JP4777006B2 - Three-dimensional fine region elemental analysis method - Google Patents

Description

The present invention relates to a three-dimensional fine region elemental analysis method, elemental particular, a metal material or a semiconductor material, or an electronic device such as semiconductor devices and magnetic recording medium head with high spatial resolution in a state controlled by one layer the structure for analyzing those concerning the three-dimensional fine region elemental analysis method with features.

  Conventionally, X-ray photoelectron spectroscopy (XPS) method, Auger electron spectroscopy (AES) method, secondary ion mass spectrometry (SIMS) method or secondary neutral particle mass spectrometry (SNMS) method, electron probe for elemental analysis of fine regions A combination of a microanalyzer (EPMA) method, a transmission electron microscope (TEM) and an X-ray analysis (EDX) method or an electron beam loss spectroscopy (EELS) method, an atom probe (AP) method, etc. are used. In the case of the AES method and EPMA method, analysis in the sample depth direction is performed in combination with ion etching.

  Among these, in the atom probe method, a thin electric wire sample having a diameter of 0.2 mm or less is made into a sharp needle shape with a radius of curvature of the tip of about 100 nm or less, and a positive high voltage is applied to the sample to generate a strong electric field generated at the tip. The atoms near the tip are subjected to field evaporation to perform mass analysis of atoms or clusters emitted by the time-of-flight method (see, for example, Patent Document 1 or Patent Document 2).

  In this atom probe method, ideally, the sample is field-evaporated one atom at a time from the surface, so the element distribution in the depth direction of the sample can be known by looking at the change in the amount of detected element with respect to the analysis time. Can do.

FIG. 22 is an explanatory diagram of the principle of the three-dimensional atom probe (3DAP) method improved so that spatial decomposition in the sample surface can be performed. From the tip of the needle-shaped sample 91 using the position sensitive detector 92, FIG. The spatial distribution of the ions 93 scattered radially is measured.
In this case, since the position on the position sensitive detector 92 is an enlarged projection of the surface of the needle-shaped sample 91, it is possible to know from which position on the surface of the needle-shaped sample 91 the atom has come. A three-dimensional element distribution can be obtained from the information and the depth information of the classic atom probe.
Hereinafter, the three-dimensional atom probe method is simply referred to as an atom probe.

In the various analysis methods described above, except for the method using 3DAP and TEM that cannot analyze in the depth direction, the in-plane resolution is about 10 nm even with the best AES.
On the other hand, the depth resolution is about 0.5 to 1 nm (several atomic layers) even in the most excellent SIMS.

  In addition, the 3DAP method can obtain atomic resolution in both in-plane and depth directions in principle as described above, but requires a needle-like sample, and currently it is difficult to analyze a general device.

In addition, it is difficult to achieve atomic layer resolution even with the SIMS method, which has the best depth resolution among the analytical methods capable of fine region elemental analysis of samples having a general shape.
This is a method in which the SIMS method collides accelerated ions with a sample and transfers the momentum of the ions to the sample atoms to break the bond of the sample surface atoms and desorb them from the surface. In many cases, collisions tend to disturb the atomic arrangement over several layers from the sample surface.

  In order to solve this problem, a gas mixture containing a reactive gas and a non-reactive buffer gas is brought into close contact with the sample surface, a probe beam is applied to a certain part on the sample surface, A method of etching a sample by interaction between a gas mixture and a sample surface has been devised (see, for example, Patent Document 3).

In this proposal, an etching product generated from a predetermined site is ionized by using a laser beam, and is accelerated toward a mass spectrometer for mass analysis.
This corresponds to performing desorption of sample constituent atoms using chemical etching instead of physical impact in the time-of-flight SIMS method or SNMS method.

  In this case, the sample structure can be prevented from being destroyed by using a low-energy electron beam as the probe beam, and the spatial resolution in the sample surface can be increased by converging the electron beam.

The etching product desorption mechanism in this case is based on the principle that the reactive gas is dissociated by the probe beam, and at the same time, the sample surface atoms are excited by the electron beam, and both combine to produce a volatile reaction product. Is based.
JP 09-152410 A JP 05-152410 A JP 2003-194748 A

However, in the above-described atom probe method, the voltage required for field evaporation of the sample increases depending on the curvature radius of the sample tip,
(1) There is a problem that a sample having an extremely sharp tip is required.

In addition, in order to use the time-of-flight method, the field evaporation must be performed in a pulsed manner.
(2) There is also a problem that the high voltage for field evaporation applied to the sample must be turned on and off at high speed.

Furthermore, ideally, the sample is considered to be field evaporated one atomic layer at a time,
(3) There is a problem that there are many things that actually evaporate as clusters.
(4) In a sample in which elements having different easiness of electric field evaporation are mixed, there is a problem that an element that easily evaporates may evaporate first.

  In the case of the above-mentioned Patent Document 3, since the supply time of the gas mixture is not controlled, the gas mixture is similarly supplied to a new surface after the reaction product is desorbed by the probe beam. Therefore, it is clear that the etching of the sample proceeds indefinitely from the surface to the inside.

  Therefore, since etching always proceeds in the portion irradiated with the probe beam, it is not easy to provide the resolution in the depth direction at the atomic layer level even if the dose of the probe beam is adjusted. There's a problem.

  Therefore, the present invention performs analysis in a controlled state one by one and without being affected by the difference in the evaporation electric field of the constituent elements without applying a high voltage pulse necessary for causing field evaporation to the sample. For the purpose.

FIG. 1 is a diagram illustrating the basic configuration of the present invention. Means for solving the problems in the present invention will be described with reference to FIG.
In order to solve the above-described problem, the present invention provides a method of stopping the supply of the halogen gas after saturation adsorption of the halogen gas to the sample 1 to be analyzed in the three-dimensional fine region elemental analysis method, and energy a step of irradiating a beam 5 Ru was only adsorbed portion of the halogen gas sample to be analyzed 1 desorbed, by performing a mass analysis of the particles 6 resulting from the analyte 1 desorbed analyte sample 1 And a step of performing elemental analysis of the surface.

In this way, by using halogen gas , typically chlorine, as the gas species 3 , and utilizing saturation adsorption of the halogen gas and subsequent etching by irradiation with the energy beam 5 for desorption of elements on the surface of the sample 1 to be analyzed. , it is not necessary to apply a high electric field necessary to field evaporation as in the prior art and, without that will be affected to a difference in the evaporation electric field constituent elements, further, only the parts halogen gas adsorbed is desorbed Therefore, controlled desorption can be performed layer by layer .

Further, since the adsorbed gas species 3 forms an element and a compound on the surface of the sample 1 to be desorbed by irradiation with the energy beam 5, it does not desorb as a cluster, and is not a field evaporation but a chemical. Therefore, a sample having an extremely sharp tip is not required as the sample 1 to be analyzed.
The energy beam 5 is a particle beam such as an electron beam or an atomic beam or a light beam such as a laser beam, but is typically an electron beam or a laser beam.

  Note that etching is not progressed by simply adsorbing to the material to be etched, an etchant that is saturated with adsorption is adsorbed, and an electron beam or the like is irradiated thereto to etch only the surface layer adsorbed to the etchant. Is known as digital etching in the semiconductor high-precision processing field (see Applied Physics Letters, Vol. 56, p. 1552, 1990 if necessary).

  In this digital etching, the atoms of the first layer on the surface of the material adsorbed by the electron beam or the like are broken by the bond with the second layer by the irradiation of the electron beam or the like, and the etchant forms a molecule with the etchant and desorbs from the material. In addition, since this reaction occurs only on the surface of the material on which the etchant is adsorbed, the material can be etched while being controlled at the atomic layer level.

  As a result of diligent research, the present inventor has focused on digital etching technology in the field of high-precision semiconductor processing that is completely unrelated to the field of analysis such as the atom probe method. It is something that has been incorporated into the method.

  In this case, the desorbed particles 6 derived from the sample 1 to be analyzed are ionized by at least one of irradiation with the energy beam 5 or application of an electric field, and then accelerated by the applied electric field to fly to the detector 7.

  Also, when performing mass spectrometry, it is typical to perform elemental analysis using time-of-flight mass spectrometry. In this case, the elemental analysis data is recorded by recording the progress of desorption. Analyzing the element distribution in the depth direction from the surface of the analysis sample 1 or by projecting the desorbed particles 6 derived from the analysis sample 1 on a position sensitive detector, the analysis sample 1 of the particles 6 It is desirable to discriminate the upper desorption position, and by combining these, it becomes possible to analyze the three-dimensional element distribution of the sample 11 to be analyzed.

  Further, when the sample 1 to be analyzed is a planar sample, the energy beam 5 may be converged to irradiate the sample 1 to be analyzed locally, thereby obtaining spatial resolution within the surface of the sample 1 to be analyzed. Can do.

In this case, by scanning and irradiating the converged energy beam 5 on the surface of the analysis sample 1, it is possible to analyze the element distribution in the plane of the planar sample 1 to be analyzed.
In particular, when the converged energy beam 5 is scanned, the energy beam 5 is scanned so as to partially overlap the already desorbed portion of the gas species 3 to which the irradiation position of the energy beam 5 is adsorbed. The spatial resolution can be improved more than the diameter.

  Further, when the sample 1 to be analyzed is a planar sample, the sample 1 may be irradiated without focusing the energy beam 5, and in this case, ionized particles derived from the sample 1 to be desorbed. 6 may be imaged on a two-dimensional detector by an ion lens, whereby a spatial resolution can be obtained in the surface of the analysis sample 1.

  In addition, even when the sample 1 to be analyzed is a planar sample, when mass analysis is performed, elemental data in the depth direction from the surface of the sample 1 to be analyzed is recorded by recording elemental analysis data with respect to the progress of etching. Can be analyzed.

  In addition, when supplying the gas species 3, the pulse is supplied by using a pulse valve connected to the gas species source, or a voltage is applied to pulse electricity to a solid electrolyte containing the gas species 3 as a constituent element. Supplying in a pulse manner is a typical supply method. When a solid electrolyte is used, the amount of the generated gas species 3 can be evaluated by the amount of electricity, so that control is facilitated.

  When the sample 1 to be analyzed is a convex sample, when supplying the gas species 3, a voltage is applied to the solid electrolyte containing the gas species 3 as a constituent element by applying pulsed electricity to the lower end of the sample 1 to be analyzed. And the sample to be analyzed 1 may be heated and diffused to move to the surface of the tip of the sample 1 to be analyzed. In this case, Since there is no release of a large amount of gas species 3, the apparatus is hardly contaminated, and since there is no waiting time for exhaust, measurement can be performed quickly.

  Further, the present invention provides a gas type supply means for supplying, to a sample to be analyzed 1, a gas type 3 that is adsorbed to the sample to be analyzed 1 and etching proceeds by irradiation with an energy beam 5 in a three-dimensional fine region elemental analyzer. 2. An energy beam irradiation means 4 for irradiating only the portion where the gas species 3 is adsorbed from the surface of the sample 1 to be analyzed by irradiating the sample 1 with the energy beam 5 and etching, and the sample to be desorbed It is characterized by comprising at least an ionizing means for ionizing the particles 6 derived from No. 1, an accelerating means for accelerating the ionized particles 6 to fly to the detector 7, and the detector 7.

  In this case, the gas species supply means 2 is a pulse valve connected to a gas species source, or a voltage application for applying a voltage for electrolysis to a solid electrolyte containing the gas species 3 as a constituent element and the solid electrolyte. Means are typical.

  When a solid electrolyte is used as the gas species supply means 2, a solid electrolytic cell is typical, and each solid electrolytic cell may be disposed opposite to the sample 1 to be analyzed, or the sample 1 to be analyzed Alternatively, a solid electrolytic cell having a hollow cylindrical structure surrounding the substrate may be used.

  Alternatively, the gas species supply means 2 is provided on the cathode, the cathode, the solid electrolyte containing the gas species 3 as a constituent element, and the bottom of the sample 1 to be analyzed is provided on the cathode via a gap. And an anode for clamping and fixing the solid electrolyte, and a heating means for adjusting the temperature of the sample 1 to be analyzed.

  In addition, a reflectron may be provided in the three-dimensional fine region elemental analyzer, thereby enabling energy compensation, so that the time of flight of the particles 6 having the same mass can be made constant, and almost all complex multi-component alloys can be used. Separation of elements becomes possible.

  In this case, the gas type 3 is typically halogen, particularly chlorine, and the solid electrolyte is typically silver halide, particularly silver chloride AgCl.

  In the present invention, a high voltage pulse necessary to cause field evaporation is not applied to the sample, and the sample is controlled layer by layer, and is not affected by the difference in easiness of field evaporation by elements. The elemental analysis of the sample can be performed three-dimensionally with atomic level resolution.

  The present invention uses an etchant in which the etching of the sample does not spontaneously proceed and the adsorption is saturated, and a mechanism for supplying the etchant to the sample and an electron or light irradiation for energizing the adsorbed etchant to etch the sample By incorporating the mechanism into a three-dimensional fine region elemental analyzer, the sample is desorbed one atomic layer at a time for mass spectrometry.

  First, a needle-shaped sample or a planar sample is prepared, but in the case of a needle-shaped sample, the tip of the sample is sharp to form a radial electric field toward the detector in the same manner as the atom probe. However, since the field evaporation is not used, the radius of curvature does not have to be as small as that of the atom probe.

  Next, the etchant is adsorbed to the sample. In order to adsorb the etchant, a method of introducing an etchant gas into the vacuum chamber, a method of irradiating the sample with an etchant gas beam, or diffusion on the sample surface is used. A method of supplying the sample from the sample holding portion to the analysis portion can be considered, and an appropriate one is selected according to the sample to be analyzed and the etchant to be used.

Next, after supplying a sufficient amount of the etchant, the supply of the etchant is stopped, and then a positive high voltage for field ionization is applied to the sample, and then an electron beam or light is pulsed on the sample. When irradiated, the atoms adsorbed by the etchant on the sample surface form molecules with the etchant and desorb from the surface.
This is the time zero in time-of-flight measurement.

The 'sample atom-etchant' molecule desorbed from the surface is then immediately field ionized as in the field ion microscope.
That is, electrons are extracted from molecules by a strong electric field generated in the vicinity of a sharp sample, and become positive ions.
In the case of a planar sample, no voltage is applied to the sample, and the light beam for ionization is irradiated so that the falling part of the pulsed light beam coincides with the falling part of the etching electron beam or light. .

In general, an imaging gas used in a field ion microscope is a light rare gas atom such as He or Ne and has a large ionization potential. Therefore, field ionization occurs unless the sample itself is an electric field close to that required for field evaporation. Nonetheless, since the ionization potential of the 'sample atom-etchant' molecules produced by etching is generally much smaller than that, field ionization occurs even in samples with a smaller applied voltage or a larger radius of curvature at the tip.
It is also effective to irradiate the ionized portion with visible to ultraviolet light in order to loosen the conditions regarding the electric field strength of ionization.

After the 'sample atom-etchant' molecule is ionized, it is the same as a normal atom probe. This positive ion is attracted by the sample electric field, flies toward the detector, and measures the time until it reaches the detector. To perform mass spectrometry.
In the case of a planar sample, an extraction electrode is provided in the vicinity of the sample and ionized 'sample atoms-etchant' molecules are accelerated toward the detector.

Here, with reference to FIG. 2 thru | or FIG. 5, the three-dimensional micro area | region element analysis method of Example 1 of this invention is demonstrated.
FIG. 2 is a conceptual configuration diagram of the three-dimensional fine region elemental analyzer used in Example 1 of the present invention. A needle-shaped sample 12 to be analyzed is placed in a vacuum vessel 11 and this analysis is performed. A collimator-equipped pulse valve 13 connected to a Cl ₂ gas source is disposed in the vicinity of the tip of the sample 12, an etching electron gun 14 is disposed, and a position several hundred mm away from the sample 12 to be analyzed A sensitive detector 15 is arranged, and the potential of the position sensitive detector 15 is set to the ground potential.

  In this case, the distance between the sample 12 to be analyzed and the position sensitive detector 15 affects the mass resolution of the three-dimensional fine region elemental analyzer, and the curvature radius and ratio of the sample tip become the magnification of this device, so that the spatial resolution is reduced. Also affects.

FIG. 3 is a schematic configuration diagram of the pulse valve 13 with a collimator, which includes a pulse valve 30 and a collimator 38 attached via a gasket 40. Etchant gas is supplied for 100 microseconds (μs). It can be supplied with directionality for an arbitrary period of time greater than about.

The pulse valve 30 includes a casing 31 having an orifice 32 and a gas supply pipe 33, a poppet 35 made of ceramic or the like attached to a magnet 34 that is accommodated in the casing 31 and opens and closes the orifice 32, a poppet A spring 36 that urges the magnet 35 toward the orifice 32 via the magnet 34 and a solenoid 37 that drives the magnet 34 are provided on the outer periphery of the housing 31. Therefore, the opening time can be shortened.
As the pulse valve 30, for example, a pulse valve manufactured by General Valve Co., Ltd. (see http://www.scilab.co.jp/general_valve.html) is used.

The collimator 38 includes a capillary plate 39 on which capillaries having a diameter of about several μm to several hundred μm and a length of about several mm to several tens of mm are integrated, and the etchant beam 16 can have directionality.
As the capillary plate 39, for example, a capillary plate manufactured by Hamamatsu Photonics Co., Ltd. (see http://www.hpk.co.jp/Jpn/products/ETD/pdf/Capillary_TMCP1017J03.pdf) is used.

The electron beam 17 from the etching electron gun 14 is accelerated by an electron beam acceleration power source 19, but a beam energy of about 100 eV is appropriate. As will be described later, GaAs is Cl ₂ and the electron beam 17. In the case of etching with, all of the adsorbed Cl ₂ can be reacted by irradiating electrons of about 10 mC / cm ² .

  If the irradiation time of the electron beam 17 is 10 ns (nanoseconds) and the repetition rate is 100 kHz, once the 100 μA beam is converged to a 0.1 mm spot, one etching is completed in about 10 seconds, which is almost a normal atom. Measurement can proceed at the same speed as the probe.

  In addition, a voltage of about 10 kV is applied between the sample 12 to be analyzed and the position sensitive detector 15 by the ionization / projection power supply 20, and the desorbed molecules are ionized and ionized by the electric field generated by this voltage. The isolated ions 21 are accelerated in the electric field.

Next, the analysis process will be described with reference to FIGS. 4 and 5. FIG. 4 is a timing chart, and FIG. 5 is a conceptual explanatory diagram of the adsorption-desorption situation.
4 and FIG. 5 As for each component, the whole apparatus is installed in a vacuum vessel, and in order to avoid contamination of the sample, an ultrahigh vacuum of about 1 × 10 ⁻⁹ Torr is set.
First,
(1) The etchant beam 16 composed of Cl _{2 is} emitted from the pulse valve 13 with a collimator for several tens of milliseconds to several hundreds of milliseconds, and the chlorine atom 18 is adsorbed by only one atomic layer on the sample to be analyzed 12 composed of GaAs.
(2) Exhaust excess etchant.

Then
(3) A field ionization voltage is applied to the sample 12 to be analyzed.
At this time, if the radius of curvature of the tip of the sample 12 to be analyzed is about 100 nm as in the field ion microscope, the ionization potentials of GaCl ₃ and AsCl ₃ generated by etching of GaAs with Cl ₂ are 11.5 eV and 11.6 eV, respectively. That is about half of 21.6 eV of He24.6 eV and Ne, which are imaging gases used in the field ion microscope, and the field ionization voltage may be about half of that of a normal field ion microscope.

Then
(4) Etching is performed by irradiating the sample 12 to be analyzed with a pulsed electron beam 17 having an energy of about 100 eV and about several ns to several μs almost simultaneously with the application timing of the field ionization voltage in (3) above.
In this case, there is no problem even if it is slightly earlier than the application timing of the field ionization voltage, but if it is late, it takes time from desorption to ionization, and the analysis result becomes inaccurate.

At this time, the adsorbed Cl and Ga and As constituting the sample 12 to be analyzed are combined at a ratio of 3: 1 and desorbed as GaCl ₃ molecules and AsCl ₃ molecules, so that the irradiation process of the etchant beam 16 is performed once. Thus, the 1/3 atomic layer of the outermost layer is detached.

Then
(5) GaCl ₃ molecules and AsCl ₃ molecules desorbed from the surface are immediately ionized by a high electric field at the tip of the needle-shaped analyte 12, and the ionized desorbed species ions 21 are position sensitive to the analyte 12. It is accelerated by the electric field between the detectors 15 and reaches the position sensitive detector 15.

Then
(6) The desorbed element is identified from the time difference from the irradiation of the electron beam 17 to the position sensitive detector 15.
Then
(7) The steps (4) to (6) are repeated until the etching with the adsorbed etchant is completed, that is, until the outermost 1/3 atomic layer is completely detached.

Then
(8) Stop application of the field ionization voltage.
Then
(9) Returning to (1) above, the next layer is analyzed.
In this case, by repeating the steps (1) to (8) three times, the analysis of the outermost one atomic layer is completed in terms of conversion, and the analysis is performed up to the analysis depth that requires this repetition.

  As described above, in Example 1 of the present invention, by introducing digital etching into the atom probe method, it is possible to control one layer at a time without applying a high voltage pulse necessary to cause field evaporation on the sample. In this state, the elemental analysis of the sample can be performed three-dimensionally with atomic level resolution without being affected by the difference in easiness of field evaporation due to elements.

  Next, a three-dimensional fine region elemental analysis method according to Example 2 of the present invention will be described with reference to FIGS. 6 and 7. This Example 2 is a laser for assisting ionization in Example 1 described above. Since the beam is irradiated, the changes will be mainly described.

FIG. 6 is a conceptual block diagram of a three-dimensional fine region elemental analyzer used in Example 2 of the present invention. Except for the excimer laser 22, the three-dimensional fine region shown in FIG. Similar to the elemental analyzer, a needle-shaped sample 12 to be analyzed is placed in the vacuum vessel 11, and a pulse valve 13 with a collimator connected to a Cl ₂ gas source in the vicinity of the tip of the sample 12 to be analyzed and etching. And an excimer laser 22 for assisting ionization are arranged, and a position sensitive detector 15 is arranged at a position several hundred mm away from the sample 12 to be analyzed. Is the ground potential.

FIG. 7 is a timing chart of the second embodiment of the present invention, which assists ionization of the desorbed molecules by irradiating the pulsed laser beam 23 in synchronization with the irradiation of the electron beam 17. .

In this case, immediately after the GaCl ₃ molecule and AsCl ₃ molecule are desorbed from the surface of the sample 12 to be analyzed, the ionization potential of the molecule is lower than that in the isolated state since it is under the influence of the surface. In, the molecules are ionized because they can move to the sample-side conduction band by tunneling through the potential barrier between the molecule and the surface simply by exciting the electrons above the Fermi level of the sample, not the vacuum level.

At this time, if a high voltage is applied to the sample 12 to be analyzed, the energy level of intramolecular electrons with respect to the sample 12 to be analyzed increases, so that the energy required for ionization further decreases, and the ionization potential of the molecule in an isolated state. Is about 10 eV, it can be ionized with several eV of light depending on the voltage applied to the sample 12 to be analyzed.
Therefore, photoionization can be performed by using the excimer laser 22 having a wavelength corresponding to 3.5 eV to 6.4 eV.

  Thus, in Example 2 of the present invention, since the ionization assist laser is used in combination, the projection electric field can be set independently of the ionization electric field, and the required electric field can be reduced.

Next, referring to FIG. 8, the three-dimensional fine region elemental analysis method of Example 3 of the present invention will be described. Since Example 3 is obtained by adding a reflectron to Example 1 described above, Only the device configuration will be described.
FIG. 8 is a conceptual configuration diagram of the three-dimensional microregion element analysis apparatus used in Embodiment 3 of the present invention, and is basically the same as the three-dimensional microregion element analysis apparatus shown in FIG. A needle-shaped sample 12 to be analyzed is disposed in the vacuum vessel 11, and a pulse valve 13 with a collimator connected to a Cl ₂ gas source is disposed in the vicinity of the tip of the sample 12 to be analyzed. The electron gun 14 is disposed, the position sensitive detector 15 is disposed on the sample 12 to be analyzed, and the reflectron 24 is disposed so as to face the sample 12 to be analyzed.

  In the third embodiment of the present invention, since the reflectron 24 made of an electrostatic reflecting plate is used, the mass resolution can be dramatically improved by performing ion energy compensation, and even a complex multi-component alloy can be used. Almost all elements can be separated.

  That is, a voltage several percent higher than the maximum energy of ions is applied to the final electrode of the reflectron 24, and ions having high energy penetrate deeply into the reflectron 24 and are reflected at low positions. This is because the time of flight of ions having the same mass is increased because the time of flight of ions having high energy is increased because the time of flight is constant regardless of the magnitude of energy.

Next, a three-dimensional fine region elemental analysis method according to Example 4 of the present invention will be described with reference to FIGS. 9 and 10. This Example 4 is an example of the etchant supply source according to Example 1 described above. Since a solid electrolytic cell is used instead of the pulse valve with collimator in Example 1, only the apparatus configuration will be described.
FIG. 9 is a conceptual block diagram of a three-dimensional fine region element analyzer used in Example 4 of the present invention, and the basic structure is the same as that of the three-dimensional fine region element analyzer shown in FIG. In the vacuum vessel 11, a needle-shaped sample 12 to be analyzed is disposed, a solid electrolytic cell 25 is disposed in the vicinity of the tip of the sample 12 to be analyzed, an electron gun 14 for etching is disposed, A position sensitive detector 15 is arranged so as to face the analysis sample 12.

FIG. 10 is a schematic configuration diagram of a solid electrolytic cell. An insulating tubular housing 41 having a diameter of, for example, 1 cm made of Pyrex (registered trademark) that also serves as a collimator is provided at the bottom of the insulating tubular housing 41. The attached cathode 42 made of Ag, the solid electrolyte 43 made of AgCl filled in the insulating tubular casing 41, and the mesh anode made of Pt provided to face the cathode 42 so as to close the solid electrolyte 43 44, a heater 45 provided on the outer peripheral portion of the insulating tubular casing 41 for heating the solid electrolyte 43, an electrolysis power supply 46 for supplying an electrolysis voltage between the cathode 42 and the anode 44, and an electrolysis voltage in a pulsed manner. And an etchant supply switch 47 that supplies the etchant beam 17 in a pulse manner (for example, Journal of Vacuum Science). nd Technology, Vol.A1, see p.1554,1983).
In this case, the heater 45 is formed by depositing SnO ₂ on the outer wall of the insulating tubular casing 41.

The principle of generation of Cl ₂ by the solid electrolytic cell 25 is based on the generation of a halogen molecular gas by the electrolysis of halide. The typical cell resistance of the solid electrolytic cell 25 is about 1 kΩ, and the electrolysis of 10 to 100 μA. By passing a current, adsorption of one atomic layer can be performed in 1 to 100 seconds.

In this case, according to Faraday's law, the amount of generated halogen can be evaluated by the amount of electricity, so that it is easy to control. However, since the thermal diffusion of ions in the solid electrolyte 43 is used, the solid electrolyte 43 is made of AgCl. In this case, it is necessary to keep the temperature of the solid electrolyte 43 at about 550 K by heating with the heater 45.
The diffusion temperature can be lowered to 420 K by adding 4 to 8% by weight of cadmium halide.

  The fourth embodiment of the present invention is basically the same as the collimator-equipped pulse valve of the first embodiment. However, since there is no mechanically operated portion, no vibration is generated, and the valve closing which is often found in pulse valves is used. Since there is no leakage of time, it can be placed near the sample and supplied from the vicinity of the sample, so there is little waste of the etchant and almost no deterioration of the pressure in the vacuum chamber.

  In addition, since the control is performed only with electric current in all solids, handling is easy, and analog (multi-value) control is possible, so that the discharge amount can be controlled more accurately.

  Next, with reference to FIG. 11, the three-dimensional fine region elemental analysis method of Example 5 of the present invention will be described. This Example 5 uses a hollow cylindrical solid electrolytic cell as the solid electrolytic cell. Since other configurations are exactly the same as those of the fourth embodiment, only the solid electrolytic cell will be described.

FIG. 11 is a schematic cutaway perspective view of a main part of a solid electrolytic cell used in the three-dimensional fine region elemental analysis apparatus according to Embodiment 5 of the present invention. A pair of donut-like insulating properties with a built-in heater 52 are shown. A cathode 53 made of Ag is provided on the outer circumferential portion of the casing 51 made of a plate, and a mesh-like anode 54 made of Pt is provided on the inner circumferential portion of the casing 51. A solid electrolyte 55 made of AgCl is filled.

  Also in the case of this hollow cylindrical solid electrolytic cell 50, an electrolysis power source 56 and an etchant supply switch 57 for supplying an electrolysis voltage are provided between the cathode 53 and the anode 54, and an electrolysis voltage is applied in a pulse manner to etchant beam. Is supplied in pulses.

  In this fifth embodiment, the basic function and effect are the same as in the fourth embodiment, but by arranging the sample 12 to be analyzed at the center of the hollow cylindrical solid electrolytic cell 50, the etchant is uniformly distributed from the surroundings. It becomes possible to supply to.

  Next, a three-dimensional fine region elemental analysis method according to Example 6 of the present invention will be described with reference to FIG. 12. Although Example 6 uses a solid electrolyte, it is not a solid electrolytic cell. Since the configuration is built in a fixing mechanism for fixing the analysis sample, and the other configuration is exactly the same as that of the fourth embodiment, only the etchant supply system will be described.

FIG. 12 is a schematic configuration diagram in the vicinity of an etchant supply system constituting the three-dimensional fine region elemental analysis apparatus according to Embodiment 6 of the present invention. The upper diagram is a top view, and the lower diagram is AA ′. Is made of an insulator such as alumina or Teflon (registered trademark), a holder 61 having a recess for accommodating and fixing the solid electrolyte 64 and the anode 63, and Ag fixed to the bottom of the holder 61. A cathode 62, a solid electrolyte 64 made of AgCl accommodated in the recess so as to be in contact with the cathode 62, an anode 63 made of Pt that clamps the needle-shaped analyte 12 and is accommodated in the recess provided in the holder 61, and It consists of a heater 65 for heating the sample 12 to be analyzed.

The Cl ₂ generation principle in this case is the same as that of the solid electrolyte cell, by passing a current intermittently between the cathode 62- anode 63, a pulsed manner to generate a Cl ₂ as the etchant, generated Cl ₂ Adsorbs by colliding with the holder 61 and the anode 63 in the vicinity of the generating portion.

When Cl ₂ adsorbed on the surfaces of the holder 61 and the anode 63 is heated by the heater 65, the chlorine atoms 18 move to the surface of the lower end of the sample 12 to be analyzed by thermal diffusion in the form of Cl or Cl ⁻ . The surface of the sample 12 to be analyzed is further moved by thermal diffusion and supplied to the tip.
The heating temperature is set to a temperature of 550 K (˜277 ° C.) or less because the temperature at which Pt and Cl ₂ react to generate PtCl ₂ is 250 ° C.

In the sixth embodiment, since Cl ₂ generated by energization uses adsorption in the vicinity of the generating portion, a large amount of etchant gas is not released into the vacuum vessel 11, which may contaminate the apparatus. Further, unlike the first to fifth embodiments, the exhaust waiting time is not required, so that the measurement can be advanced promptly.

  Next, a three-dimensional fine region elemental analysis method according to Example 7 of the present invention will be described with reference to FIGS. 13 to 17. This Example 7 can be used as it is without processing the sample to be analyzed into a needle shape. Element analysis is performed with the shape, typically a flat sample.

FIG. 13 is a conceptual configuration diagram of a three-dimensional fine region elemental analyzer used in Example 7 of the present invention. A planar sample 72 is arranged in a vacuum vessel 71, and this analysis is performed. A pulse valve 73 with a collimator connected to a Cl ₂ gas source is disposed in the vicinity of the sample 72, an electron gun 74 for etching is disposed, and an extraction electrode 75 is disposed at a position about 10 mm away from the sample 72 to be analyzed. In addition, an ion detector 76 such as a channeltron is disposed at a position several hundred mm away from the sample 72 to be analyzed, and an ionization laser 77 for ionizing the desorbed species is disposed outside the vacuum vessel 71. .

  In this case, an acceleration voltage of several kV is applied to the extraction electrode 75 with the sample 72 to be analyzed as a ground potential, and the ion detector 76 has the same potential as that of the extraction electrode 75.

Further, an acceleration voltage of several hundred V to 1 kV is applied to the electron gun 74, and an electron beam pulse with an energy of about several hundred eV to 1 keV is irradiated.
This is because the energy of about 100 eV is necessary to cause the reaction efficiently as described above, the electron beam can be converged as the acceleration voltage of the electron beam is increased, and the energy of the electron beam is too large. This is because the reaction due to secondary electrons occurs and the in-plane resolution is lowered.

In addition, the larger the electron beam current, the faster it can be desorbed, but if a large number of particles desorb in a short time, the detector may count off, and if the current density is too large, May be locally heated and damaged.
In reality, it is difficult to flow a large current while strongly focusing a relatively low energy electron beam. For example, when the irradiation area is about ² nanometers (nm ² ), the current of the electron beam pulse is It is set to about nanoampere (nA) during irradiation.

In the ionization laser 77, since the ionization energies of the reactive organisms GaCl ₃ and AsCl ₃ are 11.5 eV and 11.6 eV, respectively, the excitation light in the case of photoionization is in the vacuum ultraviolet region, and ionization is ensured. In order to do so, a high-intensity light source is required, the etching is a pulse operation, unnecessary light generates extra photoelectrons and ions, the background increases, and unintended etching proceeds. Because of the possibility, a pulse light source having a large peak intensity synchronized with the electron beam is desirable.

  For this purpose, high-order harmonics of pulsed laser light can be generated using a rare gas jet or a rare gas cell, or synchrotron radiation can be used.

Next, the analysis process will be described with reference to FIGS. 14 and 16. FIG. 14 is a timing chart, and FIGS. 15 and 16 are conceptual explanatory views of the adsorption-desorption situation.
14 and FIG. 15 As for each component other than the ionization laser 77, the entire apparatus is installed in a vacuum vessel, and an ultra-high vacuum of about 1 × 10 ⁻⁹ Torr is set to avoid contamination of the sample.
First,
(1) The etchant beam 78 made of Cl _{2 is} emitted from the pulse valve 73 with a collimator for several tens of milliseconds to several hundreds of milliseconds, and the chlorine atom 79 is adsorbed by one atomic layer on the sample 72 made of GaAs.
In this case, the exposure amount (supply amount) may be determined separately by the amount of saturated adsorption by XPS or the like, or when the energy beam is sufficiently irradiated by changing the exposure amount in the apparatus of the present invention. It is possible to actually measure the amount at which the amount of desorbed saturates. In either case, the exposure amount is controlled so strictly because an etchant that adsorbs only one layer to the sample 72 and saturates the adsorption is used. If it is sufficiently exposed, the necessary adsorption state can be obtained.

Then
(2) Exhaust excess etchant.
This operation is necessary to prevent excessive etching due to excessive etchant residue and to ensure depth resolution.

Then
(3) The sample 72 to which the etchant is adsorbed is subjected to etching by focusing and locally irradiating a pulsed electron beam 80 of about 10 ns with an electrostatic deflector or the like, and removing from the sample 72 to be analyzed. The desorbed molecule 81 is desorbed.
The electron beam pulse time width in this case is determined by a trade-off between the electron beam current value, the analysis speed, and the detection efficiency.

That is, if the number of electrons irradiated with one electron beam pulse is large, the number of times of repeated irradiation until all the etchants disappear can be reduced. However, if the time width of the electron beam pulse is too large, the electron beam pulse irradiation starts. The time until the start of ionization and ion acceleration becomes longer, and the desorbed molecules 81 desorbed at an early stage of the electron beam irradiation period are scattered from the analysis portion, so that the detection sensitivity is lowered.
Therefore, the time width of the electron beam pulse is about 10 nsec as described above.

When GaAs is etched with Cl ₂ and an electron beam, all of the adsorbed Cl ₂ can be reacted by irradiating electrons of about 10 mC / cm ² .
Therefore, assuming that the diameter of the electron beam, that is, the diameter of one analysis range is 1 nm, desorption is completed by irradiating a beam with a current of 1 nA and a pulse width of 10 nsec 10 times.

Since there are about 10 surface atoms in this range and about one particle is detached in one pulse, detection is possible without any problem.
When analyzing the range of 100 nm × 100 nm, the number of analysis points is 10,000. Therefore, if the repetition frequency of the electron beam pulse is 10 kHz, the reaction of one layer can be completed in 10 seconds.

At this time, the adsorbed Cl and Ga and As constituting the sample 72 to be analyzed are combined at a ratio of 3: 1 and desorbed as GaCl ₃ molecules and AsCl ₃ molecules, so that the irradiation process of the etchant beam 78 is performed once. Thus, the 1/3 atomic layer of the outermost layer is detached.

See FIG. 14 and FIG.
(4) A laser pulse 82 for photoionization is irradiated in accordance with the end of electron beam irradiation, and GaCl ₃ molecules and AsCl ₃ molecules desorbed from the surface are ionized positively.
In this case, high-order harmonics from the vacuum ultraviolet to the soft X-ray region are generated by irradiating a rare gas jet or the like with ultrashort pulse laser light having a wavelength of 800 nm and shorter than 100 fsec from a Ti: sapphire laser.

Then
(5) Simultaneously with the end of electron beam irradiation, a voltage of −several kV for accelerating desorption species ions is applied to the extraction electrode 75 to accelerate the desorption species ions 83 toward the ion detector 76.
At this time, since the extraction electrode 75 and the ion detector 76 are at the same potential, the ions fly toward the ion detector 76 at a constant speed after passing through the extraction electrode 75.
This time becomes zero when performing time-of-flight mass spectrometry.

Then
(6) The desorbed species ions 83 are detected by the ion detector 76.
When using time-of-flight mass spectrometry, the mass of the desorbed species ions 83 is known from the time of flight until detection, so the desorbed element is identified.

Then
(7) The steps (4) to (6) are repeated until the etching with the adsorbed etchant is completed, that is, until the outermost 1/3 atomic layer is completely detached.
Practically, the number of repetitions for completing the reaction may be obtained in advance, and the above-described steps after the electron beam irradiation may be repeated for that number of times.

Then
(8) Returning to (1) above, the next layer is analyzed.
In this case, by repeating the steps (1) to (7) three times, the analysis of the outermost one atomic layer is completed in terms of conversion, and the analysis is performed up to the analysis depth that requires this repetition.

Then
(9) The irradiation position of the electron beam is moved to the next analysis place, and (1) to (8) are repeated.
A general in-plane analysis can be performed by raster scanning the electron beam irradiation position.

  (10) When the in-plane analysis is completed, the depth information to be recorded is increased by the unit depth (layer thickness), the process returns to (1) above, the next layer is analyzed, and the necessary depth is obtained. Only (1) to (9) are repeated, and the three-dimensional analysis is performed.

  In order to advance the analysis in the depth direction, an etchant must be supplied for each layer. Therefore, the excess etchant exhaust time greatly affects the analysis speed in the depth direction, but if the exhaust time is 10 seconds, the etchant 1 nm deep analysis is possible in 1 to 2 minutes including the supply time and the net analysis time of each layer.

FIG. 17 is an explanatory diagram of the movement of the electron beam irradiation position. As shown in the upper diagram, when scanning is performed in 1 nm steps with a small spot diameter of about 1 nm, a gap is generated between analysis points. Therefore, in order not to generate a gap, the analysis point moving step may be reduced.

  Alternatively, as shown in the figure below, an electron beam with a slightly larger spot diameter may be used to scan, for example, in 1 nm steps, and etching does not occur even when the electron beam is irradiated to the part where desorption has been completed. Even if a thick electron beam is used, the in-plane resolution can be kept higher than the beam diameter.

  As described above, in Example 7 of the present invention, by introducing digital etching into the atom probe method, field evaporation is not required and is controlled in a layer-by-layer manner. The elemental analysis of the planar sample can be performed three-dimensionally with atomic level resolution without being affected by the difference in ease.

  Next, a three-dimensional fine region elemental analysis method according to Example 8 of the present invention will be described with reference to FIG. 18. This Example 8 differs only in the ionization laser pulse used, and the other steps are as described above. Since this example is exactly the same as Example 7, only the timing chart is shown.

See FIG. 18 In exactly the same manner as in the seventh embodiment, the supply of the etchant (1) to (3), the exhaust of the excess etchant, and the electron beam irradiation are performed.

Then
(4 ′) Irradiation with a laser pulse for photoionization is performed so that the electron beam irradiation start timing coincides with the rise of the pulsed laser beam, and GaCl ₃ molecules and AsCl ₃ molecules desorbed from the surface are ionized positively. .
In this case, an ArF excimer laser having a wavelength of 193 nm is used as a light source, and ionization is performed by a two-photon process.

  Thereafter, the analysis of the planar sample is completed by repeating the steps (5) to (10) in exactly the same manner as in Example 7 above.

  Next, a three-dimensional fine region elemental analysis method according to Example 9 of the present invention will be described with reference to FIGS. 19 and 20. This Example 9 does not converge the etching electron beam and covers a wide area. And a position sensitive type two-dimensional detector is used.

FIG. 19 is a conceptual configuration diagram of a three-dimensional fine region elemental analyzer used in Example 9 of the present invention. A flat sample 72 is arranged in a vacuum vessel 71, and this sample is analyzed. A pulse valve 73 with a collimator connected to a Cl ₂ gas source is disposed in the vicinity of the sample 72, an electron gun 74 for etching is disposed, and an extraction electrode 75 is disposed at a position about 10 mm away from the sample 72 to be analyzed. A position sensitive detector 84 is disposed at a position several hundred mm away from the sample 72 to be analyzed, and an ion lens 85 such as an Einzel lens composed of an entrance electrode 86, an intermediate electrode 87 and an exit electrode 88 is disposed therebetween. In addition, an ionization laser 77 for ionizing the desorbed species is disposed outside the vacuum vessel 71.

  In this case, an acceleration voltage of several kV is applied to the extraction electrode 75 with the sample 72 to be grounded, and the position sensitive detector 84, the inlet electrode 86, and the outlet electrode 88 have the same potential as the extraction electrode 75.

  Further, a deionized ion focusing voltage that is several hundred to several kV higher than the acceleration voltage is applied to the intermediate electrode 87 to form an Einzel lens. In this case, the desorbed ion focusing voltage is desorbed by the ion lens 85. Adjustment is performed so that the seed ions 83 are imaged on the position sensitive detector 84 having the same potential as the outlet electrode 88.

Similarly to the seventh embodiment, an acceleration voltage of several hundred V to 1 kV is applied to the electron gun 74 and an electron beam pulse having an energy of about several hundred eV to 1 keV is irradiated.
However, in Example 9, since the electron beam 89 having a large beam diameter that can be irradiated simultaneously to the entire analysis range is irradiated, it is not a convergent beam.

Since the current in this case is 15,000 nm ² when the radius of the irradiation range is 70 nm, a beam current of about 15 μA is required if the current density is the same as in Example 7.
However, if the current density is the same as in Example 1, the particles are desorbed all at once from the entire analysis region, so that the number of desorbed particles is too large and the analysis becomes difficult.

  In general, when performing time-of-flight measurements with a position sensitive detector such as a delay line, it is possible to measure at short time intervals, but typically no more than one particle is incident on the detector simultaneously. Therefore, the current of the electron beam needs to be about nanoamperes as a whole.

Next, the analysis process will be described with reference to FIG.
As shown in FIG. 20, each component other than the ionization laser 77 is installed in a vacuum container, and an ultrahigh vacuum of about 1 × 10 ⁻⁹ Torr is used to avoid contamination of the sample. To do.
First,
(1) An etchant beam 78 made of Cl _{2 is} emitted from a pulse valve 73 with a collimator for several tens of milliseconds to several hundreds of milliseconds, and a chlorine atom 79 is adsorbed by one atomic layer on a sample 72 made of GaAs,
(2) Exhaust excess etchant.

Then
(3) A pulsed electron beam 89 of about 10 ns is subjected to in-plane decomposition by the position sensitive detector 84 with respect to the sample 72 to which the etchant is adsorbed, so that it does not converge, for example, in a region having a radius of 70 nm. Irradiate to etch.

Then
(4) A laser pulse 82 for photoionization is irradiated in accordance with the end of electron beam irradiation, and GaCl ₃ molecules and AsCl ₃ molecules desorbed from the surface are ionized positively.
Also in this case, a high-order harmonic is generated from the vacuum ultraviolet to the soft X-ray region by irradiating a rare gas jet or the like with an ultrashort pulse laser beam having a wavelength of 800 nm and shorter than 100 fsec from a Ti: sapphire laser.

Then
(5) Simultaneously with the end of the electron beam irradiation, a voltage of −several kV for accelerating the desorption species ions is applied to the extraction electrode 75 to accelerate the desorption species ions 83 toward the position sensitive detector 84.
This time becomes zero when performing time-of-flight mass spectrometry.

The accelerated desorbed species ions 83 pass through the ion lens 85 to form an enlarged image on the position sensitive detector 84, and the flying position of the desorbed species ions 83 on the secondary plane is identified. It will be.
In SIMS, it is known to enlarge and project using an ion lens (for example, see Utility Model Registration No. 2520827).

Then
(6) The position sensitive detector 84 detects the desorbed species ions 83.
When using time-of-flight mass spectrometry, the mass of the desorbed species ions 83 is known from the time of flight until detection, so the desorbed element is identified.

Then
(7) The steps (4) to (6) are repeated until the etching with the adsorbed etchant is completed, that is, until the outermost 1/3 atomic layer is completely detached.
Practically, the number of repetitions for completing the reaction may be obtained in advance, and the above-described steps after the electron beam irradiation may be repeated for that number of times.
If the etchant remains even after the necessary number of data has been integrated, the electron beam with a large current may be irradiated to omit the analysis and complete the reaction by the etchant.

Then
(8) Returning to (1) above, the next layer is analyzed.
In this case, by repeating the steps (1) to (7) three times, the analysis of the outermost one atomic layer is completed in terms of conversion, and the analysis is performed up to the analysis depth that requires this repetition.

Then
(9) The irradiation position of the electron beam is moved to the next analysis place, and (1) to (8) are repeated.
A general in-plane analysis can be performed by raster scanning the electron beam irradiation position.

  (10) When the in-plane analysis is completed, the depth information to be recorded is increased by the unit depth (layer thickness), the process returns to (1) above, the next layer is analyzed, and the necessary depth is obtained. Only (1) to (9) are repeated, and the three-dimensional analysis is performed.

  As described above, in the ninth embodiment of the present invention, the analysis of a wide analysis region can be performed at the same time, so that the analysis time can be shortened compared to the case of the seventh embodiment.

  Next, a three-dimensional fine region elemental analysis method according to Example 10 of the present invention will be described with reference to FIG. 21. This Example 10 differs only in the ionization laser pulse to be used. Since this is exactly the same as the ninth embodiment, only the timing chart is shown.

See FIG. 21. In exactly the same manner as in the ninth embodiment, the supply of the etchant (1) to (3), the exhaust of the excess etchant, and the electron beam irradiation are performed.

Then, as in Example 8 above,
(4 ′) Irradiation with a laser pulse for photoionization is performed so that the electron beam irradiation start timing coincides with the rise of the pulsed laser beam, and GaCl ₃ molecules and AsCl ₃ molecules desorbed from the surface are ionized positively. .
Also in this case, ionization is performed by a two-photon process using an ArF excimer laser having a wavelength of 193 nm as a light source.

  Thereafter, the analysis of the planar sample is completed by repeating the steps (5) to (10) in exactly the same manner as in Example 9 above.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the conditions and configurations described in the embodiments, and various modifications can be made. For example, the devices described in the embodiments The material can be arbitrarily changed as long as its properties are maintained.

In each of the above embodiments, Cl ₂ is used as an etchant, but is not limited to Cl _2, and may be other halogen gas such as F ₂ or Br _2. An etchant other than the halogen gas may be used depending on the type of constituent elements.

  In each of the above embodiments, the sample to be analyzed is GaAs. However, it goes without saying that the sample is not limited to GaAs, and other III-V group compound semiconductors such as InAs, or IV such as Si. The present invention can also be applied to group semiconductors, and can also be applied to metal materials other than semiconductors.

For example, since a metal halide has a high vapor pressure, Cl ₂ is adsorbed on a metal sample by the method shown in Example 1 above, and then the temperature is instantaneously increased using an energy beam to cause metal chloride. What is necessary is just to detach | desorb as a thing.

In the case of a single crystal sample, for example, Cl ₂ dissociates and adsorbs on the (001) face of Ni, and the adsorption is saturated at an adsorption ratio of 0.5 ML (monolayer).
Thereafter, for example, the sample is instantaneously heated to several hundred K using an infrared to visible light pulse laser composed of Nd: YAG fundamental wave or second harmonic wave, and desorbed in the form of NiCl ₂ by thermal desorption. The elemental analysis of the surface atoms can be performed by setting the laser irradiation time to zero.
If the portion heated by the laser beam is limited to the tip of the sample, the heat is dissipated from the handle portion of the sample and the sample holder, so that the sample is quickly cooled.

  In the first to third embodiments, the entire pulse valve with a collimator is accommodated in a vacuum vessel for the sake of simplicity. However, in order to install in an ultra-high vacuum system, baking is performed. For this purpose, it is desirable to install the pulse valve unit outside the vacuum vessel and place only the capillary plate in the vicinity of the sample in the vacuum vessel.

  In Examples 4 to 6, AgCl is used as the solid electrolyte. However, other silver halides such as AgBr may be used, and the silver electrolyte is not limited to silver. Other halogen compounds may be used.

  Further, in Examples 4 to 6 described above, Ag is used as the cathode, but it is not limited to Ag, and may be other metals, and in particular, composed of the same metal as the metal element constituting the fixed electrolyte. Therefore, even when the electrolysis progresses and the metal element constituting the fixed electrolyte is deposited on the cathode, the electrolysis conditions do not change.

  Further, in Examples 4 to 6 described above, Pt is used as the anode, but it is not limited to Pt, and any metal having high resistance to the etchant used may be used.

  In the second embodiment, an excimer laser having a wavelength corresponding to 3.5 eV to 6.4 eV is used as the ionization assist laser. However, the excimer laser is not limited to the excimer laser, and the third harmonic of the Nd: YAG laser ( Harmonics such as 3.5 eV) or fourth harmonic (4.7 eV) may be used.

  In the fourth embodiment, the collimator portion is formed integrally with the housing. However, the collimator portion may be manufactured as an independent part using a material that is not corroded by the etchant halogen.

Further, in Example 6 described above, the solid electrolyte is hidden as much as possible in order to prevent the outflow of gas into the vacuum chamber while ensuring a path from the etchant generation part through the surface only to reach the sample tip as short as possible. to it are constituted, the shape surrounding almost completely the shape of the anode of the clamp from both sides through a gap the solid electrolyte, for example, a pair of horizontal cross-section by an arc-shaped anode, the Cl ₂ The outflow into the vacuum chamber can be more effectively suppressed.

  Further, in the above-described third to sixth embodiments, ionization is performed only by field ionization using an ionization electric field, but an ionization assist laser may be used in combination as in the second embodiment.

  In each of the above embodiments, at least an ionization electric field is used for ionizing the desorbed molecules. However, a particle beam including an electron beam or a laser beam may be used without using the ionization electric field at all. In this case, an energy beam having an energy of about 10 eV or more, which is the ionization potential of the molecule, may be irradiated.

  In Example 2 and Examples 4 to 6, the ionized molecules flying from the sample to be analyzed are detected as they are by the detector, but they are detected via the reflectron as in Example 3. It is also possible to perform detection with high accuracy.

  In each of the above embodiments, desorption of molecules is performed by electron beam irradiation, but the present invention is not limited to electron beams, and other particle beams such as Ar beams may be used. Furthermore, a light beam such as a laser beam may be used.

  In Examples 7 and 8, the desorbed species ions accelerated by the extraction electrode are caused to fly as they are through the flight tube and enter the charged particle detector. However, in order to increase detection efficiency, An ion lens or a collimator may be inserted into the tube, or a reflectron may be used to increase the mass resolution.

In Examples 7 and 8 described above, mass spectrometry is performed in a time-of-flight type, but other types of mass spectrometry methods such as a quadrupole mass analyzer may be used. It is possible to increase the repetition frequency of the application of the electron beam, the ionization light pulse, and the extraction voltage without being limited by time.
However, using a non-time-of-flight mass analyzer can increase the analysis speed, but at the same time, only a single mass molecular species can be detected. Lower.

Furthermore, it is also possible to use the electron beam that is not pulsed while applying the extraction voltage and continuously perform the steps (3) and subsequent steps.
In this case, it goes without saying that adjustment is performed so that the electron beam is irradiated to a desired position while the extraction voltage is applied.

Further, in the above-described Examples 9 and 10, a position sensitive detector capable of time resolution is used for detection of desorbed species ions, but it is not limited to the position sensitive detector, and a combination of a fluorescent screen and a CCD camera is used. It can be used.
In addition, when performing time-resolved measurement in units of microseconds or less with a combination of a fluorescent screen and a CCD camera, it is possible to detect incident particles simultaneously if the position on the detector surface is different. Due to speed limitations, continuous measurement cannot be performed at time intervals of about several microseconds or less, and repeated measurement must be performed under the same conditions while shifting the imaging time from the trigger. For example, a 50 microsecond period has a resolution of 10 nanoseconds. If it measures by 50,000, the measurement of 50,000 times will be needed.

  In order to reduce the influence of changes in the conditions (residual particles) due to the progress of measurement, if, for example, half of the surface atoms remain after the completion of a set of 5,000 repetitions, the total nanoamperes are also obtained. It is necessary to set the current to a degree.

The detailed features of the present invention will be described again with reference to FIG. 1 again.
Referring again to FIG. 1 (Appendix 1), the halogen gas is saturatedly adsorbed on the sample 1 to be analyzed, and then the supply of the halogen gas is stopped, and the energy gas 5 is irradiated to adsorb the halogen gas on the sample 1 to be analyzed. characterized in that it comprises the only the steps of the Ru desorbed portion, and performing elemental analysis of the sample to be analyzed first surface by performing a mass analysis of the particles 6 resulting from the analyte 1 desorbed Three-dimensional fine region elemental analysis method.
(Supplementary Note 2) after the and therefore ionize to application of an electric field the particles 6 resulting from the desorbed sample to be analyzed 1, Appendix 1, characterized in that to fly to the analyzer to accelerate desorption species ions ionized 3D micro region elemental analysis method according to.
(Supplementary Note 3) when performing the mass spectrometry, three-dimensional micro-regions elemental analysis method according to Appendix 1 or Appendix 2 perform elemental analysis using mass spectrometry time-of-flight.
(Additional remark 4) When performing the said mass spectrometry, the element distribution to the depth direction from the surface of the said to- be-analyzed sample 1 is analyzed by recording the data of the elemental analysis with respect to progress of desorption, The additional remark characterized by the above-mentioned The three-dimensional fine region elemental analysis method according to any one of 1 to Appendix 3.
(Supplementary Note 5) when performing the mass spectrometry, the by enlarged and projected position sensitive detector particles 6 resulting from the desorbed analytes 1, leaving on the sample to be analyzed 1 of the particles 6 The three-dimensional fine region elemental analysis method according to any one of supplementary notes 1 to 4, wherein the position is determined.
(Supplementary Note 6) when performing the mass spectrometry to analyze the three-dimensional element distribution of the sample to be analyzed 1 by recording the detachment position of the particles 6 resulting from the analyte 1 on the progression of desorption The three-dimensional fine region elemental analysis method according to appendix 5 , characterized by:
(Supplementary Note 7) The sample to be analyzed is planar sample, and three-dimensional micro-region elemental analysis according to Appendix 1, characterized by locally irradiating converged said energy beam to said sample to be analyzed Method.
(Supplementary Note 8) 3-dimensional microscopic region elemental analysis method described energy beam is the converged to Appendix 7, characterized in that irradiation is scanned over the surface of the analytical sample.
When scanning (Supplementary Note 9) energy beam is the convergence, and wherein the scanning the energy beam so as to overlap the energy beam part and already desorption part of the gas species is adsorbed irradiation position The three-dimensional fine region elemental analysis method according to appendix 8.
(Supplementary Note 10) In the case of the sample to be analyzed is planar sample, and irradiates the sample to be analyzed without converging said energy beam, the ionized particles derived from analytes that releases the de-ion The three-dimensional fine region elemental analysis method according to appendix 1 , wherein the image is formed on a two-dimensional detector by a lens.
(Supplementary Note 11) when performing the mass spectrometry, Appendix 7, wherein analyzing the element distribution in a depth direction from the sample to be analyzed first surface by recording the data of elemental analysis on the progression of etching The three-dimensional fine region elemental analysis method according to any one of 1 to appendix 10.
(Supplementary note 12) The three-dimensional fine region element according to any one of Supplementary notes 1 to 11, wherein the halogen gas is supplied in a pulse manner using a pulse valve connected to a halogen gas source. Analysis method.
Supply (Note 13) said halogen gas, any one of Appendixes 1 to Appendix 12 and supplying the halogen gas contains the solid electrolyte by applying a voltage to the electrical pulse in a pulsed manner but as a constituent element 1 The three-dimensional fine region elemental analysis method described in 1.
(Supplementary Note 14) The sample to be analyzed is convex sample, and, the supply of the halogen gas, by applying a voltage pulse electricity to the solid electrolyte containing as an element the halogen gas in the sample to be analyzed 1 After the pulse is supplied to the lower end and adsorbed on the surface, the sample 1 to be analyzed is heated to thermally diffuse the adsorbed halogen gas and move to the surface of the tip of the sample 1 to be analyzed. The three-dimensional fine region elemental analysis method according to any one of supplementary notes 1 to 6, which is a feature.
(Supplementary Note 15 ) Halogen gas supply means for supplying a halogen gas to the sample 1 to be analyzed, a portion where the sample 1 is irradiated with an energy beam 5 and etching proceeds to adsorb the halogen gas from the surface of the sample 1 to be analyzed Energy beam irradiation means 4 for desorbing only ions, ionization means for ionizing particles 6 derived from the desorbed sample 1 , acceleration means for accelerating and flying the ionized particles 6 to a detector 7, and A three-dimensional fine region elemental analysis apparatus comprising at least a detector (7).
(Supplementary note 16 ) The three-dimensional microregion elemental analysis apparatus according to supplementary note 15, wherein the ionized particle 6 is detected by a detector 7 through a reflectron.
(Supplementary note 17 ) The three-dimensional fine region elemental analysis apparatus according to supplementary note 15 or 16 , wherein the halogen gas supply means includes a pulse valve connected to the halogen gas source.
Appendix (Supplementary Note 18) The halogen gas supply means, characterized in that it includes a voltage application means for applying a voltage for electrolysis to the solid electrolyte and the solid electrolyte containing the halogen gas as an element 16 Or the three-dimensional fine region elemental analyzer according to appendix 17 .
(Supplementary note 19 ) The three-dimensional fine region elemental analysis apparatus according to supplementary note 18, wherein the halogen gas supply means is a solid electrolytic cell containing a solid electrolyte containing the halogen gas as a constituent element.
(Supplementary Note 20) The solid electrolytic cell, said surround the sample to be analyzed 1, 3-dimensional micro-regions elemental analyzer according to note 19, which is a solid electrolyte cell having a hollow cylindrical structure.
(Supplementary Note 21) The halogen gas supply means, a cathode, disposed on the cathode, a solid electrolyte provided on the cathode through said gap at the bottom of the sample to be analyzed 1 with containing the halogen gas as an element The three-dimensional microregion according to appendix 18 , further comprising: an anode that clamps and fixes the sample 1 to be analyzed and a solid electrolyte; and a heating unit that adjusts the temperature of the sample 1 to be analyzed. Elemental analyzer.
(Supplementary note 22) The three-dimensional fine region elemental analyzer according to any one of supplementary notes 18 to 21 , wherein the solid electrolyte is silver halide.

  As an application example of the present invention, analysis of a composition distribution such as an impurity concentration distribution of a sample using a semiconductor such as a III-V group compound semiconductor such as GaAs is typical, but a multilayer made of a metal material such as a GMR element is typical. The present invention is also applied to a three-dimensional structural analysis of a thin film laminated structure.

It is explanatory drawing of the fundamental structure of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a notional block diagram of the three-dimensional micro area | region element analyzer used for Example 1 of this invention. It is a schematic block diagram of a pulse valve with a collimator. It is a timing chart of the three-dimensional fine region elemental analysis method of Example 1 of the present invention. It is a conceptual explanatory drawing of the adsorption-desorption state in the three-dimensional fine region elemental analysis method of Example 1 of the present invention. It is a notional block diagram of the three-dimensional micro area | region element analyzer used for Example 2 of this invention. It is a timing chart of the three-dimensional fine area elemental analysis method of Example 2 of the present invention. It is a notional block diagram of the three-dimensional micro area | region element analyzer used for Example 3 of this invention. It is a notional block diagram of the three-dimensional micro area | region element analyzer used for Example 4 of this invention. It is a schematic block diagram of a solid electrolytic cell. It is a schematic principal part notch perspective view of the solid electrolytic cell used for the three-dimensional micro area | region elemental analyzer of Example 5 of this invention. It is a schematic block diagram of the etchant supply system vicinity which comprises the three-dimensional micro area elemental analyzer of Example 6 of this invention. It is a notional block diagram of the three-dimensional micro area elemental analyzer used for Example 7 of this invention. It is a timing chart of the three-dimensional fine area elemental analysis method of Example 7 of this invention. It is a conceptual explanatory drawing to the middle of the adsorption-desorption state in the three-dimensional fine region elemental analysis method of Example 7 of the present invention. It is a conceptual explanatory drawing after FIG. 15 of the adsorption | suction-desorption state in the three-dimensional micro area | region elemental analysis method of Example 7 of this invention. It is explanatory drawing of the movement condition of the irradiation position of the electron beam in the three-dimensional micro area elemental analysis method of Example 7 of this invention. It is a timing chart of the three-dimensional fine region elemental analysis method of Example 8 of the present invention. It is a notional block diagram of the three-dimensional fine area elemental analyzer used in Example 9 of the present invention. It is a timing chart of the three-dimensional fine area elemental analysis method of Example 9 of this invention. It is a timing chart of the three-dimensional fine area elemental analysis method of Example 10 of this invention. It is explanatory drawing of the principle of a three-dimensional atom probe method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Analyzed sample 2 Gas seed | species supply means 3 Gas seed | species 4 Energy beam irradiation means 5 Energy beam 6 Particle | grain 7 Detector 11 Vacuum container 12 Analyzed sample 13 Pulse valve 14 with a collimator Electron gun 15 Position sensitive detector 16 Etchant beam 17 Electron Beam 18 Chlorine atom 19 Electron beam acceleration power supply 20 Ionization / projection power supply 21 Desorption species ion 22 Excimer laser 23 Laser beam 24 Reflectron 25 Solid electrolysis cell 30 Pulse valve 31 Housing 32 Orifice 33 Gas supply pipe 34 Magnet 35 Poppet 36 Spring 37 Solenoid 38 Collimator 39 Capillary plate 40 Gasket 41 Insulating tubular housing 42 Cathode 43 Solid electrolyte 44 Anode 45 Heater 46 Electrolytic power supply 47 Etchant supply switch 51 Housing 52 Heater 53 Cathode 54 Anode 55 Solid electrolyte 56 Electrolytic power source 57 Etchant supply switch 61 Holder 62 Cathode 63 Anode 64 Solid electrolyte 65 Heater 71 Vacuum vessel 72 Sample 73 Collimated pulse valve 74 Electron gun 75 Extraction electrode 76 Ion detector 77 Ionization laser 78 Etchant Beam 79 Chlorine atom 80 Electron beam 81 Desorbed molecule 82 Laser pulse 83 Desorbed species ion 84 Position sensitive detector 85 Ion lens 86 Inlet electrode 87 Intermediate electrode 88 Exit electrode 89 Electron beam 91 Needle-shaped sample 92 Position sensitive detector 93 ion

Claims (4)

A step of saturatedly adsorbing the halogen gas to the sample to be analyzed and then stopping the supply of the halogen gas;
A step of Ru was only desorbed adsorbed portion of the energy beam halogen gas in the sample to be analyzed by irradiating,
Step of performing elemental analysis of the surface of the sample to be analyzed by performing a mass analysis of the particles derived from the analyte desorbed and
3D micro region elemental analysis method, characterized in that it comprises a. The three-dimensional microscopic image according to claim 1 , wherein the particles derived from the desorbed sample to be analyzed are ionized by applying an electric field , and then the ionized desorbed species ions are accelerated to fly to an analyzer. Domain element analysis method. The sample to be analyzed is planar sample, and three-dimensional micro-regions elemental analysis method according to claim 1, characterized in that locally irradiated by converging the energy beam on the sample to be analyzed. Wherein a sample to be analyzed is planar samples, and, according ionized particles derived from analytes that released the prolapse to claim 1, characterized in that focusing on the two-dimensional detector by the ion lens 3D fine region elemental analysis method.

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