JPH0945276A - Mass spectrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a focusing diameter through the application of a laser beam from the vertical direction and to enhance image resolution by opposing a microscope to a sample, and causing ions to fly crosswise by means of ion accelerating electrodes. SOLUTION: A sample 2 is inserted between accelerating electrodes 22. During mass spectrometry, a laser beam 7a from a laser beam source 6 is focused onto the sample 2 by a condensing lens 22. An ion beam 21b excited thereby is accelerated by an accelerating electrode 40 in an almost perpendicular direction to the direction of incidence of the laser beam and is made to impinge on a mass spectrometer part 1. The ion beam 21b is reflected by an ion reflector 30 and impinges on an ion detecting part 34. Ion flight time can be obtained by measuring the time from the application of the laser beam 7b to the arrival of the ions at the ion detector 34. Mass spectrometry of the ions can thus be performed. During observation of the sample, light from a sample illuminating light source 8 is made to impinge on the sample 2 from the condensing lens 22. An image of the sample 2 formed thereby is observed with a TV camera 10.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to mass spectrometers.

[0002]

2. Description of the Related Art A conventional mass spectrometer is disclosed in JP-A-4-3065.
As described in Japanese Patent Publication No. 49, it was as shown in FIG. 1 is a mass spectrometer, 2 is a sample, 6 is a laser light source, 8 is a light source for observation illumination, 18 is a vacuum chamber, 21b is an ion beam, 22 is a condenser lens, 24 is a light reflection mirror, 26 is a sample stage, 30 Is an ion reflector, and 34 is an ion detector. The laser light generated from the laser light source 6 is condensed on the sample 2 by the condenser lens 22 and the light reflection mirror 24. The ions excited by this laser light are subjected to mass analysis in the mass analysis unit 1.

In the conventional apparatus shown in FIG. 3, since the laser light is incident from an oblique direction, it is extremely difficult to reduce the condensing diameter of the laser light. Moreover, since the sample is observed from an oblique direction, it is difficult to improve the resolution of the observed image.

[0004]

In the above conventional apparatus, since the laser focusing objective lens exists on the ion accelerating direction side, it is necessary to tilt the lens in order to avoid collision of ions with the lens. Therefore, it is difficult to reduce the focused diameter of the laser light.

In the present invention, this problem is solved by making the sample and the sample face each other and causing the ions to fly in the direction perpendicular to the laser beam incident direction by the ion accelerating electrode.

[0006]

In order to solve the above-mentioned object, as shown in FIG. 1, an objective lens of a microscope is made to face a sample, and ions desorbed by a laser are extracted laterally by an accelerating electrode. As a result, the sample can be irradiated from the vertical direction, so that the focused diameter can be reduced.

[0007]

In the conventional apparatus, since the laser is radiated from the oblique direction, the laser focused spot also becomes elliptical and the focused diameter cannot be reduced. Further, even in the case of observing the sample, the image resolution is deteriorated because the sample is observed from an oblique direction.

In the present invention, is made to face the sample with the microscope,
Since the ions are caused to fly laterally by the ion accelerating electrode, the laser can be irradiated from the vertical direction, and the focused diameter can be reduced. Further, since the sample observation is also performed from the position directly facing as shown in FIG. 1, the image resolution is improved.

[0009]

【Example】

[Embodiment 1] FIG. 1 shows a system diagram of an embodiment of the present invention. 6
a and 6b are laser light sources, 7a and 7b are laser lights, 9 is sample illumination light, 10 is a TV camera, 11 is a half mirror, 1
5 is a camera lens, 16a and 16b are light reflecting mirrors, 1
Reference numeral 7 is an optical path, 19 is a vacuum container, and 21a is a molecular beam. 40 is an accelerating electrode.

First, the sample 2 is inserted between the acceleration electrodes 22.
At the time of mass analysis, the laser light 7a from the laser light source 6a is condensed on the sample 2 by the condenser lens 22. The ion beam 21b thus excited is accelerated by the accelerating electrode 40 in a direction substantially perpendicular to the laser light incident direction and is incident on the mass spectrometric unit 1. The ion beam 21b is reflected by the ion reflector 30 and enters the ion detector 34. By measuring the time from the irradiation of the laser beam 7b until the ions reach the ion detector 34,
I know the ion flight time. This enables mass spectrometry of ions.

At the time of observing the sample, the light from the light source 8 for illuminating the sample is made incident on the sample from the condenser lens 22. The resulting image of the sample is observed by the TV camera 10.

In this embodiment, since the condenser lens 22 faces the sample, the laser condenser diameter can be reduced. Further, since the observation is also performed at the front facing position, a clear image with high resolution can be obtained.

[Embodiment 2] FIG. 2 shows an explanatory view of an electrode portion in Embodiment 2 of the present invention. 41 is an X-axis deflection plate, 42 is a Y-axis deflection plate, and 43 is an ion reflector. Also 44
Is an electrostatic lens, 45 is a transparent electrode coated with ITO, and 46 is an electrostatic lens. In this embodiment, it is used to measure a sample such as a silicon wafer that cannot be inserted between the acceleration electrodes.

A laser is focused on the sample surface, and the excited ion beam 21b is made incident on the electrostatic lens 44 by adjusting the voltages of the accelerating electrode 40 and the transparent electrode 45. The incident ion beam is an electrostatic lens and becomes a beam with a small spread,
Reflected by the ion reflector 43, the X-axis deflection plate 41, Y
The path is corrected by the axis deflection plate 42 and the light enters the mass spectrometer.
In this case, since the sample and the objective lens are facing each other,
The same effect as in Example 1 can be obtained, and since there is no need to insert a sample between the acceleration electrodes, there is no limitation on the size of the measurement sample.

[0015]

According to the present invention, since the microscope objective lens is directly opposed to the sample and ions are extracted in a direction substantially perpendicular to the laser beam incident direction, the laser beam can be irradiated from the direction perpendicular to the sample surface. It is possible to reduce the light collecting diameter.

Further, since the sample surface is observed from the direction directly facing the sample, an image with high resolution can be obtained.

[Brief description of drawings]

FIG. 1 is a system diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an accelerating electrode unit according to a second embodiment.

FIG. 3 is a system diagram of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Mass spectrometric part, 2 ... Sample, 6 ... Laser light source, 7 ... Laser light, 8 ... Sample illumination light source, 9 ... Sample illumination light, 10 ... TV camera, 11 ... Half mirror, 15 ... Camera lens, 16 ... Light reflecting mirror, 17 ... Optical path, 18 ... Vacuum chamber, 19 ... Vacuum container, 21b ... Ion beam, 22 ... Focusing objective lens, 30 ... Ion reflector.

Claims (4)

[Claims] 1. A laser light source for exciting a sample, an illumination light source for observing the sample, a light reflection mirror for guiding light from each of the illumination light sources to the sample, and a microscope for observing the sample by converging the laser light. A sample stage on which the sample is placed, an accelerating electrode that accelerates the ions emitted from the sample, an ion reflector that reflects the accelerated ions, and an ion detector that detects the ions reflected by the ion reflector. In a mass spectrometer equipped with a vessel, the microscope is placed at a position directly facing the sample, and ions are caused to fly in a direction perpendicular to a laser light incident direction by an accelerating electrode. 2. The mass spectrometer according to claim 1, wherein the sample is placed perpendicular to the incident direction of the laser light. 3. The mass spectrometer according to claim 1, wherein the sample is inserted between the acceleration electrodes. 4. The mass spectrometer according to claim 1, wherein a mesh electrode is used as the acceleration electrode.