JPH0115986B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a secondary ion mass spectrometer. Generally speaking, a secondary ion mass spectrometer uses several dozen ions on the sample surface.
The sample surface is sputtered by irradiation with an ion beam accelerated to KV. As a result, neutral particles, secondary ions, etc. are released from the sample surface, and the secondary ions are led to a mass spectrometer and separated into mass/charge ratios. It is detected by a detector and elemental analysis of the sample is performed.

By the way, in the secondary ion mass spectrometer, in addition to detecting secondary ions emitted from a sample as described above, there are cases where it is desired to ionize and measure neutral particles to obtain information about the sample. For this reason, some secondary ion mass spectrometers are equipped with an ionization chamber. However, in a conventional secondary ion mass spectrometer equipped with an ionization chamber, the ionization chamber is disposed between the sample to be analyzed and the mass spectrometer. For this reason, the distance between the sample and the mass spectrometer increases, and when measuring secondary ions, the intensity decreases and the mass resolution decreases. In order to prevent this, attempts have been made to remove the ionization chamber when measuring secondary ions, and to install an ionization chamber when measuring neutral particles; however, when the purpose of analysis is different, It becomes necessary to attach and detach the ionization chamber each time, which complicates the analysis work.

The present invention has been made in view of the above-mentioned problems, and it is possible to permanently install an ionization chamber, and the ionization chamber ensures mass resolution without interfering with the original secondary ion measurement. The present invention aims to provide a second ion mass spectrometer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below with reference to embodiments based on the drawings.

In FIG. 1, reference numeral 1 denotes a secondary ion mass spectrometer of the present invention, 2 a sample, 3 an ion source that generates a primary ion beam, 4 an electrostatic lens that focuses this primary ion beam, and 5 a sample 2. This is a secondary ion extraction electrode that extracts generated ions. Further, 6 is a lens that narrows down the ions that have passed through the ion extraction electrode 5, 7 is a sector electric field for energy separation, 8 is a sector magnetic field for mass separation, and 9 is a detector for detecting ions. , a double focusing type mass spectrometer 1 with a sector magnetic field 8 and a detector 9
Configure 0. Note that 11 is an amplifier that amplifies the signal detected by the detector 9, and 12 is a recorder that records the spectral intensity.

As shown in FIG. 2, a cover 15 is provided near the ion extraction electrode 5 to cover the sample 2.
This cover 15 forms an ionization chamber 16 inside thereof. Then, the upper part 1 of the cover 15
5a is formed with a pore 17 for receiving the primary ion beam from the ion source 3 and extracting secondary ions emitted from the sample and neutral particles ionized in the ionization chamber 16; Through holes 18 and 19 passing through the cover 15 are formed on the left and right sides of the side portion 15b of the cover 15 at positions above the secondary ion emitting surface 2a of the sample 2. Furthermore, a deflection plate 20 is provided above the cover 15 to deflect the ions extracted from the pores 17 to the mass spectrometer 10 via the secondary ion extraction electrode 5. Side part 1 of one cover 15
5b, a filament 21 for ionizing neutral particles and a trap 22 are arranged facing each other through the left and right through holes 18 and 19, and maintaining a perpendicular relationship with the primary ion beam axis C. has been done. Note that 24 and 25 are magnets that cause the electrons to perform a spiral motion in order to increase the path of the electrons emitted from the filament 20.

Next, a case where secondary ions emitted from the sample 2 are analyzed using the secondary ion mass spectrometer 1 having the above configuration, and a case where neutral particles are ionized and analyzed will be described.

During analysis, the sample 2, cover 15, and trap 20 are all set at the same potential.

First, to analyze secondary ions, the ion source 3
A primary ion beam using argon, oxygen, or the like as an ion source is irradiated onto the sample 2 from above. This primary ion beam passes through the pores 17 of the cover 15 and hits the sample 2, sputtering the surface 2a and emitting neutral particles and secondary ions. At this time, since the filament 21 is not energized and the cover 15 is set at the same potential as the sample 2, the released secondary ions are collected in the pores 17 and pass therethrough. Ionization chamber 1 like this
6, the position of the pore 17 is considered to be a substantial secondary ion release surface, so even if the sample surface 2a is moved up and down a little, the secondary ion collection efficiency does not decrease. The next ion is deflection plate 2
0, it is deflected toward the secondary ion extraction electrode 5 and introduced into the mass spectrometer 10. In the mass spectrometer 10, the secondary ions are first focused by a lens 6 and subjected to a sector electric field 7.
The energy is separated at , and then introduced into the sector magnetic field 8 . In the sector magnetic field 8, magnetic field scanning is performed, secondary ions are mass separated, these secondary ions are detected by a detector 9, and amplified by an amplifier 11 to determine the mass and intensity of each secondary ion. It is recorded on the recorder 12.

When neutral particles emitted from the sample 2 are ionized and analyzed, the filament 21 is energized.
An electron beam is emitted from this filament 21. This electron beam passes through the through hole 18 of the cover 15 and impacts neutral particles generated from the sample 2 to ionize them. The remaining electron beam passes through the through hole 19 and is absorbed by the trap 22. The neutral particles ionized as described above in the ionization chamber 15 are collected in the pores 17 because the sample 2 and the cover 15 are kept at the same potential.
from the cover 15. The following steps are similar to those for analyzing secondary ions.

Note that the ionization chamber 16 in the above embodiment is
Although this is an example of a Neiv type ion source, it can also be applied to a B-A type ion source. Furthermore, it is also possible to use it as a gas analyzer for gas introduced into the ionization chamber 16 by operating only the filament 21 without irradiating the primary ion beam.

As described above, according to the present invention, a sample is covered with a cover forming an ionization chamber, a primary ion beam is incident on the upper part of the cover, and a pore is provided for extracting ions emitted from the sample. A deflection plate was placed above the cover to deflect ions emitted from the sample to the mass spectrometer, and the sample, cover, and deflection plate were all set at the same potential, so even if the pores were secondary ions, Even when neutral particles are ionized, it can be regarded as a substantial ion emitting surface. Therefore, since the distance between the mass spectrometer and the substantial ion emitting surface does not change, the mass resolution of secondary ions is ensured. Also,
Whether you are analyzing secondary ions or ionizing neutral particles, there is no need to install or remove the ionization chamber as in the past, which has the excellent effect of improving analysis workability. Ru.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and FIG. 1 is a sectional view showing the entire secondary ion mass spectrometer, and FIG. 2 is an enlarged sectional view of a part of FIG. 1. 1... Secondary ion mass spectrometer, 2... Sample, 1
0... Mass spectrometer, 15... Cover, 16... Ionization chamber, 17... Pore, 20... Deflection plate.

Claims (1)

[Claims] 1. Cover the sample to be analyzed with a cover that forms an ionization chamber, and provide the upper part of this cover with a pore for the incidence of the primary ion beam and the extraction of ions emitted from the sample. 1. A secondary ion mass spectrometer, characterized in that a deflection plate is arranged to deflect ions to a mass spectrometer, and the sample, the cover, and the deflection plate are all set at the same potential.