Systems and methods for analyzing sample using charged particle beams and active pixel control sensors

Abstract

To provide charged particle detector systems.SOLUTION: A charged particle detector system comprises: an active pixel control sensor having a sensor layer and a readout chip and including a plurality of pixels, each pixel in the plurality of pixels producing at least an electron and a hole upon being struck by a charged particle; a first readout circuit in communication with the sensor layer and configured to receive a unidimensional data signal corresponding to one of the electron or hole produced by the charged particle strike; and a second readout circuit in communication with the readout chip and configured to receive a multidimensional data signal corresponding to the other of the electron or hole produced by the charged particle strike.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to systems and methods for analyzing a sample using a charged particle beam and an active pixel control sensor.

Background Art

[0002] When a sample is irradiated with a charged particle beam such as an electron beam, various charged particles and / or electromagnetic radiation are emitted, scattered, or transmitted as a result of 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 in order to provide information about the sample. For example, backscattered electrons are low-energy loss electrons that are reflected or backscattered from the interaction volume of the sample by an elastic scattering interaction between the charged particle beam and the atoms of the sample. By collecting these charged particles and / or radiation using a two-dimensional detector, it is possible to determine the spatial or angular emission / reflection / transmission pattern of the particles or radiation. Next, structural information such as the local crystal orientation in the interaction volume can be determined through the analysis and interpretation of the two-dimensional pattern.

Summary of the Invention

[0003] Disclosed herein is a charged particle detector system. The charged particle detector system includes a sensor layer and a readout chip, and includes an active pixel control sensor including a plurality of pixels. Each pixel of the plurality of pixels generates at least electrons and holes when a charged particle collides therewith. The charged particle detector system includes a first readout circuit configured to communicate with the sensor layer and receive a one-dimensional data signal corresponding to one of the electrons or holes generated by the collision of the charged particle. The charged particle detector system includes a second readout circuit configured to communicate with the readout chip and receive a multi-dimensional data signal corresponding to the other of the electrons or holes generated by the collision of the charged particle.

[0004] This specification provides a method for imaging a sample. The method includes receiving charged particles from the sample at a plurality of pixels in an active pixel control sensor, the active pixel control sensor including a sensor layer and a readout chip. Each pixel of the plurality of pixels generates at least electrons and holes when a charged particle collides. The method includes transmitting a one-dimensional data signal corresponding to one of the electrons or holes generated by the collision of the charged particles 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 holes generated by the collision of the charged particles 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

[0005] To facilitate the identification of the consideration of any particular element or act, the most significant digit in the reference number refers to the figure number in which that element was first introduced.

[0006] It should be understood that the figures are not necessarily drawn to scale, and the objects within the figures are not necessarily drawn to scale in relation to each other. The figures are a depiction intended to provide clarity and understanding of various embodiments of the devices, systems, and methods disclosed herein. As far as possible, the same reference numbers are used throughout all the drawings to refer to the same or similar components. Further, it should be understood that the drawings are not intended to limit the scope of the teachings of the present invention in any way.

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DETAILED DESCRIPTION OF THE INVENTION

[0007] 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) regarding a sample inspected using a charged particle beam. In some examples, the one-dimensional data can include signal intensity from backscattered electrons received across the detector surface, and the multi-dimensional data can include signal intensity from backscattered electrons as a function of pixel position. In conventional systems, separate detectors are provided to collect one-dimensional and multi-dimensional data. By obtaining one-dimensional and multi-dimensional data from a single detector, the one-dimensional and multi-dimensional data can be obtained simultaneously at the same location.

[0008] ​The detector systems and methods taught herein can improve image quality and automate image alignment between an intensity image and a structure image or information by obtaining one-dimensional data and multi-dimensional data simultaneously. In applications where it is desirable to collect imaging data (i.e., one-dimensional data) and structure or diffraction data (i.e., multi-dimensional data) simultaneously, conventional systems in the art have placed separate detectors (e.g., a first detector in transmission mode and a second detector in reflection mode) at different positions relative to the sample. The emission / scattering of secondary charged particles from the sample is angle-dependent. Thus, while the separate detectors can be positioned near each other, the detectors do not overlap and will receive somewhat different numbers of charged particle collisions. Similarly, images obtained using two detectors in some conventional setups where the detectors are widely separated are not automatically aligned and must be transformed into a common coordinate space in order to be compared, overlaid, or merged. The detector systems and methods taught herein enable both one-dimensional data and multi-dimensional data to be obtained simultaneously from the same pixels of a single detector. As a result, the one-dimensional data and multi-dimensional data obtained using the systems and methods taught herein can produce images that have the same charged particle intensity content and / or are automatically aligned.

[0009] In some embodiments of the systems and methods taught herein, one-dimensional data collected simultaneously with multi-dimensional data can be used to estimate parameters such as noise background or appropriate detector settings. These parameters derived from the one-dimensional data can be applied in a live or real-time sense during the processing of the multi-dimensional data. For example, a one-dimensional data signal can be used by a computing device to estimate the number of charged particles (e.g., electrons) impinging on a sensor (i.e., the total current). Next, the total current information can be used to estimate and / or set a threshold or integration time in a readout chip of the multi-dimensional data signal. Adjustment of the parameters of the readout chip can be done during image (i.e., frame) acquisition or in between image acquisitions.

[0010] The detector systems and methods taught herein can improve image quality and speed up the acquisition time between an intensity image and a structure image by obtaining both one-dimensional data and multi-dimensional data at the same location using a single detector. In applications where it is desirable 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 have obtained a first image using a first detector at the imaging location, physically removed the first detector, inserted a second detector at the imaging location, and then obtained a second image. As a result, obtaining imaging data and diffraction data using separate detectors as in conventional systems introduces a significant time lag due to the need to exchange detectors. Further, detector exchange means that the detector for collecting multi-dimensional data has to be painstakingly positioned in the desired field of view at the typically slow acquisition speed of the detector, making it difficult to observe and account for position drift over time. The systems and methods taught herein enable both one-dimensional data and multi-dimensional data to be acquired 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, and the multi-dimensional data can be used to obtain structural information of the sample.

[0011] Some conventional systems use electron backscatter diffraction (EBSD). Multi-dimensional data signals from an EBSD (backscatter diffraction) detector are binned using hardware modifications and / or software data processing to form segments of one-dimensional data. This process allows both intensity and structural images of a sample over time to be obtained using a single detector, but it significantly increases readout time (often as much as several seconds) because the data must first be obtained as multi-dimensional data and then converted to one-dimensional data. The readout speed of the multi-dimensional data may depend on several factors in various systems, including the time to read out the data per pixel and the time to accumulate enough charged particle impacts to exceed the readout threshold. Furthermore, such conventional systems do not allow for the simultaneous generation of both one-dimensional and multi-dimensional data signals, and sacrifice multi-dimensional image quality by downsampling to form the one-dimensional data signal. The present system and method overcome such difficulties by simultaneously producing two data signals with the full information content in each signal, the first data signal being based on one of the holes or electrons generated in the sensor layer, and the second data signal corresponding to the other of the electrons or holes not used to produce the first data signal. One of the data signals is not constrained by the time to read out the data per pixel or other delays introduced by the readout chip electronics in the detector. Thus, the systems and methods taught herein increase data acquisition rates over conventional systems by processing multiple data streams in parallel and by allowing at least one data stream to be processed faster than another or multiple data streams.

[0012] By reducing the plurality of detectors used in a conventional setup to a single detector as taught herein, additional benefits can be obtained, such as cost reduction, system simplification, and a reduction in the number of components requiring maintenance and service. For example, a conventional configuration using separate EBSD detectors and backscattered electron (BSE) detectors leaves little free space in the vacuum chamber for operating the tool and moving stage, and may block a wide range of field-of-view angles. The size of one detector, and / or the required orientation of the sample with respect to the probe beam (e.g., 70° for standard EBSD), may force the other detector to be placed in a sub-optimal location. Separate detectors can give rise to separate maintenance and service for each detector, and the need for additional hardware to power and / or interface with the plurality of detectors. The systems and methods taught herein can reduce or eliminate some of these requirements by simplifying the system architecture.

[0013] In some examples, the systems and methods taught herein can use imaging data obtained from a single detector to identify the location of regions of interest on a sample having specified crystallographic properties as determined by structural data (e.g., diffraction data) received simultaneously with the imaging data from the sample. In particular, the systems and methods taught herein improve the location of regions of interest when the detector is used for reflection Kikuchi diffraction (RKD) or EBSD.

[0014] As used herein, "one-dimensional data" is data that is a function of only 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 location of detector pixels within an array of pixels where the data is generated. For a detector having a plurality of detection elements, such as a photomultiplier tube or pixel array, one-dimensional data can be generated from the detector by adding, averaging, or otherwise combining data from the plurality of detection elements into a single one-dimensional data signal.

[0015] 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 particles impinging on a detector. An intensity image can convey sample surface information, such as distinguishing regions within a field of view having different mass (Z) numbers through contrast, topographical features, Z-contrast (i.e., contrast arising from differences in emissivity of elements having different mass numbers, where elements with higher atomic numbers can have stronger scattering), or other features.

[0016] As used herein, "multidimensional data" is data that is a function of two or more variables. As an example, multidimensional data can include intensity, encoded with spatial information such as the location of a pixel on a detector where the data was generated, as a function of time. In one example, multidimensional data can include a data array where the rows and columns of the array correspond to the x and y positions of pixels within an array of detector pixels.

[0017] 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 through processing of a multidimensional data stream (e.g., diffraction data), which includes, but is not limited to, crystal phase, crystal orientation, or elemental composition. In some examples, a structural image is overlaid on an intensity image to form a composite image or otherwise combined with the intensity image.

[0018] As used herein, the description that two events occur "simultaneously" or are "simultaneous" means that the two events temporally overlap. As an example, two data signals resulting from the same charged particle detection event (such as generation of an electron-hole pair within a detector) are simultaneous.

[0019] FIG. 1 shows a charged particle microscope system 100 according to an embodiment of the present disclosure. The charged particle detector system 100 of FIG. 1 can be used in conjunction with a charged particle imaging system, such as the exemplary system illustrated and described with respect to FIG. 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 charged particles collide with the pixels in the active pixel control sensor 102, one or more electron-hole pairs are generated, as described in more detail below with respect to FIG. 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 multi-dimensional data signal corresponding to the other of the holes or electrons (i.e., the one not used by the first readout circuit 110) from the readout chip 106 of the active pixel control sensor 102 and processes the multi-dimensional data signal to produce multi-dimensional data. The multi-dimensional data can include, for example, data suitable for generating an image showing the structural properties of a sample, such as a crystal phase. The charged particle detector system 100 produces a one-dimensional data signal and a multi-dimensional data signal, and these signals are spatially co-registered, temporally (i.e., simultaneously) co-registered, or co-registered both spatially and temporally.

[0020] In some examples, the active pixel control sensor 102 can have sufficient sensitivity to measure 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 collisions from charged particles such as electrons and ions and does not interact with photons. In various embodiments, the active pixel control sensor 102 can include a plurality of pixels in the range of 32,000 to 1,000,000 pixels, or in the range of 32,000 to 250,000 pixels. In some examples, the surface of the active pixel control sensor 102 can have a length or width in the range of 10 to 40 millimeters, or in the range of 20 to 30 millimeters. The pixels can be arranged in a rectangular or square array (e.g., 256×256 or 500×500), a circular array, or other suitable arrangement to receive charged particles or electromagnetic radiation scattered, emitted, or transmitted from the sample. The pitch of the pixels in the array within the active pixel control sensor 102 can be in the range of 50 to 200 microns, or in the range of 50 to 150 microns. In some examples, the pitch can be 55 microns. The use of an array of consecutive pixels within the active pixel control sensor 102 as taught in some examples herein provides advantages over the use of an array of photomultiplier tubes (PMTs). In an array of PMTs, there may be gaps or dead spaces between the PMT elements, whereby charged particles passing through the gaps are lost in the data.Continuous pixels avoid this problem because the pixels can be placed very close to each other, thus ensuring that there is no, or very little, gap between the pixels where charged particles could be missed.

[0021] 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 one-dimensional data (e.g., topographic imaging data) to the first computing device 112 for analysis or display. The first readout circuit 110 can 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 a 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 can include the sum of the charges generated at all or a portion of the pixels within the sensor layer 104. One of the one-dimensional data signals output by the current mirror 114 is received by the bias voltage source 118. The bias voltage source 118 maintains a voltage difference across the active pixel control sensor 102 to deplete the bulk sensor volume of free charge carriers 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 by the amplifier 116. The amplifier amplifies the one-dimensional data signal before passing it to the scan and acquisition engine 120 (which may also be referred to as a patterning imaging acquisition module or PIA in some cases). The scan and acquisition engine 120 can digitize the imaging signal and can 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 across the region of interest of the sample, the first computing device 112 collects the one-dimensional data for each point and assembles that 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 can control the operating parameters of the amplifier 116, such as by setting or controlling the gain, offset, or bandwidth of the amplifier 116.

[0022] 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 transmitted from the second readout circuit 130 to the second computing device 134. In some examples, the second readout circuit 130 can include a field programmable gate array 132 (or FPGA). As described in more detail below with respect to FIG. 3, the readout chip 106 is interconnected with each pixel of the sensor layer 104 within the active pixel control sensor 102 and can read out a multi-dimensional data signal corresponding to the generation of holes in each pixel of 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 positions 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. The field programmable gate array 132 controls the operation of the readout chip 106 in some examples. For example, the field programmable gate array 132 can set parameters such as energy thresholds 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 behavior of the pixel analog amplifiers within the readout chip 106 such as discharge current and offset, hysteresis control of comparator circuits within the readout chip 106, and conditions related to communication drivers. The FPGA 132 can manage acquisition shutters and modes, pixel masking, and individual threshold adjustments in some examples. 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 produce a structural image 136. In some examples, the structural image 136 is overlaid, synthesized, or otherwise combined with the intensity image 122.

[0023] In some of the above examples, the one-dimensional data signal corresponds to electrons generated within the active pixel control sensor 102, and the multi-dimensional data signal corresponds to holes generated within the active pixel control sensor 102. The systems and methods taught herein are not so limited, and it will be understood that the one-dimensional data signal can correspond to holes generated within the active pixel control sensor 102, and the multi-dimensional data signal can correspond to electrons generated within the active pixel control sensor 102.

[0024] In some examples, the readout of the one-dimensional data signal corresponding to electrons from the sensor layer 104 is faster than the readout of 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 over a given time) can be in the range of 100 nanoseconds to 30 microseconds, and the speed of reading out a full frame of the multi-dimensional data signal can be in the range of 10 microseconds to 1 second. The speed of full frame readout of multi-dimensional data can be slower than the speed of readout of one-dimensional data for several reasons. In some cases, the additional processing overhead involved in handling the multi-dimensional data signal results in a delay. In some cases, the acquisition time and / or dwell time of the excitation particle beam at the impact point 203 is increased to ensure a sufficient signal-to-noise level in each bin (e.g., individual pixel) for the multi-dimensional data signal. Thus, depending on the application, the one-dimensional data signal can be faster if the signals from all bins are summed and thus the signal-to-noise ratio is improved.

[0025] 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 that identifies the height of the pixel color above the baseline at the corresponding location 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 crystal phase or orientation at the corresponding location within the region of interest. In some examples, the crystallographic information in the image can be conveyed using a false color or intensity map. In some examples, the crystallographic information can include information about how many charged particles were received from the corresponding location, information about how good the pattern is, or information about how well the pattern was indexed.

[0026] In some examples, the first computing device 112 and the second computing device 134 are separate computing devices that can be placed in the same location or separated. The first computing device 112 and the second computing device 134 can be connected via a network that enables information transfer between the devices. In one example, the first computing device 112 is a computing system attached to a charged particle microscope, and 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 computing devices suitable for use with the systems and methods taught herein are described below with respect to FIG. 7.

[0027] FIG. 2 shows an exemplary procedure for obtaining both a structural image 136 and an intensity image 122 of a region of interest (ROI) 204 obtained using the charged particle detector system 100 of FIG. 1. This example shows an arrangement of elements suitable for performing electron backscatter diffraction (EBSD) measurements. However, this arrangement of elements is merely exemplary, and it will be understood that other arrangements are possible, as described in more detail below with respect to FIGS. 6A - 6C. Although specific examples are described herein in relation to an electron beam, it will be understood that the systems and methods taught herein are not limited to the use of an electron beam and are equally applicable to various charged particle beams, such as an ion beam.

[0028] In the EBSD experiment, a charged particle beam 228 (such as an electron beam) irradiates the sample 202 along the emission axis 201. The charged particle beam 228 hits the sample 202 at the impact point 203 within the ROI 204 on the sample surface. The impact point 203 can be the volume of the sample 202 where the irradiated electrons interact. There are multiple impact points within the ROI. Here, only the impact point 203 is shown as an example. The sample 202 is positioned at a fixed angle with respect to the emission axis 201 during the irradiation and data acquisition of the sample 202. For example, the sample axis 207 perpendicular to the sample surface can be positioned at 70 degrees with respect to the emission axis 201, whereby the beam hits 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. While the impact point 203 is being irradiated by the charged particle beam 228, the backscattered electrons from the impact point 203 are detected by the active pixel control sensor 102.

[0029] Two-dimensional electron backscatter pattern 205 (electron The backscatter pattern (EBSP) is formed on the 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 crystal 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 comparing a known electron backscatter pattern (or its simulated version) with the observed electron backscatter pattern 205. In another embodiment, the crystal orientation is calculated by comparing the measured angles between the Kikuchi bands with the theoretical interplanar angles determined using standard crystallographic principles. The second computing device 134 can generate and / or display the structural image 136 in the form of a crystal orientation image, in which 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 a plurality of impact points within the ROI 204. Each pixel of the structural image 136 corresponds to one impact point 203 within the ROI 204, as indicated by the arrow 232.

[0030] The active pixel control sensor 102 also generates a one-dimensional data signal based on the electron backscatter pattern 205 transmitted to the first readout circuit 110. Unlike the two-dimensional data signal that includes a full-frame readout of all pixels and stores intensity information as a function of the number or location of pixels on the active pixel control sensor 102, the one-dimensional data signal sums or combines the signals from all pixels into a single intensity value. Thus, the one-dimensional data signal can be proportional to the total flux of charged particles (such as backscattered electrons) that hit the active pixel control sensor 102. The one-dimensional data signal is processed by the first readout circuit 110 alone or in cooperation with the first computing device 112 to generate the intensity image 122. In particular, the pixels 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 one impact point 203 within the ROI 204, as indicated by the arrow 230.

[0031] The charged particle detector system 100 taught herein increases the functionality of the active pixel control sensor 102 by enabling the active pixel control sensor 102 to act as both a structure (e.g., material or crystal) imaging sensor and an intensity imaging sensor. In some conventional systems in the art, a separate secondary detector, such as a forward scatter detector (FSD), surrounds a primary detector such as a pixelated detector. The FSD collects one-dimensional data and the pixelated detector collects multi-dimensional data. The size of the FSD is limited and is generally smaller than the size of the pixelated detector because the working space within the vacuum chamber of the instrument is limited. The charged particle detector system 100 taught herein effectively uses the active pixel control sensor 102 as a virtual diode to provide a large installation area (i.e., 100 - 2000 mm 2It is possible to collect one-dimensional data across the surface of the detector, which can be to a certain extent. Since the surface of the active pixel control sensor 102 is larger than that of a typical secondary detector such as an FSD, the active pixel control sensor 102 captures a larger number of scattered charged particles and thus exhibits an improved signal-to-noise ratio compared to conventional secondary detectors.

[0032] The charged particle detector system 100 taught herein can be used to more quickly locate an appropriate or desired ROI 204 by using information from both one-dimensional and multi-dimensional data signals. For example, the first readout circuit 110 and the first computing device 112 can generate an intensity image 122 and direct it towards 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 overlaying 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 with respect to the charged particle beam 228, the user can identify a portion of the sample that contains either a topographical structure of interest or a crystal phase of interest, helping the user to define an appropriate ROI 204 for further study.

[0033] In some exemplary workflows, acquisition of EBSD data for all impact points 203 within the ROI 204 can take several minutes or hours to complete. During this long acquisition time, the sample may drift due to thermal or mechanical changes within the system. To compensate for the drift, the one-dimensional data signal can be processed intermittently by the first readout circuit 110 throughout the acquisition of the large multi-dimensional data set to enable drift correction. In some examples, one or several multi-functional data signals, each corresponding to illumination of a different impact point 203 by the charged particle beam 228, are obtained from the active pixel control sensor 102 by the second readout circuit 130. Next, the charged particle beam 228 is rapidly scanned across the entire ROI 204 to generate a one-dimensional data signal that enables reconstruction of the full intensity image 122 of the ROI 204. If the features of the sample within the ROI 204 are shifted within the intensity image 122, drift correction can be applied to previously obtained or subsequently obtained multi-dimensional data signals corresponding to the individual impact points 203.

[0034] As described above, data collection for a single image frame is obtained by the active pixel control sensor 102 while the charged particle beam 228 is stationary at the impact point 203. However, in some exemplary workflows, the charged particle beam 228 can scan across the sample during acquisition of the data signal for a single image frame. In this methodology, the charged particle beam 228 scans continuously, and the signal received by the active pixel control sensor 102 is gradually improved over time after each scan of the ROI 204. An example of this methodology that is compatible with the charged particle detector system 100 taught herein is described in U.S. Patent No. 11,114,275, entitled "Methods and systems for acquiring electron backscatter diffraction patterns," issued 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 while acquiring single-frame multi-dimensional data while scanning the beam. Specifically, the charged particle detector system 100 can acquire multi-dimensional data signals and one-dimensional data signals simultaneously, such that the one-dimensional data signal can provide drift information that can be used to correct the simultaneously acquired multi-dimensional data signal. For example, a controller or computer system can compare the intensity image and the structural image and determine the magnitude and direction of the drift by comparing the locations of features within the two images. The computer system can then apply a beam shift (i.e., shift the probe beam to a new location) and resume or initiate further data acquisition. In some examples, drift correction can be applied during post-processing of the image to ensure image alignment.

[0035] FIG. 3 shows a cross-sectional view of a single pixel within an active pixel control sensor 102 according to several embodiments described herein. The active pixel control sensor 102 includes a sensor layer 104 and a readout chip 106. The sensor layer 104 can include a semiconductor bulk 314 and a back surface layer 316. The readout chip 106 can include a pixel readout layer 308 on an electronic chip 304. Segmented sections (i.e., single pixels) of the sensor layer 104 are each connected to a corresponding set of readout electronic circuits within the readout chip 106 using, for example, bump bonding via solder bumps 310. In some examples, the active pixel control sensor 102 has sufficient sensitivity to discriminate a single charged particle 318 event (i.e., count the number of charged particle events per pixel during the acquisition time).

[0036] In the sensor layer 104, most of the semiconductor bulk 314 is generally doped as p-type or n-type, and the injection section 312 is doped oppositely to the majority (e.g., if the semiconductor bulk 314 is n-type, the injection section 312 is p-type). When charged particles 318 pass through the semiconductor bulk 314, one or more electrons 320 and corresponding holes 322 are generated. The electrons 320 are driven towards the back surface layer 316 by an applied bias voltage (e.g., applied via the bias voltage source 118 in FIG. 1). Similarly, the holes 322 are driven towards the injection section 312 through the solder bumps 310. The holes 322 can be processed by analog and digital readout electronic circuits in the readout chip 106 to form a digital structural signal for each pixel that can be passed to the second readout circuit 130. In some examples, the readout electronic circuit can include an analog front end connected to digital logic blocks. The analog front end can include circuits that customize detection parameters such as a charge sensing preamplifier with an adaptive gain mode and an energy threshold discriminator (to ignore signals below a predetermined energy threshold). The digital logic blocks digitize the amplified signals from the analog front end. The digital logic blocks can also include or have access to a master clock, thereby encoding additional information into the structural signal to include the acquisition time (i.e., the time stamp or duration at which the signal was received) or the time exceeding a threshold (i.e., the time stamp or duration at which the signal intensity was higher than a set threshold). In some embodiments, the digital logic blocks can receive a shutter signal and control the period during which the holes 322 are accumulated by the readout electronic circuits for processing and made into a structural signal.

[0037] In an alternative embodiment, the active pixel control sensor 102 can include a segmented photodiode, such as a segmented silicon photodiode. The segmented silicon photodiode can include additional analog front-end or digital back-end electronic circuitry and, in some cases, can be free of energy threshold processing or other signal conditioning electronic circuitry.

[0038] The one-dimensional data signal can be transmitted from the sensor layer 104 to the first readout circuit 110 through a custom connector attached to the sensor layer 104. In some embodiments, the custom 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 be enabled to apply the bias voltage to the backside layer 316 while simultaneously enabling 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.

[0039] In some examples, the charged particles 318 are generated by the interaction between the sample and the charged particle beam. In various examples, the charged particles 318 can include backscattered electrons, Auger electrons, secondary electrons, inelastic scattered electrons (i.e., in the case of energy loss spectroscopy), elastic scattered electrons, or the above variations involving ions rather than electrons.

[0040] The sensor layer 104 depicted in FIG. 3 includes a semiconductor bulk 314 that directly detects charged particle collisions, although other examples of the sensor layer 104 are consistent with the teachings herein. In particular, the sensor layer 104 can include another scintillator layer coupled to an optical amplifier and / or an optoelectronic layer. Thereby, the sensor layer 104 can detect radiation emitted, scattered, or transmitted from a sample, such as cathodoluminescence photons or X-rays (e.g., in the case of energy-dispersive spectroscopy or EDS). Thus, it will be understood by those skilled in the art that the charged particle detector system 100 described herein can detect electromagnetic radiation in a related case by interacting in a functionally identical manner as otherwise 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 produce light, which is then converted into electron-hole pairs within a portion of the sensor layer. Sensor layers 104 having other activation mechanisms or pathways as known to those skilled in the art are also compatible with the systems described herein.

[0041] In some examples, the data readout rate from the first readout circuit 110 of the active pixel control sensor 102 is faster than the data readout rate from the second readout circuit 130. Since the structural signal includes information regarding the magnitude of the signal for each pixel, collecting and processing data to output as the structural signal using the readout chip 106 can occur at a slower rate than the readout of the imaging signal, which is proportional to the total charge within all pixels.

[0042] In some examples, the readout of the active pixel control sensor 102 to the first readout circuit 110 and the second readout circuit 130 can be simultaneous. For example, an electron backscatter diffraction implementation can use the active pixel control sensor 102 to output diffraction data from the second readout circuit 130 just as imaging of the sample is performed using imaging data from the first readout circuit 110.

[0043] In some examples, the thickness of the semiconductor bulk 314 can be in the range of 50 micrometers to 1 millimeter, or in the range of 300 micrometers to 500 micrometers.

[0044] In some examples of the sensors described herein, the doping of the semiconductor bulk 314 and the injection section 312 can be reversed, and the bias voltage source 118 can be arranged oppositely so that electrons 320 flow downward through the solder bumps 310 and holes 322 move upward toward the back surface layer 316.

[0045] Figures 4A - 4F show 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 across the impact points within 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 collision of scattered charged particles (e.g., electrons) with 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 the user to perform auxiliary operations such as evaluating or adjusting the location of the region of interest on the sample, estimating the detector background, evaluating whether the detector settings need to be adjusted automatically or manually, or correcting drifts that occur during acquisition. Each of Figures 4A - 4F shows a real - space image generated from the one - dimensional signal processed by the first readout circuit 110. In Figure 4A, the dwell time for each point within the region of interest is 30 microseconds, and the features of the sample within the region of interest are clearly distinguishable. The dwell time is reduced to 5 microseconds in Figure 4B, 1 microsecond in Figure 4C, 500 nanoseconds in Figure 4D, 300 nanoseconds in Figure 4E, and finally 200 nanoseconds in Figure 4F. As the dwell time is reduced, the amount of noise in the image increases and the contrast is reduced. However, the surface features of the sample remain sufficiently visible in Figure 4F (using a dwell time of 200 nanoseconds) for the user to perform auxiliary operations.

[0046] Moving on to FIG. 5, an exemplary charged particle imaging system 600 is shown that can be used to acquire images using various imaging modalities according to the present disclosure. In this example, the components of the charged particle imaging system 600 are suitable for use as a scanning electron microscope (SEM), but those skilled in the art will understand that the components of the charged particle imaging system 600 can be replaced to be suitable for converting the charged particle imaging system 600 into a focused ion-beam (FIB), dual-beam, or other charged particle microscope system, and that the components can be enhanced. 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 energetic particles (such as electrons or ions) having a selectable energy, for example, from 500 eV to 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 aperture openings 616 to form a precisely 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.

[0047] The sample chamber 620 can optionally include an airlock 622 for introducing a sample therein and placing the sample on the sample holder 624. The sample holder 624 can rotate or translate / shift the sample so that the ROI on the sample surface can be irradiated by an electron beam precisely focused at a selectable tilt angle. The sample chamber 620 further includes one or more detectors for receiving particles emitted from the sample. As described above with respect to FIG. 2 and as will be described later with respect to FIGS. 6A - 6C, the active pixel control sensor 102 can be placed at different positions within the sample chamber 620 to adapt to different imaging modalities. In FIG. 5, these positions of the active pixel control sensor 102 are each shown within a single image, but in most examples, only one active pixel control sensor 102 is used at one of the positions. However, it is contemplated that additional active pixel control sensors 102 can be placed at different locations inside the sample chamber 620 so that one charged particle imaging system 600 can obtain data from multiple imaging modalities. Also, the charged particle imaging system 600 can include an active pixel control sensor 102 in one location as shown in FIG. 5, and it is also contemplated that conventional sensors can be placed at one or more of the other locations.

[0048] To obtain different images of the sample, the sample can be positioned at different angles with respect to the emission axis 604. In some examples, by positioning the surface of the sample 202 towards the incident beam, an SEM image can be obtained when the active pixel control sensor 102 is disposed at the first position 628. That is, the sample axis is aligned with the emission axis 604. By positioning the sample 202 at an angle of approximately 70 degrees with respect to the emission axis 604, an EBSD pattern can be obtained when the active pixel control sensor 102 is disposed at the second position 626. Alternatively, by positioning the sample 202 at an angle less than 45 degrees with respect to the emission axis 604, an EBSD pattern (e.g., using reflection Kikuchi diffraction) can be obtained when the active pixel control sensor 102 is at the third position 632. In some embodiments, an SEM image can also be obtained by positioning the sample at an angle with respect to the emission axis. The active pixel control sensor 102 can be disposed at the fourth position 634 for detecting X-rays for EDS analysis.

[0049] In some embodiments, the voltages and / or currents required for the operation of the (magnetic or electrostatic) lens and the electron source are generated / controlled by the column controller 636, and 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, in some examples, a computing device such as the first computing device 112 or the second computing device 134, 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 the input device 640. The input device 640 can be a mouse, keyboard, or touchpad. The controller can translate, shift, or tilt the sample with respect to the incident beam by moving the sample holder 624. The computing device 630 can scan the sample with a charged particle beam by adjusting the beam via the deflector 612 and / or the deflector 614.

[0050] 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, thereby being able to reconstruct, for example, an SEM image of the sample, an EBSD pattern, or a crystal orientation image. 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 secondary detectors installed in the charged particle imaging system 600.

[0051] Although an SEM system is described as an example, it should be understood that the imaging system can be other types of charged particle microscope systems, such as dual beam tools like transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), or focused ion beam combined with scanning electron microscopy (FIB-SEM). This discussion of the SEM system is provided merely as an example of one suitable imaging system for acquiring backscattered electrons.

[0052] Figure 6A shows a detector arrangement for a reflection Kikuchi diffraction (RKD) imaging modality according to some embodiments described herein. In RKD, the active pixel control sensor 102 is disposed between the sample 202 and the final element of the charged particle beam column, 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 way towards the sample 202. In other examples, two or four active pixel control sensors 102 can be tiled together with an appropriate gap therebetween that allows the charged particle beam 228 to pass 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 substantially 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 sample 202 below, i.e., such that the sensor layer 104 is on the opposite side of the active pixel control sensor 102 from the column lens 702. Using the multidimensional data collected in an RKD experiment, structural information about the sample, such as crystal phase or orientation, can be identified.

[0053] In conventional systems, 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. The use of the charged particle detector system 100 in RKD imaging is particularly advantageous because, unlike in conventional systems where the backscatter RKD detector typically has to be moved or removed to enable use of the imaging detector, the charged particle detector system 100 allows the user to obtain a backscattered electron (BSE) image of the sample surface at a sufficiently fast rate (e.g., on a time scale of tens of microseconds or less), significantly reducing the time required to identify the location of the region of interest. Additionally, the ability to simultaneously output one-dimensional and multi-dimensional data signals allows for collection of the background level of the multi-dimensional data signal while the user is exploring the region of interest by referring to an image generated from the one-dimensional data signal. The background level collected during site alignment can then be used during subsequent processing of the multi-dimensional data signal in the desired region of interest, thus reducing the total acquisition time. 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. The use of the charged particle detector system 100 in RKD imaging is particularly advantageous because, unlike in conventional systems where the backscatter RKD detector typically has to be moved or removed to enable use of the imaging detector, the charged particle detector system 100 allows the user to obtain a backscattered electron (BSE) image of the sample surface at a sufficiently fast rate (e.g., on a time scale of tens of microseconds or less), significantly reducing the time required to identify the location of the region of interest. Additionally, the ability to simultaneously output one-dimensional and multi-dimensional data signals allows for collection of the background level of the multi-dimensional data signal while the user is exploring the region of interest by referring to an image generated from the one-dimensional data signal. The background level collected during site alignment can then be used during subsequent processing of the multi-dimensional data signal in the desired region of interest, thus reducing the total acquisition time.

[0054] In embodiments using a plurality of 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 separately (e.g., using separate first readout circuits 110) or the one-dimensional data signals from all active pixel control sensors 102 can be read out collectively (e.g., through a single first readout circuit 110). In embodiments where the active pixel control sensors 102 are read out separately, the one-dimensional data output from each individual first readout circuit 110 can be compared or combined to produce an image with differential contrast, i.e., orientation, atomic density, or topographic contrast.

[0055] FIG. 6B shows a detector arrangement for an in - axis transmission Kikuchi diffraction (TKD) imaging modality or a four - dimensional scanning transmission electron microscope (4 - D STEM) imaging modality according to some embodiments described herein. Here, the active pixel control sensor 102 is disposed behind the sample 202 and receives 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 interaction of the charged particle beam 228 with the sample 202. The active pixel control sensor 102 can output both one - dimensional data signals and multi - dimensional data signals to be able to reconstruct both a direct image of the field of view (e.g., a density contrast image similar to that obtained by a transmission electron microscope) and a structural image of the field of view in which structural information (e.g., crystal phase or orientation) regarding each location within the field of view is represented within the image.

[0056] FIG. 6C shows a detector arrangement for an off - axis transmission Kikuchi diffraction (TKD) imaging modality according to some embodiments described herein. Here, the active pixel control sensor 102 is disposed 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 interaction of the charged particle beam 228 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 be able to reconstruct both a direct image of the field of view (e.g., a density contrast image similar to that obtained by a transmission electron microscope) and a structural image of the field of view in which structural information (e.g., crystal phase or orientation) regarding each location within the field of view is represented within the image.

[0057] FIG. 7 is a block diagram showing a computing device 800 suitable for use with the embodiments 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 execute 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 a 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 communicating 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.

[0058] 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 execution of instructions by the processor 820. When such instructions are stored in a non-transitory storage medium accessible to the processor 820, the computing device 800 is customized into a dedicated machine that executes the operations specified by the instructions.

[0059] The computing device 800 may further include a read-only memory (ROM) 804 or other static storage device coupled to bus 810 for storing static information and instructions for processor 820. A storage device 806, such as a magnetic disk or optical disk, can be provided and coupled to bus 810 for storing information and instructions.

[0060] The computing device 800 can be coupled via 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 keys and other keys, is coupled to bus 810 for communicating information and command selections to processor 820. Another type of user input device 640 is a cursor control, such as a mouse, trackball, touch screen, or cursor direction keys, for communicating instruction information and command selections to processor 820 and for controlling cursor movement on display 638. This input device typically has two degrees of freedom in two axes, i.e., a first axis (e.g., x) and a second axis (e.g., y), which enable the device to specify positions in a plane.

[0061] In some embodiments, all or a portion of the first read circuit 110, the second read circuit 130, or both the first read circuit 110 and the second read circuit 130 can be physically housed within the computing device 800. For example, the read circuit can be implemented on a printed circuit board that is inserted into a housing that houses one or more of the other components of the computing device 800. In other examples, this configuration is optional since the first read circuit 110, the second read circuit 130, or both circuits can be implemented as stand-alone units. The first read circuit 110 and the second read circuit 130 can 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 can be directly connected to the first read circuit 110 or the second read circuit 130, or can be connected to the first read circuit 110 or the second read circuit 130 through the bus 810.

[0062] Computing device 800 can implement the techniques described herein using customized hardwired logic, one or more application specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs), firmware, and / or program logic that combines with a computer system to make or program computing device 800 as a special purpose machine. According to one embodiment, the techniques herein are performed by computing device 800 in response to a processor 820 executing one or more sequences of one or more instructions included in main memory 802. Such instructions can be read into main memory 802 from another storage medium, such as storage device 806. By executing the sequence of instructions included in main memory 802, processor 820 performs the process steps described herein. In an alternative embodiment, instead of software instructions, or in combination with software instructions, hardwired circuitry can be used.

[0063] 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 fashion. Such storage medium can include non-volatile and / or volatile media. Non-volatile media includes, for example, optical 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 disk, flexible disk, hard disk, solid state drive, magnetic tape, or any other magnetic data storage medium, CD-ROM, any other optical data storage medium, any physical medium with patterns of holes, RAM, PROM, EPROM, FLASH-EPROM, NVRAM, any other memory chip or cartridge, content-addressable memory (CAM), and ternary including a content-addressable memory (TCAM).

[0064] A memory medium is different from a transmission medium but can be used in conjunction with a transmission medium. The transmission medium is involved in transferring information between memory media. For example, the transmission medium includes coaxial cables, copper wires, and optical fibers, including wires with a bus 810. The transmission medium can also take the form of acoustic or light waves, such as those generated during radio and infrared data communication.

[0065] Various forms of media can be involved in carrying one or more sequences of one or more instructions to the processor 820 for execution. For example, the instructions can initially be carried on the magnetic disk or solid-state drive of a remote computer. The remote computer can load the instructions into its dynamic memory and transmit the instructions via a telephone line using a modem. A modem local to the computing device 800 can receive the data on the telephone line and convert the data into an infrared signal using an infrared transmitter. An infrared detector can receive the data carried by the infrared signal, and an appropriate circuit can place the data on the bus 810. The bus 810 carries the data to the main memory 802, and the processor 820 fetches and executes the instructions therefrom. The instructions received by the main memory 802 can optionally be stored in the storage device 806 either before or after execution by the processor 820.

[0066] Computing device 800 can also include a communication interface 808 coupled to bus 810. Communication interface 808 provides for bi-directional data communication coupling computing device 800 to a network link 822 connected to 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 that provides a data communication connection to a compatible LAN. A wireless link can also be implemented. In any such implementation, communication interface 808 transmits and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information.

[0067] Network link 822 typically provides data communication through one or more networks to other data devices. For example, network link 822 can provide a connection through local network 814 to host computer 812, or to a connection to a data device operated by an Internet service provider (ISP) that provides data communication services through a worldwide packet data communication network commonly referred to today 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 that carry digital data between computing device 800, signals on network link 822, and signals through communication interface 808 are exemplary forms of transmission media.

[0068] Computing device 800 can send messages and receive data including program code through a network, network link 822, and communication interface 808. In an example of the Internet, server 816 may transmit code requested for an application program through Internet 818, local network 814, and / or communication interface 808. The received code can be executed by processor 820 when received, and / or can be stored in storage device 806, and / or can be stored in other volatile or non-volatile storage devices for later execution.

[0069] FIG. 8 shows an exemplary method 900 for imaging a sample according to an embodiment taught herein. The exemplary method 900 depicts a particular sequence of operations, but 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 exemplary device or system implementing method 900 can perform functions substantially simultaneously or in a particular sequence.

[0070] According to some examples, method 900 includes directing a charged particle beam to a location within a region of interest on a sample (block 904). For example, charged particle imaging system 600 described above can direct charged particle beam 228 to impact point 203 within ROI 204 of sample 202. Method 900 also includes receiving charged particles emitted, scattered, or transmitted from that location at pixels of active pixel control sensor 102 (block 906). For example, active pixel control sensor 102 can be disposed at a location (e.g., a first location 628, a second location 626, a third location 632, a fourth location 634, or other suitable location) within sample chamber 620 such that it can receive charged particles resulting from the interaction of charged particle beam 228 and sample 202.

[0071] Next, method 900 is split 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 within active pixel control sensor 102 to first readout circuit 110 (block 908). For example, the one-dimensional data signal is transferred from sensor layer 104 to first readout circuit 110. Method 900 also includes generating one-dimensional data from the one-dimensional data signal using first readout circuit 110 (block 910). Method 900 also includes generating pixels within a first image by processing the one-dimensional data from first readout circuit 110 (block 912). For example, the first image can be intensity image 122.

[0072] In a second path, method 900 includes transmitting a multi-dimensional data signal corresponding to the other of the electrons or holes generated within the active pixel control sensor to second readout circuit 130 (block 914). For example, the multi-dimensional data signal is transferred from readout chip 106 to second readout circuit 130. Method 900 also includes generating multi-dimensional data from the multi-dimensional data signal using second readout circuit 130. Method 900 also includes generating pixels within a second image by processing the multi-dimensional data from second readout circuit 130 (block 918). For example, the second image can be structural image 136.

[0073] According to some examples, method 900 includes selecting a new location within the region of interest to be illuminated (block 920). The method 900 can then be repeated to generate additional pixels in the first or second image until all locations within the region of interest have been illuminated by the charged particle beam. It will be understood that in some examples, both paths may not be executed in each iteration. For example, the first path may be executed in several iterations to produce a complete intensity image 122 by quickly assembling the intensity image using a short dwell time (e.g., several hundred nanoseconds) of the charged particle beam at a location on the sample. The second path can then be executed one or more times to collect multi-dimensional data at a longer dwell time of the charged particle beam at that location to improve the signal-to-noise ratio. The multi-dimensional data collection may be interrupted or segmented by one-dimensional data collection at a short dwell time to prepare the intensity image or to otherwise determine if the location of the sample has drifted. Drift correction can then be applied to the multi-dimensional data. By executing method 900, a complete structural image 136 and a corresponding intensity image 122 can be generated from the signals produced by a single active pixel control sensor 102.

[0074] FIG. 9 shows an exemplary method 1000 for assembling a charged particle detector system as taught herein. The exemplary method 1000 depicts a particular sequence of operations, but the sequence may be changed without departing from the scope of the present disclosure. For example, some of the depicted operations may be performed in parallel or in a different sequence that does not substantially affect the functionality of method 1000. In other examples, different components of the exemplary device or system implementing method 1000 may function substantially simultaneously or in a particular sequence.

[0075] According to some examples, method 1000 includes, at block 1002, providing an active pixel control sensor 102 having a sensor layer 104 and a readout chip 106. Method 1000 includes, at block 1004, 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. Method 1000 includes, at block 1006, 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.

[0076] According to some examples, method 1000 includes, at block 1008, connecting a first computing device 112 to the first readout circuit 110 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, method 1000 includes, at block 1010, connecting a second computing device 134 to the second readout circuit 130 to generate a structural image 136 of the sample 202 from the multi-dimensional data provided by the second readout circuit 130.

[0077] Although the present teachings have been described in conjunction with various embodiments, it is not intended to limit the present teachings to such embodiments. Rather, the present teachings include various alternatives, modifications, and equivalents, as will be understood by those skilled in the art.

[0078] The embodiments described herein can be implemented using other computer system configurations including, but not limited to, hand-held devices, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers, and the like. The embodiments can also be implemented by distributing a computing environment that executes tasks by remote processing devices linked through a network.

[0079] It should also be understood that the embodiments described herein can use a variety of computer-implemented operations involving data stored in a computer system. These operations require physical manipulation of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transmitted, combined, compared, and otherwise manipulated. Further, the operations performed are often referred to in terms such as generating, identifying, determining, or comparing.

[0080] Certain embodiments can 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 and that is thereafter readable 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 or non-optical data storage devices. The computer-readable medium can also be distributed across a network of coupled computer systems so that the computer-readable code is stored and executed in a distributed fashion.

[0081] The section headings used herein are for organizational purposes only and should not be construed as limiting the subject matter being described in any way.

[0082] In this detailed description of 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, one of ordinary skill in the art will understand that, in some instances, these various embodiments may be practiced without these specific details. In other instances, structures and devices are shown in block diagram form. Further, the specific sequences in which methods are presented and executed are illustrative (unless explicitly stated otherwise), and it is contemplated that the sequences may be varied and still remain within the spirit and scope of the various embodiments disclosed herein, as will be readily understood by one of ordinary skill in the art.

[0083] 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 explained, 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.

[0084] There is an implicit "about" prior to the specific temperatures, concentrations, times, pressures, flow rates, cross-sectional areas, etc. contemplated in the present teachings, and thus it will be understood that extremely small and negligible deviations are within the scope of the present teachings. In this application, the use of the singular is intended to include the plural unless specifically stated otherwise. Similarly, the use of "comprise," "comprises," "comprising," "contain," "contains," "containing," "include," "includes," and "including" is not intended to be limiting. It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present teachings.

[0085] As used herein, the terms "a" or "an" can also, in some instances, refer to "at least one" or "one or more" unless expressly stated otherwise. Also, the use of "or" is inclusive, such that the phrase "A or B" applies when A applies, when B applies, or when both A and B apply. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include singulars.

[0086] As used herein, "system" refers to a set of components, whether physical or abstract, where each component interacts with or is related to at least one other component of the whole.

[0087] The advantages and features of the present disclosure can be further illustrated by the following examples.

[0088] Example 1. An active pixel control sensor having a sensor layer and a readout chip, the active pixel control sensor including a plurality of pixels, each pixel of the plurality of pixels being an active pixel control sensor that produces at least electrons and holes when charged particles collide, a first readout circuit configured to communicate with the sensor layer and receive a one-dimensional data signal corresponding to one of the electrons or holes produced by the collision of charged particles, and a second readout circuit configured to communicate with the readout chip and receive a multi-dimensional data signal corresponding to the other of the electrons or holes produced by the collision of charged particles, a charged particle detector system.

[0089] Example 2. The charged particle detector system of Example 1, wherein the first readout circuit includes a current mirror that receives the one-dimensional data signal as an input signal and outputs at least two mirrored signals corresponding to the input signal.

[0090] Example 3. The charged particle detector system of Example 2, wherein the first readout circuit includes an amplifier and a peripheral interface adapter, and the amplifier receives one of the signals mirrored from the current mirror.

[0091] Example 4. The charged particle detector system of Example 2, wherein the first readout circuit includes a bias voltage source that receives one of the signals mirrored from the current mirror.

[0092] Example 5. The charged particle detector system according to any one of Examples 1 to 4, wherein the second readout circuit includes a field programmable gate array that receives and decodes a multi-dimensional data signal from a readout chip.

[0093] Example 6. The charged particle detector system according to any one of Examples 1 to 5, wherein the one-dimensional data signal and the multi-dimensional data signal are simultaneously generated by an active pixel control sensor.

[0094] Example 7. The charged particle detector system according to any one of Examples 1 to 6, further comprising a first computing device that processes one-dimensional data to produce an intensity image and a second computing device that processes multi-dimensional data to produce a structural image.

[0095] Example 8. The charged particle detector system of Example 7, wherein the intensity image and the structural image are automatically coregistered.

[0096] Example 9. The charged particle detector system of Example 7, wherein the first computing device and the second computing device are the same computing device.

[0097] Example 10. The charged particle detector system according to any one of Examples 1 to 9, wherein the active pixel control sensor is a monolithic active pixel sensor (MAPS).

[0098] Example 11. A charged particle detector system according to any one of Examples 1 to 10, wherein the active pixel control sensor is a hybrid pixel array detector (HPAD).

[0099] Example 12. A charged particle detector system according to any one of Examples 1 to 11, wherein the active pixel control sensor is configured to be disposed at a position with respect to a sample for measuring reflection Kikuchi diffraction.

[0100] Example 13. A method of imaging a sample, including a plurality of pixels in an active pixel control sensor including a sensor layer and a readout chip, wherein each pixel of the plurality of pixels generates at least electrons and holes when charged particles collide. In the plurality of pixels, receiving charged particles from the sample, transmitting a one-dimensional data signal corresponding to one of the electrons or holes generated by the collision of the charged particles 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 holes generated by the collision of the charged particles 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.

[0101] Example 14. The method of Example 13, wherein generating one-dimensional data includes using a current mirror to generate two mirrored signals corresponding to the one-dimensional data signal.

[0102] Example 15. The method of Example 14, further including 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.

[0103] Example 16. The method of Example 14, wherein generating one-dimensional data further includes using an amplifier to amplify one of the mirrored signals.

[0104] Example 17. The method according to any one of Examples 13 to 16, wherein the step of transmitting a one-dimensional data signal and the step of transmitting a multi-dimensional data signal occur simultaneously.

[0105] Example 18. The method according to any one of Examples 13 to 17, further comprising forming an intensity image of a sample using a first computing device that receives one-dimensional data from a first readout circuit, and forming a structural image of the sample using a second computing device that receives multi-dimensional data from a second readout circuit.

[0106] Example 19. The method according to any one of Examples 13 to 18, wherein the intensity image and the structural image are automatically co-registered.

[0107] Example 20. The method according to any one of Examples 13 to 19, wherein generating multi-dimensional data includes receiving and decoding a multi-dimensional data signal in a field-programmable gate array.

Claims

1. 1. A charged particle detector system, comprising: an active pixel control sensor having a sensor layer and a readout chip, the active pixel control sensor including a plurality of pixels, each pixel of the plurality of pixels producing 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 holes created by the impact of the charged particle; a second readout circuit in communication with the readout chip and configured to receive a multidimensional data signal corresponding to the other of the electrons or holes produced by the impact of the charged particle.

2. 2. The charged particle detector system of claim 1, wherein the first readout circuitry includes a current mirror that receives the one-dimensional data signal as an input signal and outputs at least two mirrored signals corresponding to the input signal.

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

4. The charged particle detector system of claim 2 , wherein the first readout circuitry includes a bias voltage source that receives one of the mirrored signals from the current mirror.

5. 2. The charged particle detector system of claim 1, wherein the second readout circuitry includes a field programmable gate array that receives and decodes the multi-dimensional data signals from the readout chip.

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. a first computing device for processing the one-dimensional data signal to produce an intensity image; 10. The charged particle detector system of claim 1, further comprising: a second computing device that processes the multi-dimensional data signals to generate a structural image.

8. The charged particle detector system of claim 7 , wherein the intensity image and the structural 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. 2. The charged particle detector system of claim 1, wherein the active pixel control sensor is configured to be disposed at a position relative to a sample that measures reflective Kikuchi diffraction.

13. 1. A method of imaging a sample, comprising the steps of: receiving charged particles from a sample at a plurality of pixels in an active pixel control sensor including a sensor layer and a readout chip, each pixel of the plurality of pixels producing at least an electron and a hole when struck by the charged particle; transmitting a one-dimensional data signal corresponding to one of the electrons or holes created by the impact of the charged particle 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 multidimensional data signal corresponding to the other of the electrons or holes produced by the impact of the charged particles from the readout chip to a second readout circuit; and generating multi-dimensional data from the multi-dimensional data signal using the second readout circuitry.

14. 14. The method of claim 13, wherein generating the one-dimensional data comprises using a current mirror to generate two mirrored signals corresponding to the one-dimensional data signal.

15. 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 mirrored signals from the current mirror.

16. The method of claim 14 , wherein generating the one-dimensional data further comprises amplifying one of the mirrored 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. forming an intensity image of the sample using a first computing device that receives one-dimensional data from the first readout circuit; and 14. The method of claim 13, further comprising: forming a structural image of the sample with a second computing device that receives multi-dimensional data from the second readout circuit.

19. The method of claim 18 , wherein the intensity image and the structural image are automatically co-registered.

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

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