EP2198449B1 - Wide angle high resolution atom probe - Google Patents
Wide angle high resolution atom probe Download PDFInfo
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- EP2198449B1 EP2198449B1 EP08838185.0A EP08838185A EP2198449B1 EP 2198449 B1 EP2198449 B1 EP 2198449B1 EP 08838185 A EP08838185 A EP 08838185A EP 2198449 B1 EP2198449 B1 EP 2198449B1
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- 239000000523 sample Substances 0.000 title claims description 150
- 150000002500 ions Chemical class 0.000 claims description 63
- 230000005684 electric field Effects 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 11
- 230000002093 peripheral effect Effects 0.000 claims description 7
- 238000000605 extraction Methods 0.000 claims description 5
- 230000001360 synchronised effect Effects 0.000 claims 1
- 238000004458 analytical method Methods 0.000 description 20
- 238000010884 ion-beam technique Methods 0.000 description 15
- 230000004075 alteration Effects 0.000 description 12
- 238000005259 measurement Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 230000001133 acceleration Effects 0.000 description 4
- 230000010287 polarization Effects 0.000 description 3
- 230000003628 erosive effect Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 241001644893 Entandrophragma utile Species 0.000 description 1
- 241000861223 Issus Species 0.000 description 1
- 238000001389 atom probe field ion microscopy Methods 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- -1 des ions Chemical class 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 230000003902 lesion Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 230000000979 retarding effect Effects 0.000 description 1
- 238000001269 time-of-flight mass spectrometry Methods 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/26—Mass spectrometers or separator tubes
- H01J49/34—Dynamic spectrometers
- H01J49/40—Time-of-flight spectrometers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/0004—Imaging particle spectrometry
Definitions
- the present invention relates to improving the mass resolution of Large Angle Laser Tomographic Probes. It relates more particularly to the atomic probes called 3D atomic probes or "3D atom probe" according to the Anglo-Saxon name.
- the atomic probe is an instrument well known to those skilled in the art which makes it possible to analyze samples on an atomic scale. Many instrumental configurations related to this analysis technique are described in the book " Atom probe field Ion microscopy, by Miller et al Published 1996by Clarendon Press / Oxford .
- an essential parameter for obtaining a fine and precise measurement of the characteristics of the ions detected by an atomic probe is the measurement of the flight time of the ions detected, ie the time taken by the ion considered. to go through the space separating the sample from which they are torn from the detector. More specifically, the flight time is the time interval between an event triggering the pulling of the ion and its impact on the detector.
- the triggering event may be an electrical pulse carried on the electrode next to the sample or a pulse of a laser beam directed on the sample.
- the “Einzel” lens is, moreover, a device well known in the optics of charged particles and whose principle is not detailed here.
- “Einzel” lenses please refer to volume 2 of the book “ Principles of electron optics, by PWHawkes and E. Kasper, published in 1989 by Academic Press .
- tomographic atomic probes there are in particular the atomic probes known in the literature under the name of "3DAP” or " T ri D imensional A tom P gown” according to the Anglo-Saxon denomination or under the name of "PoSAP” or "Po sition ensitive S A P tom dress".
- These probes are advantageously characterized by the fact that with such a detector both the moment of the impact, which measures the flight time of an ion, the position in a plane of this impact on the detector.
- such a measure is only really possible if the position of the point of impact of a given ion is unequivocally linked to its position in the sample analyzed. This condition results in the fact that two distinct trajectories of ions must not lead to the same point of impact on the detector.
- An object of the invention is to propose a solution for obtaining a tomographic probe, a pulsed 3D probe, a pulse probe laser in particular, simultaneously having a large angle of analysis (a large acceptance) and a large resolution in mass consecutive to a great length of flight.
- the detector or a gate disposed near the detector is at a potential equal to that of the extractor.
- the detector or a gate disposed near the detector, is placed at an intermediate potential between that of the sample and that of the extractor electrode.
- the diameter d of the opening of the extractor is adapted to intercept the peripheral portion of the emitted ion beam so as to block the ions having the most peripheral trajectories.
- the extractor comprises several diaphragms of different opening diameters, which can be alternately arranged at the central opening of the extractor.
- the different diaphragms are made on a mobile bar slidable in front of the opening of the extractor so as to place the desired diaphragm in front of the opening; the slide movement of the bar being automated.
- the three electrodes are configured and arranged in such a way as to leave a free space in the flight chamber sufficient to house a removable device for adjusting the probe.
- a second electrostatic lens is placed between the first electrostatic lens and the detector.
- the first electrostatic lens is configured to focus the least open paths near the median plane of the second electrostatic lens.
- the invention has the advantage of making it possible, for a given opening angle of the emitted ion beam and a given detector surface, to produce a tomographic atom probe, in particular a "3D" probe, having a length of analysis. significantly higher than existing probes.
- Figures 1 to 3 Figures which schematically show the basic structure of a tomographic atomic probe, including an atom probe called "3D" probe.
- This type of probe is well known to those skilled in the art, so it is not a question in this document to describe in detail such a device.
- the Figures 1 to 3 however, allow you to recall the following points.
- a 3D tomographic atomic probe is intended to perform the analysis of a sample of material 11, atomic layer after atomic layer.
- it basically comprises a sample holder on which is mounted the sample 11 of the material to be analyzed and a detector 12 located at a predetermined distance L of the sample. It also includes means (not shown on the figure 1 ) to evaporate (tear off), in ionic form, the atoms constituting the sample material analyzed and accelerate them so that the ions thus released follow a path that causes each ion 13 evaporated to strike the surface of the detector 12 in one given point 14 determined by the position of this ion on the surface of the sample before its tearing.
- atom-by-atom erosion allowing a reconstruction of the composition of the atomic layer sample by atomic layer it is possible to determine the three-dimensional composition of the sample in question.
- the probe also comprises a vacuum enclosure (not shown in FIG. figure 1 ), whose potential is, for example, that of the mass of the system in which the probe takes place.
- a device comprising an ion source constituted by the sample 11, an analysis chamber, or flight chamber, of length L (analysis length) and a planar detector 12 whose dimensions cover a circular surface of diameter D.
- the electric field prevailing in the flight chamber takes variable values and may for example be zero. In the latter case, the ions propagate at constant speed inside the flight chamber.
- the detector At the arrival of an ion on the detector, it measures the position (x, y) on its surface of the point of incidence of the received ion. The detector also measures the "flight time", time counted from the moment corresponding to the tearing of the ion in question. A geometric correction is furthermore made to take into account the position of the point of impact in the calculation of the distance traveled between the tip and the detector. As a result, the position on the surface of the sample, occupied by the ion in question before it is torn off, is deduced in a known manner from the position of its point of impact on the surface of the detector, by application of a simple rule of projection.
- the detector 12 also determines the instant of arrival of the considered ion, with respect to a known time reference, generally corresponding to the time at which the analysis began. of the sample 11.
- a known time reference generally corresponding to the time at which the analysis began. of the sample 11.
- the sample 11 is a piece of material having the shape of a substantially conical tip with an end forming a spherical cap of variable radius R over the analysis time.
- the tomographic analysis consisting in tearing off, evaporating one after the other, the atoms forming the layers of atoms constituting the material, the radius of this spherical cap 21, initially of given value R 1 , a value R 2 corresponding to the spherical cap 22, existing at the end of the analysis; the erosion of the tip leading at the same time an equivalent variation in the distance between the sample 11 and the detector 12.
- a tomographic atom probe can also be characterized, in known manner, by various parameters which are in particular its magnification G and by the potential difference V which must exist between the tip 11 constituting the sample and the input of the analysis chamber itself, potential difference responsible for the acceleration printed evaporated ions to cross the analysis chamber length L the electric field to be applied.
- the coefficient b which depends on the geometry of the instrumentation, tip, detector and vacuum chamber is typically between 1 and 2.
- the evaporated ions, by field effect, on the surface of the tip 11 are identified by time-of-flight mass spectrometry.
- M represents the mass of the ion, v its velocity, n the number of elementary charges borne by the ion; e the elementary charge, ie the charge of the electron and V the acceleration voltage applied.
- T The v
- the mass resolution ⁇ M / M is proportional to the accuracy on the flight time ⁇ T / T, it is advantageous to have the greatest possible flight time T, and consequently the greatest distance L possible.
- the measurement of the flight time is essential in the instrument to identify the ratio m / q of a detected ion, m being the mass of the ion and q its electric charge, it is advantageous to increase the distance L between the sample and the detector to also increase the flight time.
- a device for focusing the ion beam emitted by the sample 11 on the detector 12 constituted.
- This device can for example be constituted as illustrated by figure 4 by an electrostatic lens 41 such as an "Einzel" lens, a device well known in charged particle optics, placed between the sample 11 and the detector 12.
- the "Einzel" lens consists of three electrodes 42, 43 and 44, placed in the path of the ions and configured to make a portion of the trajectory of these ions on an electric field which acts directly on this path. In this way the initially diverging beam 45 is modified into a convergent beam 46, the convergence obtained being a function of the intensity of the electric field produced.
- the electrodes constituting the lens are placed at the appropriate potentials.
- the "Einzel" lens may comprise a first electrode 42 placed in the vicinity of the sample 11, itself to ground, and then a second electrode 43 brought to a positive potential, then finally a third electrode 44 also grounded, so that at the exit of the lens, the ions continue their trajectories in a space without an electric field.
- the first electrode 42 also plays the role of the extraction electrode, or counter electrode, or local electrode, which is generally implemented in the tomographic atomic probes to locate the electric field that produces the initial acceleration evaporated ions from the sample.
- Such a focusing device advantageously makes it possible to limit the percentage of ions whose paths do not meet the detector. Nevertheless, its efficiency is generally limited by the fact that any electrostatic lens has what is called a spherical aberration which results in an overconversion of the outer region of the lens and a surfacing for the most eccentric trajectories which means that, as illustrated by Figures 5 and 6 (schematic sectional views) on two examples of lens configurations, the same point 51, 61, of the detector can intercept several distinct trajectories at once, resulting in a problem of indeterminacy of the original position of an ion having struck the detector at this point.
- this corresponds for example to an atomic probe in which the sample 11 sees its tip brought to a voltage of 15kV, while the first electrode 42 of the "Einzel" lens (closest to the sample), which serves as an extractor electrode, is grounded, that the second electrode 43 is brought to a voltage of 14kV and that the third electrode 44 (closest to the detector) is also grounded, just like the detector 12.
- the relative dimensions of the second and third electrodes are such that for the greater part of their path the ions remain under a focussing electric field.
- this corresponds for example to an atomic probe in which the sample 11 sees its tip brought to a voltage of 15kV, while the first electrode 42 of the "Einzel" lens (closest to the sample), which serves as an extracting electrode, is grounded, that the second electrode 43 is brought to a voltage of 12.5kV and that the third electrode 44 (closest to the detector) is also grounded, just like the detector 12.
- the relative dimensions of the second and third electrodes are such that for the greater part of their path the ions pass through. a space without a field, in which there is no focusing effect.
- the probe according to the invention also comprises an accelerating electrode, or extractor, positioned near the sample and an electrostatic lens of the "Einzel" type for focusing the produced electron beam, consisting of three adjacent electrodes 71, 72 and 73, the first electrode of the "Einzel” lens being constituted by the accelerating electrode.
- the electrodes of the electrostatic lens are polarized so that, taking into account the respective polarizations of the sample and the detector, the evaporated ions are initially accelerated towards the detector, to be then subjected for a part of their path, corresponding to the crossing of the lens, a focussing electric field.
- the three electrodes are also preferably configured and arranged so as to provide the flight chamber with sufficient free space to house a removable device for adjusting the probe.
- the adjustment device may be for example a field emission ion microscope or "Field ion microscope" according to the English name.
- the zone of the detector may furthermore, according to the embodiment considered, be brought to an intermediate potential between that of the sample and that of the extracting electrode 71.
- the setting of the potential considered is carried out directly or via a grid disposed near the detector. According to an alternative embodiment, this potential is that to which the extractor is carried.
- the electrodes of the electrostatic lens consist of mechanical parts comprising a central opening and having a symmetry of revolution about a central axis, coinciding with the axis 74 joining the top of the tip forming the sample 11 of material to the detector 12 and perpendicular to the plane of the detector.
- the first electrode 71, or extractor, located near the sample 11 and acting as an extracting electrode is preferably a thin piece having a hole 78 for passing ions, a circular hole for example.
- the third electrode 73 of the electrostatic lens is any electrode, preferably of relatively small thickness and having a central opening 79 with a diameter greater than or at least approximately equal to the diameter D of the detector 12, so as to allow the propagation up to to the detector of evaporated ions, whatever the path taken by these ions in the lens.
- Condition g) amounts to stating that all the points of the sectional profile 75 of the electrode situated between M 1 and M 3 must be situated outside the zone of the section plane delimited by the profile of a cone limited by the points M 2 and M 3 .
- This resolution is advantageously obtained without undergoing at the detector the effects of confusion of the points of impact, or at least by undergoing these effects in a very weakened manner, effects consecutive to the spherical aberration of the electrostatic lens.
- the opening angle remains otherwise unchanged, the resolution increase is done here without causing additional limitation of the analyzed surface.
- the probe according to the invention makes it possible to increase very considerably the analysis length that can be used.
- the intensity of the focus remains as for it defined by the value of the bias voltages applied to the different electrodes of the focussing lens produced.
- the ion beam will be more or less focused, the objective being however that the focused beam covers the largest possible area on the detector.
- the focused ion beam may then, for example, take the form of the beam 81 illustrated in FIG. figure 8 , or that of the beam 91 illustrated on the figure 9 .
- the beam 81 is obtained by applying, for example, a voltage of 13.7 kV to the second electrode 72 and carrying the first and third electrode to ground, the detector itself being grounded and the sample being brought to a voltage of 15 kV.
- the beam 91 is obtained by applying, for example, a voltage of 15.1 kV to the second electrode 72 and carrying the first and third electrode to ground, the detector and the sample being otherwise, as in the previous case, carried respectively to the ground and to a voltage of 15 kV.
- the architecture of the atomic probe according to the invention corresponds to a basic common architecture, the probe according to the invention being able in practice to include certain variants corresponding to applications specific ones such as those presented in a nonlimiting manner in the following description.
- the first electrode 71 constituting the focusing lens, the extracting electrode comprises a central opening 78 equipped with a multiple aperture device.
- This device consists, as illustrated by figure 12 in a barrette of diaphragms 112 arranged to slide in front of the central opening 78 of the electrode 71.
- the diameters of the various diaphragms 111 of the bar 112, smaller than that of the central opening 78, are defined so as to to decrease more or less strongly the diameter of the orifice of passage of ions emitted by the sample 11.
- the diameter of the opening 78 so as to let the entire emitted ion beam 81 pass or to eliminate from the beam the ions presenting the most peripheral trajectories, in particular for limit the width of the analyzed sample surface and therefore the opening angle of the corresponding ion beam that will be detected by the sensor.
- the diameter d of the opening of the extractor is thus adapted to intercept the peripheral portion of the emitted ion beam so as to block the ions having the most peripheral trajectories.
- the different diaphragms are arranged on the bar so that the distance between two contiguous diaphragms is sufficient so that, with the exception of the diaphragm used, all the others are perfectly masked by the electrode.
- the positioning in the two dimensions perpendicular to the axis of the beam can, moreover, be carried out by a suitable mechanism, possibly controlled by a computer and disposed outside the chamber of the probe.
- the atomic probe according to the invention comprises a second focusing lens, of the "Einzel" lens type, for example, placed between the first lens and the detector.
- This particular configuration makes it possible to compensate for the residual spherical aberration that the first focusing lens exhibits, despite its particular configuration, this spherical aberration of the first lens can not always be avoided.
- the atomic probe according to the invention comprises, besides the three electrodes 71, 72 and 73 constituting the first lens, two complementary electrodes 132 and 133, the electrode 132 being placed adjacent to the electrode 73 and the electrode 133 being placed adjacent to the electrode 132, between this electrode and the detector 12.
- the electrode 133 is brought to a potential substantially equal to that of the electrode 73, while the electrode 132 is brought to a potential allowing all three electrodes 73, 132 and 133 to constitute a second lens. electrostatic inside which reigns an electric field.
- the electric field applied to the ion beam inside the second electrostatic lens may, depending on the case of use envisaged, be an accelerator or retarding field.
- Such a device can for example be obtained from a structure such as that illustrated by FIG. figure 13 .
- the detector 12 being brought to the ground potential and the sample 11 to a potential of 15 kV, the extraction electrode 71 is then grounded as well as the electrodes 73 and 133, while the central electrode 72 of the first
- the lens is brought to a voltage of 15.3 kV and the central electrode 132 of the second lens is brought to a voltage of 14.5 kV.
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Description
La présente invention concerne l'amélioration de la résolution en masse des Sondes Tomographiques Laser Grand Angle. Elle concerne plus particulièrement les sondes atomiques appelées sondes atomiques 3D ou "3D atom probe" selon la dénomination anglo-saxonne.The present invention relates to improving the mass resolution of Large Angle Laser Tomographic Probes. It relates more particularly to the atomic probes called 3D atomic probes or "3D atom probe" according to the Anglo-Saxon name.
La sonde atomique est un instrument bien connu de l'homme du métier qui permet d'analyser des échantillons à l'échelle atomique. De nombreuses configurations instrumentales relevant de cette technique d'analyse sont décrites dans l'ouvrage "
Il est classique d'utiliser, pour cette analyse, un échantillon en forme de pointe, porté à un potentiel donné par rapport au potentiel du détecteur et de disposer, au voisinage de cet échantillon, une électrode portée à un potentiel intermédiaire entre celui de l'échantillon et du détecteur.It is conventional to use, for this analysis, a peak-shaped sample, brought to a given potential with respect to the potential of the detector and to have, in the vicinity of this sample, an electrode brought to a potential intermediate between that of the sample and detector.
Il est également classique de disposer, en plus de cette électrode une autre électrode mise à la masse, ou bien une grille également mise à la masse. De la sorte le détecteur étant mis à la masse, les ions arrachés à l'échantillon suivent une trajectoire qui les projette sur le détecteur sans subir l'influence d'un quelconque champ électrique pouvant modifier cette trajectoire. La quasi-totalité du trajet des ions est ainsi réalisée dans un espace dit "sans champ".It is also conventional to have, in addition to this electrode another electrode grounded, or a grid also grounded. In this way the detector being grounded, the ions torn from the sample follow a trajectory that projects them on the detector without being influenced by any electric field that can modify this trajectory. Almost the entire path of the ions is thus performed in a so-called "no field" space.
Il est également connu qu'un paramètre essentiel pour obtenir une mesure fine et précise des caractéristiques des ions détectés par une sonde atomique, est la mesure du temps de vol des ions détectés, c'est à dire du temps mis par l'ion considéré pour parcourir l'espace séparant l'échantillon duquel ils sont arrachés du détecteur. Plus précisément, le temps de vol est l'intervalle de temps entre un événement déclencheur de l'arrachage de l'ion et son impact sur le détecteur. L'événement déclencheur peut être une impulsion électrique portée sur l'électrode voisine de l'échantillon ou une impulsion d'un faisceau laser dirigé sur l'échantillon. Dans la mesure où la mesure du temps de vol est essentielle dans l'instrument pour identifier le rapport m/q d'un ion détecté, m étant la masse de l'ion et q sa charge électrique, il est avantageux d'augmenter la distance L entre l'échantillon et le détecteur afin d'augmenter également le temps de vol. Cependant le faisceau d'ions émis étant de nature divergente, une contrepartie de cette augmentation de la distance L est qu'une grande partie du faisceau émis peut alors échapper au détecteur, le détecteur ayant quant à lui des dimensions définies et nécessairement limitées. Pour pallier cet inconvénient, il est connu d'interposer un dispositif convergent tel qu'une lentille de type "Einzel" entre l'échantillon et le détecteur pour focaliser le faisceau d'ions sur le détecteur. La lentille "Einzel" est, par ailleurs, un dispositif bien connu en optique des particules chargées et dont le principe n'est pas détaillé ici. Pour plus d'informations sur les lentilles "Einzel" on peut notamment se référer au tome 2 de l'ouvrage "
Parmi les sondes atomiques tomographiques, on distingue en particulier les sondes atomiques connues dans la littérature sous le nom de "3DAP" ou "TriDimensional Atom Probe" selon la dénomination anglo-saxonne ou encore sous le nom de "PoSAP" ou "Position Sensitive Atom Probe". Ces sondes sont avantageusement caractérisées par le fait qu'avec un tel détecteur on mesure à la fois, outre l'instant de l'impact qui mesure le temps de vol d'un ion, la position, dans un plan, de cet impact sur le détecteur. Cependant, une telle mesure n'est réellement possible que si la position du point d'impact d'un ion donné est liée de manière univoque à sa position dans l'échantillon analysé. Cette condition se traduit par le fait que deux trajectoires distinctes d'ions ne doivent pas aboutir au même point d'impact sur le détecteur.Among the tomographic atomic probes, there are in particular the atomic probes known in the literature under the name of "3DAP" or " T ri D imensional A tom P gown" according to the Anglo-Saxon denomination or under the name of "PoSAP" or "Po sition ensitive S A P tom dress". These probes are advantageously characterized by the fact that with such a detector both the moment of the impact, which measures the flight time of an ion, the position in a plane of this impact on the detector. However, such a measure is only really possible if the position of the point of impact of a given ion is unequivocally linked to its position in the sample analyzed. This condition results in the fact that two distinct trajectories of ions must not lead to the same point of impact on the detector.
Or, s'il est facile de faire varier simplement l'angle d'émission capté par le détecteur avec une lentille Einzel, une forte focalisation du faisceau d'ions émis à l'aide d'une telle lentille, conduit à l'apparition d'une aberration sphérique sur la lentille, aberration qui produit sur les trajectoires externes des effets parasites très gênants pour le fonctionnement de la sonde 3D. En pratique, du fait de cette aberration, des trajectoires distinctes ont un même point d'impact pour extrémité.However, if it is easy to simply vary the emission angle captured by the detector with an Einzel lens, a strong focusing of the ion beam emitted with such a lens, leads to the appearance a spherical aberration on the lens, aberration which produces on the external trajectories very troublesome parasitic effects for the operation of the 3D probe. In practice, because of this aberration, distinct trajectories have the same end point of impact.
Un but de l'invention est de proposer une solution pour obtenir une sonde tomographique, une sonde 3D à impulsions, une sonde à impulsions laser en particulier, présentant simultanément un grand angle d'analyse (une grande acceptance) et une grande résolution en masse consécutive à une grande longueur de vol.An object of the invention is to propose a solution for obtaining a tomographic probe, a pulsed 3D probe, a pulse probe laser in particular, simultaneously having a large angle of analysis (a large acceptance) and a large resolution in mass consecutive to a great length of flight.
A cet effet l'invention a pour objet une sonde atomique tomographique comprenant:
- Un dispositif porte-échantillon pour recevoir un échantillon de matériau à analyser présentant une zone d'extraction de forme sensiblement pointue,
- Un détecteur sensible en position et en temps, de diamètre utile D, et espacé de l'échantillon d'une distance L;
- Une lentille électrostatique composée de trois électrodes, une première électrode ou extracteur, disposée à proximité de l'échantillon, une deuxième électrode, intermédiaire, et une troisième électrode, disposées entre l'électrode intermédiaire et le détecteur, les trois électrodes présentant une symétrie de révolution autour de l'axe Oz passant par la pointe de l'échantillon et perpendiculaire au plan P du détecteur;
- A sample holder for receiving a sample of material to be analyzed having an extraction zone of substantially pointed shape,
- A position-and-time sensitive detector with a useful diameter D and spaced from the sample by a distance L;
- An electrostatic lens composed of three electrodes, a first electrode or extractor, disposed near the sample, a second electrode, intermediate, and a third electrode, disposed between the intermediate electrode and the detector, the three electrodes having a symmetry of revolution around the axis Oz passing through the tip of the sample and perpendicular to the plane P of the detector;
Selon une variante de réalisation de la sonde atomique tomographique selon l'invention, le détecteur ou une grille disposée à proximité du détecteur est à un potentiel égal à celui de l'extracteur.According to an alternative embodiment of the tomographic atom probe according to the invention, the detector or a gate disposed near the detector is at a potential equal to that of the extractor.
Selon une variante de réalisation de la sonde atomique tomographique selon l'invention, le détecteur, ou une grille disposée à proximité du détecteur, est mis(e) à un potentiel intermédiaire entre celui de l'échantillon et celui de l'électrode extracteur.According to an alternative embodiment of the tomographic atom probe according to the invention, the detector, or a gate disposed near the detector, is placed at an intermediate potential between that of the sample and that of the extractor electrode.
Selon une autre variante de réalisation de la sonde atomique tomographique selon l'invention, le diamètre d de l'ouverture de l'extracteur est adapté de façon à intercepter la partie périphérique du faisceau d'ions émis de façon à bloquer les ions ayant les trajectoires les plus périphériques.According to another variant embodiment of the tomographic atomic probe according to the invention, the diameter d of the opening of the extractor is adapted to intercept the peripheral portion of the emitted ion beam so as to block the ions having the most peripheral trajectories.
Selon cette autre variante de réalisation, l'extracteur comporte plusieurs diaphragmes de diamètres d'ouverture différents, pouvant être alternativement disposés au niveau de l'ouverture centrale de l'extracteur.According to this alternative embodiment, the extractor comprises several diaphragms of different opening diameters, which can be alternately arranged at the central opening of the extractor.
Selon cette autre variante de réalisation, les différents diaphragmes sont réalisés sur une barrette mobile pouvant coulisser devant l'ouverture de l'extracteur de façon à placer le diaphragme voulu devant l'ouverture; le mouvement de coulisse de la barrette étant automatisé.According to this alternative embodiment, the different diaphragms are made on a mobile bar slidable in front of the opening of the extractor so as to place the desired diaphragm in front of the opening; the slide movement of the bar being automated.
Selon une troisième variante de réalisation de la sonde atomique tomographique selon l'invention, les trois électrodes sont configurées et agencées de façon à ménager dans la chambre de vol un espace libre suffisant pour loger un dispositif amovible de réglage de la sonde.According to a third variant embodiment of the tomographic atom probe according to the invention, the three electrodes are configured and arranged in such a way as to leave a free space in the flight chamber sufficient to house a removable device for adjusting the probe.
Selon une quatrième variante de réalisation de la sonde atomique tomographique selon l'invention, une deuxième lentille électrostatique est placée entre la première lentille électrostatique et le détecteur.According to a fourth variant embodiment of the tomographic atom probe according to the invention, a second electrostatic lens is placed between the first electrostatic lens and the detector.
Selon cette autre variante de réalisation, la première lentille électrostatique est configurée pour focaliser les trajectoires les moins ouvertes à proximité du plan médian de la deuxième lentille électrostatique.According to this alternative embodiment, the first electrostatic lens is configured to focus the least open paths near the median plane of the second electrostatic lens.
Avantageusement, les différentes variantes de réalisation peuvent être combinées ou associées.Advantageously, the various embodiments can be combined or associated.
L'invention présente l'avantage de permettre pour un angle d'ouverture donné du faisceau d'ion émis et une surface de détecteur donnée, de réaliser une sonde atomique tomographique, en particulier une sonde "3D", présentant une longueur d'analyse sensiblement supérieure aux sondes existantes.The invention has the advantage of making it possible, for a given opening angle of the emitted ion beam and a given detector surface, to produce a tomographic atom probe, in particular a "3D" probe, having a length of analysis. significantly higher than existing probes.
Les caractéristiques et avantages de l'invention seront mieux appréciées grâce à la description qui suit, description qui expose l'invention au travers d'un mode de réalisation particulier pris comme exemple non limitatif et qui s'appuie sur les figures annexées, figures qui représentent:
- la
figure 1 , une illustration du principe général de fonctionnement d'une sonde tomographique classique; - la
figure 2 , une illustration schématique, d'un échantillon en cours de mesure adapté à une sonde tomographique; - la
figure 3 , une illustration du principe physique de la mesure réalisée au moyen d'une sonde tomographique; - la
figure 4 , l'illustration du principe de fonctionnement d'une sonde tomographique intégrant une lentille "Einzel" dans la chambre de vol des ions; - les
figures 5 et 6 , des illustrations du phénomène d'aberration qui apparaît dans le cas d'une forte focalisation; - la
figure 7 , une illustration du dispositif de focalisation de la sonde atomique selon l'invention; - la
figure 8 , une illustration d'un exemple de faisceau obtenu au moyen du dispositif de focalisation de la sonde atomique selon l'invention; - la
figure 9 , l'illustration d'un autre exemple de faisceau focalisé obtenu au moyen du dispositif de focalisation de la sonde atomique selon l'invention; - les
figures 10 ,11 et 12 , des illustrations d'une variante de réalisation de la sonde atomique selon l'invention; - la
figure 13 , l'illustration d'une autre variante de réalisation de la sonde atomique selon l'invention.
- the
figure 1 , an illustration of the general principle of operation of a conventional tomographic probe; - the
figure 2 , a schematic illustration of a sample being measured adapted to a tomographic probe; - the
figure 3 , an illustration of the physical principle of measurement using a tomographic probe; - the
figure 4 , the illustration of the principle of operation of a tomographic probe incorporating an "Einzel" lens in the ion flight chamber; - the
Figures 5 and 6 , illustrations of the phenomenon of aberration that appears in the case of a strong focus; - the
figure 7 an illustration of the focusing device of the atomic probe according to the invention; - the
figure 8 an illustration of an example of a beam obtained by means of the focusing device of the atomic probe according to the invention; - the
figure 9 , illustration of another example of a focused beam obtained by means of the focusing device of the atomic probe according to the invention; - the
figures 10 ,11 and 12 illustrations of an alternative embodiment of the atomic probe according to the invention; - the
figure 13 , the illustration of another variant embodiment of the atomic probe according to the invention.
On s'intéresse d'abord aux
Une sonde atomique tomographique 3D est destinée à réaliser l'analyse d'un échantillon de matériau 11, couche atomique après couche atomique. A cet effet elle comporte basiquement un dispositif porte-échantillon sur lequel est monté l'échantillon 11 du matériau à analyser et un détecteur 12 situé à une distance déterminée L de l'échantillon. Elle comporte également des moyens (non représentés sur la
Afin d'isoler l'ensemble des perturbations extérieures la sonde comporte également une enceinte sous vide (non représentée sur la
On obtient ainsi, comme l'illustre la
A l'arrivée d'un ion sur le détecteur, celui-ci mesure la position (x, y) sur sa surface du point d'incidence de l'ion reçu. Le détecteur mesure également le "temps de vol", durée comptée à partir de l'instant correspondant à l'arrachement de l'ion considéré. Une correction géométrique est en outre opérée pour prendre en compte la position du point d'impact dans le calcul de la distance parcourue entre la pointe et le détecteur. Par suite, la position à la surface de l'échantillon, occupée par l'ion considéré avant son arrachement est déduite de manière connue de la position de son point d'impact à la surface du détecteur, par application d'une simple règle de projection.At the arrival of an ion on the detector, it measures the position (x, y) on its surface of the point of incidence of the received ion. The detector also measures the "flight time", time counted from the moment corresponding to the tearing of the ion in question. A geometric correction is furthermore made to take into account the position of the point of impact in the calculation of the distance traveled between the tip and the detector. As a result, the position on the surface of the sample, occupied by the ion in question before it is torn off, is deduced in a known manner from the position of its point of impact on the surface of the detector, by application of a simple rule of projection.
Dans le cas d'une sonde tomographique dite "3D" le détecteur 12 détermine également l'instant d'arrivée de l'ion considéré, par rapport à une référence de temps connue, correspondant généralement à l'instant auquel a débuté l'analyse de l'échantillon 11. La mesure de cet instant permet avantageusement de connaître la profondeur à laquelle se situait l'ion considéré par rapport à la surface initiale de l'échantillon et de réaliser ainsi un véritable positionnement en trois dimensions de l'atome à l'origine de l'ion considéré dans l'échantillon 11 de matériau analysé.In the case of a so-called "3D" tomographic probe, the
Comme l'illustrent les
Comme l'illustre la
Par suite, θ étant ainsi défini, une sonde atomique tomographique peut être également caractérisée, de manière connue, par différents paramètres qui sont notamment son grandissement G et par la différence de potentiel V qui doit exister entre la pointe 11 constituant l'échantillon et l'entrée de la chambre d'analyse proprement dite, différence de potentiel responsable de l'accélération imprimée aux ions évaporés pour traverser la chambre d'analyse de longueur L le champ électrique à appliquer. Cette différence de potentiel est classiquement définie par la relation E= V/R, où E représente le champ électrique d'évaporation et R le rayon de courbure de la pointe c'est à dire le rayon de la calotte sphérique constituant son extrémité.Therefore, θ being thus defined, a tomographic atom probe can also be characterized, in known manner, by various parameters which are in particular its magnification G and by the potential difference V which must exist between the
Le grandissement est donné par la relation G=L/bR, dans laquelle L représente sensiblement la longueur de la chambre d'analyse et bR la distance à l'extrémité 23 de la pointe d'un point P, ou point de projection, à partir duquel les trajectoires ioniques sont toutes définies. Le coefficient b qui dépend de la géométrie de l'instrumentation, pointe, détecteur et chambre sous vide est typiquement compris entre 1 et 2.The magnification is given by the relation G = L / bR, in which L substantially represents the length of the analysis chamber and bR the distance at the
Dans un tel dispositif, les ions évaporés, par effet de champ, à la surface de la pointe 11 sont identifiés par spectrométrie de masse à temps de vol. Ainsi, v la vitesse de déplacement des ions est déterminée par la tension d'accélération des ions d'après la formule:
Par suite, le temps de vol d'un ion étant donné par la relation:
As a result, the flight time of an ion is given by the relation:
La résolution de masse δM/M étant proportionnelle à la précision sur le temps de vol δT/T, il est avantageux d'avoir le temps de vol T le plus grand possible, et par conséquent, la distance L la plus grande possible. Autrement dit, comme la mesure du temps de vol est essentielle dans l'instrument pour identifier le rapport m/q d'un ion détecté, m étant la masse de l'ion et q sa charge électrique, il est avantageux d'augmenter la distance L entre l'échantillon et le détecteur afin d'augmenter également le temps de vol. Une contrepartie de cette augmentation de la distance L est une réduction de l'angle d'acceptance θ=2 arctan(D/2L): Une grande partie du faisceau émis peut alors échapper au détecteur de dimension D, certaines trajectoires 15 n'étant par interceptées par le détecteur 12.Since the mass resolution δM / M is proportional to the accuracy on the flight time δT / T, it is advantageous to have the greatest possible flight time T, and consequently the greatest distance L possible. In other words, since the measurement of the flight time is essential in the instrument to identify the ratio m / q of a detected ion, m being the mass of the ion and q its electric charge, it is advantageous to increase the distance L between the sample and the detector to also increase the flight time. A counterpart to this increase in the distance L is a reduction in the acceptance angle θ = 2 arctan (D / 2L): A large part of the emitted beam can then escape the detector D dimension, some
Ainsi, pour augmenter L, et donc la résolution en masse sans pour autant réduire l'angle d'acceptance θ, il est généralement nécessaire d'ajouter à l'agencement illustré par les
Pour créer ce champ électrique, les électrodes constituant la lentille sont placées aux potentiels adéquats. Ainsi, par exemple, pour une sonde tomographique dans laquelle le détecteur est mis au potentiel de la masse la lentille "Einzel" peut comporter une première électrode 42, placé au voisinage de l'échantillon 11, elle-même à la masse, puis une deuxième électrode 43 portées à un potentiel positif, puis enfin une troisième électrode 44 portées également à la masse, de sorte qu'en sortie de la lentille, les ions poursuivent leurs trajectoires dans un espace sans champ électrique. Dans ce cas, la première électrode 42 joue également le rôle de l'électrode extractrice, ou contre-électrode, ou encore électrode locale, qui est généralement mise en place dans les sondes atomiques tomographiques pour localiser le champ électrique qui produit l'accélération initiale des ions évaporés de l'échantillon.To create this electric field, the electrodes constituting the lens are placed at the appropriate potentials. Thus, for example, for a tomographic probe in which the detector is placed at the potential of the mass, the "Einzel" lens may comprise a
Un tel dispositif de focalisation permet avantageusement de limiter le pourcentage d'ions dont les trajectoires ne rencontrent pas le détecteur. Néanmoins son efficacité reste généralement limitée par le fait que toute lentille électrostatique présente ce qu'on appelle une aberration sphérique qui se traduit par une sur-convergence de la région externe de la lentille et une surfocalisation pour les trajectoires les plus excentrées qui fait que, comme l'illustre les
En ce qui concerne la configuration de la
En ce qui concerne la configuration de la
On s'intéresse à présent aux
Les trois électrodes sont par ailleurs préférentiellement configurées et agencées de façon à ménager dans la chambre de vol un espace libre suffisant pour loger un dispositif amovible de réglage de la sonde. Le dispositif de réglage peut être par exemple un microscope ionique à émission de champ ou "Field ion microscope" selon la dénomination anglo-saxonne.The three electrodes are also preferably configured and arranged so as to provide the flight chamber with sufficient free space to house a removable device for adjusting the probe. The adjustment device may be for example a field emission ion microscope or "Field ion microscope" according to the English name.
La zone du détecteur, peut par ailleurs, suivant le mode de réalisation considéré, être porté à un potentiel intermédiaire entre celui de l'échantillon et celui de l'électrode extractrice 71. La mise au potentiel considéré est réalisée directement ou par l'intermédiaire d'une grille disposée à proximité du détecteur. Selon une variante de réalisation ce potentiel est celui auquel est porté l'extracteur.The zone of the detector may furthermore, according to the embodiment considered, be brought to an intermediate potential between that of the sample and that of the extracting
Pour pouvoir disposer d'une longueur d'analyse L (longueur de vol) sensiblement plus grande que celle accessible avec les sondes existantes, la géométrie et l'agencement des électrodes 71, 72 et 73 constituant la lentille électrostatique répondent ici à des caractéristiques techniques spécifiques décrites dans la suite de la description.In order to be able to have an analysis length L (flight length) substantially greater than that accessible with the existing probes, the The geometry and the arrangement of the
Selon l'invention, les électrodes de la lentille électrostatique, sont constituées de pièces mécaniques comportant une ouverture centrale et présentant une symétrie de révolution autour d'un axe central, confondu avec l'axe 74 joignant le sommet de la pointe formant l'échantillon 11 de matériau au détecteur 12 et perpendiculaire au plan du détecteur.According to the invention, the electrodes of the electrostatic lens consist of mechanical parts comprising a central opening and having a symmetry of revolution about a central axis, coinciding with the
La première électrode 71, ou extracteur, située à proximité de l'échantillon 11 et jouant le rôle d'électrode extractrice est préférentiellement une pièce de faible épaisseur présentant un trou 78 de passage des ions, un trou circulaire par exemple.The
De même la troisième électrode 73 de la lentille électrostatique est une électrode quelconque, préférentiellement de relativement faible épaisseur et présentant une ouverture centrale 79 d'un diamètre supérieur ou du moins sensiblement égal au diamètre D du détecteur 12, de façon à permettre la propagation jusqu'au détecteur des ions évaporés, et ce, quelle que soit la trajectoire empruntée par ces ions dans la lentille.Similarly, the
En ce qui concerne la deuxième électrode 72, électrode centrale de la lentille, celle-ci présente une forme permettant de définir un espace interne dont les dimensions varient avantageusement sur la longueur de l'électrode. Ainsi, selon l'invention la deuxième électrode 72 comporte un premier segment 711 adjacent à la première électrode 71 et présentant une ouverture cylindrique centrée sur l'axe 74, d'un rayon r1 adapté au passage du faisceau d'ions évaporés. Elle comporte également un deuxième segment 712, présentant une ouverture cylindrique centrée sur l'axe 74 et de rayon r2 le rayon r2 adapté à la largeur du faisceau étant supérieur au rayon r1. Elle comporte encore un troisième segment 713, présentant une ouverture conique reliant l'ouverture du premier segment à celle du deuxième segment. De la sorte, comme l'illustre la vue en coupe de la
- a) 0;1·D<r1<0.65·D
- b) r2=r1
- c) D<r2<1.6·D
- d) |z1-z0|<D/3
- e) |z2-z1|<0;65·D
- f) |z3-z1|<1.4·D
- g) en tout point Mi(ri,zi) de la zone M2M3 du profil 75, c'est-à-dire pour zi>z2 on a:
- a) 0; 1 · D <r 1 <0.65 · D
- b) r 2 = r 1
- c) D <r 2 <1.6 · D
- d) | z 1 -z 0 | <D / 3
- e) | z 2 -z 1 | <0; 65 · D
- f) | z 3 -z 1 | <1.4 · D
- g) at any point M i (r i , z i ) of the zone M2M3 of the
profile 75, that is to say for z i > z 2 we have:
La condition g) revient à énoncer que tous les points du profil en coupe 75 de l'électrode situés entre M1 et M3, doivent être situés en dehors de la zone du plan de coupe délimitée par le profil d'un cône limité par les points M2 et M3.Condition g) amounts to stating that all the points of the
Des calculs menés par ailleurs par la déposante, et non présenté ici, montre que grâce à cette configuration particulière des électrodes constituant la lentille électrostatique, il est possible en appliquant les potentiels adéquats sur les différentes électrodes, comme l'illustre la figue 8, d'obtenir une focalisation du faisceau d'ions 81 suffisante pour ramener sur le détecteur un ensemble de trajectoires affectées d'aberrations de faible ampleur. L'invention permet notamment d'utiliser dans une sonde atomique un détecteur de position 12 d'un diamètre D, placé à une distance L' supérieure à 2L de l'échantillon 11, L étant telle la longueur d'analyse maximale sans focalisation, longueur définie de manière connue par la relation tan(θ/2)=(D/2)/L, équivalente à L=1.374 D lorsque la demi-ouverure θ/2 est de 20°. Ainsi, pour un angle d'ouverture θ égal à ± 20° et pour un diamètre de détecteur D égal à 80 mm, il est avantageusement possible grâce à la sonde atomique selon l'invention, d'obtenir une longueur d'analyse supérieure à deux fois la valeur L = 1,374·D = 109 mm tout en interceptant avec le détecteur toutes les trajectoires des ions émis correspondant à cet angle d'ouverture. En augmentant la distance d'analyse d'un facteur au moins égal à 2, il est possible d'obtenir, en appliquant au faisceau d'ion un champ électrique focalisateur d'intensité appropriée (c'est à dire appliquant sur les électrodes les tensions de polarisation appropriées), une résolution en masse améliorée d'un facteur supérieur à deux. Cette résolution est avantageusement obtenue sans subir au niveau du détecteur les effets de confusion des points d'impacts, ou tout au moins en subissant ces effets de manière très amoindrie, effets consécutifs à l'aberration sphérique de la lentille électrostatique. L'angle d'ouverture restant par ailleurs inchangé, l'augmentation de résolution se fait ici sans entraîner de limitation supplémentaire de la surface analysée.Calculations carried out by the applicant, and not presented here, show that thanks to this particular configuration of the electrodes constituting the electrostatic lens, it is possible by applying the appropriate potentials on the different electrodes, as illustrated in FIG. to obtain a focus of the
Ainsi grâce à ses caractéristiques de structure, la sonde selon l'invention, permet d'augmenter de manière très importante la longueur d'analyse pouvant être utilisée. L'intensité de la focalisation reste quant à elle définie par la valeur des tensions de polarisation appliquées aux différentes électrodes de la lentille focalisatrice réalisée. Suivant les polarisations appliquées, le faisceau d'ion sera plus ou moins focalisé, l'objectif étant cependant que le faisceau focalisé couvre la plus grande surface possible sur le détecteur. Le faisceau d'ion focalisé pourra alors par exemple prendre selon les cas la forme du faisceau 81 illustré sur la
L'architecture de la sonde atomique selon l'invention, telle qu'elle est présentée dans les paragraphes précédents, correspond à une architecture commune de base, la sonde selon l'invention pouvant dans la pratique comporter certaines variantes de réalisation correspondant à des applications spécifiques telles que celles présentées de manière non limitative dans la suite de la description.The architecture of the atomic probe according to the invention, as presented in the preceding paragraphs, corresponds to a basic common architecture, the probe according to the invention being able in practice to include certain variants corresponding to applications specific ones such as those presented in a nonlimiting manner in the following description.
On s'intéresse à présent aux
Il est à noter que, comme l'illustre la
On s'intéresse ensuite à la
La sonde atomique selon l'invention, dans cette variante de réalisation, comporte, outre les trois électrodes 71, 72 et 73 constituant la première lentille, deux électrodes complémentaires 132 et 133, l'électrode 132 étant placée adjacente de l'électrode 73 et l'électrode 133 étant placée adjacente de l'électrode 132, entre cette électrode et le détecteur 12.The atomic probe according to the invention, in this variant embodiment, comprises, besides the three
L'électrode 133, est portée à un potentiel sensiblement égal à celui de l'électrode 73, tandis que l'électrode 132 est portée à un potentiel permettant à l'ensemble des trois électrodes 73, 132 et 133 de constituer ainsi une seconde lentille électrostatique à l'intérieur de laquelle règne un champ électrique.The electrode 133 is brought to a potential substantially equal to that of the
Dans cette configuration particulière à deux lentilles la deuxième électrode 72 de la première lentille et la deuxième électrode 131 de la seconde lentille sont portées à des potentiels définis pour:
- réaliser, à l'aide de la première lentille, la focalisation des trajectoires de faible ouverture sur le plan médian de la deuxième lentille, matérialisé par la ligne pointillée 134 sur la
figure 13 . De la sorte la deuxième lentille, constituée par les électrodes 73, 132 et 133, est sans effet sur les trajectoires de faible ouverture. - opérer, à l'aide de la première lentille, une surfocalisation des trajectoires de plus fortes ouvertures. Les aberrations qui apparaissent alors sont corrigées en appliquant le potentiel approprié à l'électrode centrale 132 de la seconde lentille.
- using the first lens, to focus the trajectories of small aperture on the median plane of the second lens, represented by the dotted line 134 on the
figure 13 . In this way the second lens constituted by theelectrodes 73, 132 and 133 has no effect on the trajectories of small aperture. - operate, using the first lens, a surfocalisation of the trajectories of greater openings. The aberrations that appear then are corrected by applying the appropriate potential to the central electrode 132 of the second lens.
Le champ électrique appliqué au faisceau d'ion à l'intérieur de la seconde lentille électrostatique peut selon le cas d'utilisation envisagé être un champ accélérateur ou retardateurThe electric field applied to the ion beam inside the second electrostatic lens may, depending on the case of use envisaged, be an accelerator or retarding field.
Un tel dispositif peut par exemple être obtenu à partir d'une structure telle que celle illustrée par la
Claims (15)
- Tomographic atom probe comprising:- a sample-holding device for receiving a sample (11) of material to be analysed having an extraction area of substantially pointed shape,- a position-sensitive detector (12) of useful diameter D and spaced apart from the sample (11) by a distance L;- an electrostatic lens consisting of three electrodes, a first electrode (71) or extractor, arranged in proximity to the sample (11), an intermediate second electrode (72), and a distal third electrode (73) arranged between the intermediate electrode (72) and the detector (12), the three electrodes having a symmetry of revolution about the axis Oz passing through the point of the sample and perpendicular to the plane P of the detector;characterized in that, since the distance L is greater than 2.75 D, the respective potentials of the sample (11), of the first electrode (71) of the lens and of the detector (12) are such that the ions deriving from the sample (11) mounted on the sample-holder are attracted towards the first electrode (71) and towards the detector (12); the cross-sectional profile (74) of the intermediate electrode (72), in a cross-sectional plane rOz passing through the axis Oz, defining three points M1, M2 and M3 of respective coordinates (r1, z1), (r2, z2) and (r3, z3) relative to an origin z0 on the point of the sample, which satisfy the following conditions:
- Tomographic atom probe according to Claim 1, characterized in that the detector (12) or a grating arranged in proximity to the detector is at a potential equal to that of the extractor (71).
- Atom probe according to Claim 1, characterized in that the detector or a grating arranged in proximity to the detector is at an intermediate potential between that of the sample (11) and that of the extractor electrode (71).
- Tomographic atom probe according to one of Claims 1 to 3, characterized in that the diameter d of the aperture (77) of the extractor (72) is determined in such a way as to intercept the peripheral portion of the beam of emitted ions so as to block the ions that have the most peripheral trajectories.
- Tomographic atom probe according to Claim 4, characterized in that the extractor comprises a number of diaphragms (111) of different aperture diameters, that can be alternately arranged at the level of the central aperture (77) of the extractor (72).
- Tomographic atom probe according to Claim 5, characterized in that the different diaphragms (111) are produced on a moving bar (112) that can slide in front of the aperture (77) of the extractor (71) so as to place the desired diaphragm in front of the aperture; the sliding movement of the bar being automated.
- Tomographic atom probe according to any one of the preceding claims, characterized in that the three electrodes (71, 72 and 73) are configured and arranged in such a way as to provide, inside the flight chamber, a free space that is sufficient to house a removable probe adjusting device.
- Tomographic atom probe according to Claim 7, characterized in that the free space is sufficient to have a field ion microscope in the probe.
- Tomographic atom probe according to any one of the preceding claims, characterized in that a second electrostatic lens (73, 131 and 132) is placed between the first electrostatic lens (71, 72 and 73) and the detector (12).
- Tomographic atom probe according to Claim 9, characterized in that the first electrostatic lens (71, 72 and 73) is configured to focus the least open trajectories in proximity to the median plane of the second electrostatic lens (73, 131 and 132).
- Topographic atom probe according to Claim 9, characterized in that the second electrostatic lens (73, 131 and 132) generates a delaying electrical field.
- Topographic atom probe according to Claim 9, characterized in that the second electrostatic lens (73, 131 and 132) generates an accelerating electrical field.
- Topographic atom probe according to Claim 1, characterized in that the extractor (71) is subjected to a pulsed potential.
- Topographic atom probe according to Claim 1, characterized in that the ions of the material are separated from the sample (11) by means of a pulsed laser.
- Topographic atom probe according to Claim 14, characterized in that the extractor (71) is subjected to a pulsed potential synchronized with the laser emission.
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FR0707178A FR2922350B1 (en) | 2007-10-12 | 2007-10-12 | HIGH ANGLE TOMOGRAPHIC PROBE WITH HIGH RESOLUTION. |
PCT/EP2008/063462 WO2009047265A1 (en) | 2007-10-12 | 2008-10-08 | Wide angle high resolution tomographic probe |
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EP (1) | EP2198449B1 (en) |
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FR2938963B1 (en) * | 2008-11-21 | 2010-11-12 | Cameca | TOMOGRAPHIC ATOMIC PROBE COMPRISING AN ELECTRO-OPTICAL GENERATOR OF HIGH VOLTAGE ELECTRIC PULSES |
DE112012004503B4 (en) * | 2011-10-28 | 2018-09-20 | Leco Corporation | Electrostatic ion mirrors |
US10615001B2 (en) * | 2015-04-21 | 2020-04-07 | Cameca Instruments, Inc. | Wide field-of-view atom probe |
US10614995B2 (en) | 2016-06-27 | 2020-04-07 | Cameca Instruments, Inc. | Atom probe with vacuum differential |
US11340256B2 (en) | 2018-01-31 | 2022-05-24 | Cameca Instruments, Inc. | Energy beam input to atom probe specimens from multiple angles |
US11087956B2 (en) * | 2018-06-29 | 2021-08-10 | Taiwan Semiconductor Manufacturing Co., Ltd. | Detection systems in semiconductor metrology tools |
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US7157702B2 (en) * | 2003-06-06 | 2007-01-02 | Imago Scientific Instruments Corporation | High resolution atom probe |
JP4864501B2 (en) * | 2005-06-28 | 2012-02-01 | 富士通株式会社 | 3D atom level structure observation device |
US20070073364A1 (en) * | 2005-09-29 | 2007-03-29 | Siemens Aktiengesellschaft | Combined OCT catheter device and method for combined optical coherence tomography (OCT) diagnosis and photodynamic therapy (PDT) |
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US8074292B2 (en) | 2011-12-06 |
US20100223698A1 (en) | 2010-09-02 |
FR2922350B1 (en) | 2009-12-04 |
EP2198449A1 (en) | 2010-06-23 |
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