JPH0555832B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is useful, for example, in the field of measurement, particularly in the combination of secondary ion mass spectrometry, which is a highly sensitive analytical method, and electron microscopy, which is a high-resolution observation method. The present invention relates to a sample analysis device that is a means.

[Prior art]

Conventionally, as described in Japanese Patent Publication No. 52-22268 and the paper by Tamura et al.: Vacuum 19 (1976) PP280, the method shown in FIGS. 1 and 2 has been adopted as a charged particle detection method. Figure 1 shows a detection system that combines a scintillator 4 and a photomultiplier tube 6.The principle of operation is that charged particles are first received by the scintillator and converted into light, and the light output is converted into light with high electron multiplication. The purpose is to amplify and detect using a tube. When the ion beam 1 and the electron beam 2 are incident on this detector at the same time, the scintillator has different luminous efficiencies for ions and electrons, so it essentially functions as an electron-only detector. In other words, it is difficult to detect only ions. Even if ions and electrons can be detected simultaneously, the conventional technology using the secondary electron multiplier tube 7 cannot distinguish between the two. FIG. 2 shows a conventional example using a secondary electron multiplier tube 7 as a detector. In this case, both ions and electrons can be detected, but it is difficult to distinguish and detect both signals independently.

As described above, conventional detection methods have the disadvantage that it is difficult to detect electrons and ions simultaneously and separately.

[Purpose of the invention]

An object of the present invention is to provide a sample analyzer that can independently and quantitatively detect changes in the intensity of ion and electron superimposed irradiation beams.

[Summary of the invention]

The gist of the present invention is to provide a first means for irradiating a sample with a superimposed beam in which electrons and ions are superimposed;
a scintillator, the scintillator having the first film provided on its surface in order to make a part of the secondary electrons and a part of the secondary ions emitted from the sample by the irradiation with the superimposed beam enter the first film; a second means for mass-separating the secondary ions that did not enter the first membrane and provided on the downstream side of the flow of the secondary ions; and a specific mass extracted by the mass separation. a third means for detecting the secondary ions over time, and a fourth means for detecting the intensity of the secondary electrons over time based on light emission from the scintillator surface. The sample analyzer has a sample analyzer, wherein the first membrane substantially prevents the secondary ions incident on the first membrane from substantially remaining in the first membrane and reaching the scintillator. It is possible to prevent the
The film is formed to have a thickness such that the secondary electrons incident on the first film pass through the first film and enter the scintillator below the first film, causing the scintillator to emit light. The sample analyzer is characterized by:

The present invention utilizes the following three phenomena.

1. Permeability of charged particles into substances 2. Mass dependence of luminous efficiency 3. Mass dependence of magnetic field deflection In other words, when using a scintillator as a detector, the thickness of the conductive layer on the scintillator surface can be adjusted appropriately due to the phenomenon described in 1). By doing so, only electrons contribute to transmitted light emission. Even if there is light emission due to ion excitation, it can be made extremely small compared to electron light emission due to the effect 2). Ion detection utilizes the effect 3), that is, magnetic field deflection, to detect ions while distinguishing them from electrons. In this way, separate detection of electrons and ions in the ion-electron superimposed beam is realized.

An example in which the present invention is applied to a three-dimensional micro area analysis method will be shown. FIG. 3 shows the configuration in this embodiment. The device has a combined configuration that includes an ion microanalyzer and an electron microscope function.

This device mainly consists of a primary ion irradiation system, namely a charged particle source 10, a focusing/deflection system 11, and a sample chamber 1.
2. Sample 13, sector electric field 15 for secondary ion and electron deflection, scintillator 19 with a metal film attached to the surface, shield mesh 17, photomultiplier tube 16, CRT 22 for electron image observation, sector magnetic field 18,
Ion detector 21 and CRT 2 for ion image observation
It is composed of 3.

The operating principle is as follows. A dual plasmatron was used as the positive and negative charged particle source 10. This charged particle source is of a plasma type, and when an extraction voltage is applied to extract negative ions, negative ions and electrons 14 are emitted from the same source. When a high negative pressure is applied to the sample in this state, negative secondary ions 1 and secondary electrons 2 are removed from the sample due to the sputtering phenomenon.
are released at the same time. These ions 1 and electrons 2 pass along trajectories as shown in the figure due to the sector electric field 15, some hit the scintillator 19, and some pass through the center hole of the scintillator 19 and are affected by the sector magnetic field 1.
8 will be introduced. The ions 1 that hit the scintillator 19 are absorbed by the metal film on the surface of the scintillator,
It is difficult to illuminate the scintillator 19. On the other hand, the electrons 2 striking the scintillator 19 cause the scintillator 19 to glow due to its transparency. The light 20 generated by the electrons thus generated is received by a photomultiplier tube 16, and its output is used for electron image observation.
It is used as a brightness modulation signal for the CRT22.

On the other hand, the ion beam 1 that has passed through the center hole of the scintillator 19 is introduced into the sector magnetic field 18, and after mass separation is detected as a specific ion by the ion detector 21. This output is for secondary ion image observation.
It is used as a brightness modulation signal for the CRT 23, and is used as a two-dimensional elemental image as a secondary ion image.

In this embodiment, the primary charged particle beam 14 is
Scan in synchronization with the deflection of CRTs 22 and 23,
We succeeded in observing a scanning secondary ion image and a secondary electron image as independent images. In this case, the primary electron beam and ion beam are each independently focused by a combination of a magnetic field lens and an electric field lens (omitted), and the beam diameters on the sample are approximately 1 μm and 0.05 μm for ions and electrons, respectively. In other words, by using electrons, the shape of the sample surface can be reduced to 0.05 μm.
It was possible to observe with the following image resolution, and dynamically analyze changes in mass spectra and specific secondary ion images due to changes in shape.

As described above, according to the present invention, elemental distribution information corresponding to each surface condition can be dynamically obtained at the same time as observing the three-dimensional morphology of the sample, making multidimensional evaluation (characterization) of the sample possible. Summer.

〔Effect of the invention〕

The effects of the present invention are as follows.

1. Even when ions and electrons are superimposed on the signal system, both can be detected independently. This provides more reliable information.

2 By using the present invention, it is possible to observe three-dimensional shapes and three-dimensional shapes by utilizing the etching action and microanalysis ability of the ion beam (secondary ion mass spectrometry) and the microscopic observation ability of the electron beam (electron microscopy). It has become possible to simultaneously and continuously analyze the concentration distribution of the original elements and perform multidimensional evaluation (characterization) of substances.

[Brief explanation of the drawing]

1 and 2 are principle diagrams showing a conventional detection method, and FIG. 3 is a principle diagram showing an embodiment of the present invention. Explanation of symbols, 1...Ion beam, 2...Electron beam, 3...Conductive thin film, 4...Scintillator, 5...Light output, 6...Photodetector, 7...Secondary electron multiplier , 8... Secondary electron, 9... Faraday cup, 10... Charged particle source, 11... Focusing deflection system, 12... Sample chamber, 13... Sample, 14... Primary charged polarized particle beam, 15... Sector electric field, 16
...Photomultiplier tube, 17...Shield mesh,
18...Sector magnetic field, 19...Scintillator, 2
0...Light output, 21...Ion detector, 22,2
3...CRT.

Claims (1)

[Claims] 1. A first means for irradiating a sample with a superimposed beam in which electrons and ions are superimposed, and a portion of secondary electrons and secondary electrons emitted from the sample by the irradiation with the superimposed beam. a scintillator provided with the first membrane on its surface in order to allow some of the ions to enter the first membrane; and a scintillator for mass-separating the secondary ions that did not enter the first membrane. and a second means provided on the downstream side of the flow of the secondary ions, and a third means for detecting over time the secondary ions having a specific mass extracted by the mass separation; and a fourth means for detecting the intensity of the secondary electrons over time based on light emission from the surface of the scintillator, the first film comprising: The incident secondary ions can substantially remain in the first membrane and be substantially prevented from reaching the scintillator; A sample analysis device characterized in that the sample analysis device is formed to have a thickness such that secondary electrons pass through the first film and enter the scintillator located below the first film, causing the scintillator to emit light. 2. The sample analysis device according to claim 1, wherein the first film is either a conductive film or a metal film.