Abstract:
A method of processing a TEM-sample, wherein the method comprises: mounting an object in a particle beam system such that the object is disposed, in an object region of the particle beam system; directing of a first particle beam onto the object region from a first direction, wherein the first particle beam is an ion beam; and then rotating the object about an axis by 180°, wherein the following relation is fulfilled:
 
35°≦α≦55°,
 
wherein α denotes a first angle between the first direction and the axis; and then directing of the first particle beam onto the object region from the first direction; wherein material is removed from the object during the directing of the first particle beam onto the object region. Furthermore, a second particle beam may be directed onto the object region, and particles emanating from the object region can be detected.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of Patent Application No. 10 2012 020 478.7, filed Oct. 18, 2012 in Germany, the entire contents of which are incorporated by reference herein. 
     FIELD 
     The present invention relates to a particle beam system and a method of processing a TEM-sample. 
     BACKGROUND 
     A transmission electron microscope (TEM) allows for material analyses of very high spatial resolution. For example, structures with feature sizes of 1 nm or less can be resolved. For this purpose, a so-called TEM-sample must be formed of the material to be analyzed, wherein the TEM-sample is at least in part thin so that electrons of the electron beam generated by the transmission electron microscope can traverse the material. Such thin objects are also referred to as TEM-lamellae and exhibit a thickness of, for example, 100 nm or less. The manufacture of such TEM-samples is elaborate and difficult. 
     A specific kind of TEM-sample is known from US 2012/0185813 A1, wherein the full disclosure of this document is incorporated herein by reference. An example of a TEM-sample known from this reference is schematically illustrated in  FIG. 1 . For manufacturing the TEM-sample  101  illustrated in  FIG. 1 , a cuboid-shaped material-block  103  is cut out of a substrate, wherein the material-block contains the region to be analyzed using the transmission electron microscope. The cuboid-shaped material-block can exhibit thicknesses of 0.1 μm to 500 μm and lengths and widths of 5 μm to 1000 μm, for example. Here, the thickness of the cuboid-shaped material-block  103  is too large in order to be traversed appropriately by electrons in a transmission electron microscope. Hence, a strip-shaped recess is formed in each of two opposing flat sides of the cuboid, wherein the recesses extend at an angle δ of, for example, 45° with respect to an edge of the cuboid such that an angle ε between the directions of extension of the strip-shaped recesses  105  amounts to a value of, for example, 90°. A depth of the recesses  105  is somewhat smaller than half the thickness of the cuboid  103  so that a hatched region  107  in  FIG. 1 , the region of which the recesses  105  cross and overlap, provides a slight material thickness which is equal to the thickness of the cuboid  103  minus the thicknesses of both the recesses  105 . By appropriate forcing of the recesses  105 , for example, by removing material using a focused ion beam, it is possible to configure the material thickness in the region  107  small such that the material in the region  107  can be analyzed using a transmission electron microscope. 
     The TEM-sample illustrated in  FIG. 1  has the advantage that, due to the surrounding regions of the cuboid  103 , the region  107  of thin material is bared by means of a frame and protected against the deformation, wherein the frame can be attached to manipulators and object mounts without damaging the comparatively fragile thin region  107 . 
     US 2012/0185813 A1 discloses apparatuses and methods for manufacturing a TEM-sample illustrated in  FIG. 1 . Nevertheless, it is desirable to have further apparatuses and methods available which allow manufacturing of such TEM-samples. 
     SUMMARY 
     Embodiments of the present invention provide a particle beam system and a method of processing a TEM-sample providing a comparatively simple and reliable manufacture of a TEM-sample and its analysis using a transmission electron microscope. 
     According to certain embodiments, a particle beam system comprises a first particle beam column configured to generate a first particle beam incident onto an object region from a first direction, wherein the first particle beam is an ion beam, a second particle beam column configured to generate a second particle beam incident onto an object region from a second direction and an object mount configured to mount an object in the object region, wherein the object mount comprises a shaft rotatable with respect to the first particle beam column about an axis of rotation, wherein the following relation is fulfilled: 35°≦α≦55°, wherein α denotes a first angle between the first direction and the axis of rotation. 
     The first particle beam, which is an ion beam, generated by the first particle beam column serves to remove material from a TEM-sample to be manufactured or to be analysed. On the one hand, this removing of material may be used, to form the strip-shaped recesses previously described in the context of  FIG. 1 . Here, the ion beam may be, for example, a focused gallium-ion beam. Furthermore, a process-gas may be fed to a location on the object processed by the ion beam, wherein the process-gas is excited by ions of the ion beam or secondary particles dissolved from the object by the ion beam, forms a compound with material of the object and, thereby, dissolves material from the object (assisted ion beam etching). 
     On the other hand, the ion beam may be used to remove impurities on the TEM-sample generated by, for example, oxidation. Here, the ion beam may be, for example, an argon-ion beam. 
     The second particle beam generated by the second particle beam column may be used to monitor and to control the method of processing the object using the first particle beam. Here, the particle beam system may comprise a detector in order to detect secondary particles emerging from the object. Furthermore, the second particle beam column may comprise one or multiple beam deflectors in order to modify an impinging location of the second particle beam onto the object so that secondary particles emerging from the object may be detected spatially resolved. In particular, the second particle beam may be scanned across the object region systematically, wherein a microscopic image of the scanned object region is created from intensities of detected secondary particles emerging from the object. The particles of the second particle beam having interacted with the object may be electrons backscattered from the object itself and electrons transmitted through the object. 
     The second particle beam may be an ion beam as well, for example, a helium-ion beam. Furthermore, the second particle beam may be an electron beam, and the second particle beam column may be configured to be an electron microscope. Here, the second particle beam column may comprise a scanning electron microscope (SEM). Such a SEM, together with the first particle beam column, is preferably used in order to form the strip-shaped recesses in the TEM-sample illustrated with reference to  FIG. 1 . Here, the first and the second particle beam columns are integrated in a particle beam system, also referred to by cross-beam-system or dual-beam-system. Here, γ denotes a third angle between the first direction from which the first particle beam is incident onto the object region and the second direction from which the second particle beam is incident onto the object region, wherein γ amounts to a value between 20° and 90°, in particular between 30° and 60° and in particular between 40° and 55°. This particle beam system may comprise a scanning electron microscope comprising a detector detecting electrons generated by the scanning electron microscope having transmitted the object. Using such a scanning transmission electron microscope (STEM) transmission-electron-microscopic analyses may be performed directly without having to transfer the object into a separate transmission electron microscope. 
     The second particle beam column may also comprise a transmission electron microscope (TEM) configured to perform the transmission-electron-microscopic analysis of the TEM-sample. Here, the first particle beam preferably serves to remove impurities from the TEM-samples. Furthermore, γ denotes a third angle between the first direction from which the first particle beam is directed onto the object region and the second direction from which the second particle beam is directed onto the object region is preferably larger than 80°, in particular larger than 85° and according to a special embodiment equal to 90°. 
     The angle α between the first direction from which the first particle beam is incident onto the object region and the axis of rotation of the object mount is chosen such that the TEM-sample mounted to the object mount may be transferred from a first position into a second position by rotating the object mount by 180° about the axis of rotation, wherein, in the first position, one of the strip-shaped recesses illustrated with reference to  FIG. 1  may be processed by the first particle beam, and, in the second position, the other one of both the strip-shaped recesses may be processed by the first particle beam. Thus, in a particularly easy way, it is possible to perform at least one of forming both the strip-shaped recesses using the first particle beam and removing impurities from the TEM-sample comprising previously formed strip-shaped recesses. 
     Accordingly, an embodiment of a method of processing a TEM-sample may comprise the following elements: mounting an object to an object mount, disposing the object in a first particle beam system so that the object is disposed in an object region of the first particle beam system, a first directing of a first particle beam onto the object region from a first direction, wherein the first particle beam is an ion beam, and then rotating the object about an axis by 180°, wherein the following relation is fulfilled:
 
35°≦α≦55°,
 
wherein α denotes a first angle between the first direction and the axis, and then a second directing of the first particle beam onto the object region from the first direction, wherein material is removed from the object during the first directing and the second directing of the first particle beam onto the object region.
 
     Here, the first directing and the second directing of the first particle beam onto the object region may be used to form strip-shaped recesses in the object or to clean impurities, for example, oxides from the object. 
     Here, the rotating of the object about the axis may be performed by a single step of rotation about an axis of rotation. However, it is also possible to perform this rotating by multiple steps of movement which may comprise, for example, multiple consecutively executed steps of rotation about distinct axes of rotation and steps of translation in one or multiple directions. 
     Furthermore, the method may comprise a third directing of a second particle beam onto the object region and a detecting of particles emanating from the object region. Here, at least one of the first directing and the second directing of the first particle beam onto the object region may be performed based on the secondary particles detected during the third directing of the second particle beam onto the object region. As previously described, the second particle beam may be an ion beam or an electron beam, and microscopic images may be created from spatially resolved intensities detected from secondary particles emanating from the object region in order to monitor the process of forming the strip-shaped recesses or in order to perform the transmission-electron-microscopic analysis of the TEM-sample. 
     Furthermore, it is possible to manufacture the TEM-sample in the first particle beam system initially and then to transfer the TEM-sample into a second particle beam system in order to conduct further processing therein which also comprises a rotating of the object about an axis by 180° in the second particle beam system. The second particle beam system may comprise, for example, a TEM serving for a transmission-electron-microscopic analysis of the TEM-sample formed in the first particle beam system, wherein an ion beam is used therein in order to remove impurities from the TEM-sample which arose during the transfer of the TEM-sample from the first particle beam system into the second particle beam system. 
     Here, the method may further comprise the following elements: disposing the object in a second particle beam system so that the object is disposed in an object region of the second particle beam system; a fourth directing Of a third particle beam onto the object region from a fourth direction, wherein the third particle beam is an ion beam; and then rotating the object about an axis by 180°, wherein the following relation is fulfilled:
 
35°≦α≦55°,
 
wherein α denotes the first angle between the fourth direction and the axis; and then a fifth directing of the third particle bears onto the object region from the fourth direction; and then a sixth directing of a fourth particle beam onto the object region and detecting the particles transmitted through the object; wherein material is removed from the object during the fourth directing and the fifth directing of the third particle beam onto the object region and wherein the fourth particle beam is an electron beam generated by a TEM.
 
     Here, the ion beam, may be an argon-ion beam in particular. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The forgoing as well as other advantageous features of the disclosure will be more apparent from the following detailed description of exemplary embodiments with reference to the accompanying drawings. It is noted that not all possible embodiments necessarily exhibit each and every, or any, of the advantages identified herein. 
         FIG. 1  is a schematic, perspective illustration of a TEM-sample; 
         FIG. 2  is a schematic illustration of a particle beam system configured to manufacture the TEM-sample illustrated in  FIG. 1 ; 
         FIG. 3  is a schematic illustration for illustrating angle relations of the particle beam system of  FIG. 2 ; 
         FIG. 4  is a schematic cross section of a particle beam system configured to analyze the TEM-sample illustrated in  FIG. 1 ; 
         FIG. 5  is a schematic illustration for illustrating angle relations of the particle beam system illustrated in  FIG. 4 ; 
         FIG. 6  is a schematic illustration of an object mount; and 
         FIG. 7  is a flow chart of a method of processing and analyzing a TEM-sample. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     In the exemplary embodiments described below, components that are alike in function and structure are designated as far as possible by alike reference numerals. Therefore, to understand the features of the individual components of a specific embodiment, the descriptions of other embodiments and of the summary of the disclosure should be referred to. 
     In a perspective and schematically simplified illustration,  FIG. 2  illustrates a particle beam system, with which a TEM-sample as illustrated in  FIG. 1  can be manufactured. The particle beam system  1  comprises an electron microscopy system  3  with a main axis  5  and an ion beam processing system  7  with a main axis  9 . The main axis  5  of the electron microscopy system  3  and the main axis  9  of the ion beam processing system  7  intersect in an object region  11  at an angle γ amounting to a value between, for example, 45° and 55° so that an object to be manufactured can both be processed by an ion beam  17  emitted along the main axis  9  of the ion beam processing system  7  and be analyzed using an electron beam  19  emitted along the main axis  5  of the electron microscopy system  3 . 
     Here, the electron microscopy system  3  configured to generate the primary-electron beam  19  comprises an electron source  21  schematically illustrated by a cathode  23 , a thereof distantly disposed suppressor electrode  25  and a thereof distantly disposed contact electrode  26 . Furthermore, the electron microscopy system  3  comprises an acceleration electrode  27  fading into a steel pipe  25  and penetrating a collimator configuration  31  schematically illustrated by a ring coil  33  and a yoke  35 . Subsequent to passing the collimator configuration  31 , the primary-electron beam traverses a pin hole  37  and a central hole  39  in a secondary-electron detector  41 , whereupon the primary-electron beam  19  enters an objective lens  43  of the electron microscopy system  3 . The objective lens  43  configured to focus the primary-electron beam  19  comprises a magnetic lens  45  and an electrostatic lens  47 . In the schematic illustration of  FIG. 2 , the magnetic lens  45  comprises a ring coil  49 , an inner pole shoe  51  and an outer pole shoe  53 . The electrostatic lens  47  consists of a bottom end  55  of the steel pipe  29 , the inner bottom end of the outer pole shoe  53  as well as a ring electrode  59  conically tapering towards position  11  at the object. The objective lens  43  schematically illustrated in  FIG. 2  may comprise a composition as illustrated in more detail in U.S. Pat. No. 6,855,938. 
     Furthermore, the electron-microscopic system  3  may comprise a detector  41 ′ for electrons having traversed the object in order to record an electron-microscopic image of the object from intensities of transmitted electrons, wherein the intensities are detected by the detector  41 ′. 
     The detector  41 ′ for electrons having traversed the object is disposed on the side of the object region  11  opposite to the electron source  21 . Accordingly, the distance between the detector  41 ′ and the electron source  21  is larger than the distance between the object region  11  and the electron source  21 . 
     The ion beam processing system  7  comprises an ion source  63  with an extraction electrode  65 , a collimator  67 , an adjustable aperture  69 , deflection electrodes  71  and focusing lenses  73  configured to generate the ion beam  17  emerging from a housing  75  of the ion beam processing system  7 . 
     The particle beam system  1  further comprises an object mount  81  configured to mount a TEM-sample to be manufactured in the object region  11  of the particle beam system  1 . The object mount  81  comprises a shaft  83  protruding into the object region  11  and onto which the TEM-sample to be manufactured (not illustrated in  FIG. 2 ) is mounted to. The shaft  83  is mounted to an inner part  85  of a pivot bearing  86  comprising an outer part  87  which is mounted to, for example, a vacuum casing of the particle beam system  1  and, hence, is fixedly disposed relative to the electron microscopy system  3  and the ion beam processing system  7 . The inner part  85  of the pivot bearing is pivoted relative to the outer part  87  about an axis of rotation  89 , wherein the shaft  83  of the object mount extends along the axis of rotation  89 . In particular, the axis of rotation  89  may be oriented so that it intersects the object region  11  of the particle beam system  1 . By rotating the shaft  83 , the TEM-sample mounted to the shaft  83  of the object mount  81  may be rotated relative to the outer part  87  of the pivot bearing  86  about the axis of rotation  89  by more than 180°, as illustrated in  FIG. 2  by arrow  91 . 
     Furthermore, in order to position the TEM-sample in the object region  11 , either the shaft  83  may be translationally moveable or tiltable relative to the outer part  87  or the outer part  87  may be translationally moveable or tiltable relative to the vacuum casing. Here, the shaft  83  may be coaxially moveable with respect to the axis of rotation  89  as well. In addition, the shaft  83  may also be moveable or tiltable in two directions being orthogonal to the axis of rotation  89 . 
     Geometric relations between the axis of rotation  89  of the object mount  81  and the main axis  5  of the electron microscopy system and the main axis  9  of the ion beam processing system are schematically illustrated in  FIG. 3 . Therein, of the electron microscopy system  3 , merely a truncated conical, outer contour  45  of the objective lens and, of the ion beam processing system  7 , merely a truncated conical outer contour  75  of the front casing are schematically illustrated in  FIG. 3 . However, a TEM-sample  101  is schematically illustrated in  FIG. 3  which is disposed in the object region  11  of the particle beam system  1  and, there, is being mounted to the object mount  81  not illustrated in  FIG. 3 . The axis of rotation  89  of the object mount  81  and the main axis  9  of the ion beam processing system  7  being the direction from which the ion beam is incident onto the object region  11  enclose an angle α. In the illustrated embodiment, the angle α amounts to a value of 45°. The ion beam  9  can be directed to distinct locations within the object region  11  by controlling the deflectors  71  of the ion beam processing system  7  in order to form the strip-shaped recess  105  extending along the main axis  9  in the TEM-sample  101 . The formation of the strip-shaped recess  105  may be monitored using the electron microscopy system  3  by capturing electron-microscopic images of the TEM-sample and the just formed recess  105 . Here, the axis of rotation  89  of the object mount  81  is oriented at an angle β relative to the main axis  5  of the electron microscopy system  3  and, thus, relative to the direction from which the electrons are incident onto the object region  11 , wherein the angle β amounts to a value of 90° in the illustrated embodiment. 
     As soon as the first of both the recesses  105  are formed, the object mount and, thus, the TEM-sample  101  mounted thereto are rotated by 180° about the axis of rotation  89  in order to form the second of both the recesses  105  using the ion beam. 
     In the illustrated embodiment, the angle α amounts to a value of 45°. As a consequence, the angle ε (see  FIG. 1 ) between the strip-shaped recesses amounts to a value of 90°. However, deviations hereof will be possible, if the angle α amounts to different values which results in different values of the angle ε between the strip-shaped recesses, accordingly. For example, the angle α can amount to values between 35° and 55°. The angle β between the axis of rotation  89  and the direction of the electron beam amounts to a value of 90° in the illustrated embodiment in order to visualize a projection as large as possible of the surface of the TEM-sample  101  in electron-microscopic images. Though, other values of the angle β, for example, between 70° and 90°, can be chosen, too. 
       FIG. 4  illustrates another embodiment of a particle beam system configured to process and analyze a TEM-sample, respectively. The particle beam system  1   a  comprises a transmission electron microscope (TEM)  3   a  and an ion beam processing system  7   a . The transmission electron microscope  3   a  serves for a transmission-electron-microscopic analysis of a TEM-sample (not illustrated in  FIG. 4 ) mounted to an object mount  81   a  in an object region  11   a . Here, the transmission electron microscope  3   a  comprises an electron-beam source  23   a  configured to generate an electron beam  5   a , multiple electrodes  6  configured to form and to accelerate the beam  5   a  and one or multiple condenser lenses  8  or other electro-optical components for additional forming and manipulating of the beam  5   a  prior to its entry in an objective lens  45   a . The other components may comprise a monochromator, a corrector for correcting optical errors of the lens  45   a  and deflectors for scanning the beam  9  across the object region  11   a , for example. 
     In the bears path behind the lens  45   a , further electro-optical components seen as projective lenses  10 , apertures, phase plates, bi-prisms, correctors, spectrometers and the like and, at last, one or multiple detectors  41   a  can be disposed. 
     The lens  45   a  creates a magnetic field between two pole pieces  12 ,  14  focusing the electron beam  5   a , wherein each of the pole pieces comprises a through-hole  16  traversed by the electron beam  5   a . Each of the pole pieces  12 ,  14  tapers towards the object region  11   a  and comprises an end face  18  facing the object region  11   a , wherein field lines of the focusing magnetic field emerge from and enter the end face, respectively. The magnetic field is created by a live coil  20  circumventing the pole pieces  12  and  14 , respectively. The magnetic flux between the pole pieces  12 ,  14  is closed by a cylindrical, metallic yoke  22  also defining a vacuum space  24  including the object region  11   a . In the illustration of  FIG. 4 , upwards towards the electron source  23   a  and downwards towards the detector  41   a , further components  28  of the vacuum casing join the yoke  22  so that the electron source  23   a  and the detector  41   a  are also disposed within the vacuum. 
     The ion beam processing system a is mounted to the vacuum casing  22  so that an ion beam  17   a  generated by the ion beam processing system  7   a  is directed onto the object region  11   a.    
       FIG. 5  illustrates a schematic top view onto a plane traversing the object region  11   a  and being orthogonally oriented to the direction of the electron beam  5   a.    
     Due to the strong magnetic field between the end faces  18  of the pole pieces  12  and  14 , the ions of the ion beam  17   a  move on a curved trajectory within the region of the magnetic field, wherein the trajectory substantially differs from a straight line. Hence, a direction  9   a  from which the ion beam  17   a  is incident onto the object region  11   a  is different from a direction from which the ion beam  17   a  emerges from the ion beam column of the ion beam processing system  7   a.    
     The TEM-sample is mounted to a shaft  83   a  of an object mount  81   a  in the object region  11   a . Here, the shaft  83   a  is rotatable about an axis of rotation  89   a , wherein, an angle α between the axis of rotation  89   a  and the direction  9   a  from which the ion beam  17   a  is incident onto the object region  11   a  amounts to a value of 45° in the illustrated embodiment again. Nevertheless, thereof deviating values may also be chosen for the angle α. 
     An angle γ between the direction from which the electron beam  5   a  is incident onto the object region  11   a  and the direction  9   a  from which the ion beam  17   a  is incident onto the object region amounts to a value of 90° in the illustrated embodiment of the  FIGS. 4 and 5 . An angle β between the direction from which the electron beam  5   a  is incident onto the object region  11   a  and the axis of rotation  89   a  of the object mount  81   a  amounts to a value being slightly smaller than 90° so that the ion beam  17   a  is incident onto the thin region  107  (see  FIG. 1 ) of the TEM-sample disposed in the object region  11   a  at a small angle so that a grazing incidence of the ion beam  17   a  occurs on the thin region  107 . In the illustrated embodiment, the angle β amounts to a value of 87°. 
     According to an alternative embodiment, the angle β amounts to a value of 90° while the angle γ amounts to a value of less than 90° in order to achieve said grazing incidence onto the region  107  of the TEM-sample. Here, the angle γ may amount to a value of, for example, 87°. 
     The ion beam  17   a  may be, for example, an argon-ion beam serving to remove impurities from the TEM-sample mounted in the object region of the transmission electron microscope  3   a.  Here, the ion beam  17   a  is directed onto a side of the region  107  (see  FIG. 1 ) of the TEM-sample until this side is substantially free of impurities. Then, the shaft  83   a  of the object mount together with the TEM-sample mounted thereto is rotated by 180° about the axis of rotation  89   a  whereupon the other side of the region  107  is exempted from impurities with the help of the ion beam  17   a.    
     This process can be monitored by recording transmission-electron-microscopic images of the region  107  of the TEM-sample. 
       FIG. 6  illustrates a detailed view of a front part of the shaft  83   a  of the object mount  81   a . The shaft  83   a  comprises a recess  93  into which an inset  93  is set, wherein the inset comprises a projection  94  which, if the inset  92  is set into the recess, will project into the recess  93  and to which the TEM-sample  101   a  is mounted to so that the TEM-sample is disposed within the recess  93  and can be traversed by the electron beam. Furthermore, the shaft  83   a  comprises a strip-shaped recess  95  configured to let the ion beam  17   a  be incident onto the TEM-sample  101   a  without shadowing the ion beam  17   a  by the material of the shaft  83   a . A correspondent recess  95  is provided on the other side of the shaft  83   a  in order to let the ion beam  17   a  be incident onto the TEM-sample  101   a  after the shaft  83   a  has been rotated about the axis of rotation  89   a  by 180°. This strip-shaped recess  95  is illustrated by dashed lines in the top view of  FIG. 6 . 
     Furthermore, the shaft  83   a  may comprise a conical tip  96  borne by a counter bearing which can be intended to be disposed within the vacuum space  24  in order to provide a precise mount of the TEM-sample  101   a.    
     For transferring the object from the cross-beam-system, into the transmission electron microscope, the entire object mount  81  together with the object can be removed from the cross-beam-system and be mounted in the transmission electron microscope so that the object is disposed in the transmission electron microscope. However, it is also possible that the object mount  81  in the cross-beam-system comprises an intake for the inset  92  to which the object is mounted to. In this case, merely the inset  92  together with the object can be removed from the cross-beam-system and transferred to the transmission electron microscope, where the inset  92  together with the object is mounted to the object mount  81   a  of the transmission electron microscope so that the object may be analysed using the transmission electron microscope. 
     In the following, a method of processing a TEM-sample and its analysis in a transmission electron microscope is illustrated referring to the flow chart of  FIG. 7 . 
     It is assumed that an interesting region exists in a larger substrate, wherein the interesting region shall be analysed with the help of a transmission electron microscope. In a step  201 , a cuboid-shaped material object is cut free from the substrate, wherein the object comprises the interesting region. Here, the material object may exhibit a shape different from the cuboid shape, for example, a trapezoidal shape, a prism shape or a wedge shape. 
     In a step  203 , the object is released from the substrate by means of a transfer tool. This process is also referred to by in-situ lift-out. Background information- regarding an in-situ lift-out method is given, for example, in EP 2 043 131 A2, wherein the full disclosure of this document is incorporated herein by reference. Then, in a step  205 , with help of the transfer tool, the object is mounted to an object mount, for example, the object mount  83  illustrated in  FIGS. 2 to 6 , and the object mount is mounted in a particle beam system, for example, the cross-beam-system illustrated in  FIG. 2 . Thereupon, In a step  207 , a first strip-shaped recess is formed in the object. The process of forming the recess may be monitored by recording an image of the object with help of the SSM in a step  209 . In a step  211 , it is decided whether the strip-shaped recess has been formed as desired, wherein the recess contains the interesting region. If this is not the case, a further processing using the ion beam is performed in the step  207 . If the first strip-shaped recess has been formed as desired, the object is rotated by 180° in a step  213 , wherein the axis in respect to which the rotation is performed and the direction from which the ion beam is incident onto the object region enclose an angle α. Here, the rotation may be performed by a single step of rotation about an axis of rotation. However, it is also possible to perform this rotation by multiple steps of movement which may comprise, for example, multiple consecutively executed rotations about distinct axes of rotation and translations in one or multiple directions. 
     After the rotation of the object, a second strip-shaped recess is formed with help of the ion beam in a step  215 , wherein the second strip-shaped recess is disposed on the side of the object opposite to the side of the first strip-shaped recess and extends at an angle of, for example, 90° relative to the first strip-shaped recess. This process may again be monitored by recording an image of the object with help of the SEM in a step  217 . In dependence of a decision step  219 , the processing using the ion beam is continued in the step  215 , if the desired shape of the second strip-shaped recess has not yet been achieved. 
     If the second strip-shaped recess has been formed as desired, the object comprises a thin region (region  107  in  FIG. 1 ) which contains the interesting region and which may be analyzed with the help of at lease one of the SEM and the transmission electron microscope. For the analysis using the transmission electron microscope, then, in a step  221 , the object is transferred into the transmission electron microscope, for example, the particle beam system illustrated in the  FIGS. 4 and 5 . Here, the object may be disposed in an evacuated transfer container. Notwithstanding, it is possible that the object is contaminated by this transfer, for example, by oxidation. Hence, in a step  223 , the first strip-shaped recess and, thus, the one surface of the thin region  107  of the object is cleaned with help of the ion beam  17   a . Again this process may be monitored by recording a transmission-electron-microscopic image of the object in a step  225 . In dependence of the recorded image, it is decided in a step  227 , whether the processing using the ion beam in the step  223  shall be continued or whether the other side of the region  107  shall be cleaned. Here, in a step  229 , the object is rotated about an axis by 180° wherein the axis and the direction from which the ion beam is incident onto the object enclose an angle α of, for example, 45°. 
     Thereafter, in a step  231 , the second strip-shaped recess and, thus, the second side of the thin region  107  is cleaned. Again this process may be monitored by recording an image of the region  107  with help of the transmission electron microscope in a step  233 . In dependence thereof, it is decided in a decision step  235 , whether the processing using the ion beam shall be continued in the step  231  or whether the object is in a state in which the transmission-electron-microscopic analysis of the interesting region of the object can begin. If this is the case, the transmission-electron-microscopic analysis of the object is performed in a step  237 . 
     While the disclosure has been described with respect to certain exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the exemplary embodiments of the disclosure set forth herein are intended to be illustrative and not limiting in any way. Various changes may be made without departing from the spirit and scope of the present disclosure as defined in the following claims.