Computer subsystem 46 may be coupled to the detectors of the detection subsystem in any suitable manner (e.g., via one or more transmission media, which may include “wired" and/or “wireless" transmission media) such that the computer subsystem can receive the output generated by the detectors during illumination and possibly scanning of the specimen. Computer subsystem 46 may be configured to perform a number of functions described further herein using the output of the detectors.

The computer subsystem shown in Fig. 1 (as well as other computer subsystems described herein) may also be referred to herein as computer system(s). Each of the computer subsystem(s) or system(s) described herein may take various forms, including a personal computer system, image computer, mainframe computer system, workstation, network appliance, Internet appliance, or other device. In general, the term “computer system” may be broadly defined to encompass any device having one or more processors, which executes instructions from a memory medium. The computer subsystem(s) or system(s) may also include any suitable processor known in the art such as a parallel processor. In addition, the computer subsystem(s) or system(s) may include a computer platform with high speed processing and software, either as a standalone or a networked tool.

If the system includes more than one computer subsystem, then the different computer subsystems may be coupled to each other such that images, data, information, instructions, etc. can be sent between the computer subsystems. For example, computer subsystem 46 may be coupled to computer system(s) 102 as shown by the dashed line in Fig. 1 by any suitable transmission media, which may include any suitable wired and/or wireless transmission media known in the art. Two or more of such computer subsystems may also be effectively coupled by a shared computer-readable storage medium (not shown). As described further herein, the illumination and detection subsystems may be configured for generating output, e.g., images, of the specimen with multiple modes. In general, a “mode" is defined by the values of parameters of the illumination and detection subsystems used for generating output for a specimen. Therefore, modes may be different in the values for at least one of the parameters of the illumination and detection subsystems (other than position on the specimen at which the output is generated). For example, in an optical subsystem, different modes may use different wavelength(s) of light for illumination. The modes may be different in the illumination wavelength(s) as described further herein (e.g., by using different light sources, different spectral filters, etc. for different modes). In another example, different modes may use different illumination channels of the illumination subsystem. For example, as noted above, the illumination subsystem may include more than one illumination channel. As such, different illumination channels may be used for different modes. The modes may also or alternatively be different in one or more collection/detection parameters of the detection subsystem. The modes may be different in any one or more alterable parameters (e.g., illumination polarization(s), angle(s), wavelength(s), etc., detection polarization(s), angle(s), wavelength(s), etc.) of the system, The illumination and detection subsystems may be configured to scan the specimen with the different modes in the same scan or different scans, e.g., depending on the capability of using multiple modes to scan the specimen at the same time.

The systems described herein and shown in Fig. 1 may be modified in one or more parameters to provide different capability depending on the application for which they will be used. In one embodiment, the system is configured as an inspection system. In another embodiment, the system is configured as a metrology system. For example, the illumination and detection subsystems shown in Fig. 1 may be configured to have a higher resolution if they are to be used for metrology rather than for inspection. In another example, the systems may be configured for performing different scanning methods for inspection versus metrology. In other words, the embodiments of the system shown in Fig. 1 describe various configurations for the system that can be tailored in a number of manners that will be obvious to one skill ed in the art to produce systems having different capabilities that are more or less suitable for different applications. In some embodiments in which the system is configured as an inspection system, the inspection system is configured for macro inspection. In this manner, the systems described herein may be referred to as a macro inspection tool. A macro inspection tool is particularly suitable for inspection of relatively noisy back end of line (BEOL) layers such as redistribution line (RDL) and post-dice applications. A macro inspection tool is defined herein as a system that is not necessarily diffraction limited and has a spatial resolution of about 200 nm to about 2.0 microns and above. Such spatial resolution means that the smallest defects that such systems can detect have dimensions of greater than about 200 nm, which is much larger than the smallest defects that the most advanced inspection tools on the market today can detect, hence the “macro” inspector designation. Such systems tend to utilize longer wavelengths of light (e.g., about 500 nm to about 700 nm) compared to the most advanced inspection tools on the market today. These systems may be used when the DOIs have relatively large sizes.

As noted above, the system may be configured for scanning light over a physical version of the specimen thereby generating output for the physical version of the specimen. In this manner, the system may be configured as an “actual” system, rather than a “virtual” system. However, a storage medium (not shown) and computer system(s) 102 shown in Fig. 1 may be configured as a “virtual” system. In particular, the storage medium and the computer system(s) may be configured as a “virtual” inspection system as described in commonly assigned U.S. Patent Nos. 8,126,255 issued on February 28, 2012 to Bhaskar et al. and 9,222,895 issued on December 29, 2015 to Duffy et al., both of which are incorporated by reference as if fully set forth herein. The embodiments described herein may be further configured as described in these patents.

The computer subsystem, e.g., computer subsystem 46 and/or computer system(s) 102, is configured for determining information for the specimen from output generated by the detection subsystem responsive to the detected PL. In general, the information that is determined by the computer subsystem based on the detection subsystem output may be any inspection- and/or metrology-like information such as that described herein. In addition, the information that is determined for the specimen based on the detection subsystem output may be a combination of multiple types of information described herein. The computer subsystem may be configured for analyzing the PL responsive output and extracting device and/or defect information from the images. Important PL information for both individual devices or specimen regions containing multiple devices includes, but is not limited to: (1) absolute emitted intensity; (2) intensity emitted into different wavelength bands; (3) relative changes in intensity emitted into different bands (i.e., color shifts); (4) absolute or relative spectra; (5) relative changes in intensity emitted into different cone angles; (6) intensity variation as a function of illumination light level (the leakage effect); and (7) relative changes in intensity among different materials within an image.

In one such example, Fig. 5 is a plot of PL emission spectra for one abnormal micro-LED, i.e., the “dark pixel,” and a normal micro-LED, i.e., the “normal pixel.” As shown by the plotted emission spectra in Fig. 5, the emission spectra of abnormal and normal micro-LEDs are sufficiently different from each other that they can be used to reveal differences in material and/or structure. In other words, by comparing the emission spectra of micro-LEDs to each other, differences between the micro-LEDs can be detected. In addition, comparing the emission spectra of micro-LEDs to the emission spectra of a known “good” micro-LED (a “reference” spectra) can be used to detect abnormal micro-LEDs. In either case, the differences between only some portion of the spectra may be used for the applications described herein. For example, if there is a strong difference between the spectra at longer wavelengths, which is the case in the emission spectra shown in Fig. 5, that difference may be used by the embodiments described herein even if there are other differences between the spectra (such as the shift in the wavelength of the peak emission intensity from 522.26 nm to 518.73 nm). Therefore, by configuring the illumination and detection subsystems as described herein so that they can detect and generate output responsive to the emission spectra of micro- LEDs and by configuring the computer subsystem as described herein to compare the emission spectra to each other or a known good reference, information about the micro- LEDS such as which micro-LEDS are defective in material and/or structure can be determined without having to electrically test the completed micro-LEDs.

The computer subsystem may also or alternatively be configured for analyzing a PL macro-overview image (MOI) of an entire specimen or wafer. The computer subsystem may generate the MOI by stitching multiple PL images together based on various spatial relationships between the individual images. Important PL information for the entire wafer that may be generated by the computer subsystem includes, but is not limited to: (1) intensity variation across the wafer; (2) emission spectra variation across the wafer; (3) emission cone angle variation across the wafer; (4) intensity variation among different wafers, especially among those from the same batch of an epitaxy process; (5) emission spectra variation among different wafers, especially among those from the same batch of an epitaxy process; and (6) emission cone angle variation among different wafers, especially among those from the same batch of an epitaxy process.

In one embodiment, determining the information includes detecting defects on the specimen based on the output generated by the detection subsystem responsive to the detected PL. In this manner, the embodiments described herein may be configured for defect detection using PL techniques. For example, defect detection may be performed using any of the information described above. The defect detecti on may be performed using either absolute values or relative comparisons (e.g., device-to-device, region-to- region, etc.). In one such example, the computer subsystem may compare an absolute emitted intensity for each device to a threshold (or thresholds), which may correspond to a range of absolute emitted intensities below (and possibly above) the nominal or designed absolute emitted intensity that are unacceptable for the device. If a device has an absolute emitted intensity that is lower or higher than acceptable, it can be detected by the computer subsystem via such comparisons. Other algorithms and methods may also be used for determining which of the devices are defective (such as finding devices that have outlying absolute emitted intensities compared to other devices on the specimen, etc.). In addition, the embodiments described herein may use any suitable defect detection algorithms known in the art that can be applied to the PL responsive output (image or otherwise) or can be modified to operate on the PL responsive output and produce information such as defect maps, heat maps, or any other suitable defect-related information for the specimen.

In one such embodiment, determining the information includes determining a characteristic of functionality of the electro-optically active devices. The characteristic of tire functionality may simply be an indication of whether the devices function at all, i.e., emit some light and therefore appear functional or emit no light at all and therefore appear non-functional. However, the characteristic of the functionality may be qualitative or quantitative in one or more additional or other ways. One example of these qualitative characteristics may be whether the devices emit the correct wavelengths of light. Quantitatively, these characteristics may include how different the wavelength of the emitted light is from the desired or expected wavelength of light, differences in brightness between emitted and expected light, and other quantitative measures of the emitted light described further herein. The characteristic of the functionality may be determined for any or all of the devices that are examined by the embodiments described herein and may be used as described further herein for determining which of the devices are defective.

Figs. 6 and 7 illustrate how color shifts detectable using PL responsive output generated as described herein can be used to detect color shifts and/or variation among devices. In particular, Fig. 6 shows an image of specimen 600 having multiple green- emitting devices 602 formed thereon that may be generated by the embodiments described herein. More specifically, the image shown in Fig. 6 may be generated by illuminating the green-emitting devices with one or more UV illumination wavelengths and detecting the PL (and possibly other light) emitted by the devices. The computer subsystem may then perform defect detection using this image, e.g., by detecting any areas in the image that have emitted different than expected wavelengths of light. Defects 604 show some example defects that may be detected for such green-emitting devices, which may include defects of various sizes and defects that emit yellow light or light green light (e.g., green light that is out of the expected or acceptable green wavelength range). Therefore, the embodiments described herein can detect defects of varying characteristics on green-emitting devices by illuminating the devices with UV light and detecting color shifts in the resulting detected PL.

Fig. 7 shows an image of specimen 700 having multiple blue-emitting devices 702 formed thereon that may be generated by the embodiments described herein. More specifically, the image shown in Fig. 7 may be generated by illuminating the blue- emitting devices with one or more UV illumination wavelengths and detecting the PL (and possibly other light) emitted by the devices. The computer subsystem may then perform defect detection using this image, e.g., by detecting any areas in the image that have emitted different than expected wavelengths of light, any areas that have varying sizes, and/or any areas that have emitted a different than expected brightness of the expected wavelength of light. For example, the shading of the majority of devices 702 indicates devices that are determined to have normal (or acceptable) size, brightness, and color. The devices that have the same lighter shading as device 704 are devices that are of normal size and color but not brightness, i.e., they are defective only because they are not as bright as they should be. The devices that have the same darker shading as devices 706 and 708 are devices that are of normal size and color but are brighter than they should be. The devices that have the same pattern fill as devices 710 are devices that are of normal size and brightness but not color, e.g., they emit green light rather than blue light. In addition, the devices that have the same pattern fill as devices 712 are of normal size but not color or brightness, e.g., they emit green light rather than blue light and are brighter than they should be.

The above-described functionality of electro-optically active devices may also be examined at more than one illumination wavelength band or wavelength. For example, Fig. 8 is a plot of PL emission spectra under different excitation wavelengths, including 365 nm (at a normal angle of incidence), 385 nm, 405 nm (at a normal angle of incidence), and 415 nm (at a normal angle of incidence). The PL emission spectra may be normalized to the incident photon numbers of the illumination light to make comparing and contrasting the emission spectra more accurate. As can be seen in plot 800, the same electro-optically active device may produce different PL emission spectra when illuminated with different excitation wavelengths. Each (or one or more) of these PL emission spectra may be generated by the embodiments described herein and used to determine information for the electro-optically active devices such as functionality, detected defects, characteristics of the defects, etc. In addition, such PL emission spectra indicate how the flexibility of the optics of the embodiments described herein can be useful for not only detecting multiple PL emission spectra from the same device, but also for selecting from the various optics setups and configurations described herein to determine as much or as little information as desired for any one device. In another such embodiment, determining the information also includes identifying one or more of the electro-optically active devices that are anomalous based on the characteristic of the functionality. For example, one new feature of the embodiments described herein is that the systems can use PL emission to identify anomalous individual electro-optical devices or areas of the wafer containing anomalous devices. Fig. 2 shows an example of an image of a micro-LED wafer showing anomalous regions. In particular, image 200 is a standard (i.e., non-PL) BF image of a micro-LED wafer that shows no features. In contrast, PL image 202 clearly shows anomalous regions of lesser or greater emission than acceptable.

Image 300 in Fig. 3 is an image generated by zooming in on one of the anomalous regions shown in image 202. Each of the squares in this image may be individual micro- LEDs. As shown in image 300, when the computer subsystem zooms in on an anomalous region in the PL image, the computer subsystem may determine that the anomalous region actually corresponds to multiple devices on the wafer. In this manner, the computer subsystem may take certain pixels in the images of the specimen and then expand them to make the details more clear, which can be useful for determining which pixels are actually emitting light.

Fig. 4 shows how the computer subsystem may generate composite images from portions of multiple devices to enhance anomalous regions thereby making the anomalous regions easier to detect and analyze. For example, the computer subsystem may generate composite image 406 using only those pixels in raw image 400 that are near the center of each device (active area 402 but not edge area 404) and assigns the average to that device. Each pixel in the composite image represents one device. The darker region is clearly visible. In another example, the computer subsystem may generate composite image 410 using only those pixels in raw image 408 that are near the edge of each device (edge area 404 but not active area 402) and assigns the average to that device. Each pixel in composite image 410 also represents one device, and the brighter region is clearly visible. In this manner, the computer subsystem may analyze the functionality of different portions of the devices described herein in addition to how the functionality varies from device-to-device or from region-to-region on a specimen. In some such embodiments, the electro-optically active devices are unfinished devices incapable of being electrically tested. For example, one significant advantage of the embodiments described herein is that they provide PL capability that can be used to detect subtle material changes between devices or across the wafer that affect the PL- emitted light. These changes may indicate local defects or process variation that otherwise might not be detected until electrical test once the wafer is completely processed. By detecting these deviations early, users can take corrective action quickly and save time and money. In addition, the embodiments described herein can use PL to sort or screen every micro-LED on a wafer at a production worthy throughput before they are mass-transferred to a final display device at which point they can be electrically probed.

In one embodiment, the specimen includes one or more packaging structures formed thereon, and the PL includes PL emitted by the one or more packaging structures. One important new feature of the embodiments described herein is therefore that they provide systems configured for exciting and analyzing PL (or fluorescence) emission of advanced packaging devices in general. Recent years have seen the acceleration of advanced packaging techniques which make mass-production of complex mobile devices and high-performance computing processors feasible. As these devices are produced, they need to be inspected. Therefore, the inspection of advanced packaging structures is a growing and important application area. The embodiments described herein provide significant advantages for such applications because they can provide all the advantages described herein for inspecting these packaging structures.

In one such embodiment, determining the information includes determining if any of the one or more packaging structures are anomalous based on the detected PL. For example, one new feature of the embodiments described herein is that the systems can use PL emission to identify anomalous advanced packaging devices or areas of the wafer containing anomalous devices. For example, some advanced semiconductor packaging materials such as PI and PBO emit fluorescence while metals do not. Therefore, it is possible to use PL inspection to enhance the capture rate of certain hard-to-find defects. In the embodiments described herein, the system may be configured for illumination wavelengths that can cause fluorescence from such materials and for selectively detecting fluorescence from the illuminated specimen having such advanced packaging structures formed thereon. The computer subsystem may then detect defects on the specimen based on the output responsive to the fluorescence. For example, the detected fluorescence may be used to determine information for the structures and/or materials that fluoresce such as location, size, shape, etc. The computer subsystem may then apply a defect detection method to that information, e.g., applying a threshold to the size of the fluorescing structures to determine if the fluorescing structures are large enough to be considered a defect. Instead of applying a defect detection method to information determined from fluorescent responsive output, the defect detection method may be applied to the fluorescent output itself. Such defect detection may include applying one or more thresholds to a characteristic of the fluorescent responsive output, which may include any of the PL responsive output characteristics described further herein.

In another embodiment, determining the information includes determining metrological information for one or more structures formed on the specimen based on the output generated by the detection subsystem responsive to the detected PL. For example, the computer subsystem may be configured for analyzing the PL responsive output and extracting critical dimension (CD) information from the images. CD information includes, but is not limited to: (1) micro-LED light extraction window size and shape; (2) micro-LED mesa size and shape; (3) micro-LED pitch; (4) RDL width and pitch; (5) via dimension; (6) photoresist opening dimension; and (7) overlay. The computer subsystem may be configured to determine such metrological information for the specimen using any suitable methods and/or algorithms known in the art.

In a further embodiment, the illumination subsystem, detection subsystem, and computer subsystem are configured for simultaneously determining the information and performing non-PL inspection of the specimen. “Non-PL inspection” as that term is used herein is defined as inspection performed by detecting light from a specimen having the same wavelength(s) as the illumination wavelength(s) and detecting defects on the specimen based on output responsive to the detected light. For example, the system may be configured for performing any of the above PL-related functions simultaneously with traditional optical inspection. The system may be configured for performing the non-PL or traditional inspection of the specimen in any suitable manner known in the art. In one such case, light from a specimen having the same wavelength(s) as illumination and PL from the specimen may be separately detected as described further herein. The computer subsystem may be configured for separately using the different output to determine information for the specimen. For example, the computer subsystem may apply a first defect detection algorithm to the PL responsive output and may apply a second defect detection algorithm to the non-PL responsive output. The first and second defect detection algorithms may be the same or different in any one or more parameters, and the computer subsystem may apply the first and second defect detection algorithms to the different output simultaneously or at different times.

Determining the information by PL and non-PL inspection may in some instances be performed using the same method or algorithm (e.g., as when one defect detection method can be used to detect defects on the specimen with both PL responsive output and non-PL responsive output). However, in many cases, because the information being determined with PL and non-PL will more likely than not be different, even if that means simply detecting different types of defects on the specimen with PL and non-PL output, the computer subsystem may use different methods or algorithms for determining information with the PL and the non-PL responsive signals.

The computer subsystem may also be configured for simultaneously processing the images (PL and/or non-PL) in more traditional ways to detect traditional optical inspection defects such as bridges, opens, residue, over-etch, under-etch, fall-on particles, etc. Thus, the PL capability may be an add-on feature that can be enabled or not, depending on the application, and does not negatively impact throughput or sensitivity if it is not used.

The different inspections may typically be performed to detect different kinds of defects on the same specimen, but in some cases, the different inspections may be performed to detect the same kind of defect on the specimen. For example, the traditional defect inspection may be used to detect as many defects on the specimen as possible, which may include some defects that do not emit PL under any circumstances and some defects that might. PL inspection may also be performed on the specimen (possibly simultaneously as described herein) for a number of reasons including detecting defects on the specimen that emit PL and that might be missed by traditional inspection and/or for separating the detected defects into those that emit PL and those that do not. In this manner, the results of PL inspection performed in combination with traditional inspection may be used as a kind of additional defect attribute that can be used to separate different defect types from each other. The same can be true for traditional inspection defect attributes that are used as a supplement to PL-based defect attributes. In this manner, PL inspection and non-PL inspection can be used as different modes in an inspection process, which may be performed in the same manner as any other multi-mode inspection process currently performed.

In the same manner, the systems described herein may be configured for performing inspection with PL while also performing traditional metrology or vice versa. In some cases, performing inspection and metrology at the same time may not make sense because of the different measurement times typically needed for such processes, but if the metrology can be performed substantially quickly, e.g., at the same or roughly the same throughput as inspection, such a system configuration becomes more practical. Another possibility is performing PL metrology while also performing non-PL metrology on the same specimen simultaneously or otherwise. For example, it may make sense to determine a first metrological characteristic of a patterned feature on a specimen with non-PL metrology and a second metrological characteristic of the same feature with PL metrology. In another example, the system may be configured to determine a metrological characteristic of a first patterned feature on a specimen with non-PL metrology and a metrological characteristic of a second patterned feature on the specimen with PL metrology. In a further example, the system may be configured to determine the same metrological characteristic of a patterned feature on a specimen using a combination of PL and non-PL responsive output. In this manner, due to the flexibility of the systems described herein, the embodiments described herein may provide the ability to determine more metrological information for a specimen that may be better (e.g., more accurate, more detailed, etc.) than currently available metrology tools.

The computer subsystem may be configured for generating results for the specimen, which may include any of the information described herein such as information about any of the devices determined to be defective, any of the defect or metrological information described herein, a map of defect or metrological information across the specimen, etc. The results for the defective devices may include, but are not limited to, locations of the defective devices, detection scores, information about the defective device classifications such as class labels or IDs, etc., or any such suitable information known in the art. The results for the specimen may be generated by the computer subsystem in any suitable manner.

All of the embodiments described herein may be configured for storing results of one or more steps of the embodiments in a computer-readable storage medium. The results may include any of the results described herein and may be stored in any manner known in the art. The results for the specimen may have any suitable form or format such as a standard file type. The storage medium may include any storage medium described herein or any other suitable storage medium known in the art. After the results have been stored, the results can be accessed in the storage medium and used by any of the method or system embodiments described herein, formatted for display to a user, used by another software module, method, or system, etc. to perform one or more functions for the specimen or another specimen of the same type.

Such functions include, but are not limited to, altering a process such as a fabrication process or step that was or will be performed on the specimen in a feedback or feedforward manner, etc. For example, the computer subsystem may be configured to determine one or more changes to a process that was performed on the specimen and/or a process that will be performed on the specimen based on the defective devices. The changes to the process may include any suitable changes to one or more parameters of the process. The computer subsystem preferably determines those changes such that the defective devices can be reduced or prevented on other specimens on which the revised process is perfonned, the defective devices can be corrected or eliminated on the specimen in another process performed on the specimen, the defective devices can be compensated for in another process performed on the specimen, etc. The computer subsystem may determine such changes in any suitable manner known in the art.

Those changes can then be sent to a semiconductor fabrication system (not shown) or a storage medium (not shown) accessible to both the computer subsystem and the semiconductor fabrication system. The semiconductor fabrication system may or may not be part of the system embodiments described herein. For example, the imaging hardware and/or the computer subsystem described herein may be coupled to the semiconductor fabrication system, e.g., via one or more common elements such as a housing, a power supply, a specimen handling device or mechanism, etc. The semiconductor fabrication system may include any semiconductor fabrication system known in the art such as a lithography tool, an etch tool, a chemical-mechanical polishing (CMP) tool, a deposition tool, and the like.

Each of the embodiments of each of the systems described above may be combined together into one single embodiment.

Another embodiment relates to a method for determining information for a specimen. The method includes directing light having one or more illumination wavelengths to a specimen, e.g., with an illumination subsystem configured as described herein. The method also includes detecting PL from the specimen, e.g., with a detection subsystem configured as described herein. In addition, the method includes determining information for the specimen from output responsive to the detected PL, e.g., with a computer subsystem configured as described herein.

Each of the steps of the method may be performed as described further herein, The method may also include any other step(s) that can be performed by the system, computer subsystem, and/or illumination and detection subsystems described herein. The computer subsystem, the illumination subsystem, and the detection subsystem may be configured according to any of the embodiments described herein, e.g., computer subsystem 46, an illumination subsystem shown in Fig. 1 , and a detection subsystem shown in Fig. 1, respectively. In addition, the method described above may be performed by any of the system embodiments described herein.

An additional embodiment relates to a non-transitory computer-readable medium storing program instructions executable on one or more computer systems for performing a computer-implemented method for determining information for a specimen. One such embodiment is shown in Fig. 9. In particular, as shown in Fig. 9, non-transitory computer-readable medium 900 includes program instructions 902 executable on computer system(s) 904. The computer-implemented method may include any step(s) of any method(s) described herein. Program instructions 902 implementing methods such as those described herein may be stored on computer-readable medium 900. The computer-readable medium may be a storage medium such as a magnetic or optical disk, a magnetic tape, or any other suitable non-transitory computer-readable medium known in the art.

The program instructions may be implemented in any of various ways, including procedure-based techniques, component-based techniques, and/or object-oriented techniques, among others. For example, the program instructions may be implemented using ActiveX controls, C++ objects, JavaBeans, Microsoft Foundation Classes (“MFC”), SSE (Streaming SIMD Extension) or other technologies or methodologies, as desired.

Computer system(s) 904 may be configured according to any of the embodiments described herein.

Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description . For example, methods and systems for determining information for a specimen are provided. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.

The illumination and detection subsystems may be further configured as described in U.S. Patent Nos. 7,782,452 issued August 24, 2010 to Mehanian et al. and 8,218,221 issued July 10, 2012 to Solarz and U.S. Patent Application Publication No. 2009/0059215 published March 5, 2009 by Mehanian et al., which are incorporated by reference as if fully set forth herein. The embodiments described herein may be further configured as described in these references.

Computer subsystem 46 may be coupled to the detectors of the detection subsystem in any suitable manner (e.g., via one or more transmission media, which may include “wired" and/or “wireless" transmission media) such that the computer subsystem can receive the output generated by the detectors during illumination and possibly scanning of the specimen. Computer subsystem 46 may be configured to perform a number of functions described further herein using the output of the detectors.

The computer subsystem shown in Fig. 1 (as well as other computer subsystems described herein) may also be referred to herein as computer system(s). Each of the computer subsystem(s) or system(s) described herein may take various forms, including a personal computer system, image computer, mainframe computer system, workstation, network appliance, Internet appliance, or other device. In general, the term “computer system” may be broadly defined to encompass any device having one or more processors, which executes instructions from a memory medium. The computer subsystem(s) or system(s) may also include any suitable processor known in the art such as a parallel processor. In addition, the computer subsystem(s) or system(s) may include a computer platform with high speed processing and software, either as a standalone or a networked tool.

If the system includes more than one computer subsystem, then the different computer subsystems may be coupled to each other such that images, data, information, instructions, etc. can be sent between the computer subsystems. For example, computer subsystem 46 may be coupled to computer system(s) 102 as shown by the dashed line in Fig. 1 by any suitable transmission media, which may include any suitable wired and/or wireless transmission media known in the art. Two or more of such computer subsystems may also be effectively coupled by a shared computer-readable storage medium (not shown). As described further herein, the illumination and detection subsystems may be configured for generating output, e.g., images, of the specimen with multiple modes. In general, a “mode" is defined by the values of parameters of the illumination and detection subsystems used for generating output for a specimen. Therefore, modes may be different in the values for at least one of the parameters of the illumination and detection subsystems (other than position on the specimen at which the output is generated). For example, in an optical subsystem, different modes may use different wavelength(s) of light for illumination. The modes may be different in the illumination wavelength(s) as described further herein (e.g., by using different light sources, different spectral filters, etc. for different modes). In another example, different modes may use different illumination channels of the illumination subsystem. For example, as noted above, the illumination subsystem may include more than one illumination channel. As such, different illumination channels may be used for different modes. The modes may also or alternatively be different in one or more collection/detection parameters of the detection subsystem. The modes may be different in any one or more alterable parameters (e.g., illumination polarization(s), angle(s), wavelength(s), etc., detection polarization(s), angle(s), wavelength(s), etc.) of the system, The illumination and detection subsystems may be configured to scan the specimen with the different modes in the same scan or different scans, e.g., depending on the capability of using multiple modes to scan the specimen at the same time.

The systems described herein and shown in Fig. 1 may be modified in one or more parameters to provide different capability depending on the application for which they will be used. In one embodiment, the system is configured as an inspection system. In another embodiment, the system is configured as a metrology system. For example, the illumination and detection subsystems shown in Fig. 1 may be configured to have a higher resolution if they are to be used for metrology rather than for inspection. In another example, the systems may be configured for performing different scanning methods for inspection versus metrology. In other words, the embodiments of the system shown in Fig. 1 describe various configurations for the system that can be tailored in a number of manners that will be obvious to one skill ed in the art to produce systems having different capabilities that are more or less suitable for different applications. In some embodiments in which the system is configured as an inspection system, the inspection system is configured for macro inspection. In this manner, the systems described herein may be referred to as a macro inspection tool. A macro inspection tool is particularly suitable for inspection of relatively noisy back end of line (BEOL) layers such as redistribution line (RDL) and post-dice applications. A macro inspection tool is defined herein as a system that is not necessarily diffraction limited and has a spatial resolution of about 200 nm to about 2.0 microns and above. Such spatial resolution means that the smallest defects that such systems can detect have dimensions of greater than about 200 nm, which is much larger than the smallest defects that the most advanced inspection tools on the market today can detect, hence the “macro” inspector designation. Such systems tend to utilize longer wavelengths of light (e.g., about 500 nm to about 700 nm) compared to the most advanced inspection tools on the market today. These systems may be used when the DOIs have relatively large sizes.

As noted above, the system may be configured for scanning light over a physical version of the specimen thereby generating output for the physical version of the specimen. In this manner, the system may be configured as an “actual” system, rather than a “virtual” system. However, a storage medium (not shown) and computer system(s) 102 shown in Fig. 1 may be configured as a “virtual” system. In particular, the storage medium and the computer system(s) may be configured as a “virtual” inspection system as described in commonly assigned U.S. Patent Nos. 8,126,255 issued on February 28, 2012 to Bhaskar et al. and 9,222,895 issued on December 29, 2015 to Duffy et al., both of which are incorporated by reference as if fully set forth herein. The embodiments described herein may be further configured as described in these patents.

The computer subsystem, e.g., computer subsystem 46 and/or computer system(s) 102, is configured for determining information for the specimen from output generated by the detection subsystem responsive to the detected PL. In general, the information that is determined by the computer subsystem based on the detection subsystem output may be any inspection- and/or metrology-like information such as that described herein. In addition, the information that is determined for the specimen based on the detection subsystem output may be a combination of multiple types of information described herein. The computer subsystem may be configured for analyzing the PL responsive output and extracting device and/or defect information from the images. Important PL information for both individual devices or specimen regions containing multiple devices includes, but is not limited to: (1) absolute emitted intensity; (2) intensity emitted into different wavelength bands; (3) relative changes in intensity emitted into different bands (i.e., color shifts); (4) absolute or relative spectra; (5) relative changes in intensity emitted into different cone angles; (6) intensity variation as a function of illumination light level (the leakage effect); and (7) relative changes in intensity among different materials within an image.

In one such example, Fig. 5 is a plot of PL emission spectra for one abnormal micro-LED, i.e., the “dark pixel,” and a normal micro-LED, i.e., the “normal pixel.” As shown by the plotted emission spectra in Fig. 5, the emission spectra of abnormal and normal micro-LEDs are sufficiently different from each other that they can be used to reveal differences in material and/or structure. In other words, by comparing the emission spectra of micro-LEDs to each other, differences between the micro-LEDs can be detected. In addition, comparing the emission spectra of micro-LEDs to the emission spectra of a known “good” micro-LED (a “reference” spectra) can be used to detect abnormal micro-LEDs. In either case, the differences between only some portion of the spectra may be used for the applications described herein. For example, if there is a strong difference between the spectra at longer wavelengths, which is the case in the emission spectra shown in Fig. 5, that difference may be used by the embodiments described herein even if there are other differences between the spectra (such as the shift in the wavelength of the peak emission intensity from 522.26 nm to 518.73 nm). Therefore, by configuring the illumination and detection subsystems as described herein so that they can detect and generate output responsive to the emission spectra of micro- LEDs and by configuring the computer subsystem as described herein to compare the emission spectra to each other or a known good reference, information about the micro- LEDS such as which micro-LEDS are defective in material and/or structure can be determined without having to electrically test the completed micro-LEDs.

The computer subsystem may also or alternatively be configured for analyzing a PL macro-overview image (MOI) of an entire specimen or wafer. The computer subsystem may generate the MOI by stitching multiple PL images together based on various spatial relationships between the individual images. Important PL information for the entire wafer that may be generated by the computer subsystem includes, but is not limited to: (1) intensity variation across the wafer; (2) emission spectra variation across the wafer; (3) emission cone angle variation across the wafer; (4) intensity variation among different wafers, especially among those from the same batch of an epitaxy process; (5) emission spectra variation among different wafers, especially among those from the same batch of an epitaxy process; and (6) emission cone angle variation among different wafers, especially among those from the same batch of an epitaxy process.

In one embodiment, determining the information includes detecting defects on the specimen based on the output generated by the detection subsystem responsive to the detected PL. In this manner, the embodiments described herein may be configured for defect detection using PL techniques. For example, defect detection may be performed using any of the information described above. The defect detecti on may be performed using either absolute values or relative comparisons (e.g., device-to-device, region-to- region, etc.). In one such example, the computer subsystem may compare an absolute emitted intensity for each device to a threshold (or thresholds), which may correspond to a range of absolute emitted intensities below (and possibly above) the nominal or designed absolute emitted intensity that are unacceptable for the device. If a device has an absolute emitted intensity that is lower or higher than acceptable, it can be detected by the computer subsystem via such comparisons. Other algorithms and methods may also be used for determining which of the devices are defective (such as finding devices that have outlying absolute emitted intensities compared to other devices on the specimen, etc.). In addition, the embodiments described herein may use any suitable defect detection algorithms known in the art that can be applied to the PL responsive output (image or otherwise) or can be modified to operate on the PL responsive output and produce information such as defect maps, heat maps, or any other suitable defect-related information for the specimen.

In one such embodiment, determining the information includes determining a characteristic of functionality of the electro-optically active devices. The characteristic of tire functionality may simply be an indication of whether the devices function at all, i.e., emit some light and therefore appear functional or emit no light at all and therefore appear non-functional. However, the characteristic of the functionality may be qualitative or quantitative in one or more additional or other ways. One example of these qualitative characteristics may be whether the devices emit the correct wavelengths of light. Quantitatively, these characteristics may include how different the wavelength of the emitted light is from the desired or expected wavelength of light, differences in brightness between emitted and expected light, and other quantitative measures of the emitted light described further herein. The characteristic of the functionality may be determined for any or all of the devices that are examined by the embodiments described herein and may be used as described further herein for determining which of the devices are defective.

Figs. 6 and 7 illustrate how color shifts detectable using PL responsive output generated as described herein can be used to detect color shifts and/or variation among devices. In particular, Fig. 6 shows an image of specimen 600 having multiple green- emitting devices 602 formed thereon that may be generated by the embodiments described herein. More specifically, the image shown in Fig. 6 may be generated by illuminating the green-emitting devices with one or more UV illumination wavelengths and detecting the PL (and possibly other light) emitted by the devices. The computer subsystem may then perform defect detection using this image, e.g., by detecting any areas in the image that have emitted different than expected wavelengths of light. Defects 604 show some example defects that may be detected for such green-emitting devices, which may include defects of various sizes and defects that emit yellow light or light green light (e.g., green light that is out of the expected or acceptable green wavelength range). Therefore, the embodiments described herein can detect defects of varying characteristics on green-emitting devices by illuminating the devices with UV light and detecting color shifts in the resulting detected PL.

Fig. 7 shows an image of specimen 700 having multiple blue-emitting devices 702 formed thereon that may be generated by the embodiments described herein. More specifically, the image shown in Fig. 7 may be generated by illuminating the blue- emitting devices with one or more UV illumination wavelengths and detecting the PL (and possibly other light) emitted by the devices. The computer subsystem may then perform defect detection using this image, e.g., by detecting any areas in the image that have emitted different than expected wavelengths of light, any areas that have varying sizes, and/or any areas that have emitted a different than expected brightness of the expected wavelength of light. For example, the shading of the majority of devices 702 indicates devices that are determined to have normal (or acceptable) size, brightness, and color. The devices that have the same lighter shading as device 704 are devices that are of normal size and color but not brightness, i.e., they are defective only because they are not as bright as they should be. The devices that have the same darker shading as devices 706 and 708 are devices that are of normal size and color but are brighter than they should be. The devices that have the same pattern fill as devices 710 are devices that are of normal size and brightness but not color, e.g., they emit green light rather than blue light. In addition, the devices that have the same pattern fill as devices 712 are of normal size but not color or brightness, e.g., they emit green light rather than blue light and are brighter than they should be.

The above-described functionality of electro-optically active devices may also be examined at more than one illumination wavelength band or wavelength. For example, Fig. 8 is a plot of PL emission spectra under different excitation wavelengths, including 365 nm (at a normal angle of incidence), 385 nm, 405 nm (at a normal angle of incidence), and 415 nm (at a normal angle of incidence). The PL emission spectra may be normalized to the incident photon numbers of the illumination light to make comparing and contrasting the emission spectra more accurate. As can be seen in plot 800, the same electro-optically active device may produce different PL emission spectra when illuminated with different excitation wavelengths. Each (or one or more) of these PL emission spectra may be generated by the embodiments described herein and used to determine information for the electro-optically active devices such as functionality, detected defects, characteristics of the defects, etc. In addition, such PL emission spectra indicate how the flexibility of the optics of the embodiments described herein can be useful for not only detecting multiple PL emission spectra from the same device, but also for selecting from the various optics setups and configurations described herein to determine as much or as little information as desired for any one device. In another such embodiment, determining the information also includes identifying one or more of the electro-optically active devices that are anomalous based on the characteristic of the functionality. For example, one new feature of the embodiments described herein is that the systems can use PL emission to identify anomalous individual electro-optical devices or areas of the wafer containing anomalous devices. Fig. 2 shows an example of an image of a micro-LED wafer showing anomalous regions. In particular, image 200 is a standard (i.e., non-PL) BF image of a micro-LED wafer that shows no features. In contrast, PL image 202 clearly shows anomalous regions of lesser or greater emission than acceptable.

Image 300 in Fig. 3 is an image generated by zooming in on one of the anomalous regions shown in image 202. Each of the squares in this image may be individual micro- LEDs. As shown in image 300, when the computer subsystem zooms in on an anomalous region in the PL image, the computer subsystem may determine that the anomalous region actually corresponds to multiple devices on the wafer. In this manner, the computer subsystem may take certain pixels in the images of the specimen and then expand them to make the details more clear, which can be useful for determining which pixels are actually emitting light.

Fig. 4 shows how the computer subsystem may generate composite images from portions of multiple devices to enhance anomalous regions thereby making the anomalous regions easier to detect and analyze. For example, the computer subsystem may generate composite image 406 using only those pixels in raw image 400 that are near the center of each device (active area 402 but not edge area 404) and assigns the average to that device. Each pixel in the composite image represents one device. The darker region is clearly visible. In another example, the computer subsystem may generate composite image 410 using only those pixels in raw image 408 that are near the edge of each device (edge area 404 but not active area 402) and assigns the average to that device. Each pixel in composite image 410 also represents one device, and the brighter region is clearly visible. In this manner, the computer subsystem may analyze the functionality of different portions of the devices described herein in addition to how the functionality varies from device-to-device or from region-to-region on a specimen. In some such embodiments, the electro-optically active devices are unfinished devices incapable of being electrically tested. For example, one significant advantage of the embodiments described herein is that they provide PL capability that can be used to detect subtle material changes between devices or across the wafer that affect the PL- emitted light. These changes may indicate local defects or process variation that otherwise might not be detected until electrical test once the wafer is completely processed. By detecting these deviations early, users can take corrective action quickly and save time and money. In addition, the embodiments described herein can use PL to sort or screen every micro-LED on a wafer at a production worthy throughput before they are mass-transferred to a final display device at which point they can be electrically probed.

In one embodiment, the specimen includes one or more packaging structures formed thereon, and the PL includes PL emitted by the one or more packaging structures. One important new feature of the embodiments described herein is therefore that they provide systems configured for exciting and analyzing PL (or fluorescence) emission of advanced packaging devices in general. Recent years have seen the acceleration of advanced packaging techniques which make mass-production of complex mobile devices and high-performance computing processors feasible. As these devices are produced, they need to be inspected. Therefore, the inspection of advanced packaging structures is a growing and important application area. The embodiments described herein provide significant advantages for such applications because they can provide all the advantages described herein for inspecting these packaging structures.

In one such embodiment, determining the information includes determining if any of the one or more packaging structures are anomalous based on the detected PL. For example, one new feature of the embodiments described herein is that the systems can use PL emission to identify anomalous advanced packaging devices or areas of the wafer containing anomalous devices. For example, some advanced semiconductor packaging materials such as PI and PBO emit fluorescence while metals do not. Therefore, it is possible to use PL inspection to enhance the capture rate of certain hard-to-find defects. In the embodiments described herein, the system may be configured for illumination wavelengths that can cause fluorescence from such materials and for selectively detecting fluorescence from the illuminated specimen having such advanced packaging structures formed thereon. The computer subsystem may then detect defects on the specimen based on the output responsive to the fluorescence. For example, the detected fluorescence may be used to determine information for the structures and/or materials that fluoresce such as location, size, shape, etc. The computer subsystem may then apply a defect detection method to that information, e.g., applying a threshold to the size of the fluorescing structures to determine if the fluorescing structures are large enough to be considered a defect. Instead of applying a defect detection method to information determined from fluorescent responsive output, the defect detection method may be applied to the fluorescent output itself. Such defect detection may include applying one or more thresholds to a characteristic of the fluorescent responsive output, which may include any of the PL responsive output characteristics described further herein.

In another embodiment, determining the information includes determining metrological information for one or more structures formed on the specimen based on the output generated by the detection subsystem responsive to the detected PL. For example, the computer subsystem may be configured for analyzing the PL responsive output and extracting critical dimension (CD) information from the images. CD information includes, but is not limited to: (1) micro-LED light extraction window size and shape; (2) micro-LED mesa size and shape; (3) micro-LED pitch; (4) RDL width and pitch; (5) via dimension; (6) photoresist opening dimension; and (7) overlay. The computer subsystem may be configured to determine such metrological information for the specimen using any suitable methods and/or algorithms known in the art.

In a further embodiment, the illumination subsystem, detection subsystem, and computer subsystem are configured for simultaneously determining the information and performing non-PL inspection of the specimen. “Non-PL inspection” as that term is used herein is defined as inspection performed by detecting light from a specimen having the same wavelength(s) as the illumination wavelength(s) and detecting defects on the specimen based on output responsive to the detected light. For example, the system may be configured for performing any of the above PL-related functions simultaneously with traditional optical inspection. The system may be configured for performing the non-PL or traditional inspection of the specimen in any suitable manner known in the art. In one such case, light from a specimen having the same wavelength(s) as illumination and PL from the specimen may be separately detected as described further herein. The computer subsystem may be configured for separately using the different output to determine information for the specimen. For example, the computer subsystem may apply a first defect detection algorithm to the PL responsive output and may apply a second defect detection algorithm to the non-PL responsive output. The first and second defect detection algorithms may be the same or different in any one or more parameters, and the computer subsystem may apply the first and second defect detection algorithms to the different output simultaneously or at different times.

Determining the information by PL and non-PL inspection may in some instances be performed using the same method or algorithm (e.g., as when one defect detection method can be used to detect defects on the specimen with both PL responsive output and non-PL responsive output). However, in many cases, because the information being determined with PL and non-PL will more likely than not be different, even if that means simply detecting different types of defects on the specimen with PL and non-PL output, the computer subsystem may use different methods or algorithms for determining information with the PL and the non-PL responsive signals.

The computer subsystem may also be configured for simultaneously processing the images (PL and/or non-PL) in more traditional ways to detect traditional optical inspection defects such as bridges, opens, residue, over-etch, under-etch, fall-on particles, etc. Thus, the PL capability may be an add-on feature that can be enabled or not, depending on the application, and does not negatively impact throughput or sensitivity if it is not used.

The different inspections may typically be performed to detect different kinds of defects on the same specimen, but in some cases, the different inspections may be performed to detect the same kind of defect on the specimen. For example, the traditional defect inspection may be used to detect as many defects on the specimen as possible, which may include some defects that do not emit PL under any circumstances and some defects that might. PL inspection may also be performed on the specimen (possibly simultaneously as described herein) for a number of reasons including detecting defects on the specimen that emit PL and that might be missed by traditional inspection and/or for separating the detected defects into those that emit PL and those that do not. In this manner, the results of PL inspection performed in combination with traditional inspection may be used as a kind of additional defect attribute that can be used to separate different defect types from each other. The same can be true for traditional inspection defect attributes that are used as a supplement to PL-based defect attributes. In this manner, PL inspection and non-PL inspection can be used as different modes in an inspection process, which may be performed in the same manner as any other multi-mode inspection process currently performed.

In the same manner, the systems described herein may be configured for performing inspection with PL while also performing traditional metrology or vice versa. In some cases, performing inspection and metrology at the same time may not make sense because of the different measurement times typically needed for such processes, but if the metrology can be performed substantially quickly, e.g., at the same or roughly the same throughput as inspection, such a system configuration becomes more practical. Another possibility is performing PL metrology while also performing non-PL metrology on the same specimen simultaneously or otherwise. For example, it may make sense to determine a first metrological characteristic of a patterned feature on a specimen with non-PL metrology and a second metrological characteristic of the same feature with PL metrology. In another example, the system may be configured to determine a metrological characteristic of a first patterned feature on a specimen with non-PL metrology and a metrological characteristic of a second patterned feature on the specimen with PL metrology. In a further example, the system may be configured to determine the same metrological characteristic of a patterned feature on a specimen using a combination of PL and non-PL responsive output. In this manner, due to the flexibility of the systems described herein, the embodiments described herein may provide the ability to determine more metrological information for a specimen that may be better (e.g., more accurate, more detailed, etc.) than currently available metrology tools.

The computer subsystem may be configured for generating results for the specimen, which may include any of the information described herein such as information about any of the devices determined to be defective, any of the defect or metrological information described herein, a map of defect or metrological information across the specimen, etc. The results for the defective devices may include, but are not limited to, locations of the defective devices, detection scores, information about the defective device classifications such as class labels or IDs, etc., or any such suitable information known in the art. The results for the specimen may be generated by the computer subsystem in any suitable manner.

All of the embodiments described herein may be configured for storing results of one or more steps of the embodiments in a computer-readable storage medium. The results may include any of the results described herein and may be stored in any manner known in the art. The results for the specimen may have any suitable form or format such as a standard file type. The storage medium may include any storage medium described herein or any other suitable storage medium known in the art. After the results have been stored, the results can be accessed in the storage medium and used by any of the method or system embodiments described herein, formatted for display to a user, used by another software module, method, or system, etc. to perform one or more functions for the specimen or another specimen of the same type.

Such functions include, but are not limited to, altering a process such as a fabrication process or step that was or will be performed on the specimen in a feedback or feedforward manner, etc. For example, the computer subsystem may be configured to determine one or more changes to a process that was performed on the specimen and/or a process that will be performed on the specimen based on the defective devices. The changes to the process may include any suitable changes to one or more parameters of the process. The computer subsystem preferably determines those changes such that the defective devices can be reduced or prevented on other specimens on which the revised process is perfonned, the defective devices can be corrected or eliminated on the specimen in another process performed on the specimen, the defective devices can be compensated for in another process performed on the specimen, etc. The computer subsystem may determine such changes in any suitable manner known in the art.

Those changes can then be sent to a semiconductor fabrication system (not shown) or a storage medium (not shown) accessible to both the computer subsystem and the semiconductor fabrication system. The semiconductor fabrication system may or may not be part of the system embodiments described herein. For example, the imaging hardware and/or the computer subsystem described herein may be coupled to the semiconductor fabrication system, e.g., via one or more common elements such as a housing, a power supply, a specimen handling device or mechanism, etc. The semiconductor fabrication system may include any semiconductor fabrication system known in the art such as a lithography tool, an etch tool, a chemical-mechanical polishing (CMP) tool, a deposition tool, and the like.

Each of the embodiments of each of the systems described above may be combined together into one single embodiment.

Another embodiment relates to a method for determining information for a specimen. The method includes directing light having one or more illumination wavelengths to a specimen, e.g., with an illumination subsystem configured as described herein. The method also includes detecting PL from the specimen, e.g., with a detection subsystem configured as described herein. In addition, the method includes determining information for the specimen from output responsive to the detected PL, e.g., with a computer subsystem configured as described herein.

Each of the steps of the method may be performed as described further herein, The method may also include any other step(s) that can be performed by the system, computer subsystem, and/or illumination and detection subsystems described herein. The computer subsystem, the illumination subsystem, and the detection subsystem may be configured according to any of the embodiments described herein, e.g., computer subsystem 46, an illumination subsystem shown in Fig. 1 , and a detection subsystem shown in Fig. 1, respectively. In addition, the method described above may be performed by any of the system embodiments described herein.

An additional embodiment relates to a non-transitory computer-readable medium storing program instructions executable on one or more computer systems for performing a computer-implemented method for determining information for a specimen. One such embodiment is shown in Fig. 9. In particular, as shown in Fig. 9, non-transitory computer-readable medium 900 includes program instructions 902 executable on computer system(s) 904. The computer-implemented method may include any step(s) of any method(s) described herein. Program instructions 902 implementing methods such as those described herein may be stored on computer-readable medium 900. The computer-readable medium may be a storage medium such as a magnetic or optical disk, a magnetic tape, or any other suitable non-transitory computer-readable medium known in the art.

The program instructions may be implemented in any of various ways, including procedure-based techniques, component-based techniques, and/or object-oriented techniques, among others. For example, the program instructions may be implemented using ActiveX controls, C++ objects, JavaBeans, Microsoft Foundation Classes (“MFC”), SSE (Streaming SIMD Extension) or other technologies or methodologies, as desired.

Computer system(s) 904 may be configured according to any of the embodiments described herein.

Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description . For example, methods and systems for determining information for a specimen are provided. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.