Unsupervised pattern synonym detection using image hashing

Abstract

Images of semiconductor wafers can be hashed to determine a fixed-length hash string for each of the images. Pattern synonyms can be determined from the hash strings. The pattern synonyms can be grouped. The similarity between images within a group can be adjusted via Hamming distance. This can be used for a variety of applications, including determining potential defects.

Description

[Technical field]

[0001] The present disclosure relates to defect detection in semiconductor wafers. [Background technology]

[0002] REFERENCE TO RELATED APPLICATIONS This application claims priority to Indian Patent Application No. 202041038794, filed September 8, 2020, and U.S. Provisional Application No. 63 / 105,916 (October 27, 2020), the disclosures of which are incorporated herein by reference.

[0003] The evolution of the semiconductor manufacturing industry is placing greater demands on yield management, especially on metrology and inspection systems. As critical dimensions continue to shrink, the industry must reduce the time to achieve high-yield, high-value production. Minimizing the total time from detecting a yield problem to fixing it maximizes the return on investment for semiconductor manufacturers.

[0004] Fabricating semiconductor devices, such as logic and memory devices, typically involves processing semiconductor wafers using a number of manufacturing processes to form the various features and levels of the semiconductor devices. For example, lithography is a semiconductor manufacturing process that involves transferring a pattern from a reticle to a photoresist disposed on a semiconductor wafer. Further examples of semiconductor manufacturing processes include, but are not limited to, chemical mechanical polishing (CMP), etching, deposition, and ion implantation. An array of multiple semiconductor devices fabricated on a single semiconductor wafer may be separated into individual semiconductor devices.

[0005] Inspection processes are used at various steps during semiconductor manufacturing to detect defects on wafers to promote higher yields in the manufacturing process and therefore higher profits. Inspection has always been an important part of manufacturing semiconductor devices such as integrated circuits (ICs). However, as the dimensions of semiconductor devices decrease, inspection becomes even more important to the successful manufacture of acceptable semiconductor devices because smaller defects can cause device failures. For example, as the dimensions of semiconductor devices shrink, detection of defects of reduced size has become necessary because even relatively small defects can cause undesirable aberrations in the semiconductor device.

[0006] Pattern synonyms are groups of inaccurate design patterns that are similar enough to fail due to similar root causes. Pattern synonyms can be grouped together to detect and control critical patterns, such as latent defects and part failures, in-line during manufacturing. These defects that affect reliability are typically not statistically significant.

[0007] Detecting pattern synonyms is a tedious, manual, and time-consuming process. Results can be based on user experience. Optical proximity correction (OPC) rule-based search is another method for detecting pattern synonyms. Given one pattern, an inexact search can be performed to detect other similar patterns. Unfortunately, this OPC rule-based process is slow, supervised, and cannot be practically implemented for all patterns. Design-Based Grouping (DBG) algorithms are faster and unsupervised, but are accurate search algorithms that do not always serve this purpose. Aspects of DBG are disclosed in U.S. Pat. No. 8,139,843, which is incorporated herein by reference. Furthermore, DBG can work at the wafer level, so bending across the wafer cannot be easily analyzed.

[0008] In these previous techniques, the inexact search algorithms have slow turnaround times that impact production schedules. Exact search solutions are faster, but they split the data set into an unmanageable number of groups that usually cannot be practically monitored in production. Exact search solutions also split designs with similar root causes into multiple groups, which hinders root cause analysis. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2020 / 064542 [Patent Document 2] US Patent Application Publication No. 2015 / 0154746 Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, new systems and techniques are needed. [Means for solving the problem]

[0011] In a first embodiment, a system is provided. The system includes a semiconductor wafer inspection system and a processor in electronic communication with the semiconductor wafer inspection system. The semiconductor wafer inspection system may include a light source or an electron beam source. The processor is configured to receive a plurality of images from the semiconductor wafer inspection system, hash the images to thereby determine a fixed length hash string for each of the images, thereby determining a plurality of hash strings, and determine pattern synonyms from the hash strings. The images are semiconductor inspection images.

[0012] The processor may be further configured to group the hash strings using pattern synonyms. The grouping may be based on similarity. The similarity may be adjusted by Hamming distance. In one example, one of the pattern synonyms is a potential defect.

[0013] Each of the images may be of the entire surface of the semiconductor wafer, an entire layer of the semiconductor wafer, or a device of the semiconductor wafer.

[0014] In a second embodiment, a method is provided. The method includes receiving a plurality of images at a processor. The images are semiconductor inspection images. The images are hashed using the processor to determine a fixed length hash string for each of the images, thereby determining a plurality of hash strings. Pattern synonyms are determined from the hash strings using the processor.

[0015] The hash strings can be grouped by pattern synonyms using a processor. The grouping can be based on similarity. The similarity can be adjusted by Hamming distance. In one example, one of the pattern synonyms is a potential defect.

[0016] Each of the images may be of the entire surface of the semiconductor wafer, an entire layer of the semiconductor wafer, or a device of the semiconductor wafer.

[0017] In one example, at least one of the plurality of images has been previously grouped using design-based grouping.

[0018] In a third embodiment, a computer readable storage medium is provided. The computer readable storage medium includes one or more programs for performing the following steps on one or more computing devices: hashing a plurality of images to determine a fixed length hash string for each image, and determining a plurality of hash strings; the images are semiconductor inspection images; and pattern synonyms are determined from the hash strings.

[0019] The steps may further include grouping the hash strings using pattern synonyms. The grouping may be based on similarity. The similarity may be adjusted by modifying the Hamming distance. [Brief description of the drawings]

[0020] For a fuller understanding of the nature and objects of the present disclosure, reference should be had to the following detailed description taken in conjunction with the accompanying drawings, in which: [Figure 1] 1 is an exemplary flow chart of a method according to the present disclosure. [Diagram 2] 1 is an exemplary flow chart of image hashing. [Diagram 3] FIG. 1 illustrates an example grouping interface. [Figure 4] We show an example where, on average, there is a 42% reduction in bin counts when comparing image hashes with DBG. [Diagram 5] An example of 11 DBG groups supergrouped using image hashing, where each clip represents a DBG seed window and the corresponding DBG ID is represented in the first row. [Figure 6] 1 is a system according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Although the claimed subject matter is described with respect to certain embodiments, other embodiments, including embodiments that do not provide all of the benefits and features described herein, are also within the scope of this disclosure. Various structural, logical, process step, and electronic changes may be made without departing from the scope of the disclosure. Accordingly, the scope of the disclosure is defined solely by reference to the appended claims.

[0022] The embodiments disclosed herein use image hash-based grouping to perform rapid unsupervised pattern synonym detection. These techniques can be used by semiconductor manufacturers at different steps of the manufacturing process. The embodiments can group multiple patterns together and work with a minimum common polygon algorithm that rules out some inexact matches.

[0023] Systematic defects can cause a greater percentage of yield loss as technology nodes shrink. Root cause analysis of low failure rates (and therefore detection rate patterns) can be particularly challenging because they are difficult to detect or trend in statistical process control charts. Identifying and grouping pattern synonyms improves the statistical probability of detecting and controlling these defects.

[0024] FIG. 1 is an exemplary flow chart of method 100. Some or all of the steps of method 100 can use a processor. Method 100 can be used as an improvement to the unsupervised DBG algorithm. The DBG algorithm is an exact search algorithm. This means that patterns can be split into multiple groups even if there are angstrom-level differences in the design. In a production scenario, this can be cumbersome to handle and it can be impractical to analyze trends over time to determine how important a group of patterns is. The embodiments disclosed herein can be used with DBG. For example, after DBG performs an exact search and groups patterns into one or more groups, one pattern per DBG group is extracted and a hashing method is used to group "similar but inexact" patterns together. This helps reduce the overall number of pattern groups in a meaningful way to enable analysis in production.

[0025] At 101, images are received. The images are semiconductor inspection images. These images may be, for example, an entire surface of a semiconductor wafer, a portion of a surface of a semiconductor wafer, an entire layer of a semiconductor wafer, a portion of a layer of a semiconductor wafer, an entire device of a semiconductor wafer, a portion of a device of a semiconductor wafer, or other inspection images. Each image may be of a different wafer. Each image may also be of a different device or die on the same or different wafer. Thus, method 100 may be used for production across wafers, layers, and devices, instead of being performed only on a wafer-by-wafer basis.

[0026] In one example, the images received at 101 have been previously grouped using DBGs. One pattern or image of the DBG group is selected. The selected pattern or image can be used as a basis for finding other pattern synonyms in the DBG group or across multiple DBG groups. This can enable the search for defects that were otherwise missing or hidden during DBG grouping.

[0027] The images are hashed at 102. The hashing determines a fixed-length hash string for each of the images. In one example, the output of the algorithm is a 64-bit string. The string can be stored for further analysis.

[0028] A hash is a function that can be used to map data of any size to data of a fixed size. A perceptual hash is a type of hash that is sensitive to locality and may be similar if the multimedia features are similar. Perceptual hashing uses such a function to generate fixed-length hash strings for images. These bit strings will be similar for images that are perceptually similar. The Hamming distance between two hashes (i.e., the number of bits they differ) indicates how similar the two images are.

[0029] In one example, one exact match design excerpt per DBG group is selected and sent as input to the image hashing algorithm. One seed window (i.e., an exact match across all design clips in one DBG group) is selected per DBG group and sent as input to the image hashing algorithm. Figure 2 shows the image hashing flow.

[0030] Hash algorithms such as Averagehash, Differencehash, pllash, or other algorithms can be used. Averagehash was seen to give the best results in terms of grouping purity in the examples. Averagehash converts the input image to grayscale and then reduces it. The average of the 11 gray values ​​of the image is then determined, and then the pixels are examined individually from left to right. If the gray value is greater than the average, a 1 is added to the hash. If not, a 0 is added to the hash. Differencehash first produces a grayscale image from the input image. From each row, the first eight pixels are examined successively from left to right and compared to their neighbors to the right, which, like Averagehash, results in a hash string. PHash or Perceptual Hash determines the gray value image and reduces it. A discrete cosine transform is applied to the image, first row-wise and then column-wise. The pixels with the higher frequency are located in the upper left corner. The median gray value in this image is determined, which, like Averagehash, results in a hash string.

[0031] In one example, a hash length of 64 bits is used. The 64-bit hash length may provide improved performance and accuracy. Other hash lengths are possible. For example, the hash length may be from 64 bits to 256 bits. The hash string length may be increased for larger image sizes to preserve their details.

[0032] The resolution of the input images may affect the hashing. The pixels of the image affect the hashing, so changes in the resolution or size of the image may affect the resulting hash string. In one example, the best resolution is used for each image. In another example, the same resolution is used for each image in the method 100.

[0033] Returning to Figure 1, pattern synonyms are determined from the hash string at 103. After the images are hashed, they are grouped to infer pattern synonyms. Various pattern synonyms, such as potential defects, can be determined.

[0034] Hash strings with pattern synonyms can be grouped. The grouping can be based on similarity. The similarity can be adjusted by changing the Hamming distance. Thus, the Hamming distance can be used as a tolerance parameter to control the purity of the resulting collection.

[0035] Iterative tolerance based grouping may be used in some instances. The AUTL MATCH.EDIT DIST ANCE function can calculate the Hamming distance for performing a "looks like" query. It can test the similarity between two strings by counting the number of character changes (inserts, updates, deletes) required to transform the first string into the second string. The number of changes required is considered as the distance.

[0036] Clustering-based grouping is used in another instance. Clustering algorithms such as Balanced Iterative Shrinkage and Hierarchical Clustering (BIRCH) can enable grouping of similar patterns. BIRCH is an unsupervised data mining algorithm used to perform hierarchical clustering over a data set. The BIRCH algorithm takes as input a set of N data points represented as real-valued vectors and a desired number of clusters K. The Hamming distance between the hash codes of the pattern images is the Euclidean distance used for clustering. This method can avoid the crawling problem while maintaining performance.

[0037] For example, a design clip of a pattern can be provided. A semiconductor manufacturer can attempt to print the pattern from the design clip. Method 100 can be used to find patterns that are likely to not print properly because the lines are too close together.

[0038] In one example, method 100 enabled a meaningful reduction in the number of design bins by an average of 42% compared to previous methods that generated exact polygon searches, thereby reducing analysis time for inspection.

[0039] Method 100 can be used in conjunction with a pattern library manager. An option in the pattern library manager can use method 100. Source and target patterns can be manually selected and grouping can be performed based on a user-defined "tolerance." This can provide root cause analysis. A grouping interface (e.g., the "PattemGroupViewer" window in FIG. 3) allows a user to analyze and accept the grouping results generated from method 100.

[0040] An embodiment of the method 100 can be used to group pattern synonyms together to detect and control critical patterns, such as potential defects and partial defects, in-line during manufacturing. Potential defects that impact reliability are not statistically significant. Potential defects may require grouping to make meaningful inferences due to low occurrence but high kill rates. The method 100 can be used to collate design-based data across devices, layers, and wafers and perform root cause analysis over time.

[0041] The results of method 100 can be used as independent attributes in a database and can be used to study defect counts / patterns (e.g., with charts and galleries of images). The hash can be kept in the database so it can be compared to patterns from future data sets. Unlike methods that change from run to run, this hash is persistent and is the same regardless of run, device, or layer. This allows for pattern-based yield analysis over time and across devices in a production environment.

[0042] In one embodiment, the image hash code generated for the pattern image may be persistently stored in a database for performing fuzzy pattern matching. Fuzzy matching (also called approximate string matching) can identify two elements of hash strings that are nearly similar but not exactly the same.

[0043] Minor artifacts within the seed window can be ignored, which can provide more meaningful groupings for examination / care area generation and control charts. These minor artifacts tend not to affect the resulting hash strings or only affect the resulting hash strings to a minor extent. The hash strings can still be grouped according to the parameters used.

[0044] In terms of dimensions, smaller hot spots can be detected based on larger detected hot spots. Typically, it is easier for optical systems to detect larger defects (e.g., large bridges) due to the way defects interact with the light source. After capturing larger systematic defects, DBG can be used to determine the underlying pattern. However, with the methods disclosed herein, this analysis can be extended to determine other smaller dimension but similar appearance patterns and create target care areas. These target care areas can be fed into future inspections to perform more sensitive inspections in the target care areas and detect smaller defects (e.g., smaller bridges).

[0045] The groups can be analyzed and fed forward into a custom rule-based search function. Thus, feed forward process control can be performed by the semiconductor manufacturer. If the hash string group results identify a defect, the defect can be used in other defect review methods.

[0046] Although disclosed with images of a wafer, the embodiments disclosed herein can also be used with wafer signatures.

[0047] The following examples are offered by way of illustration and not by way of limitation.

[0048] Figure 4 shows the bin reduction across two data sets. The 28 nm design data set and the 7 nm design data set were used to compare DBG against the method described herein. Hamming distance (or tolerance) was found to be a useful parameter for adjusting the purity of the group.

[0049] FIG. 5 shows an example of the achieved grouping. All design clips have a common basic pattern (horizontal line through the center) along right-angled vertical lines. This combination potentially leads to the same failure mechanism, such as a single line open. Because DBG is an exact search algorithm, clips are grouped separately due to slight differences in dimensions, additional jogs, and unrelated structures at the corners of the seed window. This potentially leads to the same hotspot type being separated into different bins. This can make it nearly impossible to sample from all these bins for review or to create process control charts across them. Image hashing using method 100 helps overcome these shortcomings.

[0050] A "looks like" query on a 5 million row table takes less than 2 seconds. Preliminary performance results are shown in the table below. [Table 1]

[0051] Therefore, image hashing with unsupervised and imprecise image grouping can improve results compared to previous techniques.

[0052] One embodiment of system 200 is shown in FIG. 6. System 200 includes an optical-based subsystem 201. Generally, optical-based subsystem 201 is configured to generate an optical-based output for sample 202 by directing (or scanning) light at sample 202 and detecting light from sample 202. In one embodiment, sample 202 includes a wafer. The wafer may include any wafer known in the art. In another embodiment, sample 202 includes a reticle. The reticle may include any reticle known in the art.

[0053] In the embodiment of the system 200 shown in FIG. 6, the optical-based subsystem 201 includes an illumination subsystem configured to direct light to the sample 202. The illumination subsystem includes at least one light source. For example, as shown in FIG. 6, the illumination subsystem includes a light source 203. In one embodiment, the illumination subsystem is configured to direct light to the sample 202 at one or more angles of incidence, which may include one or more oblique angles and / or one or more normal angles. For example, as shown in FIG. 6, light from the light source 203 passes through an optical element 204 and then through a lens 205 and is directed to the sample 202 at an oblique angle of incidence. The oblique angle of incidence may include any suitable oblique angle of incidence, which may vary depending on, for example, the properties of the sample 202.

[0054] The optical-based subsystem 201 can be configured to direct light to the sample 202 at different angles of incidence at different times. For example, the optical-based subsystem 201 can be configured to change one or more properties of one or more elements of the illumination subsystem so that light can be directed to the sample 202 at angles of incidence different than the angles of incidence shown in Figure 6. In one such example, the optical-based subsystem 201 can be configured to move the light source 203, the optical element 204, and the lens 205 so that light is directed to the sample 202 at different oblique or normal (or near normal) angles of incidence.

[0055] In some cases, the optical-based subsystem 201 may be configured to direct light to the sample 202 at multiple angles of incidence simultaneously. For example, the illumination subsystem may include multiple illumination channels, one of which may include a light source 203, optical elements 204, and a lens 205, as shown in FIG. 6, and another of the illumination channels (not shown) may include similar elements that may be configured differently or may be the same, or may include at least a light source and, in some cases, one or more other components, such as those further described herein. When such light is directed to the sample simultaneously with other light, one or more characteristics (e.g., wavelength, polarization, etc.) of the light directed to the sample 202 at different angles of incidence may be different such that light resulting from illumination of the sample 202 at different angles of incidence may be distinguished from one another at the detector.

[0056] In another example, the illumination subsystem may include only one light source (e.g., light source 203 shown in FIG. 6 ), and the light from the light source may be separated into different optical paths (e.g., based on wavelength, polarization, etc.) by one or more optical elements (not shown) of the illumination subsystem. The light in each of the different optical paths may then be directed to the sample 202. The multiple illumination channels may be configured to direct light to the sample 202 simultaneously or at different times (e.g., when different illumination channels are used to sequentially illuminate the sample). In another example, the same illumination channel may be configured to direct light having different characteristics to the sample 202 at different times. For example, in some cases, the optical element 204 may be configured as a spectral filter, and the characteristics of the spectral filter may be changed in a variety of different ways (e.g., by swapping out the spectral filter) such that light of different wavelengths may be directed to the sample 202 at different times. The illumination subsystem may have any other suitable configuration known in the art for directing light having different or the same characteristics to the sample 202 sequentially or simultaneously at different or the same angles of incidence.

[0057] In one embodiment, the light source 203 may include a broadband plasma (BBP) source. In this manner, the light generated by the light source 203 and directed to the sample 202 may include broadband light. However, the light source may include any other suitable light source, such as a laser. The laser may include any suitable laser known in the art and may be configured to generate light at any suitable wavelength or wavelengths known in the art. In addition, the laser may be configured to generate light that is monochromatic or nearly monochromatic. In this manner, the laser may be a narrowband laser. The light source 203 may also include a polychromatic light source that generates light at multiple discrete wavelengths or wavelength bands.

[0058] Light from the optical element 204 may be focused onto the sample 202 by the lens 205. Although the lens 205 is shown in FIG. 6 as a single refractive optical element, it should be understood that in practice the lens 205 may include several refractive and / or reflective optical elements that combine to focus the light from the optical elements onto the sample. The illumination subsystem shown in FIG. 6 and described herein may include any other suitable optical elements (not shown). Examples of such optical elements may include, but are not limited to, polarizing components, spectral filters, spatial filters, reflective optical elements, apodizers, beam splitters (such as beam splitter 213), apertures, and the like, and may include any such suitable optical elements known in the art. Additionally, the optical-based subsystem 201 may be configured to alter one or more of the elements of the illumination subsystem based on the type of illumination used to generate the optical-based output.

[0059] The optical-based subsystem 201 may also include a scanning subsystem configured to cause the light to be scanned over the sample 202. For example, the optical-based subsystem 201 may include a stage 206 on which the sample 202 is positioned during optical-based output generation. The scanning subsystem may include any suitable mechanical and / or robotic assembly (including the stage 206) that may be configured to move the sample 202 such that the light may be scanned across the sample 202. Additionally or alternatively, the optical-based subsystem 201 may be configured such that one or more optical elements of the optical-based subsystem 201 perform some scanning of the light across the sample 202. The light may be scanned across the specimen 202 in any suitable manner, such as a serpentine-like path or a spiral path.

[0060] The optical-based subsystem 201 further includes one or more detection channels. At least one of the one or more detection channels includes a detector configured to detect light from the sample 202 resulting from illumination of the sample 202 by the subsystem and generate an output in response to the detected light. For example, the optical-based subsystem 201 shown in FIG. 6 includes two detection channels, one formed by a collector 207, an element 208, and a detector 209, and the other formed by a collector 210, an element 211, and a detector 212. As shown in FIG. 6, the two detection channels are configured to collect and detect light at different collection angles. In some examples, both detection channels are configured to detect scattered light, and the detection channels are configured to detect light scattered from the sample 202 at different angles. However, one or more detection channels can be configured to detect another type of light (e.g., reflected light) from the sample 202.

[0061] As further shown in FIG. 6, both detection channels are shown positioned in the plane of the paper, and the illumination subsystem is also shown positioned in the plane of the paper. Thus, in this embodiment, both detection channels are positioned (e.g., centered) in the plane of incidence. However, one or more of the detection channels may be positioned off the plane of incidence. For example, the detection channel formed by collector 210, element 211, and detector 212 may be configured to collect and detect light scattered from the plane of incidence. Such detection channels may therefore be generally referred to as "side" channels, and such side channels may be centered in a plane that is substantially perpendicular to the plane of incidence.

[0062] Although FIG. 6 illustrates an embodiment of the optical-based subsystem 201 including two detection channels, the optical-based subsystem 201 may include a different number of detection channels (e.g., only one detection channel, or two or more detection channels). In one such case, the detection channel formed by the collector 210, the element 211, and the detector 212 may form one side channel, as described above, and the optical subsystem 201 may include an additional detection channel (not shown) formed as another side channel located on the opposite side of the incidence face. Thus, the optical-based subsystem 201 may include a detection channel including the collector 207, the element 208, and the detector 209, located at the center of the incidence face, and configured to collect and detect light at a scattering angle normal or near normal to the sample 202 surface. Thus, this detection channel may be generally referred to as the "top" channel, and the optical-based subsystem 201 may also include two or more side channels configured as described above. Thus, the optical-based subsystem 201 may include at least three channels (i.e., one top channel and two side channels), each of the at least three channels having its own concentrator, each of which is configured to collect light at a different scattering angle than each of the other concentrators.

[0063] As further described above, each of the detection channels included in the optical subsystem 201 may be configured to detect scattered light. Thus, the optical-based subsystem 201 shown in FIG. 6 may be configured for dark-field (DF) output generation for the sample 202. However, the optical-based subsystem 201 may additionally or alternatively include a detection channel configured for bright-field (BF) output generation for the sample 202. In other words, the optical-based subsystem 201 may include at least one detection channel configured to detect light specularly reflected from the sample 202. Thus, the optical-based subsystem 201 described herein may be configured for DF only, BF only, or both DF and BF imaging. Although each of the collectors is shown in FIG. 6 as a single refractive optical element, it should be understood that each of the collectors may include one or more refractive optical dies and / or one or more reflective optical elements.

[0064] The one or more detection channels may include any suitable detectors known in the art. For example, the detectors may include photomultiplier tubes (PMTs), charge-coupled devices (CCDs), time-delay integration (TDI) cameras, and any other suitable detectors known in the art. The detectors may also include non-imaging or imaging detectors. In this manner, when the detectors are non-imaging detectors, each of the detectors may be configured to detect a particular characteristic of the scattered light, such as intensity, but may not be configured to detect such a characteristic as a function of position in the imaging plane. Thus, the output generated by each of the detectors included in each of the detection channels of the optical-based subsystem may be a signal or data, but is not an image signal or image data. In such a case, a processor, such as the processor 214, may be configured to generate an image of the sample 202 from the non-imaging output of the detectors. However, in other cases, the detectors may be configured as imaging detectors, configured to generate imaging signals or image data. Thus, the optical-based subsystem may be configured to generate an optical image or other optical-based output described herein in several ways.

[0065] It should be noted that FIG. 6 is provided herein to generally illustrate configurations of optical-based subsystem 201 that may be included in or generate optical-based output used by system embodiments described herein. The configurations of optical-based subsystem 201 described herein may be modified to optimize performance of optical-based subsystem 201, as is typically done when designing commercial power acquisition systems. In addition, the systems described herein may be implemented using existing systems (e.g., by adding functionality described herein to an existing system). For some such systems, the methods described herein may be provided as optional functionality of the system (e.g., in addition to other functions of the system). Alternatively, the systems described herein may be designed as entirely new systems.

[0066] The processor 214 may be coupled to the components of the system 200 in any suitable manner (e.g., via one or more transmission media, which may include wired and / or wireless transmission media) such that the processor 214 can receive the output. The processor 214 may be configured to perform several functions using the output. The system 200 may receive instructions or other information from the processor 214. The processor 214 and / or the electronic data storage unit 215 may optionally be in electronic communication with a wafer inspection tool, a wafer metrology tool, or a wafer review tool (not shown) to receive additional information or send instructions. For example, the processor 214 and / or the electronic data storage unit 215 may be in electronic communication with a scanning electron microscope.

[0067] The processor 214, other systems, or other subsystems described herein may be part of a variety of systems, including a personal computer system, an image computer, a mainframe computer system, a workstation, a network appliance, an Internet appliance, or other devices. The subsystems or systems may include any suitable processor known in the art, such as a parallel processor. In addition, the subsystems or systems may include platforms with high speed processing and software, either as stand-alone tools or as network tools.

[0068] The processor 214 and electronic data storage unit 215 may be located within or part of the system 200 or another device. In an example, the processor 214 and electronic data storage unit 215 may be part of a stand-alone control unit or may be a centralized quality control unit. Multiple processors 214 or electronic data storage units 215 may be used.

[0069] The processor 214 may in fact be implemented by any combination of hardware, software, and firmware. Also, its functions as described herein may be performed by one unit or may be divided among different components, each of which may in turn be implemented by any combination of hardware, software, and firmware. Program codes or instructions for the processor 214 to implement the various methods and functions may be stored in a readable storage medium, such as a memory in the electronic data storage unit 215 or other memory.

[0070] Where system 200 includes multiple processors 214, the different subsystems may be coupled to one another such that images, data, information, instructions, etc. may be transmitted between the subsystems. For example, one subsystem may be coupled to additional subsystems by any suitable transmission medium, which may include any suitable wired and / or wireless transmission medium known in the art. Two or more of such subsystems may also be effectively coupled by a shared computer-readable storage medium (not shown).

[0071] The processor 214 may be configured to perform a number of functions using the output of the system 200 or other outputs. For example, the processor 214 may be configured to send the output to an electronic data storage unit 215 or another storage medium. The processor 214 may be configured according to any of the embodiments described herein. The processor 214 may also be configured to perform other functions or additional steps using the output of the system 200 or using images or data from other sources.

[0072] The various steps, functions, and / or operations of the system 200 and methods disclosed herein may be performed by one or more of the following: electronic circuits, logic gates, multiplexers, programmable logic devices, ASICs, analog or digital controls / switches, microcontrollers, or computing systems. Program instructions implementing methods such as those described herein may be transmitted through or stored on a carrier medium. The carrier medium may include a storage medium such as a read-only memory, a random access memory, a magnetic or optical disk, a non-volatile memory, a solid-state memory, a magnetic tape, etc. The carrier medium may include a transmission medium such as a wire, a cable, or a wireless transmission link. For example, the various steps described throughout this disclosure may be performed by a single processor 214 or, alternatively, by multiple processors 214. Furthermore, different subsystems of the system 200 may include one or more computing or logic systems. Thus, the above description should not be construed as a limitation on the present disclosure, but merely as an example.

[0073] In one example, the processor 214 is in communication with the system 200. The processor 214 is configured to perform an embodiment of the method 100. The processor 214 can receive a plurality of images (e.g., semiconductor inspection images) from the system 200. The process 214 can hash the images, thereby determining a fixed length hash string for each of the images, and determine pattern synonyms from the hash strings.

[0074] Further embodiments relate to a non-transitory computer readable medium storing program instructions executable on a controller to perform a computer-implemented method for classifying a wafer map as disclosed herein. In particular, as shown in FIG. 6, an electronic data storage unit 215 or other storage medium may include a non-transitory computer readable medium including program instructions executable on a processor 214. The computer-implemented method may include any step of any method described herein, including method 100.

[0075] The program instructions may be implemented in any of a variety of 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), Streaming SIMD Extensions (SSE), or other techniques or methodologies, as desired.

[0076] Although system 200 uses light, method 100 can be performed using different semiconductor inspection tools. For example, method 100 can be performed using results from a system that uses an electron beam or an ion beam, such as a scanning electron microscope. Thus, the system can have an electron beam source or an ion beam source.

[0077] Although the present disclosure has been described with respect to one or more particular embodiments, it will be understood that other embodiments of the present disclosure may be made without departing from the scope of the present disclosure, and therefore the present disclosure is deemed to be limited only by the appended claims and their reasonable interpretation.

Claims

1. 1. A system comprising: A semiconductor wafer inspection system; A processor in electronic communication with the semiconductor wafer inspection system, the processor comprising: receiving a plurality of images from the semiconductor wafer inspection system, the images being semiconductor inspection images; hashing the images, thereby determining a fixed length hash string for each of the images, whereby a plurality of said hash strings are determined; Determine pattern synonyms from the hash string It is configured as follows: The system, wherein the processor is further configured to group the hash strings using the pattern synonyms, the grouping being based on a similarity measure, the similarity measure being modulated by a Hamming distance.

2. The system of claim 1 , wherein the semiconductor wafer inspection system includes a light source or an electron beam source.

3. The system of claim 1 , wherein one of the pattern synonyms is a potential defect.

4. 2. The system of claim 1, wherein each image is an image of an entire surface of a semiconductor wafer.

5. The system of claim 1 , wherein each image is an image of an entire layer of a semiconductor wafer.

6. The system of claim 1 , wherein each image is an image of a device on a semiconductor wafer.

7. 1. A method comprising: receiving a plurality of images at a processor, the images being semiconductor inspection images; hashing the images using said processor to determine a fixed length hash string for each of the images, whereby a plurality of said hash strings are determined; determining pattern synonyms from the hash string with the processor; Equipped with further comprising using the processor to group the hash strings by the pattern synonyms; The grouping is based on similarity, and the similarity is adjusted by changing the Hamming distance.

8. The method of claim 7 , wherein one of the pattern synonyms is a latent defect.

9. 8. The method of claim 7, wherein each image is an image of an entire surface of a semiconductor wafer.

10. 8. The method of claim 7, wherein each image is an image of an entire layer of a semiconductor wafer.

11. The method of claim 7 , wherein each image is an image of a device on a semiconductor wafer.

12. The method of claim 7 , wherein at least one of the plurality of images is pre-grouped using design-based grouping.

13. 1. A non-transitory computer-readable storage medium, comprising: One or more programs for executing, on one or more computing devices, the steps of: determining a fixed length hash string for each of a plurality of images by hashing the images, a plurality of said hash strings being determined, the images being semiconductor inspection images; determining pattern synonyms from the hash string; Equipped with 11. A computer-readable storage medium having recorded thereon a program comprising: grouping the hash strings using pattern synonyms, the grouping being based on a similarity measure, the similarity measure being adjusted by modifying a Hamming distance.

Images