JPH076894B2 - Fast atom bombardment type secondary ion mass spectrometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a fast atom bombardment secondary ion mass spectrometer for composition analysis of a solid sample.

(Prior art) A high-speed atomic bombardment type secondary ion mass spectrometer that analyzes the composition of a sample by bombarding an analytical sample with a high-speed atomic beam and performing mass analysis of secondary ions emitted from the surface of the sample. Is known as shown in FIG.

This conventional secondary ion mass spectrometer is used in the fast atom beam source 1.
Ar gas is introduced to generate Ar fast atoms having a kinetic energy of about 3 keV, which are then emitted as fast atom beams 3. Then, the remaining ions are removed by passing through a deflector 4 to obtain a pure high-speed atomic beam 3,
The sample 6 on the sample holder 5 is irradiated with this. Then, the surface of the sample 6 is impacted by the high-speed atomic beam 3 and is sputtered to emit secondary ions 7. Then, the secondary ions 7 are passed through an energy filter 8 to select those having an appropriate kinetic energy, and the secondary ions 7 are guided to the mass spectrometer 9. The mass spectrometer 9 performs mass analysis of the secondary ions 7 to identify the composition of the sample 6.

However, in such a conventional apparatus, since the sputter phenomenon caused by the impact of the fast atom beam on the sample is utilized, the crystal orientation and the incidence of the fast atom beam are incident especially when the sample is single crystal. The emission efficiency of secondary ions differs depending on the angle.

As an example, the secondary ion intensity when a single crystal of crystal coordination (100) copper was bombarded with Ar ions having a kinetic energy of 10 keV or 15 keV was measured by changing the incident angle of Ar ions. It is shown in FIG.

As is clear from this figure, when the sample is a single crystal,
It can be seen that even with the same substance, the intensity of the secondary ions changes depending on the crystal orientation, and even if the attachment angle of the sample is slightly different, the intensity of the secondary ions is affected. If the intensity of the generated secondary ions changes depending on the mounting angle of the sample, there is a problem that the accuracy of composition analysis of the sample is affected.

Further, in the conventional apparatus, even when segregation occurs on the sample surface, the sensitivity of the secondary ion varies depending on the analysis site on the sample, which may lead to a decrease in analysis accuracy.

(Problems to be Solved by the Invention) As described above, in the conventional fast atom bombardment secondary ion mass spectrometer, the composition analysis results are different due to the difference in the mounting angle of the sample and the difference in the irradiation site of the fast atom beam. There was a problem that high analysis accuracy could not be expected because of the influence.

The present invention has been made in view of such conventional problems, and irradiates the sample surface with a high-power pulsed laser to make it an amorphous state, and suppresses fluctuations in the emission intensity of secondary ions due to crystallinity. An object of the present invention is to provide a high-speed atom bombardment type secondary ion mass spectrometer capable of highly accurate composition analysis.

[Structure of the Invention] (Means for Solving Problems) A high-speed atom bombardment secondary ion mass spectrometer of the present invention includes a sample holder for supporting an analysis sample and a sample supported by the sample holder. A high-speed atom beam source for irradiating a high-speed atom beam, a laser device for irradiating a sample before irradiation of the high-speed atom beam with a pulse laser to amorphize the surface of the sample, and a laser device. When the sample is irradiated with the pulsed laser beam by the method, a shutter for blocking irradiation of the sample with a high-speed atomic beam and a mass spectrometer for analyzing secondary ions from the sample are provided.

(Operation) In the fast atom bombardment type secondary ion mass spectrometer of the present invention,
When a sample is irradiated with a high-speed atom beam from a high-speed atom beam source to emit secondary ions, and a mass spectrometer is used for mass analysis, a high-power pulsed laser is applied to the surface of the sample to make it amorphous, and then the high-speed atom beam is emitted. The surface of the sample is irradiated with a ray, and the secondary ions emitted are subjected to mass spectrometry.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. First
The figure shows one embodiment, a high-speed atomic beam source 11,
The deflector 12 placed in front of this, the sample holder 14 that supports the sample 13, and the shield case that houses this sample 13
15, equipped with a mass spectrometer 16 for analyzing secondary ions from the sample 13.

A power supply 17 is connected to the deflector 12.
An energy filter 18 is installed in front of the mass spectrometer 16.

Further, between the deflector 12 and the shield case 15, there is provided a shutter 19 that blocks high-speed atom beams. A pulse laser device 20 for irradiating the sample 13 in the shield case 15 with a high-power pulse laser is provided.

The operation of the fast atom bombardment type secondary ion mass spectrometer having the above configuration will be described below. Ar gas 21 is introduced into the fast atom beam source 11 to emit a fast atom beam 22 of Ar having a kinetic energy of about 3 keV as in the conventional example. Deflector 12
Is applied with a voltage by a power supply 17, ions remaining in the fast atom beam 22 passing therethrough are removed, and a pure fast atom beam is emitted to the shield case 15 side.

The high-power pulse laser device 20 outputs a laser 23 in a pulsed manner, irradiates the sample 13 and melts its surface. A YAG laser having a pulse width of 100 Jns to 10 ms and a JAG pulse of 0.5 J / pulse is suitable for use as the high power pulse laser 23, but is not particularly limited.

When the surface of a crystalline solid is irradiated with such a high-power laser with a narrow pulse width, the surface is instantly heated and melted, and the crystallinity is lost. Then, it is rapidly cooled and solidified before the crystallinity is restored to an amorphous state. This amorphous layer is 0.001 for the above laser.
It is formed only on the surface layer portion of ˜1 μm.

In mass spectrometry of secondary ions, with the shutter 19 closed, the high-power pulse laser device 20 irradiates the sample 13 with a single-pulse laser 23 to amorphize the surface, and then the shutter 19 is opened to open at high speed. The atomic beam 22 is guided from the high-speed atomic beam source 11 to the shield case 15, and the surface of the sample 13 is bombarded.

Due to this impact, secondary ions 24 are emitted from the surface of the sample 13, and those having an appropriate kinetic energy are selected by the energy filter 18 and reach the mass spectrometer 16. The mass spectrometer 16 performs mass analysis of incident secondary ions, and the composition of the sample 13 is analyzed based on the result.

In this way, when the amorphized sample surface is bombarded to emit secondary ions, the surface of the sample 13 has no crystallinity, so there is no change in the secondary ion emission efficiency due to the impact site, and reliability is improved. It will be possible to perform high mass spectrometry.

EFFECTS OF THE INVENTION Since the present invention has the above configuration, the surface of the sample is made amorphous by irradiation with a pulse laser, and a high-speed atomic beam is bombarded on the surface to emit secondary ions, thereby performing mass spectrometry. You can Therefore, even if the original material has crystallinity or segregation, fluctuations in analysis sensitivity and analysis accuracy due to it can be suppressed, and highly reliable composition analysis can be performed.

[Brief description of drawings]

FIG. 1 is a perspective view showing the outline of an embodiment of the present invention, and FIG.
FIG. 3 is a perspective view showing the outline of a conventional example, and FIG. 3 is a graph showing the dependency of secondary ion emission intensity of a crystalline sample on the primary beam incident angle. 11 …… High-speed atomic beam source 12 …… Deflector 13 …… Sample 14 …… Sample holder 15 …… Shield case 16 …… Mass spectrometer 17 …… Power supply 18 …… Energy filter 19 …… Shutter 20 …… Large output pulse Laser device 22 …… High-speed atomic beam 23 …… High-power pulsed laser 24 …… Secondary ion

Claims (1)

[Claims] 1. A sample holder for supporting an analytical sample, a high-speed atomic beam source for irradiating a sample supported by the sample holder with a high-speed atomic beam, and a high-speed atomic beam for irradiating the sample with the high-speed atomic beam. A laser device for irradiating the sample with a pulse laser to amorphize the surface of the sample; a shutter for irradiating the sample with a high-speed atomic beam when the sample is irradiated with the pulse laser by the laser device; A high-speed atom bombardment secondary ion mass spectrometer comprising a mass spectrometer for analyzing secondary ions from a sample.