JPS61148758A - Surface analyzer - Google Patents

Abstract

PURPOSE:To enable secondary particles to be subjected to mass spectrography regardless of whether they are atoms or ions by passing the secondary particles through an electric charge converter consisting of an encircling case and a circular filament for producing thermions which has an electric potential slightly positive to that of the encircling case to convert the secondary particles into negatively charged ions. CONSTITUTION:In the surface analyzer of this invention, a beam 17 from an ion source 16 strikes against a sample 3 to produce secondary particles 9 which then pass through an electric charge converter 10 before entering a mass spectrometer 5. The electric charge converter 10 consists of a cylindrical encircling case 12 and a circular filament 13 for producing thermions which is located inside the case 12. A voltage slightly negative to that of the filament 13 is applied to the case 12 to produce thermions which are then concentrated on the center of the filament 13 thereby producing an electron cloud. Therefore, among the secondary particles 9, negatively charged ions pass as they are through the converter 10 and positively charged ions and sputter atoms are converted into negatively charged ions while passing through the converter 10 before these negatively charged ions are subjected to pass spectrography. Consequently, the accuracy of mass spectrography can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a surface analysis device that determines the composition of the surface of a solid.

<Prior art> A secondary ion mass spectrometer collides accelerated ions (referred to as -order ions) with a sample to be analyzed, guides the secondary ions emitted from the sample to a mass spectrometer, and calculates their mass. It is a struggle to identify and analyze samples. An example of the conventional method is shown in FIG. As shown in the figure, an analysis sample 3 is installed in a vacuum container 7 equipped with a vacuum pump 8, an ion source 1 is placed above the analysis sample 3, and an ion source 1 is placed above the analysis sample 3. A mass spectrometer 5 is placed diagonally above.
The mass spectrometer 5 is also connected to an amplifier 6 installed outside the vacuum vessel 7.

Secondary ion mass spectrometers such as

First, after fully evacuating the vacuum container 7 with the vacuum starch 8,
An analysis sample 3 is irradiated with an accelerated ion beam 2 generated by an ion source 1 . As a result, atoms on the surface of the sample 3 are sputtered and scattered away from the surface. Some of the stuttered atoms are ionized. This is the secondary ion 4. The secondary ions 4 are introduced into a mass spectrometer 5 to analyze their quality tt', and are extracted as electrical signals. The electric signal is amplified and recorded by the sound amplifier 6, and the composition of the sample 3 is analyzed.

<Problems to be solved by the invention> Among the secondary ions 4 emitted from the sample 3, there are those with a positive charge and those with a negative charge. Since the secondary ions have different content ratios, it is necessary to examine both positive and negative secondary ions at the same time in order to perform accurate analysis of sample 3.

However, in order to perform both measurements of positively charged secondary ions and negatively charged secondary ions with the conventional secondary ion mass spectrometer described above, it is necessary to reverse the positional relationship between the sample 3 and the mass spectrometer 5. Time is spent on this ←. Therefore, in conventional secondary ion mass spectrometers, it is difficult to simultaneously measure positive and negative secondary ions. Even if negative charged ions of gold were measured as soon as possible after measuring positive secondary ions, the state of the sample would have changed and a large error would be introduced into the analysis.

The present invention eliminates these drawbacks, and allows negatively charged secondary ions to be analyzed as they are, while positively charged secondary ions and S/4' tutter atoms can be converted into negatively charged ions by adding electrons and analyzed. Yes, negative ions, positive ions, and suA! The object of the present invention is to provide a complete surface analysis device that can simultaneously perform an analysis of Tutar atoms.

<Means for Solving the Problems> The structure of the surface analysis apparatus of the present invention that achieves the above object is to impact a sample with an accelerated primary beam and emit a secondary beam from the surface of the sample; In surface analysis, the secondary beam is passed through a charge converter and its quality is completely analyzed by a mass spectrometer. Filamen for development?
? By applying a slightly negative voltage to the cylindrical envelope' with respect to the filament, the thermoelectrons generated from the filament are concentrated in the center of the filament and formed into electrons IK'. It is characterized by becoming.

Effect> When a sample is bombarded with an accelerated ion beam or atomic beam (collectively referred to as a seventh-order beam), positive ions, negative ions, and atoms (collectively referred to as secondary particles) are sputtered from the sample surface. .This secondary particle passes through a charge converter.

In this charge converter, thermoelectrons generated from the filament are concentrated near the center of the filament to form an electron cloud, and secondary particles rush into this electron cloud. When the secondary particles are atoms, this atom captures one electron in the electron cloud and converts it into a negatively charged ion, which is ejected from the charge converter. When the secondary particles are positively charged ions,
These positively charged ions capture and neutralize electrons in the electron cloud,
After capturing another electron and converting it into a negatively charged ion,
Ejected from the charge converter. In the case of both atoms and positively charged ions, after they turn into negatively charged ions, electrical repulsion occurs between them and the electron in the center, and no further electrons attach. When the secondary particles are negatively charged ions, electrical repulsion occurs between them and the electrons in the electron cloud, so the negatively charged ions are directly ejected from the charge converter. Even if the secondary particles that enter the charge converter are atoms, positively charged ions, or negatively charged ions, they become negatively charged ions when emitted. , the mass of this negatively charged ion is analyzed by a mass spectrometer and 1. The composition of the sample surface will be fixed.

Embodiment> Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 2, an analysis sample 3 is placed in a vacuum container 7 equipped with a vacuum pump 8, and a primary beam source 16 is placed above the analysis sample 3, and further diagonally above the analysis sample 3. is a charge converter 10. A mass spectrometer 5 is arranged in sequence, and this mass spectrometer 5 is connected to an amplifier 6 installed outside the vacuum vessel 7.

In the charge converter 10, as shown in FIG.
3 are arranged concentrically and a power source 14 for filament ignition is connected to the filament 13, while a DC power source 15 connects the filament 1 to the cylindrical envelope 12.
A voltage several volts lower than 3 is applied. A large amount of thermoelectrons are emitted from the filament 13 for generating hot electrons heated by the power source 14, and these thermoelectrons are heated by the filament 13.
Since the potential of the filament 13 is maintained several volts higher than that of the envelope 12, an electron cloud is formed concentrated near the center of the filament 13. In this cloud of electrons, there is a field of snow vines.

When the particles enter, these atoms capture atoms in the electron cloud, convert them into negatively charged ions, and exit from the charge converter. Also, when positively charged secondary ions rush into such an electron cloud,
This ion captures an electron in the electron cloud, neutralizes it, attaches another electron, and is converted into a negative electron ion 10, while negatively charged secondary ions rush into the electron cloud. Then, an electrical repulsion force acts, and the capture and attachment of electrons does not occur, and these secondary ions fly out of the envelope 23 for the time being.

The surface analysis device of this embodiment having the above configuration is used as follows.

First, the vacuum container 7 and vacuum pump 8 are used to sufficiently exhaust the air. −
Next, a beam source 16 generates a high-speed ion beam or atomic beam (
- make a second beam 17) and bombard the analysis sample 3 with it; Secondary particles 9 consisting of sputtered atoms and positively charged secondary ions emitted from the sample 3 are guided to a charge converter 10 . Of the secondary particles 9 that enter this charge converter 10,
Negative and charged secondary ions pass through as they are and enter the mass spectrometer 5.
The mass is discriminated at , turned into an electrical signal, amplified by an amplifier 6, and recorded. In other words, the positively charged secondary ions of the secondary particles 9 acquire Kameko tMI inside the charge converter 10 and become neutral atoms, and then add one electron to become negatively charged ions 11. It exits the charge converter 10, is analyzed by a mass spectrometer 5, and is amplified by an amplifier 6.

Among the secondary particles 9, the sputtered atoms have one electron added to them while passing through the charge converter 10 to become negatively charged ions 11, which are analyzed by the mass spectrometer 5 and amplified by the amplifier 6. (9) Negatively charged secondary ions that enter the electron cloud inside the envelope 12 do not capture or add electrons due to electrical repulsion, and then leave the envelope 12 for subsequent mass analysis. analyzed by the meter.

<Effects of the Invention> As explained above, the present invention uses a charge converter to convert secondary particles emitted from a sample into negatively charged ions, regardless of whether they are atoms or ions, and performs mass spectrometry. It has the advantage of being able to conduct analysis with a high degree of friction, which is not affected by fluctuations in the content ratio of atoms and positive/negative ions in secondary particles originating from.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a charge converter according to an embodiment of the present invention,
FIG. 2 is a block diagram of a surface analysis device according to an embodiment of the present invention, and FIG. 3 is a block diagram of a conventional secondary ion mass spectrometer. In the drawing, 1 is an ion source, 2 is a quaternary ion beam, and 3 is an analysis sample. 4 is a secondary ion, 5 is a mass spectrometer 5, 6 is an amplifier, 7 is a vacuum container, 8 is a vacuum pump, 9 is a secondary particle, 10 is a charge converter, 11 is a negatively charged secondary ion and converts it into a negative charge 12 is an envelope, 13 is a filament for generating thermionic electrons, 14 is a power source for filament ignition, 15 is a DC power source, 16 is a quaternary beam source, 17 is a fourth-order beam. Figure 2

Claims (1)

[Claims] In a surface analysis device that impacts a sample with an accelerated primary beam to emit secondary particles from the surface of the sample, and passes the secondary particles through a charge converter to analyze their mass with a mass spectrometer, the charge The converter has a circular thermoelectron generating filament arranged concentrically inside a cylindrical envelope, and by applying a slightly negative voltage to the cylindrical envelope, the filament is A surface analysis device characterized in that thermionic electrons generated from the filament are concentrated at the center of the filament to form an electron cloud.