the detection element 8 in the X-ray detector 7, and the detection element 8
Is detected and converted into an electrical signal. Detection element 8
Are cooled by the liquid nitrogen 11 in the liquid nitrogen layer 10 via the heat conducting rods 12 which are in thermal contact. Further, a collimator 13 is provided at the tip of the X-ray detector 7 to prevent the electron beam from entering the X-ray detector 7. Although a cooled field effect transistor (FET) is installed behind the detection element 8, these are not shown because they are not directly related to the present invention.

FIG. 2 is a sectional view of the tip portion of the X-ray detector 7. A passage hole is formed in the collimator 13 so that X-rays can pass therethrough, and magnets 14 for generating a magnetic field for bending so that an electron beam that has entered do not irradiate the X-ray detection element are provided on both sides of the passage hole. It is provided. A heater 15 is provided inside the passage hole.

In the apparatus constructed as described above, since the detection element 8 and the window 9 are extremely close to each other, the detection element 8 cooled by the liquid nitrogen 11 via the heat conducting rod 12 which is in thermal contact with the liquid nitrogen 11. Therefore, the window 9 is also cooled. Therefore, by supplying a current to the heater 15 provided in the X-ray passage hole of the collimator 13 to heat the collimator 13 and the window 9, the temperature of the window 9 is made equal to or higher than the temperature in the sample chamber, and the temperature of the window 9 is increased. Prevents adhesion of contamination. Furthermore, by making the heater 15 a non-inductive winding, the electron beam 2 with which the sample 5 is irradiated can be prevented from being affected. Further, by using the heater 15 as a ceramic heater, it is possible to suppress the generation of gas and prevent the degree of vacuum in the sample chamber from being affected. In this case, as shown in FIG. 3, by inserting carbon or a metal tube equipped with carbon into the inner surface of the heater 15, charging of the heater 15 due to collision of electrons can be prevented.

[0012]

According to the present invention, by equipping the collimator with the heater, the detecting element can be cooled without lowering the temperature of the window of the X-ray detector, so that the detection sensitivity of low energy X-rays can be improved. X-ray analysis can be performed without deterioration.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a tip portion of an X-ray detector.

FIG. 3 is a cross-sectional view of the tip portion of the X-ray detector of another embodiment.

[Explanation of symbols]

1 ... Electron gun, 2 ... Electron beam, 5 ... Sample, 6 ... X-ray, 7 ... X
Line detector, 8 ... Detection element, 9 ... Window, 12 ... Heat conduction rod, 1
3 ... Collimator, 15 ... Heater, 16 ... Metal tube.

Claims (5)

[Claims] 1. An electron gun, and an electron lens for narrowing down an electron beam emitted from the electron gun and irradiating the electron beam onto a sample.
An X-ray detector for detecting X-rays generated from the sample by the irradiation of the electron beam, and an X-ray comprising a collimator for preventing the electron beam from entering the X-ray detector.
An X-ray microanalyzer, wherein the collimator is provided with a heater. 2. The X-ray microanalyzer according to claim 1, wherein the magnetic field generated by the heater does not affect the electron beam with which the sample is irradiated. 3. The X-ray microanalyzer according to claim 2, wherein the heater is a non-induction winding. 4. The X-ray microanalyzer according to claim 2, wherein a ceramic heater is used as the heater. 5. The inner surface of the heater according to claim 2,
An X-ray microanalyzer equipped with carbon or a metal tube equipped with carbon inside.