System and method for analyzing sample using charged particle beam and active pixel control sensor

Abstract

Systems and methods for analyzing a sample using a charged particle beam and an active pixel control sensor. The systems and methods taught herein utilize a single detector to provide both one-dimensional data (e.g., for direct topography imaging) and multi-dimensional data (e.g., for crystallographic data) for a sample interrogated with a charged particle beam. In some examples, the one-dimensional data may include signal strengths due to backscattered electrons received across the entire detector surface, while the multi-dimensional data may include signal strengths due to backscattered electrons as a function of pixel positions. By obtaining one-dimensional and multi-dimensional data from a single detector, the one-dimensional and multi-dimensional data may be obtained at the same location, simultaneously, or both at the same location and simultaneously.

Description

BACKGROUND OF THE INVENTION

[0001] When irradiating a sample with a charged particle beam, such as an electron beam, various charged particles and / or electromagnetic radiation are emitted, scattered, or transmitted due to the interaction between the charged particle beam and the sample. The emitted, scattered, or transmitted particles and / or radiation can be detected by a detector to provide information about the sample. For example, backscattered electrons are low-energy-loss electrons that are reflected or backscattered out of the interaction volume of the sample through elastic scattering interactions between the charged particle beam and the atoms of the sample. By collecting these charged particles and / or radiation using a two-dimensional detector, the spatial or angular emission / reflection / transmission pattern of the particles or radiation can be determined. Then, the structural information in the interaction volume, such as the local crystal orientation, can be determined by analyzing and interpreting the two-dimensional pattern. SUMMARY OF THE INVENTION

[0002] Provided herein is a charged particle detector system. The charged particle detector system includes an active pixel control sensor having a sensor layer and a readout chip and including a plurality of pixels. Each pixel of the plurality of pixels generates at least electrons and holes when struck by a charged particle. The charged particle detector system includes a first readout circuit in communication with the sensor layer and configured to receive a one-dimensional data signal corresponding to one of the electrons or the holes generated by the impact of the charged particle. The charged particle detector system includes a second readout circuit in communication with the readout chip and configured to receive a multi-dimensional data signal corresponding to the other of the electrons or the holes generated by the impact of the charged particle.

[0003] Provided herein is a method of imaging a sample. The method includes receiving charged particles from the sample at a plurality of pixels in an active pixel control sensor, where the active pixel control sensor includes a sensor layer and a readout chip. Each pixel of the plurality of pixels generates at least electrons and holes when struck by a charged particle. The method includes transmitting a one-dimensional data signal corresponding to one of the electrons or the holes generated by the impact of the charged particle from the sensor layer to a first readout circuit. The method includes using the first readout circuit to generate one-dimensional data from the one-dimensional data signal. The method includes transmitting a multi-dimensional data signal corresponding to the other of the electrons or the holes generated by the impact of the charged particle from the readout chip to a second readout circuit. The method includes using the second readout circuit to generate multi-dimensional data from the multi-dimensional data signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] To facilitate easy identification of the discussion of any particular element or action, one or more of the most significant digits in the reference numerals refer to the figure number in which that element was first introduced.

[0005] It should be understood that the drawings are not necessarily to scale, and the relationships between objects in the drawings are not necessarily to scale. The drawings are depictions intended to clarify and understand the various embodiments of the apparatuses, systems, and methods disclosed herein. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. Additionally, it should be understood that the drawings are not intended to limit the scope of the teachings in any way.

[0006] Figure 1 An example charged particle detector system in accordance with one example of the teachings herein is illustrated.

[0007] Figure 2 An example process of using the charged particle detector system of an example of the teachings herein to obtain both a structural image and an intensity image of a region of interest (ROI) is illustrated.

[0008] Figure 3 A side - view cross - sectional view of a single pixel in an active pixel control sensor in accordance with some examples described herein is illustrated.

[0009] Figure 4A An experimental image obtained using the charged particle detector system of the present disclosure with a dwell time of 30 microseconds is illustrated.

[0010] Figure 4B An experimental image obtained using the charged particle detector system of the present disclosure with a dwell time of 5 microseconds is illustrated.

[0011] Figure 4C An experimental image obtained using the charged particle detector system of the present disclosure with a dwell time of 1 microsecond is illustrated.

[0012] Figure 4D An experimental image obtained using the charged particle detector system of the present disclosure with a dwell time of 500 nanoseconds is illustrated.

[0013] Figure 4E An experimental image obtained using the charged particle detector system of the present disclosure with a dwell time of 300 nanoseconds is illustrated.

[0014] Figure 4F An experimental image obtained using the charged particle detector system of the present disclosure with a dwell time of 200 nanoseconds is illustrated.

[0015] Figure 5 An example charged particle imaging system 600 for obtaining images using various imaging modalities in accordance with the present disclosure is illustrated.

[0016] Figure 6A A detector arrangement for a reflection Kikuchi diffraction (RKD) imaging modality in accordance with some examples described herein is illustrated.

[0017] Figure 6B Illustrates a detector arrangement for an in - axis transmission Kikuchi diffraction (TKD) imaging modality or a four - dimensional scanning transmission electron microscopy (4 - D STEM) imaging modality according to some examples described herein.

[0018] Figure 6C Illustrates a detector arrangement for an off - axis transmission Kikuchi diffraction (TKD) imaging modality according to some examples described herein.

[0019] Figure 7 Is a block diagram illustrating a computing device suitable for use with examples as taught herein.

[0020] Figure 8 Illustrates an example method for imaging a sample according to examples taught herein.

[0021] Figure 9 Illustrates an example method for assembling a charged particle detector system according to some examples taught herein. DETAILED DESCRIPTION

[0022] The systems and methods taught herein utilize a single detector to provide both one - dimensional data (e.g., for direct intensity imaging similar to secondary electron (SE) or backscattered electron (BSE) imaging in many scanning electron microscope systems) and multi - dimensional data (e.g., for crystallographic data) for a sample interrogated with a charged particle beam. In some examples, the one - dimensional data may include signal intensity due to backscattered electrons received across the entire detector surface, while the multi - dimensional data may include signal intensity due to backscattered electrons as a function of pixel position. In conventional systems, separate detectors are provided to collect one - dimensional data and multi - dimensional data. By obtaining one - dimensional data and multi - dimensional data from a single detector, one - dimensional data and multi - dimensional data can be obtained simultaneously at the same location.

[0023] The detector systems and methods taught herein can improve image quality and automate image registration between an intensity image and a structural image or information by simultaneously obtaining one-dimensional data and multi-dimensional data. For applications where it is desired to simultaneously collect imaging data (i.e., one-dimensional data) and structural or diffraction data (i.e., multi-dimensional data), conventional systems in the art place separate detectors at different positions relative to the sample (e.g., a first detector in transmission mode and a second detector in reflection mode). The emission / scattering of secondary charged particles from the sample has an angular dependence. Thus, while the separate detectors can be positioned close to each other, they do not overlap and will receive slightly different numbers of charged particle impacts. Similarly, in some conventional setups where the detectors are spaced far apart, images obtained using two detectors are not automatically registered and must be transformed into a common coordinate space to enable comparison, overlay, or merging of the images. The detector systems and methods taught herein enable both one-dimensional and multi-dimensional data to be obtained simultaneously from the same pixels of a single detector. Thus, the one-dimensional and multi-dimensional data obtained using the systems and methods taught herein can result in images having the same charged particle intensity content and / or being automatically registered.

[0024] In some examples of the systems and methods taught herein, the one-dimensional data collected simultaneously with the multi-dimensional data can be used to estimate parameters such as the noise background or appropriate detector settings. These parameters derived from the one-dimensional data can be applied in a live or real-time manner during the processing of the multi-dimensional data. For example, the one-dimensional data signal can be used by a computing device to estimate the number of charged particles (e.g., electrons) impinging on the sensor (i.e., the total current). Then, the total current information can be used to estimate and / or set the threshold or integration time in the readout chip for the multi-dimensional data signal. Adjustment of the parameters of the readout chip can be made during image (i.e., frame) acquisition or between image acquisitions.

[0025] The detector systems and methods taught herein can improve image quality and speed up the acquisition time between intensity images and structural images by obtaining both one-dimensional data and multi-dimensional data at the same location using a single detector. For applications where it is desired to collect imaging data (i.e., one-dimensional data) and structural or diffraction data (i.e., multi-dimensional data) from the same location, conventional systems in the art use a first detector at the imaging location to obtain a first image, physically remove the first detector, insert a second detector at the imaging location, and then obtain a second image. Thus, obtaining imaging data and diffraction data using separate detectors as in conventional systems results in a significant time lag due to the need to replace the detector. In addition, the interchange of detectors means that the detector for collecting multi-dimensional data must be painstakingly positioned at the desired field of view at the usually slow acquisition rate of the detector, and it is difficult to observe and correct for position drift over time. The systems and methods taught herein enable the acquisition of both one-dimensional data and multi-dimensional data from the same location using a single detector. The one-dimensional data can be used to form an intensity image that enables rapid identification of the desired field of view and drift correction during acquisition, while the multi-dimensional data can be used to obtain structural information of the sample.

[0026] In some conventional systems, binning is performed on multi-dimensional data signals from an electron backscatter diffraction (EBSD) detector using hardware modification and / or software data processing to form segments of one-dimensional data. While this process enables the use of a single detector to obtain intensity and structural images of a sample over time, the readout time is significantly increased (typically taking up to several seconds) because the data must first be obtained as multi-dimensional data and then converted to one-dimensional data. The readout speed of multi-dimensional data can depend on several factors in various systems, including the time to read out data per pixel and the time to accumulate enough charged particle impacts to exceed the readout threshold. In addition, such conventional systems do not allow the simultaneous generation of both one-dimensional data signals and multi-dimensional data signals, and sacrifice multi-dimensional image quality by downsampling to form one-dimensional data signals. The present systems and methods overcome such difficulties by generating two data signals simultaneously with full information content in each signal, where the first data signal is based on either holes or electrons generated in the sensor layer, and the second data signal corresponds to the other of the electrons or holes not used to generate the first data signal. One of the data signals is not constrained by the time to read out data per pixel or other delays introduced by the readout chip electronics in the detector. Thus, the systems and methods taught herein increase the data acquisition speed relative to conventional systems by processing multiple data streams in parallel and by enabling at least one data stream to be processed faster than another data stream or multiple data streams.

[0027] Additional benefits are achieved by reducing the number of multiple detectors used in conventional setups to a single detector as taught herein, such as cost savings, system simplification, and fewer components to maintain and service. For example, a conventional configuration using separate EBSD and backscattered electron (BSE) detectors leaves little free space in the vacuum chamber to manipulate tools and stages and may block large areas of the viewing angle. The size of one detector and / or the required orientation of the sample relative to the probing beam (e.g., 70° for standard EBSD) may force the placement of the other detector in a sub-optimal position. Separate detectors may create a need for separate maintenance and service of each detector and additional hardware to power and / or interface with multiple detectors. The systems and methods taught herein may reduce or eliminate some of these requirements by simplifying the system architecture.

[0028] In some examples, the systems and methods taught herein may use imaging data obtained from a single detector to locate regions of interest on a sample that have specified crystallographic properties as determined by structural data (e.g., diffraction data) received concurrently with the imaging data from the sample. Specifically, when the detector is used for reflection Kikuchi diffraction (RKD) or EBSD, the systems and methods taught herein improve the location of regions of interest.

[0029] As used herein, "one-dimensional data" is data that is only a function of a single variable such as time. As an example, one-dimensional data that is a function of time does not encode spatial information such as the position of detector pixels within a pixel array where the data is generated. For a detector having multiple detection elements (such as photomultipliers or pixel arrays), one-dimensional data may be generated from the detector by summing, averaging, or otherwise combining data from the multiple detection elements into a single one-dimensional data signal.

[0030] As used herein, an "intensity image" is an image formed using one-dimensional data. The pixels of an intensity image typically correspond to the intensity (i.e., number) of charged particle impacts on the detector. The intensity image may convey sample surface information such as exemplary topographical features, Z-contrast (i.e., using contrast caused by differences in the emissivity of elements with different mass numbers to distinguish regions of different mass (Z) numbers in the field of view, where elements with higher atomic numbers may have stronger scattering), or other features through contrast.

[0031] As used herein, "multidimensional data" is data that is a function of more than one variable. As an example, multidimensional data can include intensity as a function of time and be encoded using spatial information such as the position of pixels on a detector that generates the data. In one example, the multidimensional data can include an array of data where the rows and columns of the array correspond to the x and y positions of pixels in an array of pixels of a detector.

[0032] As used herein, a "structural image" is an image formed using multidimensional data. The pixels of an intensity image typically correspond to structural information determined by processing a multidimensional data stream (e.g., diffraction data), including but not limited to crystallographic phase, crystallographic orientation, or elemental composition. In some examples, the structural image is overlaid on the intensity image or otherwise combined with the intensity image to form a composite image.

[0033] As used herein, a description of two events that occur "simultaneously" or are "simultaneous" means that the two events overlap in time. As an example, two data signals generated from the same charged particle detection event (such as generating an electron-hole pair in a detector) are simultaneous.

[0034] Figure 1 A charged particle detector system 100 according to an example of the present disclosure is illustrated. Figure 1 The charged particle detector system 100 can be used in combination with a charged particle imaging system (such as the example systems illustrated and described with respect to Figure 5 ). The charged particle detector system includes an active pixel control sensor 102 having a plurality of pixels, a first readout circuit 110, and a second readout circuit 130. When a charged particle strikes a pixel in the active pixel control sensor 102, one or more electron-hole pairs are generated, as described in more detail below with respect to Figure 3 . The first readout circuit 110 receives a one-dimensional data signal corresponding to one or more electrons or holes from the sensor layer 104 of the active pixel control sensor 102 and processes the one-dimensional data signal to produce one-dimensional data. The one-dimensional data can include, for example, data suitable for generating an image of the surface topology or height of features on a sample. The second readout circuit 130 receives a multidimensional data signal corresponding to the other of the holes or electrons (i.e., the holes or electrons not used by the first readout circuit 110) from the readout chip 106 of the active pixel control sensor 102 and processes the multidimensional data signal to produce multidimensional data. The multidimensional data can include, for example, data suitable for generating an image of the structural characteristics (such as crystallographic phase) of an illustrated sample. The charged particle detector system 100 produces one-dimensional data signals and multidimensional data signals that are spatially co-registered, temporally co-registered (i.e., simultaneous), or co-registered in both space and time.

[0035] In some examples, the active pixel control sensor 102 may have a sensitivity sufficient to enable measurement of a single charged particle detection event. The active pixel control sensor 102 can be a hybrid pixel array detector (HPAD), a segmented photodiode (such as a segmented silicon photodiode), a monolithic active pixel sensor (MAPS), or any other suitable sensor with individual pixel control. In some embodiments, the active pixel control sensor 102 detects impacts from charged particles such as electrons and ions and does not interact with photons. In various embodiments, the active pixel control sensor 102 may include a number of pixels in the range from 32,000 to 1,000,000 pixels or in the range from 32,000 to 250,000 pixels. In some examples, the surface of the active pixel control sensor 102 may have a length or width in the range from 10 millimeters to 40 millimeters or in the range from 20 millimeters to 30 millimeters. The pixels may be arranged in a rectangular or square array (e.g., 256 by 256 or 500 by 500), a circular array, or other suitable arrangement to receive charged particles or electromagnetic radiation scattered, emitted, or transmitted from a sample. The pitch of the pixels in the array in the active pixel control sensor 102 may be in the range from 50 micrometers to 200 micrometers or in the range from 50 micrometers to 150 micrometers. In some examples, the pitch may be 55 micrometers. As taught in some examples herein, using a continuous pixel array in the active pixel control sensor 102 provides advantages over using a photomultiplier tube (PMT) array. In a PMT array, there may be gaps or dead spaces between PMT elements, whereby charged particles passing through the gaps are missed in the data. The continuous pixels avoid this problem because the pixels can be placed very close together, ensuring that there is no or almost no gap where charged particles could be missed between the pixels.

[0036] The first readout circuit 110 receives a one-dimensional data signal from the sensor layer 104 of the active pixel control sensor 102 and outputs the one-dimensional data (e.g., topographic imaging data) to the first computing device 112 for analysis or display. The first readout circuit 110 may include a current mirror 114, a bias voltage source 118, an amplifier 116, and a scan and acquisition engine 120. The current mirror 114 receives the one-dimensional data signal from the active pixel control sensor 102 and generates two identical data signals as outputs. In some embodiments, the imaging signal may include the sum of charges generated in all or a portion of the pixels in the sensor layer 104. One of the one-dimensional data signals output by the current mirror 114 is received at the bias voltage source 118. The bias voltage source 118 maintains a voltage difference across the active pixel control sensor 102 to deplete free charge carriers in a substantial volume of the sensor and drive the movement of electrons and holes generated within the sensor layer 104 due to the passage of charged particles. One of the one-dimensional data signals output by the current mirror 114 is received at the amplifier 116. The amplifier amplifies the one-dimensional data signal before passing it to the scan and acquisition engine 120 (also referred to in some cases as a patterned imaging acquisition module or PIA). The scan and acquisition engine 120 may digitize the imaging signal and may also provide control of the amplifier 116. In some examples, the scan and acquisition engine 120 includes one or more analog-to-digital converters. The scan and acquisition engine 120 passes the digitized one-dimensional data to the first computing device 112. As the charged particle beam is scanned point-by-point over the region of interest of the sample, the first computing device 112 collects the one-dimensional data for each point and assembles the one-dimensional data into an intensity image 122 of the region of interest of the sample. In some examples, the scan and acquisition engine 120 may control the operating parameters of the amplifier 116, such as by setting or controlling the gain, offset, or bandwidth of the amplifier 116.

[0037] The second readout circuit 130 receives a multi-dimensional data signal from the readout chip 106 of the active pixel control sensor 102 and decodes the multi-dimensional data signal to form multi-dimensional data. The multi-dimensional data is sent from the second readout circuit 130 to the second computing device 134. In some examples, the second readout circuit 130 may include a field programmable gate array 132 (or FPGA). As described below with respect to Figure 3More specifically, the readout chip 106 is interconnected with each pixel of the sensor layer 104 in the active pixel control sensor 102, and can read out a multi-dimensional data signal corresponding to the generation of holes in each of the pixels in the active pixel control sensor 102. The multi-dimensional data signal can be a two-dimensional array of intensity values, where the x-y position of the elements of the array represents the pixel position within the active pixel control sensor 102. The readout chip 106 outputs the digitized multi-dimensional data signal to the field programmable gate array 132. In some examples, the field programmable gate array 132 controls the operation of the readout chip 106. For example, the field programmable gate array 132 can set parameters such as an energy threshold or control the master clock of the readout chip 106, as described in more detail below. In some examples, the FPGA 132 can control the pixel analog amplifier behavior in the readout chip 106, such as discharge current and offset, hysteresis control for the comparator circuit in the readout chip 106, and conditions for the communication driver. In some examples, the FPGA 132 can manage acquisition shutter and mode, pixel mask, and individual threshold adjustment. The field programmable gate array 132 can decode the multi-dimensional data signal to form multi-dimensional data. The multi-dimensional data is then transferred from the field programmable gate array 132 to the second computing device 134. The second computing device 134 processes the multi-dimensional data to generate a structural image 136. In some examples, the structural image 136 is superimposed, synthesized, or otherwise combined with the intensity image 122.

[0038] In some of the above examples, the one-dimensional data signal corresponds to electrons generated within the active pixel control sensor 102, while the multi-dimensional data signal corresponds to holes generated within the active pixel control sensor 102. It should be understood that the systems and methods taught herein are not limited thereto, and the one-dimensional data signal can correspond to holes generated within the active pixel control sensor 102, while the multi-dimensional data signal corresponds to electrons generated within the active pixel control sensor 102.

[0039] In some examples, reading out the one-dimensional data signal corresponding to electrons from the sensor layer 104 is faster than reading out the multi-dimensional data signal corresponding to holes from the readout chip 106. In various examples, the speed of reading out a full frame of the one-dimensional data signal (i.e., the signal accumulated in all pixels within a given time) can range from 100 nanoseconds to 30 microseconds, while the speed of reading out a full frame of the multi-dimensional data signal can range from 10 microseconds to 1 second. For several reasons, the full frame readout speed of multi-dimensional data can be slower than that of one-dimensional data. In some cases, the additional processing overhead involved in handling the multi-dimensional data signal introduces latency. In some cases, the acquisition time and / or dwell time of the exciting particle beam at the impact point 203 is increased to ensure a sufficient signal-to-noise ratio level in each bin (e.g., individual pixel) of the multi-dimensional data signal. Depending on the application, if the signals from all bins are summed and the signal-to-noise ratio is thus improved, the one-dimensional data signal can be faster as a result.

[0040] In some examples, the one-dimensional data output by the first readout circuit 110 is processed by the first computing device 112 to generate an image of the surface topography of the sample. In some examples, the one-dimensional data signal output by the first readout circuit 110 is processed by the first computing device 112 to generate a Z-contrast map of the surface of the sample, i.e., an image of the region of interest, where the pixel color identifies the height above the baseline of the corresponding position within the region of interest. In some examples, the multi-dimensional data output by the second readout circuit 130 is processed by the second computing device 134 to generate an image of the region of interest containing crystallographic information. In some examples, the pixel color in the image can identify the crystallographic phase or orientation of the corresponding position in the region of interest. In some examples, the crystallographic information in the image can be conveyed using false colors or intensity maps. In some examples, the crystallographic information can include information about how many charged particles are received from the corresponding position, information about how good the pattern is, or information about how well the pattern is indexed.

[0041] In some examples, the first computing device 112 and the second computing device 134 are separate computing devices that can be co-located or remotely located. The first computing device 112 and the second computing device 134 can be connected via a network that enables information transmission between the devices. In one example, the first computing device 112 is a computing system attached to a charged particle microscope, while the second computing device 134 is a dedicated computing system for data analysis and visualization. In some examples, the first computing device 112 and the second computing device 134 are the same computing device. Further examples of suitable computing devices for use with the systems and methods taught herein are described below with respect to Figure 7 Describe further examples of suitable computing devices for use with the systems and methods taught herein.

[0042] Figure 2 Illustrates obtaining using Figure 1Example process for both a structural image 136 and an intensity image 122 of a region of interest (ROI) 204 obtained by the charged particle detector system 100. This example illustrates the arrangement of elements suitable for performing electron backscatter diffraction (EBSD) measurements. However, it should be understood that this arrangement of elements is merely illustrative, and other arrangements are possible, as will be described in more detail below with respect to Figures 6A to 6C Although specific examples are described herein in the context of an electron beam, it should be understood that the systems and methods taught herein are not limited to the use of an electron beam, but are equally applicable to a variety of charged particle beams, such as ion beams.

[0043] In an EBSD experiment, a charged particle beam 228 (such as an electron beam) irradiates a sample 202 along an emission axis 201. The charged particle beam 228 impinges on the sample 202 at an impact point 203 within the ROI 204 on the surface of the sample. The impact point 203 can be the volume of the sample 202 with which the irradiated electrons interact. Multiple impact points are located within the ROI. In this document, only the impact point 203 is shown as an example. During the irradiation and data acquisition of the sample 202, the sample 202 is positioned at a fixed angle with respect to the emission axis 201. For example, a sample axis 207 perpendicular to the surface of the sample can be positioned at 70 degrees with respect to the emission axis 201, such that the beam impinges on the sample surface at a shallow angle of 20 degrees. In another example, the angle between the sample axis 207 and the emission axis 201 can be less than 45 degrees. When the impact point 203 is irradiated by the charged particle beam 228, backscattered electrons from the impact point 203 are detected by the active pixel control sensor 102.

[0044] A two-dimensional electron backscatter pattern 205 (EBSP) is formed on pixels of the active pixel control sensor 102 by backscattered electrons from the impact point 203. The two-dimensional electron backscatter pattern 205 is transmitted as a multi-dimensional data signal from the active pixel control sensor 102 to the second readout circuit 130. The second readout circuit 130 can analyze the multi-dimensional data signal either alone or in cooperation with the second computing device 134 to determine information such as the crystal orientation or crystallographic phase at the impact point 203. For example, the crystal orientation can be calculated from the measured Kikuchi bands in the electron backscatter pattern 205. In one example, the crystal orientation is determined by matching a known electron backscatter pattern (or its simulated version) with the observed electron backscatter pattern 205. In another example, the crystal orientation is calculated by comparing the measured angles between Kikuchi bands with the theoretical interplanar angles determined using standard crystallographic principles. The second computing device 134 can generate and / or display a structural image 136 in the form of a crystallographic orientation image, where the crystal orientation of the sample at the impact point 203 is color-coded and shown as pixels 206 in the structural image 136. Each pixel of the structural image 136 is generated by scanning multiple impact points within the ROI 204. Each pixel of the structural image 136 corresponds to an impact point 203 in the ROI 204, as indicated by the arrow 232.

[0045] The active pixel control sensor 102 also generates a one-dimensional data signal based on the electron backscatter pattern 205, and the one-dimensional data signal is transmitted to the first readout circuit 110. Different from the two-dimensional data signal that includes all pixels and saves the intensity information as a function of the number of pixels or the position on the active pixel control sensor 102, the one-dimensional data signal is the sum or combination of signals from all pixels into a single intensity value. Therefore, the one-dimensional data signal can be proportional to the total flux of charged particles (such as backscattered electrons) that have impacted on the active pixel control sensor 102. The one-dimensional data signal is processed by the first readout circuit 110 either alone or in combination with the first computing device 112 to generate an intensity image 122. Specifically, the pixel 234 of the intensity image 122 can correspond to the magnitude of the one-dimensional signal. Each pixel of the intensity image 122 is generated by scanning multiple impact points within the ROI 204. Each pixel of the intensity image 122 corresponds to an impact point 203 in the ROI 204, as indicated by the arrow 230.

[0046] As taught herein, the charged particle detector system 100 increases the functionality of the active pixel control sensor 102 by enabling the active pixel control sensor 102 to act as both a structural (e.g., material or crystallographic) imaging sensor and an intensity imaging sensor. In some conventional systems in the art, separate auxiliary detectors such as a forward scatter detector (FSD) are employed around a main detector such as a pixelated detector. The FSD collects one-dimensional data, while the pixelated detector collects multi-dimensional data. Due to the limited working space within the vacuum chamber of the instrument, the size of the FSD is limited and is typically smaller than the size of the pixelated detector. The charged particle detector system 100 taught herein can effectively use the active pixel control sensor 102 as a virtual diode to collect one-dimensional data over a large footprint (i.e., the surface of the detector, which can be approximately 100 - 2000 mm 2 ). Since the surface of the active pixel control sensor 102 is larger than a typical auxiliary detector such as an FSD, the active pixel control sensor 102 collects a greater number of scattered charged particles and thus exhibits an improved signal-to-noise ratio compared to conventional auxiliary detectors.

[0047] The charged particle detector system 100 taught herein can be used to more quickly locate a suitable or desired ROI 204 by using information from both the one-dimensional data signal and the multi-dimensional data signal. For example, the first readout circuit 110 and the first computing device 112 can generate an intensity image 122 to orient the user in a live view. The live intensity image 122 can be generated simultaneously or alternately with the crystallographic structure image 136 prepared by the second readout circuit 130 and the second computing device 134. By comparing (or superimposing or combining) the information from the structure image 136 and the information from the intensity image 122 while moving the field of view of the sample relative to the charged particle beam 228, the user can identify the portion of the sample that contains the morphological structure of interest or the crystallographic phase of interest to assist the user in defining a suitable ROI 204 for further study.

[0048] In some example workflows, obtaining EBSD data for all of the hit points 203 in the ROI 204 can take minutes or hours to complete. During this long acquisition time, the sample may drift due to thermal or mechanical changes in the system. To compensate for drift, a one-dimensional data signal can be intermittently processed by the first readout circuit 110 during the acquisition of the entire large multi-dimensional data set to effect drift correction. In some examples, one or more multi-functional data signals are obtained from the active pixel control sensor 102 by the second readout circuit 130, each of the one or more multi-functional data signals corresponding to the irradiation of different hit points 203 by the charged particle beam 228. Then, the charged particle beam 228 is rapidly scanned across the entire ROI 204 to generate a one-dimensional data signal capable of reconstructing the full-intensity image 122 of the ROI 204. If the features of the sample in the ROI 204 have shifted in the intensity image 122, drift correction can be applied to the multi-dimensional data signals corresponding to the individual hit points 203 that were previously acquired or subsequently acquired.

[0049] As described above, when the charged particle beam 228 is stationary at the hit point 203, data collection for a single image frame is acquired by the active pixel control sensor 102. However, in some example workflows, the charged particle beam 228 can be scanned across the sample during the acquisition of the data signal for a single image frame. In this method, the charged particle beam 228 is scanned continuously, and after each scan of the ROI 204, the signal received at the active pixel control sensor 102 gradually improves over time. An example of this method compatible with the charged particle detector system 100 taught herein is described in U.S. Patent 11,114,275, entitled “Methods and systems for acquiring electron backscatter diffraction patterns,” which was issued on September 7, 2021, the entire contents of which are incorporated herein by reference. The charged particle detector system 100 taught herein can advantageously provide seamless drift correction during single-frame multi-dimensional data acquisition while scanning the beam. Specifically, the charged particle detector system 100 enables the simultaneous acquisition of multi-dimensional data signals and one-dimensional data signals, whereby the one-dimensional data signal can provide drift information that can be used to correct the simultaneously acquired multi-dimensional data signals. For example, a controller or computer system can compare the intensity image and the structural image and determine the amount and direction of drift by comparing the positions of features in the two images. The computer system can then apply a beam offset (i.e., offset the probe beam to a new position) and can resume or initiate further data acquisition. In some examples, drift correction can be applied during post-processing of the image to ensure alignment of the images.

[0050] Figure 3Illustrates a side - view cross - section of a single pixel in an active pixel control sensor 102 according to some examples described herein. The active pixel control sensor 102 includes a sensor layer 104 and a readout chip 106. The sensor layer 104 may include a semiconductor bulk 314 and a back - side layer 316. The readout chip 106 may include a pixel readout layer 308 on an electronics chip 304. Segmented sections (i.e., individual pixels) of the sensor layer 104 are each connected to a corresponding set of readout electronics in the readout chip 106 using, for example, bump bonding via solder bumps 310. In some examples, the active pixel control sensor 102 is sensitive enough to distinguish individual charged - particle 318 events (i.e., to count the number of charged - particle events for each pixel during an acquisition time).

[0051] In the sensor layer 104, most of the semiconductor bulk 314 is typically doped either p - type or n - type, while the implant section 312 is doped contrary to that majority (e.g., if the semiconductor bulk 314 is n - type, the implant section 312 is p - type). When a charged particle 318 passes through the semiconductor bulk 314, one or more electrons 320 and corresponding holes 322 are generated. The electrons 320 are driven towards the back - side layer 316 by an applied bias voltage (e.g., applied via Figure 1 the bias voltage source 118). Similarly, the holes 322 are driven towards the implant section 312 and pass through the solder bumps 310. The holes 322 are processed by analog and digital readout electronics in the readout chip 106 to form a digital structured signal for each pixel, which can be passed to a second readout circuit 130. In some examples, the readout electronics may include an analog front - end connected to a digital logic block. The analog front - end may include circuitry for customizing detection parameters, such as a charge - sensitive pre - amplifier with an adaptive gain mode and an energy - threshold discriminator (to ignore signals that fall below a pre - determined energy threshold). The digital logic block digitizes the amplified signal from the analog front - end. The digital logic block may also include or have access to a master clock and can thus encode additional information into the structured signal, which includes the acquisition time (i.e., the timestamp or time period when the signal was received) or the time over threshold (i.e., the timestamp or time period when the signal strength is greater than a set threshold). In some embodiments, the digital logic block may accept a shutter signal to control the time period during which the holes 322 are accumulated by the readout electronics for processing into the structured signal.

[0052] In an alternative embodiment, the active pixel control sensor 102 may include segmented photodiodes, such as segmented silicon photodiodes. The segmented silicon photodiodes may include additional analog front - end or digital back - end electronics and in some cases may not include energy - threshold processing or other signal - conditioning electronics.

[0053] A one-dimensional data signal can be transmitted from the sensor layer 104 to the first readout circuit 110 through a customized connector attached to the sensor layer 104. In some embodiments, the customized connector between the sensor layer 104 and the first readout circuit 110 can include a metal wire that supplies a bias voltage from the voltage source 118 to the backside layer 316. Thus, the current mirror 114 can enable the bias voltage to be applied to the backside layer 316 while allowing the current induced by the charged particles 318 to flow to the amplifier 116. In some examples, the current mirror 114 can include a physical connector, such as an SMA connector that acts as a signal splitter.

[0054] In some examples, the charged particles 318 are generated by the interaction between the sample and a charged particle beam. In various examples, the charged particles 318 can include backscattered electrons, Auger electrons, secondary electrons, inelastically scattered electrons (i.e., for energy loss spectroscopy), elastically scattered electrons, or variants thereof involving ions instead of electrons as described above.

[0055] Although Figure 3 the sensor layer 104 depicted in

[0056] includes a semiconductor bulk 314 that directly detects the impact of charged particles, other examples of the sensor layer 104 are compatible with the teachings herein. Specifically, the sensor layer 104 can include one or more scintillator layers coupled to an optical amplifier and / or an optoelectronic layer. The sensor layer 104 can thereby detect radiation emitted, scattered, or transmitted from the sample, such as cathodoluminescence photons or x-rays (e.g., for energy dispersive spectroscopy or EDS). Thus, those skilled in the art will understand that the charged particle detector systems 100 described herein can interact in a functionally identical manner to detect electromagnetic radiation in relevant cases, as further taught herein with respect to the detection of charged particles. Alternatively, the sensor layer 104 can include a scintillator and / or a particle detector that interacts with charged particles to generate light, which is then converted into electron-hole pairs within a portion of the sensor layer. Sensor layers 104 with other activation mechanisms or paths known to those skilled in the art are also compatible with the systems described herein.

[0057] In some examples, reading the active pixel control sensor 102 into the first readout circuit 110 and the second readout circuit 130 can be simultaneous. For example, electron backscatter diffraction embodiments can use the active pixel control sensor 102 to output diffraction data from the second readout circuit 130 while using imaging data from the first readout circuit 110 to perform imaging of a sample.

[0058] In some examples, the thickness of the semiconductor bulk 314 can be in the range of 50 microns to 1 millimeter or in the range of 300 microns to 500 microns.

[0059] In some examples of the sensors described herein, the doping of the semiconductor bulk 314 and the implant section 312 can be reversed, and the bias voltage source 118 can be arranged oppositely such that electrons 320 flow downward through the solder bump 310 while holes 322 travel upward to the dorsal layer 316.

[0060] Figures 4A to 4F Illustrates experimental images obtained using the charged particle detector system 100 of the present disclosure at different dwell times. As described with respect to Figure 2 A charged particle beam (e.g., an electron beam of a scanning electron microscope) is scanned above the point of impact in the region of interest on the sample and dwells at each point for a specified time. During each dwell time, one-dimensional and multi-dimensional data signals are generated by the impact of scattered charged particles (e.g., electrons) on the active pixel control sensor 102. The one-dimensional data from the active pixel control sensor 102 processed by the first readout circuit 110 can be used by a user to perform auxiliary operations such as evaluating or adjusting the position of the region of interest on the sample, estimating the detector background, assessing whether detector settings need to be adjusted automatically or manually, or correcting for drifts that occur during acquisition. Figures 4A to 4F Each of the Figure 4A shows a real-space image generated from the one-dimensional signal processed by the first readout circuit 110. In Figure 4B , the dwell time at each point in the region of interest is 30 microseconds, and the features of the sample in the region of interest are clearly identifiable. The dwell time is reduced to 5 microseconds in Figure 4C , to 1 microsecond in Figure 4D , to 500 nanoseconds in Figure 4E , to 300 nanoseconds in Figure 4F , and finally to 200 nanoseconds in Figure 4F . As the dwell time decreases, the amount of noise in the image increases and the contrast decreases. However, the surface features of the sample are still sufficiently visible in

[0061] Turning to Figure 5, an example charged particle imaging system 600 is illustrated, which can be used to acquire images using various imaging modalities in accordance with the present disclosure. In this example, the components of the charged particle imaging system 600 are adapted to function as a scanning electron microscope (SEM), but those skilled in the art will understand that alternative components are appropriately augmented to convert the charged particle imaging system 600 into a focused ion beam (FIB), dual beam, or other charged particle microscope system. The charged particle imaging system 600 can include a charged particle beam column 610 disposed on a sample chamber 620. The charged particle beam column 610 includes an electron source 602 for generating a beam of high-energy particles (such as electrons or ions) having a selectable energy, for example, between 500 eV and 30 keV, along an emission axis 604. The charged particle beam can be manipulated by lenses (606, 608, 618), deflectors (612, 614), and one or more beam limiting apertures 616 to form a finely focused spot on the sample 202. Both the charged particle beam column 610 and the sample chamber 620 can be connected to a high vacuum pump to evacuate the enclosed volume.

[0062] The sample chamber 620 can optionally include an air lock 622 for introducing a sample therein and placing the sample on a sample holder 624. The sample holder 624 can rotate or translate / offset the sample such that an ROI on the sample surface can be irradiated by the finely focused electron beam at a selectable tilt angle. The sample chamber 620 also includes one or more detectors for receiving particles emitted from the sample. As described above with respect to Figure 2 and below with respect to Figures 6A to 6C , the active pixel control sensors 102 can be located at different positions within the sample chamber 620 to accommodate different imaging modalities. In Figure 5 , each of these positions for the active pixel control sensors 102 is shown in a single image, although in most examples, only one active pixel control sensor 102 is employed at one of these positions. However, it is contemplated that additional active pixel control sensors 102 can be placed inside the sample chamber 620 at different positions such that one charged particle imaging system 600 can obtain data from multiple imaging modalities. It is also contemplated that the charged particle imaging system 600 can include an active pixel control sensor 102 at one position as shown in Figure 5 , while conventional sensors are located at one or more of the other positions.

[0063] The sample can be positioned at different angles relative to the emission axis 604 to obtain different images of the sample. In some examples, when the active pixel control sensor 102 is located at the first position 628, an SEM image can be obtained by positioning the surface of the sample 202 to face the incident beam. That is, the sample axis is aligned with the emission axis 604. When the active pixel control sensor 102 is located at the second position 626, an EBSD pattern can be obtained by positioning the sample 202 at an angle of approximately 70 degrees relative to the emission axis 604. Alternatively, when the active pixel control sensor 102 is in the third position 632, an EBSD pattern can be obtained by placing the sample 202 at an angle less than 45 degrees relative to the emission axis 604 (e.g., using reflection Kikuchi diffraction). In some embodiments, an SEM image can also be obtained by positioning the sample at an angle relative to the emission axis. The active pixel control sensor 102 can be located at the fourth position 634 to detect x-rays for EDS analysis.

[0064] In some embodiments, the voltages and / or currents required for operation of the (magnetic or electrostatic) lens and the electron source are generated / controlled by the column controller 636, while the computing device 630 generates a deflection signal for the deflector and processes data from the first readout circuit 110 or the second readout circuit 130. The computing device 630 can be a computing device such as the first computing device 112 or the second computing device 134 in some examples, or can act as both the first computing device 112 and the second computing device 134. The computing device 630 can be connected to a display 638 for displaying information such as an image of the sample 202. The computing device 630 can also receive operator input from an input device 640. The input device 640 can be a mouse, keyboard, or touchpad. The controller can translate, offset, or tilt the sample relative to the incident beam by moving the sample holder 624. The computing device 630 can scan the sample with the charged particle beam by adjusting the beam via the deflector 612 and / or the deflector 614.

[0065] As described in detail above, the computing device 630 is configured to process data received from the first readout circuit 110 or the second readout circuit 130 and can thus reconstruct, for example, an SEM image, an EBSD pattern, or a crystallographic orientation image of the sample. In some embodiments, the computing device 630 can include one or more field programmable gate arrays (FPGAs) configured to process data from the first readout circuit 110 or the second readout circuit 130 or signals from other auxiliary detectors installed in the charged particle imaging system 600.

[0066] Although the SEM system has been described by way of example, it should be understood that the imaging system can be other types of charged particle microscope systems, such as a transmission electron microscope (TEM), a scanning transmission electron microscope (STEM), or a dual-beam tool, such as a focused ion beam and scanning electron microscope combination (FIB-SEM). The current discussion of the SEM system is provided only as an example of a suitable imaging system for obtaining backscattered electrons.

[0067] Figure 6A An example of a detector arrangement for a reflection Kikuchi diffraction (RKD) imaging modality in accordance with some examples described herein is illustrated. In RKD, an active pixel control sensor 102 is placed between the sample 202 and the final element of the charged particle beam column, which is represented as the column lens 702 in this figure. In some examples, the active pixel control sensor 102 includes a hole or aperture 718 through which the charged particle beam 228 passes on its path to the sample 202. In other examples, two or four active pixel control sensors 102 can be tiled together with a suitable gap therebetween to allow the charged particle beam 228 to pass through unobstructed. When the charged particle beam 228 interacts with the sample 202, charged particles (e.g., electrons or ions) are scattered, reflected, or emitted from the sample 202 in a direction that is almost anti-parallel to the initial charged particle beam 228 and impinge on the active pixel control sensor 102. In some examples, the active pixel control sensor 102 is oriented such that the sensor layer 104 faces the underlying sample 202, i.e., the sensor layer 104 is on the side of the active pixel control sensor 102 opposite the column lens 702. The multi-dimensional data collected in an RKD experiment can be used to identify structural information about the sample, such as crystallographic phase or orientation.

[0068] In a conventional system, the presence of an RKD detector (e.g., a concentric backscatter (CBS) detector or a directional backscatter (DBS) detector) often interferes with a separate imaging detector because the RKD detector blocks or reduces the signal to the imaging detector when inserted. Using the present charged particle detector system 100 in RKD imaging is particularly advantageous because there is no need to move or remove the backscatter RKD detector to enable use of the imaging detector, as is typically done in conventional systems. Specifically, the charged particle detector system 100 enables a user to obtain a backscattered electron (BSE) image of a sample surface at a speed fast enough (e.g., on a time scale of tens of microseconds or less) to significantly reduce the time required to locate a region of interest. Additionally, the possibility of simultaneously outputting a one-dimensional data signal and a multi-dimensional data signal enables collection of the background level of the multi-dimensional data signal during the time the user is searching for the region of interest by referring to an image generated from the one-dimensional data signal. The background level collected during the position adjustment can then be used during processing of the subsequent multi-dimensional data signal at the desired region of interest, thereby reducing the total acquisition time.

[0069] In an example using multiple active pixel control sensors 102 (i.e., two or four sensors), the one-dimensional data signals for each active pixel control sensor 102 can be read out individually (e.g., using a separate first readout circuit 110) or the one-dimensional data signals from all active pixel control sensors 102 can be read out jointly (e.g., through a single first readout circuit 110). In an embodiment where the active pixel control sensors 102 are read out individually, the one-dimensional data output from each separate first readout circuit 110 can be compared or combined to produce an image with differential contrast (i.e., orientation, atomic density, or topography contrast).

[0070] Figure 6B A detector arrangement for an in-line transmission Kikuchi diffraction (TKD) imaging modality or a four-dimensional scanning transmission electron microscopy (4-D STEM) imaging modality according to some examples described herein is illustrated. Here, the active pixel control sensors 102 are placed behind the sample 202 and receive charged particles that are scattered, reflected, emitted, or transmitted through the sample 202 on substantially the same axis as the charged particle beam 228 after the charged particle beam 228 interacts with the sample 202. The active pixel control sensors 102 can output both one-dimensional data signals and multi-dimensional data signals to enable reconstruction of both a direct image of the field of view (e.g., a density contrast image similar to the density contrast image obtained by a transmission electron microscope) and a structural image of the field of view, where the structural information (e.g., crystallographic phase or orientation) about each position in the field of view is represented in the structural image.

[0071] Figure 6CIllustrated is a detector arrangement for off-axis transmission Kikuchi diffraction (TKD) imaging modality according to some examples described herein. Here, the active pixel control sensor 102 is placed behind the sample 202 and receives charged particles that are scattered, reflected, emitted, or transmitted through the sample 202 at an angle with respect to the axis of the charged particle beam 228 after the charged particle beam 228 interacts with the sample 202. In some examples, the active pixel control sensor 102 is positioned to receive particles from the sample 202 at an angle of about 70° with respect to the transmission axis of the charged particle beam 228. The active pixel control sensor 102 can output both one-dimensional data signals and multi-dimensional data signals to enable reconstruction of both a direct image of the field of view (e.g., a density contrast image similar to the density contrast image obtained by a transmission electron microscope) and a structural image of the field of view, where the structural information (e.g., crystallographic phase or orientation) about each position in the field of view is represented in the structural image.

[0072] Figure 7 Is a block diagram illustrating a computing device 800 suitable for use with examples as taught herein. For example, the computing device 800 can operate as the first computing device 112 or the second computing device 134 as described above, or can perform the functions of both the first computing device 112 and the second computing device 134. The computing device 800 can be an example of computing hardware included with the charged particle detector system 100, such as the first computing device 112 or the second computing device 134. The computing device 800 includes at least a bus 810 or other communication mechanism for conveying information, and one or more processors 820 coupled to the bus 810 for processing information. The processor 820 can be, for example, a general-purpose microprocessor or other hardware processor. The computing device 800 can be used to implement the methods and techniques disclosed herein, such as method 900.

[0073] The computing device 800 also includes a main memory 802, such as a random access memory (RAM) or other dynamic storage device coupled to the bus 810 for storing information and instructions to be executed by the processor 820. The main memory 802 can also be used to store temporary variables or other intermediate information during the execution of instructions to be executed by the processor 820. When stored in a non-transitory storage medium accessible by the processor 820, such instructions cause the computing device 800 to be a special-purpose machine that is customized to perform the operations specified in the instructions.

[0074] The computing device 800 may also include a read-only memory (ROM) 804 or other static storage device coupled to the bus 810 for storing static information and instructions for the processor 820. A storage device 806, such as a magnetic disk or optical disk, can be provided and coupled to the bus 810 for storing information and instructions.

[0075] The computing device 800 may be coupled via a bus 810 to a display 638, such as a cathode ray tube (CRT) or flat screen display, for displaying information to a computer user. An input device 640, including alphanumeric and other keys, is coupled to the bus 810 for communicating information and command selections to the processor 820. Another type of user input device 640 is a cursor control, such as a mouse, trackball, or cursor direction keys, for communicating direction information and command selections to the processor 820 and for controlling cursor movement on the display 638. This input device typically has two degrees of freedom in two axes (a first axis (e.g., x) and a second axis (e.g., y)), which allow the device to specify a position in a plane.

[0076] In some embodiments, all or a portion of the first readout circuit 110, the second readout circuit 130, or both the first readout circuit 110 and the second readout circuit 130 may be physically housed within the computing device 800. For example, the readout circuit may be implemented on a printed circuit board inserted into a housing of one or more of the other components that house the computing device 800. This arrangement is optional, as the first readout circuit 110, the second readout circuit 130, or both circuits may be implemented as stand-alone units in other examples. The first readout circuit 110 and the second readout circuit 130 may be connected to the bus 810 of the computing device 800 to enable data transfer and analysis by the processor 820. In some examples, the active pixel control sensor 102 may be directly connected to the first readout circuit 110 or the second readout circuit 130, or may be connected to the first readout circuit 110 or the second readout circuit 130 via the bus 810.

[0077] The computing device 800 may implement the techniques described herein using custom hardwired logic, one or more application specific integrated circuits (ASICs), or field programmable gate arrays (FPGAs), firmware, and / or program logic that in combination with the computer system cause the computing device 800 to be a special purpose machine or program the computing device to be a special purpose machine. According to one embodiment, the techniques herein are performed by the computing device 800 in response to one or more sequences of one or more instructions contained in the main memory 802 being executed by the processor 820. Such instructions may be read into the main memory 802 from another storage medium, such as the storage device 806. Execution of the sequence of instructions contained in the main memory 802 causes the processor 820 to perform the processing steps described herein. In an alternative embodiment, hardwired circuitry may be used in place of or in combination with the software instructions.

[0078] As used herein, the term "storage medium" refers to any non-transitory medium that stores data and / or instructions that cause a machine to operate in a particular manner. Such storage media may include non-volatile media and / or volatile media. Non-volatile media includes, for example, optical discs or magnetic disks, such as storage device 806. Volatile media includes dynamic memory, such as main memory 802. Common forms of storage media include, for example, floppy disks, flexible disks, hard disks, solid state drives, magnetic tape, or any other magnetic data storage media, CD-ROMs, any other optical data storage media, any physical media with hole patterns, RAM, PROM, and EPROM, flash EPROM, NVRAM, any other memory chip or cartridge, content addressable memory (CAM), and ternary content addressable memory (TCAM).

[0079] Storage media is different from transmission media, but can be used in combination with transmission media. Transmission media participates in transferring information between storage media. For example, transmission media includes coaxial cables, copper wire, and fiber optics, including the wires that comprise bus 810. Transmission media can also take the form of acoustic or light waves, such as those generated during radio wave and infrared data communications.

[0080] Various forms of media may be involved in carrying one or more sequences of one or more instructions to processor 820 for execution. For example, the instructions may initially be carried on a disk or solid state drive of a remote computer. The remote computer may load the instructions into its dynamic memory and send the instructions over a telephone line using a modem. A modem local to computing device 800 may receive the data on the telephone line and convert the data into an infrared signal using an infrared transmitter. An infrared detector may receive the data carried in the infrared signal, and appropriate circuitry may place the data on bus 810. Bus 810 carries the data to main memory 802, from which processor 820 retrieves and executes the instructions. The instructions received by main memory 802 may optionally be stored on storage device 806 before or after being executed by processor 820.

[0081] Computing device 800 may also include a communication interface 808 coupled to bus 810. Communication interface 808 provides two-way data communication that couples computing device 800 to network link 822 that is connected to a local network 814. For example, communication interface 808 can be an integrated services digital network (ISDN) card, cable modem, satellite modem, or a modem that provides a data communication connection to a corresponding type of telephone line. As another example, communication interface 808 can be a local area network (LAN) card to provide a data communication connection to a compatible LAN. A wireless link can also be implemented. In any such implementation, communication interface 808 sends and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information.

[0082] Network link 822 generally provides data communication to other data devices via one or more networks. For example, network link 822 can provide a connection to host computer 812 or to a data device operated by an Internet service provider (ISP) via local network 814, and the Internet service provider provides data communication services via the global packet data communication network now commonly referred to as the Internet 818. Both local network 814 and Internet 818 use electrical, electromagnetic, or optical signals that carry digital data streams. Signals through various networks, signals on network link 822, and signals through communication interface 808 are example forms of transmission media that carry digital data to and from computing device 800.

[0083] Computing device 800 can send messages and receive data (including program code) via a network, network link 822, and communication interface 808. In the Internet example, server 816 can transmit request code for an application via Internet 818, local network 814, and / or communication interface 808. The received code can be executed by processor 820 when it is received, and / or stored in storage device 806, and / or stored in other volatile or non-volatile storage devices for later execution.

[0084] Figure 8 An example method 900 for imaging a sample according to the teachings herein is illustrated. Although example method 900 depicts a specific sequence of operations, the sequence can be changed without departing from the scope of the present disclosure. For example, some of the depicted operations can be performed in parallel or in a different sequence that does not substantially affect the functionality of method 900. In other examples, different components of an example apparatus or system implementing method 900 can perform functions substantially simultaneously or in a specific sequence.

[0085] According to some examples, method 900 includes directing a charged particle beam to a location in the region of interest on the sample (block 904). For example, the above-described charged particle imaging system 600 can direct charged particle beam 228 to impact point 203 in ROI 204 of sample 202. Method 900 also includes receiving, at a pixel of active pixel control sensor 102, charged particles emitted, scattered, or transmitted from that location (block 906). For example, active pixel control sensor 102 can be placed inside sample chamber 620 at a location (e.g., first location 628, second location 626, third location 632, fourth location 634, or other suitable location) such that it can receive charged particles generated by the interaction of charged particle beam 228 with sample 202.

[0086] Method 900 then splits into two parallel paths. These paths can be executed in parallel (i.e., simultaneously) or at different times. According to some examples, method 900 includes transmitting a one-dimensional data signal corresponding to one of the electrons or holes generated in the active pixel control sensor 102 to the first readout circuit 110 (block 908). For example, the one-dimensional data signal is transmitted from the sensor layer 104 to the first readout circuit 110. Method 900 also includes using the first readout circuit 110 to generate one-dimensional data from the one-dimensional data signal (block 910). Method 900 also includes generating pixels in the first image by processing the one-dimensional data from the first readout circuit 110 (block 912). For example, the first image can be the intensity image 122.

[0087] In the second path, method 900 includes transmitting a multi-dimensional data signal corresponding to the other of the electrons or holes generated in the active pixel control sensor to the second readout circuit 130 (block 914). For example, the multi-dimensional data signal is transmitted from the readout chip 106 to the second readout circuit 130. Method 900 also includes using the second readout circuit 130 to generate multi-dimensional data from the multi-dimensional data signal. Method 900 also includes generating pixels in the second image by processing the multi-dimensional data from the second readout circuit 130 (block 918). For example, the second image can be the structural image 136.

[0088] According to some examples, method 900 includes selecting a new position within the region of interest for irradiation (block 920). Method 900 can then be iterated to generate additional pixels in the first image or the second image until all positions within the region of interest have been irradiated by the charged particle beam. It should be understood that in some examples, both paths may not be executed in each iteration. For example, the first path can be executed in multiple iterations to quickly assemble the intensity image 122 by using a short dwell time (e.g., hundreds of nanoseconds) at the position of the charged particle beam on the sample to produce a complete intensity image. Then, the second path can be executed one or more times to acquire multi-dimensional data at a longer dwell time of the charged particle beam at that position to improve the signal-to-noise ratio. The multi-dimensional data acquisition can be interrupted or interleaved by the one-dimensional data acquisition during the short dwell time to prepare the intensity image or otherwise determine whether the sample position has drifted. Then, drift correction can be applied to the multi-dimensional data. By executing method 900, a complete structural image 136 and the corresponding intensity image 122 can be generated from the signals produced by a single active pixel control sensor 102.

[0089] Figure 9Illustrates an example method 1000 for assembling a charged particle detector system as taught herein. Although the example method 1000 depicts a particular sequence of operations, the sequence can be changed without departing from the scope of the present disclosure. For example, some of the depicted operations can be performed in parallel or in a different sequence that does not substantially affect the functionality of the method 1000. In other examples, different components of an example apparatus or system implementing the method 1000 can perform functions substantially simultaneously or in a particular sequence.

[0090] According to some examples, the method 1000 includes providing an active pixel control sensor 102 having a sensor layer 104 and a readout chip 106 at block 1002. The method 1000 includes connecting the sensor layer 104 of the active pixel control sensor 102 to a first readout circuit 110 configured to process one-dimensional data signals from the sensor layer 104 at block 1004. The method 1000 includes connecting the readout chip 106 of the active pixel control sensor 102 to a second readout circuit 130 configured to process multi-dimensional data signals from the readout chip 106 at block 1006.

[0091] According to some examples, the method 1000 includes connecting a first computing device 112 to the first readout circuit 110 at block 1008 to generate an intensity image 122 of a sample 202 from the one-dimensional data provided by the first readout circuit 110. According to some examples, the method 1000 includes connecting a second computing device 134 to the second readout circuit 130 at block 1010 to generate a structural image 136 of the sample 202 from the multi-dimensional data provided by the second readout circuit 130.

[0092] Although the present teachings are described in connection with various embodiments, it is not intended to limit the present teachings to such embodiments. On the contrary, the present teachings cover various alternatives, modifications, and equivalents, as will be understood by those skilled in the art.

[0093] The embodiments described herein can be practiced with other computer system configurations including: hand-held devices, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers, etc. The embodiments can also be practiced in a distributed computing environment where tasks are performed by remote processing devices connected through a network.

[0094] It should also be understood that the embodiments described herein can employ various computer-implemented operations involving data stored in a computer system. These operations are operations that require the physical manipulation of physical quantities. Usually, but not necessarily, these quantities take the form of electrical or magnetic signals that can be stored, transferred, combined, compared, and otherwise manipulated. Additionally, the manipulations performed are often explicitly referred to as, for example, generating, identifying, determining, or comparing.

[0095] Certain embodiments may also be embodied as computer-readable code on a computer-readable medium. A computer-readable medium is any data storage device that can store data that can later be read by a computer system. Examples of computer-readable media include hard drives, network attached storage (NAS), read-only memory, random access memory, CD-ROMs, CD-Rs, CD-RWs, magnetic tape, and other optical and non-optical data storage devices. The computer-readable medium may also be distributed over a network of coupled computer systems such that the computer-readable code is stored and executed in a distributed fashion.

[0096] The section headings used herein are for organizational purposes only and should not be construed as limiting the subject matter described in any way.

[0097] In the detailed description of the various embodiments, for purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the disclosed embodiments. However, in some instances, those of ordinary skill in the art will understand that the various embodiments may be practiced with or without these specific details. In other instances, structures and devices are shown in block diagram form. Additionally, those skilled in the art can readily recognize that the particular order in which the methods are presented and executed is illustrative and that the order can vary (unless otherwise explicitly stated) and still remain within the substance and scope of the various embodiments disclosed herein.

[0098] All documents and similar materials cited in this application, including but not limited to patents, patent applications, articles, books, papers, and Internet web pages, are hereby expressly incorporated by reference in their entirety for any purpose. Unless otherwise described, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which the various embodiments described herein belong.

[0099] It should be understood that there is an implicit “about” preceding the specific temperatures, concentrations, times, pressures, flow rates, cross-sectional areas, etc. discussed in this teaching, such that minor and non-substantive deviations are within the scope of this teaching. In this application, unless otherwise specifically stated, the use of the singular includes the plural. Additionally, the use of “comprising,” “including,” and “containing” is not intended to be limiting. It should be understood that both the foregoing general description and the following detailed description are merely exemplary and illustrative and not restrictive of this teaching.

[0100] As used herein, in some cases, “a” or “an” may also mean “at least one” or “one or more” unless otherwise expressly stated. Additionally, the use of “or” is inclusive such that the phrase “A or B” is true when A is true, B is true, or both A and B are true. Further, unless the context otherwise requires, singular terms shall include the plural and plural terms shall include the singular.

[0101] As used herein, a "system" describes a set of real or abstract components, including a whole, where each component interacts or is related to at least one other component within the whole.

[0102] The advantages and features of the present disclosure are further described by the following examples:

[0103] Example 1. A charged particle detector system, the charged particle detector system comprising: an active pixel control sensor having a sensor layer and a readout chip and including a plurality of pixels, each of the plurality of pixels generating at least electrons and holes when struck by a charged particle; a first readout circuit in communication with the sensor layer and configured to receive a one-dimensional data signal corresponding to one of the electrons or the holes generated by the impact of the charged particle; and a second readout circuit in communication with the readout chip and configured to receive a multi-dimensional data signal corresponding to the other of the electrons or the holes generated by the impact of the charged particle.

[0104] Example 2. The charged particle detector system according to any one of the preceding examples, wherein the first readout circuit includes a current mirror to receive the one-dimensional data signal as an input signal and output at least two mirror signals corresponding to the input signal.

[0105] Example 3. The charged particle detector system according to Example 2, wherein the first readout circuit includes an amplifier and a peripheral interface adapter, the amplifier receiving one of the mirror signals from the current mirror.

[0106] Example 4. The charged particle detector system according to Example 2, wherein the first readout circuit includes a bias voltage source that receives one of the mirror signals from the current mirror.

[0107] Example 5. The charged particle detector system according to any one of the preceding examples, wherein the second readout circuit includes a field programmable gate array that receives the multi-dimensional data signal from the readout chip and decodes the multi-dimensional data signal.

[0108] Example 6. The charged particle detector system according to any one of the preceding examples, wherein the one-dimensional data signal and the multi-dimensional data signal are generated simultaneously by the active pixel control sensor.

[0109] Example 7. The charged particle detector system according to any one of the foregoing examples, wherein the charged particle detector system further comprises: a first computing device that processes the one-dimensional data to generate an intensity image; and a second computing device that processes the multi-dimensional data to generate a structural image.

[0110] Example 8. The charged particle detector system according to Example 7, wherein the intensity image and the structural image are automatically co-registered.

[0111] Example 9. The charged particle detector system according to Example 7, wherein the first computing device and the second computing device are the same computing device.

[0112] Example 10. The charged particle detector system according to any one of the foregoing examples, wherein the active pixel control sensor is a monolithic active pixel sensor (MAPS).

[0113] Example 11. The charged particle detector system according to any one of the foregoing examples, wherein the active pixel control sensor is a hybrid pixel array detector (HPAD).

[0114] Example 12. The charged particle detector system according to any one of the foregoing examples, wherein the active pixel control sensor is configured to be disposed at a position relative to the sample to measure reflection Kikuchi diffraction.

[0115] Example 13. A method for imaging a sample, the method comprising: receiving charged particles from the sample at a plurality of pixels in an active pixel control sensor, the active pixel control sensor comprising a sensor layer and a readout chip, each of the plurality of pixels generating at least electrons and holes when struck by a charged particle; transmitting a one-dimensional data signal corresponding to one of the electrons or the holes generated by the impact of the charged particle from the sensor layer to a first readout circuit; using the first readout circuit to generate one-dimensional data from the one-dimensional data signal; transmitting a multi-dimensional data signal corresponding to the other of the electrons or the holes generated by the impact of the charged particle from the readout chip to a second readout circuit; and using the second readout circuit to generate multi-dimensional data from the multi-dimensional data signal.

[0116] Example 14. The method according to Example 13, wherein generating the one-dimensional data comprises using a current mirror to generate two mirror signals corresponding to the one-dimensional data signal.

[0117] Example 15. The method according to Example 14, the method further comprising applying a bias voltage to the active pixel control sensor using a bias voltage source that receives one of the mirrored signals from the current mirror.

[0118] Example 16. The method according to Example 14, wherein generating the one-dimensional data further comprises amplifying one of the mirrored signals using an amplifier.

[0119] Example 17. The method according to any one of the preceding examples, wherein the steps of transmitting the one-dimensional data signal and transmitting the multi-dimensional data signal occur simultaneously.

[0120] Example 18. The method according to any one of the preceding examples, the method further comprising: forming an intensity image of the sample using a first computing device that receives one-dimensional data from the first readout circuit; and forming a structural image of the sample using a second computing device that receives multi-dimensional data from the second readout circuit.

[0121] Example 19. The method according to any one of the preceding examples, wherein the intensity image and the structural image are automatically co-registered.

[0122] Example 20. The method according to any one of the preceding examples, wherein generating the multi-dimensional data comprises receiving the multi-dimensional data signal at a field programmable gate array and decoding the multi-dimensional data signal.

Claims

1. A charged particle detector system, the charged particle detector system comprising: an active pixel control sensor having a sensor layer and a readout chip and comprising a plurality of pixels, each of the plurality of pixels generating at least electrons and holes when struck by a charged particle; a first readout circuit in communication with the sensor layer and configured to receive a one-dimensional data signal corresponding to one of the electrons or the holes generated by a charged particle impact; and A second readout circuit is in communication with the readout chip and is configured to receive a multi-dimensional data signal corresponding to the other of the electrons or the holes generated by the charged particle impact. 2 . The charged particle detector system according to claim 1 , wherein the first readout circuit comprises a current mirror to receive the one-dimensional data signal as an input signal and output at least two mirror signals corresponding to the input signal.

3. The charged particle detector system of claim 2, wherein the first readout circuit comprises an amplifier and a peripheral interface adapter, the amplifier receiving one of the image signals from the current mirror.

4. The charged particle detector system of claim 2, wherein the first readout circuit comprises a bias voltage source that receives one of the image signals from the current mirror. 5 . The charged particle detector system of claim 1 , wherein the second readout circuit comprises a field programmable gate array that receives the multi-dimensional data signal from the readout chip and decodes the multi-dimensional data signal.

6. The charged particle detector system of claim 1, wherein the one-dimensional data signal and the multi-dimensional data signal are generated simultaneously by the active pixel control sensor.

7. The charged particle detector system according to claim 1, further comprising: a first computing device that processes the one-dimensional data to generate an intensity image; and A second computing device processes the multi-dimensional data to generate a structural image.

8. The charged particle detector system of claim 7, wherein the intensity image and the structure image are automatically co-registered.

9. The charged particle detector system of claim 7, wherein the first computing device and the second computing device are the same computing device.

10. The charged particle detector system of claim 1, wherein the active pixel control sensor is a monolithic active pixel sensor (MAPS).

11. The charged particle detector system of claim 1, wherein the active pixel control sensor is a hybrid pixel array detector (HPAD).

12. The charged particle detector system of claim 1, wherein the active pixel control sensor is configured to be disposed in a position relative to a sample to measure reflection Kikuchi diffraction.

13. A method for imaging a sample, the method comprising: receiving charged particles from a sample at a plurality of pixels in an active pixel control sensor, the active pixel control sensor comprising a sensor layer and a readout chip, each pixel of the plurality of pixels generating at least electrons and holes when struck by the charged particles; transmitting a one-dimensional data signal corresponding to one of the electrons or the holes generated by the charged particle impact from the sensor layer to a first readout circuit; generating one-dimensional data from the one-dimensional data signal using the first readout circuit; transmitting a multi-dimensional data signal corresponding to the other of the electrons or the holes generated by the charged particle collision from the readout chip to a second readout circuit; and The second readout circuit is used to generate multi-dimensional data from the multi-dimensional data signal. 14 . The method of claim 13 , wherein generating the one-dimensional data comprises using a current mirror to generate two mirror signals corresponding to the one-dimensional data signal.

15. The method of claim 14, further comprising applying a bias voltage to the active pixel control sensor using a bias voltage source that receives one of the mirror signals from the current mirror.

16. The method of claim 14, wherein generating the one-dimensional data further comprises amplifying one of the image signals using an amplifier.

17. The method of claim 13, wherein the steps of transmitting the one-dimensional data signal and transmitting the multi-dimensional data signal occur simultaneously.

18. The method according to claim 13, further comprising: forming an intensity image of the sample using a first computing device that receives the one-dimensional data from the first readout circuit; as well as A structural image of the sample is formed using a second computing device that receives the multi-dimensional data from the second readout circuit.

19. The method of claim 13, wherein the intensity image and the structural image are automatically co-registered.

20. The method of claim 13, wherein generating the multi-dimensional data comprises receiving the multi-dimensional data signal at a field programmable gate array and decoding the multi-dimensional data signal.

Images