JPS61171048A - Analyzing device - Google Patents

Abstract

PURPOSE:To obtain a device which can carry out the local analysis of a solid surface by irradiating ions on a body to be analyzed to carry out the mass analyzing of a substance emitted from the body to be analyzed. CONSTITUTION:After evacuating the inside of a vacuum vessel 61 to given pressure, a refrigerant 15 is injected into a refrigerant tank 14. And thereafter given gas is introduced out of a gas blowing pipe 33. The introduced gas is condensed on the surface of a needle anode 11 which was cooled and was set to given temperature by means of a heater 21, and the needle anode becomes like one wetted by liquid. When operating a drawing power source 42 and an accelerating power source 19, it is possible to take out the ions of the introduced gas from the tip of the needle anode 11 as an extremely fine beam 18. The ion beam 18 can be throttled to an extremely fine beam. The finely throttled beam impinges on the surface of a body 72 to be analyzed to generate secondary ions. The generated secondary ions are introduced into a four plate mass spectrometer 90 through a dropping electrode 101, a deflecting plate 102 and a slit 103 to carry out the mass analyzing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an analytical device, and particularly to an analytical device that is particularly effective when applied to local analysis of substances present on the surface of a solid.

(Prior art and its problems) First, let us briefly describe typical devices of this type.
On the one hand, there are secondary ion mass spectrometers called 5Ml5 and IMA. With this type of device, if you try to narrow down the -order ion beam to about 1 μm for local analysis, you will need a huge system and it will be expensive.On the other hand, in order to solve this problem, a liquid metal ion source (Hereafter L
It appears that SIMS using MIS is being researched, but the details have not yet been disclosed. However, in SIMS using this LMIS, metal ions (mainly gallium appears to be used) remain on the substrate, and there is a risk that it may not be possible to determine whether the metal was present in the analyte before the first analysis. There is. Another disadvantage is that analysis cannot be attempted by switching to various ions. Another representative system is an analyzer called SN-MS, which performs mass spectrometry on sputtered neutral particles, but this system also has the same drawbacks as described above. There is also a method called GD-MS, which performs mass spectrometry on ions generated in the glow discharge (GD) region.This method, like the aforementioned SN-MS, is excellent in quantitative performance, but local analysis is extremely difficult. It has the disadvantage of being difficult.

(Objective of the Invention) The object of the present invention is to provide a new and excellent analysis device that does not have these drawbacks and is capable of performing local analysis of a solid surface.

(Structure of the Invention) The present invention provides a vacuum container equipped with an exhaust system that can evacuate the interior to a predetermined pressure, and a needle-like anode with a sharp tip and a substance present on the surface of the needle-like anode. The analyte is irradiated with the ions, and the substance emitted from the analyte is analyzed by mass spectrometry. The above objective has been achieved by using an analyzer that does this.

One of the key points of this invention is the technology for extracting a narrow ion beam. Furthermore, the ion beam is an ion beam that is a gas at the temperature of the analyte. The reason for choosing a heated ion beam is that after the ions lose their charge, they become a gas and scatter, and do not remain on the substrate.

Next, as a device equipped with a means for ionizing a substance that is a gas at almost room temperature and a means for turning it into a beam, a device configured to extract ions from the surface of a needle-shaped electrode is effective.

The technology of sending such a gas and extracting the elements contained in the gas as an ion beam belongs to a very recent technology, and the literature on it is mainly the following, which is one of the very few documents. One is:

rH, and rare gas field ion
5source with hi-gh angula
r currentJ [Gary R, Hanson
and B enjamin M, Siegel.
Ko (J, Vac, sci, Techn-°1°・
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0 American Vacuum 5oc
iety) The device in this document uses liquid helium for cooling, and hydrogen is selected as the gas to be fed.

The other document is of the first order, "Gas ion source for microfabrication" [Takashi Kawauchi, 4 others] (Japan Society for the Promotion of Science 132nd Committee 81st Study Group Materials (57, 9, 24) ) p. 21) In the device of this document, liquid nitrogen is used for cooling, and hydrogen is selected as the gas to be fed.

These devices that use liquid helium, liquid nitrogen, etc. for cooling have the disadvantage that the device can only be used within an extremely narrow temperature range unique to these refrigerants, which naturally limits the types of ions that can be selected. Originally, each of the gases to be fed has an optimum temperature for use, and it is necessary to adjust the temperature conditions to the optimum temperature point, but the above-mentioned devices cannot take this into account.

(Example) Next, the present invention will be described in detail with reference to the drawings and examples. In the embodiment shown in FIG. 1 and FIG. 2, which shows an enlarged view of the main parts thereof, 10 is an ion source, 11 is a needle-like anode, and 12 is an ion source.
13 is a base, 14 is a refrigerant reservoir, 15 is a refrigerant such as liquid nitrogen, 16 is a gas container, 17 is an insulator, and 19 is an acceleration power source.

If you do not want the refrigerant reservoir 14 to have a high positive potential with respect to the ground potential, the base 13 may be made of a thermal insulator such as sapphire, and only the needle anode 11 may be kept at a high positive potential. The insulator 17 may be an ordinary metal, 20 is a heating means, 21 is a heater, 22 is a lead wire, 23 is a power source, 24 is an insulator, and 25 is a temperature controller.

If the heater 21 is likely to disturb the electric field in the vicinity of the needle-like anode 12, it is recommended to install it at the position 26.The potential of the heater may be a positive high potential or a ground potential, and is determined according to necessity. 30 is means for sending a predetermined gas, 31 is a gas pipe, 32 is a thermal and electrical insulator, 33 is a gas blowing pipe, 3
4 is a flow rate regulator, 35 is a valve, and 36 is a cylinder.

When the base portion 13 mentioned above is made of an insulator, the insulator 3 is usually
2 is unnecessary. 40 is an ion extraction system, 41 is an extraction electrode, and 42 is an extraction power source. Reference numeral 50 indicates other systems as necessary, such as a lens system for constricting the ion beam 18, a deflection system for deflecting the beam, and various types of systems using either an electric field or a magnetic field, or both, for sorting out impurities. The system is used. Reference numeral 51 collectively shows various electrodes for this purpose. 52 is a power supply for that purpose. 60 is a vacuum system, and 61 is a vacuum container. Although an exhaust system mainly consisting of a vacuum pump is not shown, various pumps are used depending on the degree of necessity.

70 is a cathode system, 71 is a cathode which also serves as a stand on which the object to be analyzed 72 is placed, and 73 is a heater. 80 is means for exhausting excess gas sent from the gas sending means 30;
1 is an exhaust pipe, 82 is a thermal and electrical insulator, and 83 is an exhaust port, which is evacuated in the direction of arrow 84 by a pump not shown in the figure. 90 is a mass spectrometer, 91 is a quadrupole, 92 is a quadrupole control power source, and 93 is a detector. 100 is an energy filter system, 101 is a lead-in electrode, 102 is a deflection plate, 103 is a slit, 104 is a deflection plate control power source, and 105 is a DC power source.

The operation of this device begins with the extraction of the ion beam 18. First, after evacuating the inside of the vacuum container 61 to a predetermined pressure, for example, a pressure of 10-'Pa or less, the refrigerant reservoir 14
For example, liquid nitrogen is injected as the refrigerant 15 into the refrigerant 15. after that,
For example, xenon (
The boiling point and melting point are 164.8 and 161.3, and argon is introduced at 87.3"K and 84.0", etc. In the case of introducing argon, for example, argon condenses on the surface of the needle-shaped anode 11, which has been cooled and set to a predetermined temperature by the heater 21, and becomes as if it were wetted with liquid. Then, by operating the extraction power source 42 and the acceleration power source 19, argon ions can be extracted from the tip of the needle-like anode 11 as an extremely thin beam. This ion beam 18
can be squeezed or deflected according to the purpose of use, or tp6bz4t'F'm (71elIl&
H°? =uLl [t6° J The temperature that the needle-like anode should take varies greatly depending on the material of the needle-like anode and the combination of the liquid formed on the surface, but in general, if there is no large difference in viscosity between the boiling point and melting point, It is best to choose between the midpoint and the boiling point. However, in consideration of vapor pressure, etc., a temperature closer to the melting point is sometimes used. When there is a large difference in viscosity depending on temperature, it is best to choose the temperature point where the viscosity is as small as possible. The material of the needle-shaped anode is also determined by the combination with the gas, and its shape may be made porous, stepped, or all or part of the surface is covered with a material that is particularly compatible with the specified gas. is determined by necessity.

The ion beam 18 can be focused into an extremely narrow beam with a diameter of 1 μm or less, for example. Recent experimental results have shown that it is possible to narrow down the thickness to 0.04 μm or less. This finely focused beam hits the surface of the object to be analyzed 72 and promotes the emission of various particles as the ions are incident. For example, the generated secondary ions are transferred to the drawing electrode 1
01, a deflection plate 102, a slit 103, and then guided to a concave plate mass spectrometer 90 for mass analysis. Also, for example.

Neutral particles sputtered from the surface of the analyte 72 are ionized by the ionization mechanism 110 and its electrode 111, and similarly led to the concave plate mass spectrometer 90 via the pull-in electrode 101, deflection plate 102 and slit 103, where the mass is (Methods used in the ionization mechanism 110 include various commonly used methods such as an ion gauge method, a Penning gauge method, a high wave method, and a plasma method.) As described above, the analyte 72 can analyze substances on the surface of For example, the ion beam is 0.04 μm.
By narrowing down the size to 1 μm, analysis of extremely small local areas can be performed. Furthermore, highly sensitive analysis is possible. In this case, for example, patent application No. 58-2475 of the same applicant
Good results can be obtained by using the quadrupole used in the secondary ion mass spectrometer of No. 37, and when this device is used, it is also possible to analyze insulators. As a result of selecting a substance that is a gas at the temperature of the analyte as the ion species for the ion beam 18, all ions except those ions implanted from the surface of the analyte into the interior are exhausted as a gas, so the ion species will not be mixed into the analysis results. Particularly in the past, when gallium was used as the ionic species, the needle anode 12
Gallium evaporated from the sample adheres to the surface of the analyte 72,
As a result, it may be erroneously assumed that gallium was present in the body to be analyzed from the beginning, but analysis using the apparatus of the present invention does not suffer from this problem at all.

However, even in this analysis method, it cannot be avoided that ion species are implanted into the sample and this appears in the analysis results. However, when interpreting the analysis results, for example in the case of gallium mentioned above, there are many cases where it is not surprising that it exists inside the analyte.
It is extremely rare that a normally gaseous substance such as argon or xenon exists inside the analyte, and it is easy to determine. In this way, according to the analysis device of the present invention, local analysis can be performed with high reliability.

Further, by providing a large number of gas supply means 30 in one device 10, the type of ions can be easily changed, which is very convenient.

FIG. 3 shows another embodiment of the ion source 10. In FIG.

This embodiment is the simplest and is an embodiment in which cooling with a refrigerant is not performed.The gas in the atmosphere around the needle-shaped anode 12 forms a thin adsorption layer on the surface of the needle-shaped anode, and removes ions from the surface. This is an example of a case where it can be extracted.

Furthermore, in the embodiment shown in FIG.
(which also serves as the extraction electrode 41) increases the pressure around the needle-shaped anode 11. This allows ions to be extracted more efficiently.

FIG. 5 shows another embodiment of the ion mechanism 110. A ring-shaped magnet 112 is provided inside the cylindrical electrode 111 and sets a magnetic field in the direction of an arrow 113. Inside the cylindrical electrode, the electric field and magnetic field applied from the power source 114 are perpendicular to each other, forming a Penning discharge. As a result, the neutral substance released from the surface of the analyte 72 is ionized and the drawing electrode 1014: lJ*1llO° (') J l'l '='
-210ii! ! 8 h 1% 91 r,
v and undergo mass spectrometry.

FIG. 6 shows another embodiment of the ionization mechanism 110. 111 is a coiled grid, 115 is a hot cathode,
116 is a hot cathode power source, and 117 is a grid power source. Here, electrons emitted from the hot cathode 115 ionize neutral substances emitted from the surface of the analyte 72 in the same manner as in the interior of the ion gauge, and the ions are
It is subjected to mass spectrometry in the same way as in the case shown in the figure.

Although the present invention has been described in detail above, these are not meant to be limiting in any way, and it goes without saying that many modifications are possible. Some examples will be described below.

Any ion species may be used as long as it is a gas at the temperature of the analyte, but in most cases it is desirable to select an inert species that does not react with the analyte.

The method of the present invention is based on the above-mentioned documents and patent No. 58-16562.
It goes without saying that it is possible to use a number of conventionally used techniques such as 8, as well as techniques to be developed in the future. Many techniques currently used in the field of analysis, such as moving the object to be analyzed to determine the required analysis points, can all be applied to the apparatus of the present invention. Also, the ionization mechanism 110. The energy filter system 100, deflection electrodes, etc. are designed to obtain optimal conditions each time. Although a quadrupole mass spectrometry system 90 is used in the embodiment, it may be of any type, such as a sector type or a time-of-flight type.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the invention. FIG. 2 is an enlarged sectional view of the ion source section. FIG. 3 and FIG. 4 are diagrams each showing another embodiment of the needle-like anode portion of the ion source. FIG. 5 and FIG. 6 are diagrams each showing an example of the ionization mechanism. 61
is a vacuum container. 11 is a needle anode, 12 is its tip, power source 4
2 and 19 are an extraction power source and an accelerating power source forming a means for extracting substances present on the surface of the needle-shaped anode as ions. 72 is the object to be analyzed. 18 is an ion beam, and 90 is a mass spectrometer.

Claims (1)

[Claims] A vacuum container that evacuates the inside to a predetermined pressure, its exhaust system, a needle-like anode with a sharp tip located inside the vacuum container, and a substance existing on the surface of the needle-like anode. , comprising a means for extracting the substance which is a gas at the temperature of the analyte as ions, irradiating the ion to the analyte and subjecting the substance emitted from the analyte to mass spectrometry analysis. Analyzer for