DE102010046902B4 - Particle beam microscope and method for operating this - Google Patents

Abstract

A method of operating a particle beam microscope comprising an objective lens (30) having an object region (OR), the method comprising: detecting (100) light rays emanating from a structure, the structure comprising at least a portion of a surface of an object (10 ) and / or comprises a part of a surface of an object holder (20) of the particle beam microscope, calculating (101) a surface model of the structure (90) in dependence on the detected light rays; Determining (102) a position and orientation of the surface model of the structure (90) relative to the object region (OR); Determining (103) a measurement location (P) relative to the surface model of the structure (90); and positioning (105) the object (10) in dependence on the calculated surface model of the structure (90), the particular position and orientation of the surface model of the structure (90) and the determined measurement location (P).

Description

Technical area

The present application relates to a particle beam microscope and a method for operating a particle beam microscope. Specifically, the present application relates to an electron microscope such as a scanning electron microscope and a method of operating such.

Brief description of the prior art

In particle beam microscopes, such as electron microscopes, samples are usually imaged and / or processed under vacuum conditions in a sample chamber. The sample is located in a sample chamber, which is pumped by vacuum pumps. For example, in Scanning Electron Microscopes, a measurement is made at a pressure in the sample chamber, which is usually in a range between high vacuum and about 22.5 Torr. The sample chamber is therefore usually designed as a vacuum chamber having solid walls and flanges so that the leakage rate to the environment can be kept low enough. As a result, the sample chamber does not have large windows that would allow a user to control the positioning of the object in front of the objective lens via direct visual observation.

The sample positioning is therefore usually observed by a CCD camera arranged in the vacuum chamber. The camera captures a video image of the sample and the objective lens. The video image is shown on a display. Through the video image, the user can observe the positioning process in real time and control the positioning of the object via control signals to a positioning device.

However, the image of the CCD camera shown on the display gives the user only a two-dimensional image of the interior of the sample chamber, so that accurate positioning of the object relative to the objective lens is made more difficult. Further, the viewing angle of the CCD camera on the object surface is usually limited by the objective lens and by detectors, especially when the object is close to the objective lens. Therefore, the user often can not recognize which part of the sample is being irradiated by the electron beam.

In the sample chamber of a scanning electron microscope are located next to the objective lens, a variety of other components that restrict a view of the sample in a positioning process and can collide in a positioning process with the sample. Examples of such components are detectors, gas supply systems and manipulators.

A positioning is made more difficult if several objects and / or objects with a complex geometry are fixed on the object holder and are to be positioned in front of the objective lens.

Incorrect positioning can lead to a collision. This can lead to damage to components of the electron microscope or the object.

It has been found that the positioning of a sample in a particle beam microscope involves difficulties, which usually require the user to have a lot of experience in using the particle beam microscope in order to be able to perform a precise positioning in a reasonable time.

The article "Design of a novel visual control system for the prevention of micro-handling in a SEM chamber" by Al. Cvetanovic et al., Published in Microelectronic Engineering 87 (2010), p. 139-143, relates to a video system for preventing collisions between a microgripper and a stage on which a sample is placed.

The article "Smart Flexible Microrobots for Scanning Electron Microscope (SEM) Applications" by Ferdinand Schmoeckel and Serge] Fatikow, published in the "Journal of intelligent material systems and structures" 11 (2000), pp. 191-200, relates to the use of Microrobots in a scanning electron microscope.

The article "Surface Digitization Technology based on multisensor integration" by Xuerong YANG, Siyuan CHENG, Xiangwei ZHANG and Bin ZHAO refers to a combination of a coordinate measuring machine and a fringe projection measuring unit.

The article "Multisensor data fusion in dimensional metrology" by A. Weckenmann et al., Published in "CIRP Annals - Manufacturing Technology" 58 (2009) 701-721, relates to data fusion in the field of dimensional metrology.

document DE 10 2005 026 022 A1 relates to a coordinate measuring apparatus comprising a tactile distance sensor and an interferometer which measures the surface of the workpiece according to the interferometric principle.

It is therefore an object, a particle beam microscope, or method for operating a To provide particle beam microscope, which allows a more efficient positioning of the object.

This object is solved by the subject matter of the independent claims. Further embodiments are the subject of the dependent claims.

Summary of the invention

The present invention has been made in consideration of the above problems.

According to embodiments, there is provided a method of operating a particle beam microscope having an objective lens with an object region, the method comprising: detecting light rays emanating from a structure, the structure comprising at least a portion of a surface of an object and / or a portion of an object Surface of an object holder of the particle beam microscope has; Calculating a surface model of the structure dependent on the detected light rays; Determining a position and orientation of the surface model of the structure relative to the object region; Determining a measurement location relative to the surface model of the structure; and positioning the object depending on the calculated surface model of the structure, the particular position and orientation of the surface model of the structure and the particular measurement location.

The particle beam microscope may be, for example, a scanning electron microscope. Further examples of a particle beam microscope are a focused ion beam system, in particular a helium ion microscope or a transmission electron microscope.

The detection of the light beams can be effected by a photosensitive sensor, in particular a semiconductor sensor. The calculation of the surface model can be done by a computer. The positioning of the object may include automatic positioning controlled by the computer.

The object area can be defined as a spatial area in which a part of an object must be positioned so that an image of this part of the object can be picked up by the particle beam microscope.

The object may be, for example, a wafer or a workpiece. For example, an image of a surface of the wafer or the workpiece is taken by a scanning electron microscope.

The light beams may, for example, have a wavelength in the visible range. The light rays can be emitted by a light source and scattered on the structure, in particular reflected. For example, a light source which illuminates the interior of the sample chamber can be arranged in the sample chamber of the particle beam microscope. Examples of light beams may also be laser beams that are emitted by a laser scanner, wherein the laser scanner is designed such that it scans the surface of the structure with the light beams. Alternatively or additionally, it is also conceivable that the light beams are generated by light sources which are arranged on the structure. For example, light-emitting diodes may be arranged on the structure.

The structure may be defined as a surface having at least a portion of the surface of the object and / or a portion of the surface of the object holder. However, it is also conceivable that the structure also comprises at least part of a surface of another component of the particle beam microscope. It is possible that the structure does not cover the entire surface of the object. The structure does not have to have a surface of the object. For example, with very small objects, as compared to the size of the object holder, it may be sufficient for the structure to have a portion of the surface of the object holder without having a portion of the surface of the object.

The detection of the light beams can be done for example by an image capture device, such as a camera. The camera can be designed and arranged such that an image of the structure can be received by the image sensor of the camera. Furthermore, it is conceivable that reflected laser beams are detected. The laser beams may be generated by a laser scanner which scans the surface of the structure. The reflected laser beams can be detected, for example, by measuring the pulse transit time, the phase difference of the reflected laser beams in comparison to a reference, and / or by triangulation. In addition or as an alternative to a CCD sensor, it is conceivable that the light beams are detected by a spatially resolving photodiode.

An object holder may be defined as a component of the particle beam microscope configured to support an object on which measurements are taken. For example, the object holder may have a surface to which the object can be adhesively bonded and / or to which the object can be fixed by screwing the object holder.

The surface model of the structure may be a model that represents the shape of the structure, the structure being defined as a surface can. In other words, the surface model can be a mathematical description of the structure. The surface model can reflect the structure to a predetermined accuracy. The accuracy of the surface model can be chosen so that a positioning of the structure in front of the objective lens can be made with a predetermined positioning accuracy. For example, a positioning accuracy of 0.1 millimeters, 0.5 millimeters, 1 millimeter or 5 millimeters can be specified.

For example, the surface model may represent a flat, two-dimensional structure. Thus, for example, the surface model of a wafer can be represented by a circular disk, wherein the edge of the circular disk represents the outer edge of the wafer. Furthermore, the surface model may be a three-dimensional surface model. A three-dimensional surface model can be defined as having an uneven surface. For example, a three-dimensional surface model may be a surface of a cylinder or a cuboid without its bottom surface.

For example, the surface model may include a set of points, the points being connected by geometric objects such as lines, triangles, and / or curved surfaces. The dots may be spaced on the order of, for example, one millimeter from each other.

Alternatively or additionally, the surface model may be described at least in part by splines. In other words, the surface model may be described by a set of polynomial surface functions, where a polynomial surface function describes a portion of the surface, and where multiple portions together form the surface model. For example, a plurality of polynomial surface functions of at most four degrees may be sufficient to achieve a predetermined accuracy of the surface model.

The surface model may further include markers corresponding to marks on the structure. For example, the structure may include markings that are detectable by detecting the light rays. Such markings may be, for example, color markers or locations on the structure which differ in their reflectivity from the reflectivity of surrounding areas of the structure.

The calculation of the surface model of the structure is dependent on the detected light rays. The calculation can be done exclusively depending on the detected light beams. In other words, from the information obtained from the detected light beams, the surface model of the structure can be derived. However, it is also conceivable that additional information is used to calculate the surface model. For example, parameters describing the surface of the object holder and / or the object may be known. This can increase the speed for calculating the surface model. For example, the surface of the object holder may already be known. For example, a part of the surface of the object holder may be detected by a CAD drawing or measurements, and the surface model of the structure may be calculated depending on the known surface of the object holder.

The objective lens may be, for example, an electron beam objective lens, or an objective lens for focused ion beams. Other components of the particle beam microscope may include object areas, such as detectors or components for the preparation of the object. Examples of detectors include a secondary electron detector (also referred to as an SE detector), an energy dispersive X-ray detector (also referred to as an EDX detector) and a detector for detecting diffraction of backscattered electrons (also referred to as an EBSD detector). Examples of components for the preparation of the object are a gas injection system, a Focused Ion Beam System (FIB) and a micromanipulator.

For example, the detection of the light rays may occur when the structure is in a sample chamber of the particle beam microscope. Alternatively or additionally, the detection of the light rays can take place when the object is outside the sample chamber of the particle beam microscope. For example, the detection of the light beams can take place in a lock chamber of the particle beam microscope. The lock chamber can be designed so that objects are first introduced into the lock chamber and the objects are transferred after evacuation of the lock chamber in the sample chamber, so that the sample chamber does not have to be vented when introducing new samples. As a result, it can be achieved, for example, that the time in which the lock chamber is evacuated is used to detect the light beams and to calculate the three-dimensional surface model. It is conceivable that the detection of the light rays takes place outside the vacuum system, which comprises the lock chamber and the sample chamber. In other words, the detection of the light beams can be carried out under ambient pressure.

Furthermore, the position and orientation of the surface model relative to the object area is determined. A rigid body has six degrees of freedom of movement.

For example, the six degrees of freedom of the motion can be described with three coordinates of translation and three coordinates of rotation. In a translation, all points of the rigid body are moved parallel by an equal distance. The three coordinates of translation define the position of the body. During a rotation, all points of the rigid body move through an angle about an axis of rotation. The three coordinates of the rotation define the orientation of the rigid body. The orientation of the surface model can be specified, for example, by roll, pitch and yaw angles or by the Euler angles.

Determining the position and orientation of the surface model of the structure can be done depending on the surface model of the structure. For example, the extent of the structure and / or distances between markings can be known from the calculated surface model of the structure. Furthermore, the determination of the position and orientation of the surface model relative to the object region can be effected as a function of the detected light beams. Additionally or alternatively, the determination of the position and orientation may be dependent on signals transmitted between the computer and the positioning device. For example, the positioning device may have a measuring device, by means of which a position and / or orientation of the object holder can be determined with a specific accuracy.

The positioning of the structure can be done for example by the positioning of the particle beam microscope. The positioning device may have one or more drive units. Furthermore, the object holder can be arranged on the positioning device. As a result, the positioning device can be designed such that by controlling one or more drive units, the object can be positioned in the particle beam microscope in front of an objective lens, in front of a detector and / or in front of a component for preparation. The positioning can in particular comprise a positioning of the measuring location in the object area of the objective lens. Furthermore, the positioning may also include the setting of a measurement orientation. The measurement orientation can be defined as the orientation of the object at which a measurement is taken. The measurement orientation can be specified by three angles, for example.

The measurement location may represent a location on the surface of the object at which a measurement is to be made. The determination of the measurement location relative to the surface model can be made dependent on input of the user into the computer. For example, based on a two-dimensional representation of the surface model on a display of the computer, the user can select a location on the structure or relative to the structure on which he wants to take a measurement. The computer may then determine or calculate a location relative to the surface model depending on the user's input. In other words, the measurement location can represent a point relative to the surface model. For example, the measuring location may be a point on the surface of the surface model. However, it is also conceivable that the measuring location lies outside the surface model.

The positioning is done depending on the calculated surface model. For example, depending on the surface model and the measuring location relative to the surface model, a positioning direction can be determined in order to arrange the measuring location in the object area. Furthermore, it can be determined based on the surface model, for example, in which measurement orientation the measurement is to be made. The positioning of the object can be controlled by the computer. However, it is also conceivable for a user to manually control the positioning of the object, wherein, for example, the surface model of the structure, the position and position of the surface model of the structure and the measuring location are displayed on a display of the computer. Depending on the user's input, the computer positions the object.

With this embodiment, a method for operating a particle beam microscope is provided, which makes it possible to position a sample precisely in front of a component of the particle beam microscope, in particular an objective lens. In particular, a location on the sample at which a measurement is to be made can be arranged precisely and quickly in the object area of the objective lens. This also makes it possible for inexperienced users to carry out a measurement in a short time.

According to a further embodiment, the positioning of the object comprises determining a positioning path. The positioning path can be determined, for example, by the computer depending on the surface model, on the specific position and orientation of the surface model relative to the object area, the measuring location and the measuring orientation. The positioning path can be calculated so that the measuring location is arranged in the object area. Further, the positioning can be calculated so that the positioning is collision-free. For example, this can avoid a collision between the objective lens and the object.

According to one embodiment, the positioning of the object comprises arranging the measurement location in the object area.

According to a further embodiment, the method further comprises: adjusting a focus of the objective lens after arranging the measurement location in the object area.

Due to the arrangement of the measuring location in the object area according to the method, the position and orientation of the structure in front of the objective lens is known comparatively accurately. A focus of a scanning electron microscope is typically set with an accuracy that can range from a few nanometers (nm) to a few micrometers (μm), depending on the magnification of the scanning electron microscope. Adjusting the focus can be done automatically by adjusting operating parameters of the particle beam optical system depending on recorded particle beam microscopic images. Due to the comparatively precise knowledge of the position and orientation of the structure, an automatic adjustment of the focus can be facilitated. As a result, in particular the adjustment of the focus can be done faster.

According to one embodiment, the method further comprises: calculating a surface model of a microscope section of the particle beam microscope; Merging the surface model of the structure and the surface model of the microscope section into a common surface model; and calculating a distance between the surface model of the structure and the surface model of the microscope section in dependence on the common surface model; wherein positioning the object comprises monitoring the distance.

The microscope section may for example be at least part of a surface of a component of the particle beam microscope. Examples of such a component may be: the sample chamber, a detector, a manipulator, a gas supply and / or an objective lens.

The common surface model may be defined as a model in which the model of the structure and the model of the microscope section are arranged relative to one another as corresponds to the relative arrangement of the structure and the microscope section in the sample chamber. The common surface model can be merged by the computer. In particular, depending on such a common surface model, a distance between the structure and the microscope section can be determined. The determined distance can be used to detect a possible risk of collision between the microscope section and the structure.

According to one embodiment, the method comprises: determining a positioning path depending on the common surface model. The positioning path can be calculated automatically by the computer. Depending on the specific positioning path, automatic positioning can be performed by the computer. The positioning path can be determined so that the structure is positioned without collision relative to the microscope section.

The distance may represent a smallest distance between the structure and the microscope section. In other words, a smallest distance between the structure and the microscope section can be approximated by the calculated distance. For example, the calculation of the distance can be done by comparing distances between points of the surface model of the structure and points of the surface model of the microscope section. From the comparison then a pair of points can be determined, which has the smallest distance of all pairs of points. Therefore, the calculated distance can approximate the true smallest distance between the structure and the microscope section with a certain accuracy. The distance can be calculated by the computer.

For example, the common surface model may comprise a set of points, the points being connected by geometric objects such as lines, triangles, and / or curved surfaces. Calculating the distance may then include: calculating distances between pairs of points, each pair of points consisting of a point of the structure and a point of the microscope section; and determining the pair of points that has the smallest distance.

Algorithms for the determination of collisions on the basis of surface models are disclosed in the thesis "Virtual Reality in Assembly Simulation - Collision Detection, Simulation Algorithms, and Interaction Techniques" by Gabriel Zachmann, made at the Technical University of Darmstadt and published by Fraunhofer IRB Verlag. The content of this document is hereby incorporated in full. Furthermore, algorithms for collision detection are disclosed in the article "Fast Collision Detection by Parallel Distance Calculation" by Dominik Henrich, et al., Published in the 13th Expert Meeting Autonomous Mobile Systems (AMS'97), Stuttgart, October 6 and 7, 1997, Springer Verlag, Series of Computer Science News ". The content of this document is hereby incorporated in full.

The monitoring of the distance may comprise, for example, issuing a warning signal by the particle beam microscopy system if the distance falls below a predetermined or a predeterminable minimum distance. Alternatively or additionally, it is conceivable that the positioning of the object holder is automatically stopped by the positioning device when the distance is smaller than the minimum distance.

The minimum distance can be predetermined, for example. The minimum distance can be predetermined so that a collision between the structure and the microscope section is avoided. Furthermore, the minimum distance may take into account an accuracy with which the common surface model approximates the structure and the microscope section.

This embodiment enables the object in the particle beam microscope to be moved quickly and without collision. In particular, it can be avoided that the object or the particle beam microscope is damaged by a collision. Furthermore, a secure positioning is made possible, in particular when complex objects or when a plurality of objects are arranged on the sample holder.

According to a further embodiment, the positioning of the object comprises determining a positioning path depending on the common surface model. Determining the positioning path may include calculating distances between the surface model of the structure and the surface model of the microscope section along the positioning path. The positioning of the object can be done depending on the calculated positioning path.

By automatically calculating the positioning path by a computer, a fast and automatic positioning without collision can be made. But it is also conceivable that a user makes a manual positioning, positioning movements, which can lead to a collision can be prevented by warning signals or interrupting the positioning.

According to another embodiment, determining the position and orientation of the surface model of the structure relative to the object area comprises: capturing a digital image of the structure from a pick-up position relative to the object area; and comparing the surface model of the structure with the digital image.

The taking of the digital image may be done by an image capture device, such as a camera. The camera can be arranged, for example, in the sample chamber. The camera can also be arranged outside the sample chamber such that an image of the interior of the sample chamber can be received through a window of the sample chamber. The digital image may have an image of the structure.

By way of example, the comparison may comprise determining properties of the digital image, the properties of the digital image corresponding to properties of the surface model. Such properties may be, for example, edges, surface boundaries and / or markings on the structure.

This makes it possible to easily determine a position of the structure in the particle beam microscope. In particular, it may thereby be possible to follow the position and orientation of the structure in the chamber in real time, without recalculating the surface model when the position and / or orientation of the structure is changed.

According to another embodiment, the method further comprises: storing the measurement location relative to the surface model of the structure; and setting a second measuring location in dependence on the stored measuring location.

Storing the measurement location relative to the surface model may include, for example, storing coordinates of a point relative to the surface model. The coordinates of the point can be stored in a computer memory. Alternatively or additionally, a measurement orientation relative to the surface model can be stored, and a second measurement orientation can be set as a function of the stored measurement orientation. The measurement orientation can be defined by indicating an orientation of the structure during a measurement. The second measuring location can be the same measuring location as the stored measuring location. Thereby, a place where a measurement has been made can be retrieved. The second measurement orientation can be the same as the stored measurement orientation.

This makes it possible to readjust a measuring location and / or a measuring orientation after the object has been moved, for example to carry out a preparation outside of the particle beam microscope. This makes it possible to obtain reliable comparative measurements of exactly the same location and / or in exactly the same orientation. Furthermore, it is possible to save saved pictures with the Particle beam microscope were recorded to assign stored measurement locations and / or measurement orientations.

According to a further embodiment, the method further comprises: fine positioning of the object as a function of particle beam microscopic images after the positioning of the object.

The fine positioning in response to particle beam microscopic images can be done with an accuracy that is higher than the accuracy of positioning depending on the surface model of the structure. In other words, positioning depending on the surface model of the structure can provide coarse positioning, followed by fine positioning. In particular, the combination of coarse positioning and fine positioning can be used to reproducibly set a measuring location with an accuracy which corresponds to the resolution of the particle beam microscopic image. In particular, the fine positioning may include taking particle beam microscopic images and comparing the captured images to stored particle beam microscopic images. The stored particle beam microscopic images may have been taken in a previous fine positioning operation. Fine positioning can be done automatically by the computer.

Embodiments provide a method of operating a particle beam microscope, the method comprising: detecting light rays emanating from a structure, the structure comprising at least a portion of a surface of an object and / or a portion of a surface of an object holder of the particle beam microscope; Calculating a surface model of the structure dependent on the detected light rays; Calculating a surface model of a microscope section of the particle beam microscope; Merging the surface model of the structure and the surface model of the microscope section to - a common surface model; Calculating a distance between the surface model of the structure and the surface model of the microscope section depending on the common surface model; and monitor the distance when positioning the object.

The positioning of the object may include arranging the measuring location in the object area of the objective lens.

According to one embodiment, detecting the light beams comprises acquiring digital image information of the structure; wherein the calculation of the surface model of the structure is dependent on the acquired digital image information.

Capturing digital image information may include capturing at least one image with an image sensor of a camera. The digital image information may include a frame or a series of frames.

From the digital image information, for example, the surface model can be calculated by means of a computer. Such algorithms are described, for example, in "3D Reconstruction from Multiple Images: Part 1 Principles" by Theo Moons, Luc van Gool and Maarten Vergauwen, published in "Foundations and Trends in Computer Graphics and Vision" volume 4, 4th edition, pages 287 to 404. The full disclosure of this document is included here. Furthermore, such algorithms are described in the article "DLP-Based 3D Metrology by Structured Light or Projected Fringe Technology for Life Sciences and Industrial Metrology" by G. Frankowski and R. Hainich, published in "Proceedings of SPIE Phoonics West 2009". The content of this document is hereby incorporated in full. Further, such algorithms are described in the article "ProFORMA: Probabilistic Feature-based On-line Rapid Model Acquisition" by Qi Pan et al., Published in the Proceedings of the "BMVC 2009" of the British Machine Vision Association, London (available on the website http://www.bmva.org/bmvc/2009/index.htm).

The content of this document is hereby incorporated in full.

Alternatively or additionally, it is also conceivable that - for example due to other measurements on the structure - a coarse model is already present, which is adjusted depending on the digital image information. For example, a surface model of at least part of the surface of the object holder may already be stored. The surface model of the object holder is then supplemented by the surface model of at least part of the surface of the object. Depending on the digital image information, the stored surface model of the part of the surface of the object holder is thus supplemented to the surface model of the structure.

This allows the surface model of the structure to be easily obtained from digital images. For example, one or more cameras may be arranged in the sample chamber of the particle beam microscope, which are designed so that digital image information can be detected by the structure through them.

The digital image information of this camera can additionally be used to determine the position and orientation of the surface model relative to the object area. In other words this camera is a positioning camera. For example, the recording position of the camera relative to the object area, the recording direction and / or the magnification of the camera can be known. This may make it possible to determine the position and orientation of the surface model.

This makes it possible to detect digital image information in the sample chamber of the particle beam microscope, which makes it possible to calculate the surface model. Therefore, surface models can be flexibly calculated for the object that is currently in the sample chamber of the particle beam microscope.

Alternatively or additionally, the digital image information can be detected before the structure is introduced into the sample chamber. For example, one or more cameras can be arranged in a lock chamber of the particle beam microscope. In the lock chamber, it may be possible to obtain more accurate image information of the structure, since in the lock chamber usually no detectors and no objective lens are arranged, which can limit a detection angle of the camera.

The pump down time for evacuating the lock chamber or measuring chamber can be used to calculate the surface model of the structure.

According to a further embodiment, acquiring digital image information comprises: acquiring digital image information from at least two different pickup directions relative to the structure.

For example, capturing digital images from different shooting directions may involve changing the orientation and / or position of the structure relative to an image capture device, such as a camera. For example, the orientation and / or the position of the structure can be changed in front of an image capture device, such as a camera, so that the structure can be picked up by the camera from different pickup directions relative to the structure. A pickup direction may be defined, for example, by a vector that is parallel to the optical axis of a camera and indicates the direction of the detected light beams.

Additionally or alternatively, the image capture device may include a plurality of cameras arranged to have different pickup directions relative to the structure. For example, the image capture device may have two, three or more cameras.

According to another embodiment, detecting the light beams comprises detecting a laser beam reflected at the surface of the structure.

Algorithms for the determination of surface models from reflected laser beams of a laser scanner are disclosed in the thesis "Model-based Analysis and Evaluation of Point Sets from Optical 3D Laser Scanners" by Christian Teutsch, produced at the Otto von Guericke University in Magdeburg and published in Shaker Verlag, Herzogenrath. The content of this document is hereby incorporated in full.

For example, the particle beam microscope may include a laser scanner configured to scan at least a portion of the surface of the structure. The laser scanner can be designed such that the reflected laser beams are detected by measuring the pulse transit time, the phase difference of the reflected laser beams in comparison to a reference and / or by triangulation. Furthermore, the laser scanner can be designed such that the position and orientation of the structure can be determined as a function of the detected reflected laser beams.

This makes it possible to simultaneously obtain the surface model of the structure, the position and the orientation of the structure relative to the object area.

According to one embodiment, there is further provided a computer program product comprising computer readable instructions which, when loaded into the memory of a computer and / or computer network and executed by a computer and / or computer network, cause the computer and / or computer network to perform a method as aforesaid performs.

Embodiments provide a particle beam microscopy system, comprising: an objective lens having an object area; an object holder on which an object can be arranged; a positioning device configured to change a position and / or an orientation of the object holder relative to the object area; a detection device configured to detect light rays emanating from a structure, the structure having at least a part of a surface of the object holder and / or a part of a surface of the object; a computer having a signal connection with the positioning device and the detection device, the computer configured to calculate a surface model of the structure dependent on the detected light rays; a position and orientation of the surface model of the structure relative to To determine object area; determine a measurement location relative to the surface model of the structure; and to position the object depending on the calculated surface model of the structure, the particular position and orientation of the surface model of the structure, and the particular measurement location.

The detection device may comprise an image capture device, such as a camera. Alternatively or additionally, the detection device may comprise a laser scanner, which is designed to scan at least a part of the surface of the structure.

The object holder can be connected directly to a positioning device of the particle beam microscope. But it is also conceivable that the object holder is connected via another component with the positioning device, so that the object holder can be positioned by the positioning device. The positioning device may have one or more drive units, such as piezoactuators and / or servo motors.

The computer may be configured to control the positioning of the object fully automatically. However, it is also conceivable for the computer to represent the surface model of the structure, the position and orientation of the surface model of the structure and the measuring location on a display and to perform the positioning of the object depending on user inputs.

As a result, a particle beam microscopy system can be obtained which enables automatic, fast, accurate and easy positioning of the object in front of the objective lens.

According to another embodiment, the computer is further configured to calculate a surface model of a microscope section of the particle beam microscopy system; to merge the surface model of the structure and the surface model of the microscope section into a common surface model; determine a distance between the surface model of the structure and the surface model of the microscope section depending on the common surface model; and to monitor the distance when positioning the object.

In accordance with another embodiment, the particle beam microscopy system includes a position determining camera configured to capture a digital image of the structure; and wherein the computer is further configured to determine the position and orientation of the surface model of the structure relative to the object region depending on a comparison of the surface model of the structure with the digital image.

The position-determining camera can also be designed such that it can detect the light beams used to calculate the surface model of the structure.

According to a further embodiment, the computer is further configured to store the measurement location relative to the surface model of the structure and to position a second measurement location in the object area as a function of the stored measurement location.

According to a further embodiment, the computer is further configured to control, after the positioning of the object, a fine positioning of the object relative to the objective lens depending on particle beam microscopic images.

The computer may be configured to control fine positioning by control signals to the positioning device. The computer may be further configured to automatically evaluate the particle beam microscopic images to control fine positioning.

Embodiments provide a particle beam microscopy system comprising: an objective lens having an object area; an object holder to which an object can be arranged; a positioning device configured to change a position and / or an orientation of the object holder relative to the object area; a detection device configured to detect light rays emanating from a structure, the structure having at least a part of a surface of the object holder and / or a part of a surface of the object; a computer having a signal connection with the positioning device and the detection device; wherein the computer is configured to calculate a surface model of the structure dependent on the detected light rays, to calculate a surface model of a microscope section of the particle beam microscopy system; to merge the surface model of the structure and the surface model of the microscope section into a common surface model; calculate a distance between the surface model of the structure and the surface model of the microscope section depending on the common surface model; and to monitor the distance when positioning the object.

According to a further embodiment, the detection device has an image capture device, which is designed to detect the light beams by acquiring digital image information of the structure.

The image capture device can be, for example, a camera, in particular a single-frame camera or a video camera.

According to a further embodiment, the image capture device and the positioning device are designed such that a receiving direction of the image capture device is variable relative to the structure.

For example, the positioning device can be designed so that the recording direction of the image capture device is changed relative to the structure by changing the position and / or orientation of the structure relative to the image capture device.

According to one embodiment, the image capture device has a first camera and a second camera, wherein a take-up direction of the first camera and a take-up direction of the second camera are different.

The digital image information of the first camera and the second camera can be used to calculate the surface model of the structure and / or to determine the position and orientation of the structure relative to the object region.

According to a further embodiment, the detection device has a laser scanner.

The features and advantages described with reference to the method according to the invention for operating a particle beam microscope are correspondingly also applicable to the particle beam microscopy system according to the invention. The above embodiments and aspects described therein need not be considered separately, but may be combined with each other.

Brief description of the drawings

The foregoing and other advantageous features of the invention will become more apparent from the following detailed description of the exemplary embodiments with reference to the accompanying drawings. It is emphasized that not all possible embodiments of the present invention necessarily achieve all or some of the advantages indicated herein.

1 schematically shows an arrangement of an object, an object holder, an objective lens and a BSE detector according to an embodiment;

2 schematically shows a structure in front of an objective lens of a particle beam microscope;

3 schematically shows a surface model of a structure that has been calculated by a method according to an embodiment;

4 schematically shows a common surface model calculated according to a method according to an embodiment;

5 Fig. 12 schematically shows the determination of the position and orientation of the surface model in a method according to an embodiment;

6 schematically shows a method of operating a particle beam microscope according to an embodiment;

7 schematically shows a method for operating a particle beam microscope according to another embodiment.

Detailed Description of Exemplary Embodiments

1 shows an exemplary arrangement of a structure in the vicinity of an objective lens 30 a particle beam microscope, which is for example a scanning electron microscope. The objective lens 30 has an optical axis OA and an object region OR. The particle beam of the particle beam microscope is focused in the object area OR. In other words, a surface area of an object disposed in the object area OR can be imaged by the particle beam microscope. The object area OR points from the objective lens 30 a working distance WD. The working distance WD and the extent of the object area depend on the construction of the particle-optical system of the particle beam microscope and on operational parameters of the particle-optical system, such as the magnification.

A first object 10 , a second object 11 and a third object 12 are on a object holder 20 arranged. The object holder 20 is arranged on a positioning device, which in 1 not shown. The positioning device is designed such that the object holder 20 along an X-axis, a Y-axis and a Z-axis is movable. This is through the double arrows 50 . 51 and 53 shown. Therefore, the positioning device provides three degree of freedom positioning. The positioning device may further be configured such that the object holder 20 is rotatable about the X-axis, the Y-axis and / or the Z-axis. This is through the arrows 54 . 55 and 56 illustrated. As a result, the positioning device can be designed such that the object holder 20 movable in six degrees of freedom is. The positioning device may have one or more drive units. The drive units can, for example, have stepper motors and / or piezoactuators.

At an exit end of the objective lens 30 can be a detector 40 be arranged, the particles detected on the surface of the first object 10 be backscattered. In the example of a scanning electron microscope, this is a BSE detector (back-scattered electron detector). The particle beam microscope may have further detectors, which are not illustrated. For example, a scanning electron microscope may be a secondary electron detector (also referred to as an SE detector), an energy dispersive detector for X-radiation (also referred to as an EDX detector) and / or a detector for detecting diffraction of backscattered electrons (electron backscattering diffraction detector, also referred to as an EBSD detector) ) exhibit. Furthermore, the particle beam microscope can have further, non-illustrated components, which are designed so that the object can be prepared. Examples of such components are a gas injection system, a Focused Ion Beam System (FIB) and a micromanipulator.

To an electron microscopic picture with the objective lens 30 of the particle beam microscope from a location P on the surface of the first object 10 to receive, must be the first object 10 be arranged in a position and orientation, so that the location P is arranged in the object area OR. The orientation can be indicated by three angles, for example. For example, the orientation of the object may be indicated by Euler angles. The position of the object may be indicated, for example, by three coordinate values along an X-direction, a Y-direction, and a Z-direction.

On the object holder 20 can marks 21 . 22 to be appropriate. The marks 21 . 22 are designed so that they can be seen in an image of a CCD camera. Therefore, calculating a surface model and / or determining the position and orientation of the surface model relative to the object region may be dependent on the detectable marks 21 . 22 respectively.

2 shows a schematic representation of a particle beam microscopy system 1 which includes, for example, a scanning electron microscope. The sample chamber 80 has a vacuum pump system 83 on, with which the sample chamber 80 can be evacuated to a pressure so that measurements with the particle beam are vornehmbar. The vacuum pump system 83 may include a backing pump and a turbomolecular pump. The pressure at which a measurement is made may range from 1 mbar to 10 ^-7 mbar. Around the sample chamber 80 when changing the samples 10 . 11 . 12 not completely ventilate may be at the sample chamber 80 a lock chamber 85 be arranged. At the lock chamber 85 is a lock vacuum pump 81 arranged. Samples 10 . 11 . 12 attached to the object holder 20 can be placed first in the lock chamber 85 be introduced. After evacuation of the lock chamber 85 can the samples 10 . 11 . 12 and the object holder 20 into the sample chamber 80 transferred and at the positioning device 60 of the particle beam microscopy system 1 be attached.

The particle beam microscopy system 1 has a first CCD camera 31 on that in the sample chamber 80 is arranged. The first CCD camera 31 is designed so that digital images of at least a part of the surface of the first object 10 and / or a part of the surface of the object holder 20 are receivable. The first CCD camera 31 is via a first signal line 34 with a computer 70 of the particle beam microscopy system 1 connected. The computer 70 has a memory 71 on. On the store 71 the digital images of the first CCD camera can be stored. The positioning device 60 may be configured such that the first, second, third object 10 . 11 . 12 and / or the object holder 20 through the first CCD camera 31 are receivable from different receiving directions. For example, the positioning device 60 perform a rotation about the Z-axis by a predetermined angle, so that through the first CCD camera 31 the first, second, third object 10 . 11 . 12 and / or the object holder 20 from at least two different receiving direction can be accommodated. From pictures of the first CCD camera 31 from different shooting directions can be through the computer 70 a surface model of a structure can be calculated, wherein the structure has at least a part of a surface of the first, second and / or third object. Additionally or alternatively, the structure may comprise at least part of a surface of the object holder 20 exhibit. The particle beam microscopy system 1 may also be a second CCD camera 32 that are in the sample chamber 80 is arranged. The second CCD camera 32 and the first CCD camera 31 have different shooting directions. By using two CCD cameras, it may be possible that the positioning device 60 does not have to perform any movement to obtain digital images of the structure from different picking directions relative to the structure.

The particle beam microscopy system 1 has a particle-optical system 39 on, that's an objective lens 30 having. At an exit end of the objective lens, a detector 40 (like for example a BSE detector). The particle-optical system 39 and the detector 40 are via a third signal line 37 with the computer 70 connected. About the third signal line 37 can the computer 70 the particle-optical system 39 and the detector 40 control and signals of the detector 40 read. However, it is also conceivable that at the objective lens 30 no detector 40 is arranged.

The digital pictures in memory 71 are stored by the computer 70 further processed. The computer 70 calculates a surface model of the structure from the digital images. The computer 70 is further configured to compute a surface model of a microscope section of the particle beam microscopy system from the digital images. Alternatively, it is possible for the computer to compute the surface model of the microscope section from a CAD model. The microscope section may, for example, a surface of a lower portion of the objective lens 30 with the detector 40 be. The computer 70 is further configured to merge the surface model of the structure and the surface model of the microscope section into a common surface model. The surface model of the structure can be used to position the location P in the object area OR. The common surface model can be used to monitor a distance between the structure and the microscope section, thus avoiding collisions in a positioning operation.

A third CCD camera 33 can in the lock chamber 85 be arranged. The third CCD camera 33 is via a fourth signal line 36 with the computer 70 connected. Furthermore, the lock chamber may have a positioning device, which is designed such that through the third CCD camera 33 digital images of the structure from different receiving directions relative to the structure are receivable. In the lock chamber 85 It is also possible to arrange more than one CCD camera, for example two CCD cameras. The CCD cameras in the lock chamber know to be arranged so that they have different receiving directions relative to the structure.

The one or more CCD cameras in the lock chamber 85 can be designed so that digital image information of the structure can be detected and that a surface model of the structure can be calculated from this digital image information. After acquiring the digital image information of the structure in the lock chamber 85 and after evacuating the lock chamber to a transfer pressure, the first, second, and third objects become 10 . 11 . 12 and the object holder 20 from the lock chamber 85 into the sample chamber 80 transferred. After transfer, the first and / or second CCD cameras in the sample chamber acquire digital images of the structure. The surface model can be used to compare with the digital images taken by the first CCD camera 31 and / or the second CCD camera 32 in the sample chamber, the position and orientation of the structure in the sample chamber 80 to determine. In other words, the first and / or the second CCD camera may be a positioning camera.

This allows the surface model to be calculated as a function of digital image information acquired in the lock chamber. In the lock chamber, the acquisition of the digital image information is not obstructed by the objective lens and / or detectors.

Alternatively, it is conceivable that the calculation of the surface model depends on the digital image information of the first CCD camera 31 and / or the second CCD camera 32 he follows.

3 shows an exemplary surface model 90 the structure. The structure comprises the uppermost horizontal surfaces and the lateral surfaces of the first, second and third objects 10 . 11 . 12 , Furthermore, the structure comprises the uppermost horizontal surface of the object holder 20 , Those surfaces of the object holder 20 that are not in the surface model of the structure 90 are included in the 3 represented by dashed lines. The surface model of the structure 90 includes a lot of points 94 , where the amount of points 94 through geometric objects, such as lines, triangles 94A and / or curved surfaces are connected.

Furthermore, the surface model of the structure 90 marks 97 . 98 on, with the marks 97 . 98 in the 1 shown marks 21 . 22 correspond to the structure.

The computer 70 is configured to a position and orientation of the surface model 90 relative to the object area (OR). Further, the computer is configured to have a measurement location P relative to the surface model 90 to determine. For example, the computer 70 be formed so that a two-dimensional representation 73 , as in 2 shown on a display 72 of the computer 70 is shown. The user can then select a desired location where he wants to take a measurement. Furthermore, the user can view the perspective 73 choose. The user can select the perspective from which to make a decision about the location where a measurement should be made. The representation 73 can also be in a camera image of the structure or in a Camera image of the structure and the, microscope section are faded in. The computer 70 then associates the user's input with a measurement location P relative to the surface model 90 to. From the position and orientation of the surface model 90 relative to the object area OR, as well as from the measuring point P, the computer can determine a positioning path T. The positioning path T can have translational movements and / or rotational movements. In 4 the positioning path T is shown simplified as a vector that connects the measurement site P with the object area OR. However, it is also conceivable that the positioning path T has a curved translation path. After the determination of the positioning path T, the computer controls 70 the positioning device 60 in order to arrange the location on the structure corresponding to the measurement location P in the object area OR.

4 shows an example of a common surface model 93 that comes from the surface model of the structure 90 and a surface model of a microscope section 92 through the in 2 represented computer 70 was merged. Merging in this context can mean that the surface model of the structure 90 and the surface model of the microscope section 92 be arranged relative to each other so that it corresponds to the relative arrangement between the structure and the microscope section in the particle beam microscope.

The surface model of the microscope section 92 can be calculated depending on the detected light rays. Alternatively or additionally, it is possible that the surface model of the microscope section 92 In the storage room 71 of in 2 illustrated computer 70 is stored and retrieved for merging with surface models of different structures.

The computer 70 is configured to be dependent on the common surface model 93 a distance D between the surface model of the structure 90 and the surface model of the microscope section 92 is calculable. For example, the computer 70 all distances between pairs of points of the common surface model 93 calculate, where a pair of points from a point of the surface model of the structure 90 and from a point of the surface model of the microscope section 92 consists. From the calculated distances of the pairs of points a smallest distance D can be determined. The Indian 4 shown. Distance D is the distance between the point Q of the surface model of the microscope section 92 and the point R of the surface model of the structure 90 , If the distance D is smaller than a predetermined minimum distance, a warning signal is emitted by the particle beam microscope. Furthermore, the particle beam microscopy system 1 be configured so that positioning movements are automatically blocked, which lead to a smaller distance D than the specified minimum distance. Furthermore, the particle beam microscopy system 1 be configured so that it depends on the common surface model 93 calculates a positioning path T, wherein the positioning path T is calculated so that no collision between the microscope section and the structure takes place.

5 shows by way of example how the position and orientation of the surface model of the structure is determined relative to the object area. After calculating the surface model 90 takes the in 2 illustrated first CCD camera 31 an Indian 5 illustrated digital image 94 from the structure up. In other words, the first CCD camera 31 a positioning camera of the particle beam microscopy system 1 , The computer 70 is configured to display the digital image 94 with the surface model of the structure 90 is compared. For example, the digital image 94 with two-dimensional representations 90A . 90B compared to the surface model 90 in different orientations. The comparison may be, for example, extracting an edge 96 from the digital picture 94 of the structure that with an edge or a border 96A the representation of the surface model 90 is compared. Further, the comparing may include extracting the tag 99 include that with a marker 99A the presentation 90A of the surface model 90 is compared. Determining the position and orientation of the surface model 90 may depend on a known recording direction, a known recording position relative to the object area OR, a known magnification of the first CCD camera 31 and / or the surface model of the structure 90 respectively. Furthermore, it is possible to determine the position and orientation of the surface model 90 comprises acquiring digital image information from at least two different pickup directions relative to the structure. Image pairs taken from the two shooting directions may represent stereoscopic digital image information of the structure. From the comparison of the extracted edge 96 with the edge 96A can be an assignment 95 the two-dimensional representation 90A of the surface model 90 to the picture 94 respectively. The determination of the position and orientation of the surface model 90 relative to the object area OR takes place depending on the assignment 95 ,

6 shows by way of example the sequence of a positioning operation according to an embodiment, wherein the in 2 illustrated particle beam microscopy system 1 Reference is made. Further, on the in 3 illustrated Surface model of the structure 90 Referenced. Through the first CCD camera 31 a detection takes place 100 of rays of light emanating from the structure. Detecting 100 the light rays may further include imaging the structure with the second CCD camera 32 include. The shooting direction of the first CCD camera 31 and the second CCD camera 32 are different from each other. Depending on the geometry of the structure and / or the required accuracy in the calculation of the surface model 90 can also take a picture or multiple pictures of the first CCD camera 31 sufficient to calculate the surface model of the structure. Additionally or alternatively, the computer 70 the positioning device 60 between two shots of the first and / or second CCD camera 31 . 32 rotate so that through the first and / or second CCD camera 31 . 32 the structure of different receiving directions relative to the structure is receivable. The captured digital images representing digital image information are transmitted over the first and second signal lines 34 . 35 to the computer 70 transmitted and in memory 71 of the computer 70 saved. Depending on the acquired digital images, the calculation takes place 101 of the surface model 90 through the computer 70 , The calculated surface model 90 will be in memory 71 of the computer 70 saved.

Depending on the known positions, the known shooting directions and magnifications of the first and / or second CCD camera 31 . 32 , and / or from the calculated surface model 90 will be determining 102 a position and an orientation of the surface model of the structure 90 performed relative to the object area OR. It will be - as in 5 shown - digital pictures 94 the first and / or second CCD camera 31 . 32 with representations 90A . 90B of the surface model of the structure 90 compared. Alternatively or additionally, the determining 102 the position and orientation of the surface model of the structure 90 relative to the object area OR depending on signals between the positioning device 60 and the computer 70 be determined. For example, the positioning device 60 Have sensors that a set position of the positioning 60 measure up. Alternatively or additionally, the control signals of the computer 70 to the positioning device 60 to be recorded.

The computer 70 is configured to be a two-dimensional representation 73 of the surface model on the display 72 display. Depending on the illustration shown 73 For example, the user may select a location where a particle micrograph is to be taken. The computer 70 performs a determination depending on the user input 103 a measuring point P relative to the surface model of the structure 90 by.

Depending on the relative position and orientation of the surface model 90 to the object area OR and the specific location P, the computer performs 70 a determination 104 a positioning by. The Positionierweg may include translational movements and / or rotational movements. Depending on the determined positioning path T, the computer controls 70 by signals to the positioning device 60 a positioning 105 of the object. After positioning 105 of the object is the location of the object 10 at which the measurement is to take place in the object area OR. Then the computer can 70 a new determination 102 the position and orientation of the surface model 90 carry out.

7 shows an exemplary method according to another embodiment. This is on the in 2 illustrated particle beam microscope 1 and that in 4 illustrated common surface model 93 Referenced. The steps Detect 110 of light rays and calculating 111 of the surface model of the structure are carried out accordingly, as already described with reference to FIG 6 described. Furthermore, the computer leads 70 a calculation 112 a surface model of a microscope section 92 by. The microscope section may, for example, at least part of a surface of a detector 40 , an objective lens 30 , a manipulator, a gas supply device, and / or a wall of the sample chamber 80 exhibit. After that, the computer leads 70 a merge 113 to a common surface model 93 by. In the common surface model 93 are the surface model of the structure 90 and the surface model of the microscope section 92 arranged in a relative position and relative orientation to each other, the relative orientation and relative position in the sample chamber 80 equivalent. The merge 113 can be based on pictures of the first CCD camera 31 and / or the second CCD camera 32 respectively. Alternatively or additionally, the merging 113 depending on signals between the positioning device 60 and the computer 70 respectively.

The surface model of the structure 90 and the surface model of the microscope section 92 can be calculated separately, in particular one after the other. However, it is also conceivable that the surface model of the structure 90 and the surface model of the microscope section 92 be calculated simultaneously, in particular in one process from the same digital image information. In this case, the merge takes place 113 to a common surface model 93 along with computing the common surface model 93 , In other words, it becomes a common surface model 93 directly from the pictures of the first and / or second CCD camera 31 . 32 calculated. Depending on the common surface model 93 becomes a distance between the surface model of the structure 90 and the surface model of the microscope section 92 calculated.

Depending on the calculated common surface model 93 and the calculated distance leads the computer 70 a determination 115 a positioning path T through. The positioning path T is calculated so that there is no collision of the structure with the microscope section. After positioning 116 leads the computer 70 again a merge 113 to the common surface model 93 by taking into account the new relative position and orientation of the structure and the microscope section at the measuring position and in the measuring orientation. After recalculating 114 the distance, in turn, will be determining 115 a positioning carried out so that no collision between the structure and the microscope section takes place on the positioning. This is followed by positioning 116 along the positioning path.

Claims (18)

Method for operating a particle beam microscope comprising an objective lens ( 30 ) having an object area (OR), the method comprising: detecting ( 100 ) of light rays emanating from a structure, the structure comprising at least a part of a surface of an object ( 10 ) and / or a part of a surface of an object holder ( 20 ) of the particle beam microscope, calculating ( 101 ) of a surface model of the structure ( 90 ) depending on the detected light rays; Determine ( 102 ) a position and an orientation of the surface model of the structure ( 90 ) relative to the object area (OR); Determine ( 103 ) of a measuring location (P) relative to the surface model of the structure ( 90 ); and positioning ( 105 ) of the object ( 10 ) depending on the calculated surface model of the structure ( 90 ), the specific position and orientation of the surface model of the structure ( 90 ) and the determined location (P). The method of claim 1, further comprising: calculating ( 111 ) of a surface model of a microscope section ( 92 ) of the particle beam microscope; Merge ( 113 ) of the surface model of the structure ( 90 ) and the surface model of the microscope section ( 92 ) to a common surface model ( 93 ); and calculating ( 114 ) of a distance (D) between the surface model of the structure ( 90 ) and the surface model of the microscope section ( 92 ) depending on the common surface model ( 93 ); where positioning ( 105 ; 116 ) of the object ( 10 ) comprises monitoring the distance (D). Method according to claim 1 or 2, wherein said determining ( 102 ) the position and orientation of the surface model of the structure ( 90 ) relative to the object area (OR) comprises: taking a digital image ( 94 ) of the structure from a pickup position relative to the object area (OR); and comparing the surface model of the structure ( 90 ) with the digital image ( 94 ). Method according to one of the preceding claims, further comprising: storing the measuring location (P) relative to the surface model of the structure ( 90 ); and positioning a second measuring location in the object area as a function of the stored measuring location. Method according to one of the preceding claims, further comprising: fine positioning of the object as a function of particle beam microscopic images after positioning ( 116 ) of the object. A method of operating a particle beam microscope, the method comprising: detecting ( 110 ) of light rays emanating from a structure, the structure comprising at least a part of a surface of an object ( 10 ) and / or a part of a surface of an object holder ( 20 ) of the particle beam microscope; To calculate ( 111 ) of a surface model of the structure ( 90 ) depending on the detected light rays; To calculate ( 112 ) of a surface model of a microscope section ( 92 ) of the particle beam microscope; Merge ( 113 ) of the surface model of the structure ( 90 ) and the surface model of the microscope section ( 92 ) to a common surface model ( 93 ); To calculate ( 114 ) of a distance (D) between the surface model of the structure ( 90 ) and the surface model of the microscope section ( 92 ) depending on the common surface model ( 93 ); and monitoring the distance in positioning ( 116 ) of the object. Method according to one of the preceding claims, wherein the detecting ( 100 ; 110 ) of the light beams comprises acquiring digital image information of the structure, and wherein calculating the surface model of the structure ( 90 ) takes place depending on the acquired digital image information. The method of claim 7, wherein acquiring digital image information comprises: acquiring digital image information from at least two different pickup directions relative to the structure. Method according to one of the preceding claims, wherein the detecting ( 100 ; 110 ) of the light beams comprises detecting a laser beam reflected at the surface of the structure. A computer program product comprising computer readable instructions that, when loaded into the memory of a computer and / or computer network, and executed. from a computer and / or computer network, cause the computer and / or the computer network to perform a method according to any one of claims 1 to 9. Particle beam microscopy system ( 1 ), comprising: an objective lens ( 30 ) having an object area (OR); an object holder ( 20 ) on which an object ( 10 ) can be arranged; a positioning device ( 60 ) which is adapted to a position and / or an orientation of the object holder ( 20 ) relative to the object area (OR) to change; a detection device, which is designed to detect light beams emanating from a structure, the structure comprising at least a part of a surface of the object holder ( 20 ) and / or a part of a surface of the object ( 10 ) having; a computer ( 70 ), which provides a signal connection with the positioning device ( 60 ) and the detection device, wherein the computer ( 70 ) is configured to a surface model of the structure ( 90 ) depending on the detected light rays; a position and an orientation of the surface model of the structure ( 90 ) relative to the object area (OR); a measuring location (P) relative to the surface model of the structure ( 90 ) to determine; and the object ( 10 ), depending on the calculated surface model of the structure ( 90 ), the specific position and orientation of the surface model of the structure ( 90 ) and the determined location (P). Particle beam microscopy system ( 1 ) according to claim 11, wherein the computer ( 70 ) is further configured to provide a surface model of a microscope section ( 92 ) of the particle beam microscopy system ( 1 ) to calculate; the surface model of the structure ( 90 ) and the surface model of the microscope section ( 92 ) to a common surface model ( 93 ) merge; a distance (D) between the surface model of the structure ( 90 ) and the surface model of the microscope section ( 92 ) depending on the common surface model ( 93 ) to determine; and when positioning the object ( 10 ) to monitor the distance (D). Particle beam microscopy system ( 1 ) according to claim 11 or 12, wherein the particle beam microscopy system ( 1 ) a positioning camera ( 31 ), which is designed to be a digital image ( 94 ) of the structure; and wherein the computer ( 70 ) is further configured to determine the position and orientation of the surface model of the structure ( 90 ) relative to the object area (OR) depending on a comparison of the surface model of the structure ( 90 ) with the digital image ( 94 ). Particle beam microscopy system ( 1 ) according to one of claims 11 to 13, wherein the computer ( 70 ) is further configured, after the positioning of the object ( 10 ) a fine positioning of the object ( 10 ) relative to the objective lens ( 30 ) depending on particle beam microscopic images. Particle beam microscopy system ( 1 ) comprising: an objective lens ( 30 ) having an object area (OR); an object holder ( 20 ) on which an object ( 10 ) can be arranged; a positioning device ( 60 ), which is adapted to a position and / or an orientation of the object holder ( 20 ) relative to the object area (OR) to change; a detection device which is designed to detect light beams emanating from a structure, the structure comprising at least a part of a surface of the object holder and / or a part of a surface of the object ( 10 ) having; a computer ( 70 ), which provides a signal connection with the positioning device ( 60 ) and the detection device; the computer ( 70 ) is configured to a surface model of the structure ( 90 ) depending on the detected light beams, a surface model of a microscope section ( 92 ) of the particle beam microscopy system ( 1 ) to calculate; the surface model of the structure ( 90 ) and the surface model of the microscope section ( 92 ) to a common surface model ( 93 ) merge; a distance (D) between the surface model of the structure ( 90 ) and the surface model of the Microscope section ( 92 ) depending on the common surface model ( 93 ) to calculate; and the distance (D) when positioning the object ( 10 ). Particle beam microscopy system ( 1 ) according to one of claims 11 to 15, wherein the detection device comprises an image detection device which is adapted to detect the light beams by detecting digital image information of the structure. Particle beam microscopy system ( 1 ) according to claim 16, wherein the image capture device is a first camera ( 31 ) and a second camera ( 32 ), wherein a recording direction of the first camera ( 31 ) and a take-up direction of the second camera ( 32 ) are different. Particle beam microscopy system ( 1 ) according to one of claims 11 to 17, wherein the detection device comprises a laser scanner.

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