JPS59201357A - Secondary ion mass spectrometer - Google Patents

Abstract

PURPOSE:To analyze the arbitrary minute area of an insulating sample using a simple type micro-beam ion gun with the beam diameter of approximately several mm. by providing an electro-optic system and such that irradiate the arbitrary minute area in the irradiation area using a primary ion beam with an electron beam. CONSTITUTION:A micro-beam ion gun 1 forms a primary ion beam. An electrostatic lens system L converges the primary ion beam on a sample 2. An electro-optic system 3 forms the minute image of an electron source on the surface of the sample 2 and the diameter can be adjusted within the range of 0.1 to 100mum. The ion gun 1 and the electro-optic system 3 intersect each optical axis on the surface of the sample 2 and the minute area within the wide irradiation range of the primary ion beam I is irradiated with an electron beam E on the surface of the sample 2. A spherical electric field type ion energy analyzer 4 passes through only the secondary ion of low energy emitted from the surface of the sample 2 and amplifies the output signal of an ion detector 6 in an amplifier 7 through a mass spectrometer 5. The analyzer inputs the signal to a recorder 8 and records mass spectrum by using the recorder 8.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a secondary ion mass spectrometer capable of analyzing a minute region with a diameter of several μm or less.

(b) Conventional technology Secondary ion mass spectrometers irradiate the sample surface with a partial ion beam of argon ions, etc., and mass analyze the secondary ions emitted from the sample surface. A mass spectrometer requires a large duoplasmatrothermal ion system and a large electrostatic lens system as an ion gun in order to perform local analysis of several micrometers or less as described above. The equipment became expensive.

Generally, in the case of an electrically insulating sample, the sample is charged by negative ions, and the potential of the emitted secondary ions changes, causing the ions to be unable to pass through the energy analyzer that is part of the analysis system, or the ion source In many cases, this analysis method could not be applied because the potential difference between the material and the material became small.

(c) Purpose The present invention provides a secondary ion mass spectrometer that uses a simple macro beam ion gun with a beam diameter of several millimeters and is capable of analyzing a minute region of an insulating sample. The purpose is to

(d) Configuration The secondary ion mass spectrometer of the present invention uses an ion gun that uses a macro beam to irradiate a sample surface, such as a BA-type ion gun, as well as a 0.
A microbeam electron gun capable of obtaining a beam diameter of 1 to 100 μm is provided, and this electron beam can be used to target any point on the sample surface within a region that is partially irradiated by the ion beam emitted from the ion gun. By irradiating it with a ion beam, it is possible to distinguish that ion from secondary ions from other parts, and this low-energy secondary ion is selected for mass spectrometry.

Embodiment FIG. 1 shows an embodiment of the present invention. 1 is a macro beam ion gun that partially forms a beam of ions, F is a filament, G is a grid, and R-shaped liberator electrode. A gas such as argon is introduced into the repeller electrode R, and atoms of the gas are ionized by electrons accelerated between the filament F and Gri-Rad 0. It constitutes an L-sized electrostatic lens system, and focuses the -order ion beam onto the sample 2.

In the case of this ion gun, it is assumed that the ions are focused onto the sample. 3 is an electron optical system, f is a filament, W is a Wehnelt electrode, l and l' are electrostatic lens systems, which form a reduction projection system, which forms a minute image of the electron source on the surface of the sample 2, and its diameter. can be adjusted in the range of 0°1 to 100 μm. Furthermore, the scanning electrode allows the electron beam to be swung in both the X and Y directions on the surface of the sample 2. The ion gun 1 and the electron optical system 3 are arranged so that their respective optical axes intersect at the surface of the sample 2, and as shown in FIG.
The ion beam is designed to partially irradiate a small area on the surface of the sample 2 within a wide irradiation range of the ion beam. When sample 2 is electrically insulating, when irradiated with positive partial ions,
The irradiated area is positively charged, and the charged potential causes a change in the energy of the secondary ions. When the electron beam E scans the irradiated area by some of the ions, the sample The charge caused by some ions on the surface is neutralized, and secondary ions are released from that location that can pass through the energy analyzer.

Returning to FIG. 1, 4 is a spherical electric field type ion energy analyzer, which allows only low-energy secondary ions emitted from the surface of the sample 2 to pass through. Reference numeral 5 denotes a mass spectrometer, and although a quadruple separation type mass spectrometer is used in this embodiment, it may also be of a magnetic field type. Reference numeral 6 denotes an ion detector, and its output signal is amplified by an amplifier 7 and inputted to a recorder 8, which records the mass spectrum. Alternatively, the applied voltage of the mass analyzer 5 is set so that only ions of one specific mass are detected, and the output of the amplifier 7 is inputted to the CRT 9 as a brightness signal,
By synchronously scanning the CRT 9 and the electron optical system 3, it is possible to display the distribution of specific elements on the sample surface and the C-turn. In short, since it uses an ion gun that cannot focus the ion beam into a narrow one, the equipment cost is low, and even though the ion beam is relatively thick, it is generally easy to obtain a thin beam. By using an electron beam, local analysis of insulating samples has become possible.

[Brief explanation of drawings]

FIG. 1 is a side view of an apparatus according to an embodiment of the present invention, and FIG. 2 is a side view showing the relationship between a partial ion beam and an electron beam on a sample surface in the present invention. 1...Ion gun? ... Sample, 3... Electron optical system, 4... Ion energy analyzer, 5... Mass spectrometer, 6... Ion detector. Agent Patent Attorney Kosuke Agata

Claims (1)

[Claims] A macro beam ion gun that generates a partial ion beam that irradiates the sample surface, an electron optical system that irradiates an arbitrary micro region within the irradiation area of the above-mentioned secondary ion beam on the sample surface with an electron beam, and a macro beam ion gun that generates a partial ion beam that irradiates the sample surface. A secondary ion mass spectrometer comprises energy analysis means for secondary ions that pass through the energy analysis means, and mass analysis means into which ions that have passed through the energy analysis means are incident.