In microscopic applications, it is typically necessary for a user to view a larger area of the object at a lower magnification in order to locate multiple small areas to be viewed. When the smaller area to be viewed is located, the user refocuses and switches the magnification. Thereby, the user typically generates a set of images of the object, which covers a range of magnifications. The user has to browse this set of images for identifying object features or for deciding at which locations of the object to acquire further images.
However, when comparing images of widely different magnifications, it is difficult to see how they are related to each other.
In the field of scanning electron microscopy, objects are often analyzed by using images of different detector configurations each of them revealing different characteristics of the object. For example, a secondary electron detector (SE detector) allows to identify topographic features of object. The resolution of the SE detector is typically 1 to 3.5 nm at an energy of the primary electron beam of 30 kV, enabling very fine details of the surface topography to be resolved.
A backscattered electron detector (BSE detector) is typically placed close to the exit opening of the electron optical system to capture electrons, which are reflected or backscattered at acute angles from the object. Since the intensity of the BSE signal is strongly related to the atomic number (Z) of the object, BSE images can provide information about the distribution of chemical elements in the sample. BSE detectors are typically solid-state devices, often with multiple components. For example, by switching of two of the four quadrants of a 4-Quadrant BSE detector, some shadowing can be created resulting in a better topographical contrast.
Moreover, scanning electron microscopes are often provided with an energy-dispersive spectrometer (EDX detector). When the primary electron beam removes an inner shell electron from an atom of the object, characteristic X-rays are emitted when higher energy electrons fill the inner shell of the atom and release energy. These characteristic X-rays are measured by the EDX detector, resulting in a spectrum which may be used to identify the elemental composition of the object and to measure the abundance of specific elements.
Therefore, a comprehensive study of an object with a scanning electron microscope may involve studying images of different magnifications which have been acquired by using different detectors from different locations on the specimen. However, it is typically difficult for the user to determine how these images are related to each other making the analysis of a complex object a time-consuming task.
Accordingly, it is considered desirable to provide a method for operating a charged-particle microscope which allows a more efficient acquisition and analysis of image data of an object.
Embodiments provide a method of operating a charged-particle microscope, wherein the method comprises: recording a first image of a first region of an object using the charged-particle microscope in a first setting; recording a second image of a second region of the object using the charged-particle microscope in a second setting, wherein the second setting differs from the first setting with respect to at least one of a kinetic energy of primary charged particles used for imaging, a detector setting used for imaging, a beam current of the charged particles used for imaging and a pressure in a measuring chamber of the charged-particle microscope; recording a third image of a third region of the object using the charged-particle microscope, wherein the first and second regions are contained at least partially within the third region; displaying at least a portion of the third image; displaying a representation of the first image at least partly within the displayed third image, wherein the representation of the first image includes a first indicator which is indicative of the first setting; displaying a representation of the second image at least partly within the displayed third image, wherein the representation of the second image includes a second indicator which is indicative of the second setting, and wherein the displayed second indicator is different from the displayed first indicator.
The method may be in particular a computer-implemented method. The charged-particle microscope may for example be an electron microscope or a helium ion microscope. The electron microscope may be a scanning electron microscope or a transmission electron microscope.
The third image may be read from a storage medium. The storage medium may be part of a computer system or a data base. Additionally or alternatively, the third image may be read via a signal line from a light microscope or from the charged-particle microscope.
The first region of the object may for example be a region of the object which is scanned by the charged-particle beam for acquiring the first image.
The first and/or second setting may be defined as a set of operational parameters of the charged-particle microscope which are specified at a time when the first image is acquired. The first and/or second setting may comprise at least one of a kinetic energy of the electron beam, a detector setting used for imaging, a beam current of the charged particles used for imaging and a pressure in a measuring chamber. The detector setting may comprise at least one of the following: a type of a detector used for acquiring the image, a number of the detectors used for acquiring the image and a value of an operational parameter of the one or more detectors used for imaging. The measuring chamber may be a vacuum chamber. The pressure may be measured at the time when the image is acquired.
The operational parameters of the one or more detectors used for imaging may for example comprise: a detector voltage, identifier of detector segments of a 4-Quadrant-BSE detector used for imaging and an arrangement of the detector with respect to an object region of the charged-particle microscope.
For example in the case of a scanning electron microscope, the detector used for acquiring the image may be one or more from a combination of the following: a secondary electron detector (SE detector), an in-lens secondary electron detector (annular SE detector), a backscattered electron detector (BSE detector) and/or an in-lens detector for detecting backscattered electrons.
At least a portion of the third image is displayed. The third image may be displayed on a display of a computer. The computer may comprise a graphical user interface which is configured to display the third image in a rendering space of a window of the graphical user interface.
A representation of the first image is displayed on the display. The representation of the first image may comprise an unfilled frame in addition to the representation of the first image, also at least a portion of the first image may be displayed. For example, in case the first image comprises a non-overlapping region with the third image, image data of the first image which correspond to the non-overlapping region may be displayed in the non-overlapping region.
The representation of the first image is displayed at least partially within the third image. In other words, the first image may be located within the third image or may comprise both an overlapping region with the third image and a non-overlapping region with the third image.
The method may comprise determining the representation of the first image such that the representation of the first image is indicative of and/or depends on a location and an extent of the first region relative to the third region.
The location of the first region relative to the third region may be expressed by a displacement vector representing a displacement of a reference point of the first region relative to a reference point of the third region. Additionally, the location of the first region relative to the third region may be expressed by angles by which the orientation of the first region relative to the third region is described. In other words, the location of the first region relative to the third region may be expressed in the same manner as the linear position and angular position of a rigid body.
The extent may be a lateral extent, which is measured perpendicular to the optical axis of the charged-particle microscope. The lateral extent may be measured by projecting the surface topography of the imaged region of the object onto the object plane of the charged-particle microscope.
The extent of the first region relative to the third region may be expressed for example by a scale factor or by a first and a second scale factors, wherein the first scale factor corresponds to a first coordinate axis and the second scale factor corresponds to a second coordinate axis, wherein the first coordinate axis is non-parallel to the second coordinate axis.
Each of the representation of the first image and the representation of the second image comprises an indicator. The indicator may be a color and/or geometry of the respective representation. An indicator, which is represented by the geometry of the representation may for example be a line pattern of the representation and/or an icon of the representation. Each of the indicators is indicative of the setting of the electron microscope at which the respective image was taken. For example, a red-colored frame may indicate that the first image has been acquired by using an SE detector, wherein a blue-colored frame may indicate that the first image has been acquired by using a BSE detector.
Each of the indicators may be determined from a group of pre-defined indicators. For example, the color “red” for the first indicator may chosen from the group of colors “red” and “blue”.
The first indicator may indicate a setting of the charged-particle microscope independently from the indicating of the location and extent of the first region by the location and the form of the representation of the first image. Accordingly, the second indicator may indicate a setting of the charged-particle microscope independently from the indicating of the extent and the location of the second region by the location and the form of the representation of the second image.
The first and second indicator may indicate first and second settings independently from the extent and locations of the first and second region relative to the third region. Thereby, the first and second indicator may provide additional information about the first and second settings. This additional information may comprise a detector setting and/or a primary charged-particle beam setting.
The second indicator is different from the first indicator. For example, the second indicator may be visibly different from the first indicator.
Accordingly, a method is provided which allows to operate a charged-particle microscope in an efficient way. In particular, the method combines the information of an image with its context (i.e. the information provided by other images). Thereby, it is easier for a user to relate the features of an image to features of an object and to determine which images are necessary to conduct a comprehensive study of the object. Consequently, the method allows to conduct a thorough and comprehensive study of complex objects within a short time.
According to an embodiment, the method further comprises recording the third image using a light microscope or the charged-particle microscope.
Alternatively, the method may comprise, recording the third image using a confocal laser scanning microscope, an atomic force microscope or a scanning tunneling microscope.
According to an embodiment, the second indicator is different from the first indicator such that the difference indicates and/or is dependent on a difference of the kinetic energies of the primary charged particles of the first and the second setting and/or a difference of the detector settings of the first and the second setting.
By way of example, the first indicator may depend on the detector setting and/or the energy of the charged-particle beam of the first setting. The second indicator may depend on the detector setting and/or the energy of the charged-particle beam of the second setting.
According to a further embodiment, a form and a location of the representation of the first image is indicative of and/or dependent on an extent and a location of the first region of the object relative to the third region of the object; and a form and a location of the representation of the second image is indicative of and/or dependent on an extent and a location of the second region relative to the third region of the object.
The form and location, of the representation of the first image and the second image may be determined depending on a magnification factor of the third image. The magnification factor of the third image may be defined as a magnification of the displayed third image. In particular, a size of the representation of the first image may be determined by multiplying the extent of the first image with the magnification factor. The location of the representation of the first image relative to the third image may be determined by multiplying the location of the first region relative to the third region with the magnification factor.
According to a further embodiment, the displayed second indicator has a color different from a color of the displayed first indicator. The color of the first indicator and the color of the second indicator may be visually distinguishable.
According to a further embodiment, the displayed second indicator has a geometry different from a geometry of the displayed first indicator. The geometry of the first indicator may be visually distinguishable from the geometry of the second indicator.
For example, the geometry of the first indicator may comprise an icon. The icon may indicate the first setting. The icon may example comprise a symbol which represents the detector, which has been used when acquiring the first image. As a further example, the representation of the first image may comprise a frame. The line pattern of the frame may be determined from the group of a solid line, a dashed line and a dashed-dotted line, depending on the first setting.
According to an embodiment, the charged-particle microscope is an electron microscope and a first detector is used for imaging of the first image and a second detector is used for imagine of the second image, wherein the first detector has a higher relative sensitivity for backscattered electrons than the second detector.
For example, the first detector is a BSE detector and the second detector is an SE detector.
According to an embodiment a first kinetic energy of the primary charged particles is used for imaging of the first image and a second kinetic energy of the primary charged particles is used for imaging of the second image, wherein the first kinetic energy is greater than 1.1 times or greater than 1.5 times or greater than 2 times the second kinetic energy.
According to a further embodiment, a lateral extent of the first region of the object is greater than a lateral extent of the second region of the object; wherein the third image and the representations of the first and second images are displayed on a display medium; and wherein a lateral extent of the displayed representation of the first image on the display medium is greater than a lateral extent of the displayed representation of the second image on the display medium.
A lateral extent of the first region may for example be a diameter of the first region, an area of the first region or a length of the first region along a coordinate axis.
According to a further embodiment, an angle between a line between a center of the first region of the object and a center of the third region of the object and a line between a center of the second region of the object and a center of the third region of the object is a first angle; wherein an angle between a line between a center of the displayed representation of the first image and a center of the displayed third image and a line between a center of the representation of the second image and the center of the displayed third image is a second angle; and wherein an absolute value of a difference between the first angle and the second angle is less than 30 degrees.
The absolute value of the difference between the first angle and the second angle may be less than 10 degrees, less than 5 degrees or less than 1 degree.
Accordingly, it is possible for the user to recognize, based on the displayed representations of the first and second image, and the displayed third image the location of the first region and the second region relative to the third region. Thereby, it is possible for the user to see from the representations which portions of the object already have been imaged and which setting of the charged-particle microscope have been used for acquiring those images.
According to an embodiment, the representation of the first image includes a frame which represents and/or which depends on a lateral extent of the first region. According to an embodiment, the first representation is displayed within the third image and image data, which are enclosed by the first frame, represent the first region and image data, which are enclosed by the second frame represent the second region.
The frame may comprise lines, which are connected and arranged to define a region on the display. In other words, the frame may be an unfilled circle or an unfilled polygon, such as a rectangle. In the region enclosed by the frame, image data values of the third image are displayed in case the frame is located completely inside the third image. In case the frame has a non-overlapping region with the third image, image data of the first image may be displayed in the non-overlapping region. In case the frame is located outside of the third image, image data of the first image may be displayed inside the frame and outside the displayed third frame. A form of the frame relative to the displayed third image may correspond to an extent of the imaged region of the object relative to an extent of the third image. In particular, a size of the frame relative to a size of the displayed third image may correspond to an extent of the first region of the object relative to an extent of the third region. The size of the frame relative to the third image may be expressed by the size of the frame divided by the size of the third image. A location of the frame relative to the displayed third image may correspond to a location of the first region relative to the third region. The form and location of the frame may be determined depending on a magnification factor of the displayed third image. The magnification factor of the third image may be defined as a magnification of the displayed third image. In particular, a size of the frame may be determined by multiplying the extent or the first image with the magnification factor. The location of the frame relative to the third image may be determined by multiplying the location of the first region relative to the third region with the magnification factor.
According to an embodiment, the method further comprises selecting one of the first and second images by selecting one of the representation of the first image and representation of the second image and displaying the selected image. According to a further embodiment, the first and/or second representation is configured to be selectable. According to a further embodiment, the method further comprises displaying at least one of the first and the second image after the representation of the at least one of the first and the second image has been selected. According to a further embodiment, the method comprises displaying a list or links, which are provided by at least one of the first and second representation after the at least one of the first and second representation has been selected.
Selecting a representation may comprise selecting the representation with a pointer of a mouse.
According to an embodiment, a lateral extent of the displayed selected image on a display medium is greater than a lateral extent of the displayed representation of the respective image on the display medium.
According to an embodiment, the method further comprises: selecting a region within the displayed third image; determining a fourth region of the object based on the selected region within the displayed third image; and recording an image of the fourth region of the object using the charged-particle microscope. The charged-particle microscope may be an electron microscope.
Accordingly, it is possible for the user to identify a region of the object, where an image is to be acquired, based on the displayed third image and based on the displayed representations of the first and second image.
According to a further embodiment, a size of the fourth region of the object is at least 10 times smaller than a size of the third region of the object.
According to an embodiment, the method further comprises: recording a fifth image of a fifth region of the object using a second microscope, and displaying a representation of the fifth image at least partially within the third image, wherein the representation of the fifth image includes an indicator, which is indicative of the second microscope.
The indicator, which is indicative of the second microscope may be different, in particularly visually different, from the first indicator and the second indicator. The fifth image may be displayed at least partially within the third image. The fifth image may be recorded using the second microscope in a second setting. The indicator which is indicative of the second microscope may be further indicative of the setting of the second microscope.
The second microscope may be a light microscope. The light microscope may comprise an optical system for imaging an object region onto a detector surface of an image sensor. Alternatively, the second microscope may be a confocal laser scanning microscope, an atomic force microscope, a scanning tunneling microscope or any type of microscope known in the art.
Accordingly, there is provided a method which combines image data which are acquired by using different microscopic techniques. Thereby, it is possible for the user to conduct a thorough and efficient microscopic study of an object by combining different microscopes.
According to an embodiment, a form and a location of the representation of the first image relative to the third image corresponds to an extent and a location of the first region of the object relative to the third region of the object; and a form and a location of the representation of the second image relative to the third image corresponds to an extent and a location of the second region relative to the third region of the object.
The form of the representation of the first image may be for example a quadrilateral, wherein each of the angles of the quadrilateral is greater or less than 90 degrees. Thereby, the representation indicate that the first region is inclined with respect to the third region. According to an embodiment, the form or the indicator of the first representation indicates an angle of an imaging direction of the first image relative to an imaging direction of the third image in case the angle is greater than 0 degrees. The imaging direction may be defined as a direction parallel to the optical axis of the charged-particle microscope or the light microscope when the image is acquired. The imaging direction is expressed relative to the object's coordinate system. Thereby, it is possible for the user to identify images, which at least partially show a same object portion but which are imaged from different imaging directions. This may allow to determine features of surface topography.
The electron microscope may comprise a positioning system which is configured to rotate the object with respect to the object region of the charged-particle microscope. Thereby, the first, second and third image may correspond to different orientations of the object with respect to the object region of the charged-particle optical system.
According to a further embodiment, the displaying of the third image, the displaying of the representation of the first image and the displaying of the representation of the second image is performed depending on a pre-selectable viewing direction.
By way of example, in case the representation of the first image indicates that the first region is inclined with respect to the third region or that an imaging direction of the first region and the imaging direction of the third region form an angle greater than 0 degrees, the user may change a viewing direction such that the representation of the first image is shown as a rectangle or a square, indicating that the viewing direction is parallel to the optical axis of the charged-particle microscope at the time of acquiring the first image, or that the viewing direction is parallel to the imaging direction of the first image. Then, the first image and a representation of the third image may be displayed, wherein a form and a location of the representation of the third image indicates and/or is dependent on a location and extent of the third region relative to the first region.
According to an embodiment, the method further comprises: acquiring a spectrum and/or a diffraction pattern from an interaction region of the charged-particle beam with the object; and displaying a representation of the spectrum and/or the diffraction pattern at least partially within the third image; wherein the representation of the spectrum and/or diffraction pattern includes an indicator of the spectrum and/or diffraction pattern.
The spectrum may be for example an X-ray spectrum, a secondary ion mass spectrum or a cathodoluminescence spectrum. The diffraction pattern may for example be a pattern of diffracted backscattered electrons. The X-ray spectrum may be for example measured by an energy dispersive spectrometer (EDX spectrometer) or a wavelength dispersive spectrometer (WDS spectrometer). The pattern of diffracted backscattered electrons may be for example acquired by an electron backscattered diffraction detector (EBSD detector).
A location of the representation of the spectrum and/or diffraction pattern relative to the third image may be indicative of and/or depend on a location of the interaction region relative to the location of the third image. The representation of the spectrum and/or the diffraction pattern may be for example a mark or an unfilled frame. The representation of the spectrum and/or diffraction pattern may be selectable. The displayed indicator of the spectrum and/or diffraction pattern may be different from indicators of representations of images, thereby indicating the presence of a spectrum or a diffraction pattern. An indicator of a representation of a spectrum may be different from an indicator of a representation of a diffraction pattern. The indicator may be indicative of and depend on characteristics of the spectrum and/or diffraction pattern. For example, the indicator of a spectrum may be indicative of and/or depend on an element, which is revealed by the spectrum. Further by way of example, the indicator of a diffraction pattern may be indicative of and/or depend on a crystallographic orientation.
According to a further embodiment, the method further comprises displaying an icon at an icon location within the third image; wherein the icon is configured to provide at least one link to a data object of the icon.
The icon may be placeable by the user at a selected location within the third image, which thereby gets the location of the icon. The data necessary for defining the icon may be saved in a data file. The data object may comprise metadata. The data object may be an instance of a data type. The data type may be a primitive data type or a complex data type. The complex data type may be for example a data structure or a class. Generating the data object may comprise extracting contents of a data file and/or sending a request to a data base. By way of example, at least one of the links may provide access to the data object via a computer network. For example, the link may be a weblink. The data object may be generated by extracting contents of an application data file to which the link points. The file may contain a text, image data, video data and/or audio data. Examples for such files are: a word processor file, an audio file, a spreadsheet file, a slide presentation file, an image file, a video file and an audio file. By way of example, the data object contains measurement data taken from the object, information related to the object, information related to the measurement process, information related to the charged-particle microscope and/or information related to the light microscope. By way of example, the measurement data may be a particle microscopic image acquired with the charged-particle microscope, a spectrum and/or a diffraction pattern from an interaction region of the charged-particle beam with the object. The measurement data may further comprise data, which have been generated by applying an evaluation routine to at least one of the images. The information related to the object may comprise an object identifier or parameters of object preparation. The information related to the measurement process or the microscope system may be for example control signals for a positioning device for positioning the object, wherein the control signals are indicative, of the icon location, a magnification of the charged-particle microscope or a magnification of the light microscope. The data object may correspond to one or a combination of the following: a voice recording, a text document, a spectrum, a camera image, a video recording, an audio recording, a charged-particle microscopic image and a light microscopic image. Additionally or alternatively, the data object may be stored on a computer of the microscope system and/or on a remote computer.
The charged-particle microscope may be configured such that the icon is selectable. Selecting the icon may comprise selecting the icon with the pointer of the mouse. After having selected the icon, the graphical user interface may display a dialog box. The dialog box may be configured to display a list of the at least one link, wherein links are attachable or removable from the list of links. The dialog box may further be configured such that a link of the one or more links is activatable. Activating the link may result in displaying at least a portion of the contents of the data object. The graphical user interface may be configured such that the icon is displaceable to a different location within the same image or to a different location within a different image.
The icon may include an indicator, which is indicative of one or more of the following: a number of the at least one link of the icon, the data type of the data objects to which the link points, the contents of the data object and the file type of the file from which the data object is generated. The indicator may be a geometry and/or a color of the icon. For example, the icon may be in the form of a symbol of an audio cassette when the linked data object corresponds to a voice recording.
According to an embodiment, the method further comprises placing an icon at the icon location within the third image; and adding a link to the icon. Placing the icon at the icon location may comprise selecting an image region of the third image. Parameters defining the region may be saved as part, of the data, which defines the icon. Thereby, the data object of the icon is assigned to the selected image region.
According to a further embodiment, the method further comprises displaying the first image; and displaying the icon at a location within the first image, wherein the location within the first image corresponds to a portion of the object, which corresponds to the icon location within the third image.
Accordingly, when the first image is displayed, the icon is still displayed at a location, which corresponds to the location at which the user originally has placed the icon within the third image. Thereby, it is possible for the user to attach information to a selected location on the surface of the object, wherein the information is accessible for the user irrespective of which image data is displayed on the display. The displaying may be performed after the representation of the first image has been selected.
A data value, which indicates the time, when the data object of the icon has been generated, may be assigned to the icon. Thereby, it is possible to display the icon only in those images, which have been acquired at substantially the same time as the data object of the icon. For example, the icon may represent a comment, which has been generated substantially at the same time as a first set of images. Then, the icon may be displayed only in those images, which show a portion of the object, which corresponds to the icon location and which are part of the first set of images.
According to a further embodiment, the representation of the first image is configured to provide at least one link to a data object of the first image. According to a further embodiment, the third image is configured to provide at least one link to a data object of the third image.
The links of the representation and/or images and the data objects to which the links point may be configured in the same manner, as has been described with reference to the links and the data objects of the icons.
The representation may be configured provide a link to image data of one or more images. By way of example, the representation of the first image may provide a link to image data of the first image. The representation of the first image may also provide a link to one or more further images. Each of the images which are linked to a common representation may at least partially show a same portion of the object. The images may differ from each other, for example, in the detector setting used for acquiring the respective image. By way of example, a representation of an image may provide a link to a BSE image and a link to an SE image, wherein both images show the same portion of the object surface.
The identifier of the representation may depend on one or more of the following: the data type of the data object and the content of the data object. For example, the representation may appear in dashed lines when it provides a link to a text document.
According to an embodiment, the method further comprises: adding a further link to the at least one link. Thereby, it is possible for the user to attach further information to the representation of an image.
According to a further embodiment, one of the at least one link is activatable by selecting the representation. By way of example, after the representation has been selected, a list of the at least one link is displayed. Each of the links, which are displayed in the list of links is configured to be selectable, for example with the pointer of the mouse. By activating the link, the user may access the contents of the data object.
According to embodiments, there is provided a method of operating a user-interface of a charged-particle microscope, comprising: reading a first image of a first region of an object, wherein the first image corresponds to a first setting of the charged-particle microscope; reading a second image of a second region of an object, wherein the second image corresponds to a second setting of the charged-particle microscope, wherein the second setting differs from the first setting with respect to at least one of a kinetic energy of primary charged particles used for imaging, a detector setting used for imaging, a beam current of the primary charged particles used for imaging and a pressure in a measuring chamber of the charged-particle microscope; reading a third image of a third region of the object, wherein the first and second regions are contained, at least partially within the third region; displaying at least a portion of the third image; displaying a representation of the first image at least partially within the displayed third image, wherein the representation of the first image includes a first indicator which is indicative of the first setting; displaying a representation of the second image at least partially within the displayed third image, wherein the representation of the second image includes a second indicator which is indicative of the second setting, and wherein the displayed second indicator is different from the displayed first indicator. These embodiments may be combined with any one of the previously described embodiments.
The user interface may be a graphical user interface of a computer. The method may be a computer-implemented method. The computer having the graphical user-interface for performing the method may be in signal connection to a microscope or may be a computer which is isolated from microscopes. The images may be read from a memory of a computer or a data base. The images may be acquired by a charged-particle microscope or a light microscope. In other words, the group consisting of the first image, the second image and the third image may be acquired by using a light microscope, a charged-particle microscope or a combination of a light microscope and a charged-particle microscope.
The first image corresponds to the first setting and the second image corresponds to the second setting. In other words, the first image is acquired using a charged-particle microscope at a first setting and the second image is acquired using a charged-particle microscope at a second setting.
According to embodiments, there is provided a charged-particle microscope configured to perform the method according to the embodiments as described above.