KR101674698B1 - Detecting defects on a wafer - Google Patents

Abstract

 Methods and systems are provided for detecting defects on a wafer.

Description

DETECTING DEFECTS ON A WAFER < RTI ID = 0.0 >

This application claims priority to U. S. Provisional Application No. 61 / 152,477, filed February 13, 2009, entitled " Methods and Systems for Detecting Defects on a Wafer ", which is incorporated herein by reference in its entirety .

The present invention generally relates to detecting defects on a wafer. Certain embodiments relate to assigning each output of a raw output to a wafer produced by an inspection system to different segments.

The following description and examples are not admitted to the prior art due to their inclusion in this section.

Wafer inspection using optical or electron beam techniques is an important technique for debugging semiconductor manufacturing processes, monitoring process variations, and improving manufacturing yield in the semiconductor industry. BACKGROUND OF THE INVENTION With the scale reduction of modern integrated circuits (ICs) and the increased complexity of manufacturing processes, testing is becoming increasingly difficult.

In each processing step performed on a semiconductor wafer, the same circuit pattern is printed on each die on the wafer. Most wafer inspection systems utilize this fact and use a relatively simple die-to-die comparison to detect defects on the wafer. However, the circuit printed on each die may include a plurality of patterned features that are repeated in the x or y direction, such as areas of DRAM, SRAM, or FLASH. This type of area is commonly referred to as an array area (the remaining areas are referred to as random or logic areas). To achieve better sensitivity, the improved inspection systems use different strategies to inspect array areas and random or logic areas.

To set up a wafer inspection process for array inspection, a number of inspection systems currently in use manually set up corresponding zones (ROIs) and apply the same set of parameters for defect detection in the same ROI. However, this setting method has drawbacks due to a number of causes. For example, as design rules shrink, area regulations become more complex and can be significantly smaller in the area. With limitations on the stage accuracy and resolution of the inspection system, the manual setting of the ROI will eventually become impossible. On the other hand, if the distance between page breaks is greater than the Fourier filtering that can be performed, the page break will not be mitigated in the array area.

In yet another method, the intensity is used as a feature of segmentation to group similar intensity pixels together. Next, the same set of parameters is applied for the same group of pixels (intensity-based). However, this method also has a number of disadvantages. For example, intensity-based refinement algorithms can be used when geometric feature geometries are scattered uniformly. But often this alone is not enough. Therefore, other feature-based segmentation is required.

Accordingly, methods and systems are developed to detect defects on the wafer that can achieve better detection of defects by utilizing knowledge that the defects and the obstacles / noise are in geometrically different segments. It will be beneficial to do so.

The following description of the various embodiments is not to be construed as limiting the scope of the appended claims in any manner.

One embodiment relates to a computer-implemented method for detecting defects on a wafer. A computer implemented method includes obtaining a raw output for a wafer produced by an inspection system. The computer implemented method also includes identifying one or more features of the raw output corresponding to one or more geometric features of the patterned features formed on the wafer. In addition, the computer implemented method may further include the step of determining each output of the raw output based on the identified one or more features of the raw output to different segments, such that the one or more geometric features of the patterned features corresponding to each of the different segments are different . Also, a computer implemented method includes individually assigning one or more detection parameters to different segments. The computer implemented method also includes applying one or more defect detection parameters assigned for each output assigned to different segments to detect defects on the wafer.

Each of the steps of the computer-implemented method disclosed above may be performed as further disclosed herein. The computer-implemented method described above may include any other step (s) of any other method (s) disclosed herein. The previously described computer implemented method may be performed using any of the systems described herein.

Yet another embodiment relates to a computer-readable medium comprising program instructions executable on a computer system to perform a method for detecting defects on a wafer. The method includes steps of a computer-implemented method as described above. The computer-readable medium may be further configured as disclosed herein. The steps of the method may be performed as further disclosed herein. Also, the manner in which program instructions may be executed may include any other step (s) of any other method (s) disclosed herein.

A further embodiment is directed to a system configured to detect defects on a wafer. The system includes an inspection subsystem configured to generate a raw output for a wafer by scanning the wafer. The system also includes a computer subsystem configured to obtain the raw output. The computer system is also configured to identify one or more features of the raw output corresponding to one or more geometric features of the patterned features formed on the wafer. The computer subsystem may also be configured to assign each output of the raw output to different segments based on the identified one or more features of the raw output such that the one or more geometric features of the patterned features corresponding to each of the different segments are different . The computer subsystem is further configured to individually assign one or more fault detection parameters to different segments. The computer subsystem is also configured to apply one or more defect detection parameters assigned to respective outputs assigned to different segments to detect faults on the wafer. The system may be further configured as disclosed herein.

Other objects and advantages of the present invention will become apparent by reading the following detailed description with reference to the accompanying drawings.
1 is a block diagram illustrating one embodiment of a computer-readable medium having computer-executable program instructions for executing one or more method embodiments disclosed herein.
Figure 2 is a schematic diagram illustrating a side view of one embodiment of a system configured to detect defects on a wafer.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope and spirit of the invention as defined by the appended claims. But are intended to be inclusive.

Although embodiments have been disclosed herein with respect to wafers, it will be appreciated that embodiments may be used to detect defects on other specimens, such as a reticle, which may typically be referred to as a mask or a photomask. A number of different types of reticles are known in the art, and the terms "reticle", "mask" and "photomask" as used herein are intended to encompass all types of reticles known in the art.

One embodiment relates to a computer-implemented method for detecting defects on a wafer. A computer implemented method includes obtaining a raw output for a wafer produced by an inspection system. Obtaining the raw output for the wafer can be performed using an inspection system. For example, raw output acquisition may include using an inspection system to scan the light onto the wafer and produce an unprocessed output responsive to the light scattered and / or reflected from the wafer detected by the inspection system during the scan . In this way, raw output acquisition may include wafer scanning. However, raw output acquisition does not necessarily require wafer scanning. For example, raw output acquisition may include obtaining raw output from a storage medium in which the raw output has been stored (e.g., by an inspection system). Obtaining the raw output from the storage medium may be performed in any suitable manner, and the storage medium from which the output is obtained may include any of the storage mediums described herein. In any case, the method includes collecting the raw output (e.g., raw data).

In one embodiment, the raw output is responsive to scattered light from the wafer. In particular, the raw output is scattered from the wafer and can respond to light detected by the inspection system. Alternatively, the raw output may be reflected from the wafer and responsive to light detected by the inspection system. The raw output may include any suitable raw output and may vary depending on the configuration of the inspection system. For example, the raw output may include signals, data, image data, and so on. In addition, the raw output is generally defined as the output for at least a portion of the total output generated for the wafer by the inspection system (e.g., a number of pixels). The raw output also includes all raw outputs generated for the entire wafer by the inspection system, all raw outputs generated for the entire portion of the wafer being scanned by the inspection system, regardless of whether the raw output corresponds to defects on the wafer Output, all raw output generated for a wafer by one channel of the inspection system, and the like.

Conversely, each output can be generally defined as an output for each pixel of the total output generated for the wafer by the inspection system. Thus, the raw output may comprise a plurality of respective outputs. In other words, each output may be an output generated separately for different locations on the wafer. For example, each output may comprise a respective discrete output generated for different locations on the wafer. In particular, different locations may correspond to different "inspection points" on the wafer. In other words, different locations may correspond to locations on the wafer where the output is generated separately by the inspection system. In this way, the different positions may correspond to respective positions on the wafer where "measurement" is performed by the inspection system. As such, the different locations may vary depending on the configuration of the inspection system (e.g., the manner in which the inspection system generates the output for the wafer). Each output includes a respective output corresponding to defects on the wafer and not corresponding to defects on the wafer.

The inspection system can be configured as disclosed herein. For example, the inspection system may be configured for darkfield (DF) inspection of the wafer. In this manner, the inspection system may include a DF inspection system. A DF inspection system can be constructed as further disclosed herein. In another example, the inspection system may be configured for the brightfield (BF) inspection of the wafer. In this manner, the inspection system may include a BF inspection system. The BF inspection system may have any suitable configuration known in the art. In addition, the inspection system can be configured for BF and DF inspection. In addition, the inspection system may comprise a scanning electron microscope (SEM) inspection and review system, which may have any suitable configuration known in the art. In addition, the inspection system can be configured for inspection of patterned wafers as well as possibly unpatterned wafers.

The computer implemented method also includes identifying one or more features of the raw output corresponding to one or more features of the patterned features formed on the wafer. In one embodiment, the identified one or more features of the raw output include projections along lines of the raw output. A projection can generally be defined as a group, cluster, or summation of each output having some pattern within the raw output. Projections along the horizontal and vertical lines of the raw output can be collected. In this manner, the x and y projections in the raw output can be identified as defining or corresponding to one or more geometric features of the patterned features. As such, identifying one or more features of the raw output may include performing a two-dimensional (2D) projection of the raw output. However, one or more features of the raw output corresponding to one or more geometric features of the patterned features formed on the wafer may include any other feature (s) of raw output. Identifying one or more characteristics of the raw output as described above may be performed in any suitable manner using any suitable method and / or algorithm.

In one embodiment, the one or more geometric features of the patterned features include mathematical calculations, edges, shapes, textures, or some combination thereof that define the geometry of the patterned features. For example, features that may be used for geometric-based refinement that may be performed as further disclosed herein include edges, shapes, textures, mathematical calculations, Some combinations are included. Although all of the patterned features formed on the wafer may have some roughness and some "textures ", the textures typically have a roughness in that the roughness is used to describe and illuminate the roughness on only the periphery of the patterned features But the texture is generally considered to be the entire texture of the patterned features (e.g., designated or unspecified). One example of a mathematical computation / transformation that can be used to define the geometry of the patterned features is the Fourier filtering algorithm, which can be used to define the relationship between geometry and light scattering. For example, a Fourier filtering algorithm can be used to predict projections at the raw output corresponding to one or more geometric features of the patterned features.

In one embodiment, identifying one or more features of the raw output is performed based on how the design layout of the patterned features affects one or more features of the raw output. For example, a feature that may be used for segmentation that may be performed as disclosed herein is a design layout. In particular, the design layout can be used to identify one or more geometric features of the patterned features of the design layout. One or more features (e.g., projections) of the raw output corresponding to one or more of the identified geometric features may then be determined (e.g., experimentally, theoretically, etc.). In this manner, one or more expected features of the raw output corresponding to one or more geometric features of the patterned features may be determined. The one or more anticipated features may be compared to one or more features of the raw output in any suitable manner to identify one or more features of the raw output corresponding to the one or more geometric features of the patterned features. The design layout used in this step can be obtained in any suitable manner and can have any suitable format.

In another embodiment, identifying one or more characteristics of the raw output is performed while acquiring the raw output is performed. In this way, identifying one or more features of the raw output may be performed on-the-fly as the wafer is scanned by the inspection system. For example, identifying one or more characteristics of the raw output may be accomplished by comparing the raw output to detect defects on the wafer and using a reference raw output for the wafer obtained for the wafer in the same scan as the raw output . ≪ / RTI > The reference raw output may include any criteria disclosed herein. As such, other steps (e.g., segmentation) described herein that are performed using one or more of the identified features of the raw output may be performed during operation while obtaining the raw output for the wafer.

In addition, the computer implemented method may further include the step of determining each output of the raw output based on the identified one or more features of the raw output to different segments, such that the one or more geometric features of the patterned features corresponding to each of the different segments are different And < / RTI > In this manner, the embodiments disclosed herein are configured for geometric-based refinement. More specifically, the embodiments disclosed herein utilize how the geometric feature (s) (e.g., shape) of the wafer pattern affects the raw output and determine how the raw output will affect patterns that have different effects on different segments Separate. In other words, the embodiments disclosed herein utilize how the geometric feature (s) (e.g., shape) of the patterns on the wafer will affect the raw output to separate each output of the raw output into different segments . For example, patterned features with one or more different geometric features may have different influences on the raw output produced for the wafer due to different effects on the scattered light from the wafer. Such patterned features may be efficiently separated into different segments by the embodiments disclosed herein. Assigning each output of the raw output to different segments as described herein may be performed in any suitable manner using any suitable method and / or algorithm.

A "segment" is generally defined as the different parts of the full range of possible values for each output. The segments may be defined based on values for different features of each output according to a fault detection algorithm using segments. For example, in a number of die auto-thresholding (MDAT) algorithms, the values for the characteristics of each output used to define the segment may include a median intensity value. In this illustrative, non-limiting example, if the entire range of intermediate intensity values is 0 to 255, the first segment may include intermediate intensity values from 0 to 100 and the second segment may include intermediate intensity values from 101 to 255 can do. In this manner, the first segment corresponds to the darker regions in the raw output and the second segment corresponds to the brighter regions in the raw output. In some instances, the segments may be defined using a single wafer, and for wafers having a geometry similar to one wafer, predefined segments may be used.

In one embodiment, identifying one or more features of the raw output and assigning each output to different segments is performed automatically without user input. For example, the embodiments disclosed herein may utilize geometric features (s) (e.g., shapes) of the projections and patterns on the wafer to automatically separate each output of the raw output into different segments. In this manner, unlike methods that involve manually setting up the region of interest (ROI) and applying the same set of parameters for defect detection in the same ROI, as the design rules are reduced and different regions on the wafer become smaller and smaller , The refinement will not be further complicated using the embodiments disclosed herein. Also, unlike the manual methods, the automatic identification of one or more features of the raw output and the assignment of each output to different segments without user input is unaffected by inspection system stage accuracy and resolution constraints. Thus, using the embodiments disclosed herein for refinement, inspection system stage accuracy and resolution constraints will not make the segmentation impossible.

In yet another embodiment, assigning each output to different segments is performed independently of the design of the data associated with the patterned features. For example, a design layout may be used as previously described to determine the expected one or more characteristics of the raw output corresponding to one or more geometric features of the patterned features, but the segmentation is not performed based on the design data itself. In other words, the refinement is based on how one or more geometric features of the patterned features will affect the raw output, but is not based on one or more geometric features of the patterned features themselves. In this manner, segmentation is performed based on how one or more geometric features of the patterned features will affect the raw output, as opposed to other methods and systems that subdivide the raw output based on design data associated with the patterned features Is that the performance of the device formed using different design data, different electrical functions, different electrical characteristics, patterned features, etc., assigned to the same segment when these patterned features affect the raw output in the same way The patterned features associated with different criticalities or the like. For example, performing a refinement based on how the geometric feature (s) will affect the feature (s) of the raw output (s) instead of the geometric structure itself (e.g., how it will affect the strength is dependent on the design data associated with these other patterned features To produce negligible noise in the raw output that is reallocated to a different segment regardless of the patterned features that yield significant noise in the raw output assigned to the same segment, irrespective of the design data associated with these other patterned features In this manner, the high-noise patterned features can be subdivided one another, and the low-noise patterned features can be subdivided into one another.

In a further embodiment, assigning each output to different segments is performed independently of the strength of each output. In other words, the segmentation is performed based on the identified one or more features of the raw output that can be identified based on the strength of each of the multiple outputs of the raw output, but the segmentation is performed based on the strength of each output itself Do not. For example, projections along lines in the raw output may include a respective output having a variety and possibly dramatically different intensities. Nevertheless, all of the respective outputs may correspond to the same one or more geometric features of the patterned features, such as page breaks. As such, all of the respective outputs corresponding to the same one or more geometric features of the patterned features may be assigned to the same segment even though each of the outputs has dramatically different intensities. In this manner, contrary to the methods of performing segmentation based on the intensity of each pixel, the segmentation performed by the embodiments disclosed herein is not affected by non-uniform scattering from the patterned features.

In some embodiments, assigning each output to different segments includes analyzing one or more identified characteristics of the raw output and applying thresholds to each output. For example, projections may be collected along the horizontal and vertical lines of the raw output, as described above. The following projections can be split, and the thresholds can be set to divide each output of the raw output into its different zones (segments). Analyzing the identified one or more features of the raw output and applying the thresholds to each output may reduce the number of respective outputs corresponding to boundary regions that are improperly assigned to the segments.

In one embodiment, one or more geometric features corresponding to one or more different segments include one or more geometric features of page breaks, and one or more geometric features corresponding to different different segments include one or more geometric features of the array regions do. Generally, page breaks are defined in the industry as areas of the die that separate substantially contiguous areas of physical memory. Each of the contiguous regions of the physical memory may be commonly regarded as a page frame. By performing refinement as described herein, one or more features of the raw output (e.g., x and / or y projections) that define the geometric structure for the page breaks of the array regions may be applied to page breaks Can be identified and used to allocate each corresponding output and assign each output corresponding to the array regions to a different segment.

In yet another embodiment, one or more features of the raw output corresponding to one or more geometric features of a portion of the patterned features can not be suppressed by Fourier filtering. For example, unlike some methods for fragmentation, even if the distance between page breaks is greater than the Fourier filtering that can be performed, page breaks can be suppressed in the array region. In this example, for some inspection systems, if the width of the page break is about 5 microns and the spacing between the page breaks is about 5 microns, then the Fourier filtering would be impractical if possible, while the ROI setup would be non- . Thus, the signal (noise) produced in the raw output by the page break may not be suppressed, thereby reducing the defect detection sensitivity that can be achieved using the raw output. However, using the embodiments disclosed herein, each output corresponding to page breaks can be identified (e.g., based on projections in the raw output), and each output corresponding to page breaks can be identified as one While each of the other outputs may be assigned to other segments such that different sensitivities may be used to detect defects in different segments, as further disclosed herein.

The computer implemented method further includes individually assigning one or more fault detection parameters to different segments. One or more defect detection parameters may be individually assigned to all of the different segments. Thus, each of the outputs of some of them may not be ignored when detecting a defect. Instead, defects can be detected using each output assigned to all of the different segments. In other words, defects can be detected using all segments of the raw output. In this way, different segments can be handled differently with different inspection recipes. Different inspection recipes may be different in defect detection algorithms assigned to different segments. Alternatively, different inspection recipes may differ in one or more parameters of the same defect detection algorithm assigned to different segments. The defect detection algorithms assigned to different segments or one or more parameters assigned to different segments may comprise any suitable defect detection algorithms. For example, the fault detection algorithm may be a granular auto-thresholding (SAT) algorithm or an MDAT algorithm. These fault detection algorithms may be particularly suitable for BF inspection. However, the defect detection algorithm may be a defect detection algorithm suitable for the DF inspection. For example, the fault detection algorithm may be FAST algorithm or HLAT algorithm.

In addition, different inspection recipes may differ in one or more of the optical parameters of the inspection system used to obtain the raw output for the wafer. For example, in a multi-pass inspection, different passes may be performed with different values for at least one optical parameter of the inspection system (such as polarization, wavelength, illumination angle, collection angle, etc.) , The raw output generated in the different passes can be used to detect defects in different areas of the wafer where patterned features with one or more different geometric features are formed. In this manner, regions of the wafer including patterned features having one or more different geometric features can be inspected using raw output generated in different passes of a multi-pass inspection performed using one or more different optical parameters have.

In one embodiment, the one or more fault detection parameters include a threshold to be applied to the difference between each output and reference. In this way, different thresholds may be applied to the difference between each output and the reference depending on the segment to which each output was assigned. For example, a reference (e.g., an 8-bit reference image) may be subtracted from each output of a raw output (such as an 8-bit test image), regardless of the segment to which each output was assigned. The criteria may include any appropriate criteria, such as a die on a wafer different from the die on which the output was generated, a respective output corresponding to a cell on the wafer different from the cell where each output was subtracted from the reference, have. Each output having a difference equal to or greater than the assigned threshold can be identified as a defect. In this way, defects can be detected with different thresholds with respect to the segment to which each output was assigned.

In another embodiment, individually assigning one or more defect detection parameters to different segments is performed so that defects can be detected using each output assigned to different segments with different sensitivities. Thus, the embodiments disclosed herein can achieve better defect detection by utilizing information that the corresponding defects (DOI) and the obstacle / noise reside in geometrically different segments. For example, different geometries may represent different types of defects. In this example, in the array pattern region, the raw output may comprise line-shaped patterns with alternating outputs of relatively bright and relatively dark respectively. In some of these instances, the DOI may be located in portions of the raw output that include relatively bright respective outputs, whereas nuisance defects may be located in portions of the raw output that include relatively dark respective outputs . In this way, with the segmentation using the feature (s) that define the geometry (such as the x or y projection for page breaks in the array region), the sensitivity of the detection algorithm is less than that in the array area Can be set differently for better sensitivity. Thus, the embodiments disclosed herein advantageously allow an automated manner of separating the different geometric patterns of the wafer into different segments. This refinement allows these zones to be treated differently and better sensitivity can be achieved. In addition, different geometries scatter light differently. In this way, some geometric structures may cause the raw output to be relatively noisy while other geometric structures may cause the raw output to be relatively quiet. However, using only the sensitivity of each output for subdivision, each output relative to relatively noise and relatively quiet regions in the raw output can be grouped together (e.g., due to poorly bounded boundaries) have. In contrast, in the embodiments disclosed herein, higher sensitivities can be achieved for defects located in regions of the wafer with one or more geometric features corresponding to less noise at the green output . Also, for narrow band inspection systems, defects are often buried because the patterns scatter a significant amount of light. However, the embodiments disclosed herein enable detection of such defects detuned by noise from adjacent patterns.

The computer implemented method further comprises applying one or more defect detection parameters assigned to detect defects on the wafer to respective outputs assigned to different segments. As described above, different segments can be processed differently with different inspection recipes. In this manner, applying one or more defect detection parameters assigned to each output may include inspecting the segments with different recipes to detect defects on the wafer. For example, a segment to which each output has been assigned may be used to determine a threshold to be applied to the difference between each output and reference. After determining which segment each output was assigned to and assigning one or more defect detection parameters to different segments, the assigned one or more defect detection parameters may be applied to each output assigned to the different segments as they are normally performed.

In one embodiment, obtaining the raw output is performed in one pass of the multi-pass inspection of the wafer, and the computer implemented method is not performed on the raw output obtained in another pass of the multi-pass inspection. In this way, the segmentation as disclosed herein can be performed for only one pass of the multi-pass check. The raw output obtained in the other passes can be used for other purposes. For example, a multi-pass check may aid in the segmentation purpose with one pass having the best signal for the defects and another pass providing the geometry-based segmentation. In particular, different passes of the multi-pass inspection may be performed with one or more different defect detection parameters and / or one or more different optical parameters such that the raw output and / or defect detection results are different for different passes. In this example, one optical mode used in one pass of the multi-pass inspection may allow refinement, while the other optical mode of the inspection system used in the other pass of the multi-pass inspection has the highest sensitivity Can be provided.

In yet another embodiment, additional defects are detected using the raw output obtained in the other pass, and the method includes combining defects and additional defects to produce inspection results for the wafer. For example, as previously described, one pass of the multi-pass check may be used for refinement while another pass of the multi-pass check may be used to detect the DOI as an optimization signal. Thus, different passes of the multi-pass check can detect defects of different types. In this way, the results of the different passes of the multi-pass inspection can be combined to produce the overall inspection results for the wafer. The results of defects detected using raw outputs obtained on different passes can be combined after defect detection is performed using raw outputs generated on both of the different passes. Alternatively, defect detection results generated using raw outputs obtained in different passes may be combined during operation or while a portion of the raw output is acquired.

In a further embodiment, the method includes applying one or more predetermined defect detection parameters to the raw output to detect additional defects on the wafer, and combining defects and additional defects to generate inspection results for the wafer . For example, a reference (e.g., an 8-bit reference image) may be subtracted from each output of the raw output (such as an 8-bit test image), regardless of the segment to which each output was assigned. The criteria may include any suitable criteria as described above. The same criterion can also be used to detect defects by applying one or more defect detection parameters assigned to each output and by applying one or more predetermined defect detection parameters to the raw output. The subtraction result may be an absolute difference. A predetermined direct difference threshold can be applied to the absolute difference and any respective output having an absolute difference above the threshold can be identified as defective. Also, the same predetermined, direct difference threshold can be applied to the absolute difference regardless of the segment to which each output was assigned. Defects detected in this manner can be combined with defects detected by applying one or more defect detection parameters or the like assigned to each output to produce final inspection results for the wafer. For example, a defective mask may be generated separately for all defects detected in any manner. The area "grow" is performed from both difference images and a final mask for all defects can be generated.

Detecting defects in different ways as described above can provide for defect re-detection that may be desirable for a number of reasons. For example, automatic 2D projection and geometry-based refinement provide ease of use for robust defect re-detection and defect re-detection. In addition, the fragmentation described herein provides for dynamic method defects and mapping of reference images. For example, if there is noise in the segment, the difference can be detuned. Conversely, if the segment is cleaner, the car can be magnified. Also, dual detection as described above lowers the likelihood of error alarms from either detection method.

The method may also include storing the results of any step (s) of the method in a storage medium. The results may include any of the results disclosed herein and may be stored in any manner known in the art. For example, one or more defect detection parameters assigned to each segment of output and / or different segments of each output may be generated, such as a look up table, stored in a storage medium coupled to the inspection system Can be used. The storage medium may comprise any suitable storage medium known in the art. After the results are stored, the results can be accessed on a storage medium, used as described herein, formatted for display to the user, and used by other software modules, methods, or systems. In addition, the results may be stored "permanently "," semi-permanently ", "momentarily" For example, the storage medium may be random access memory (RAM), and the results may not necessarily persist indefinitely on the storage medium. Storing the results can be performed as disclosed in co-owned U.S. Patent Application Serial No. 12 / 234,201, filed September 19, 2008, by Bhaskar et al., Which is incorporated herein by reference in its entirety, 2009/0080759, which is incorporated herein by reference.

Returning to the drawings, it is noted that the figures are not drawn to scale. In particular, the scale of some of the members in the figures has been excessively enlarged to emphasize the features of the member. It is also noted that the figures are not drawn to scale. The components shown in more than one of the figures that may be similarly configured are denoted using the same reference numerals.

Still other embodiments are directed to a computer-readable medium comprising program instructions executable on a computer system for performing a method (i.e., a computer implemented method) for detecting defects on a wafer. One such embodiment is shown in Fig. 1, the computer-readable medium 10 includes program instructions 12 executable on a computer system 14 for performing a method for detecting defects on a wafer as previously described do. A computer implemented method by which program instructions may be executed may include any other step (s) of any other method (s) disclosed herein.

Program instructions 12 that implement methods such as those described herein may be stored in the computer-readable medium 10. The computer-readable medium can be, for example, a read-only memory, a RAM, a magnetic or optical disk, or a magnetic tape or any other suitable computer-readable medium.

Program instructions may be implemented in any of a variety of ways, including, inter alia, procedural-based techniques, component-based techniques, and / or object-oriented techniques. For example, the program instructions may be, depending on the request, Matlab, Visual Basic, ActiveX controls, C and C ++ objects, C #, JavaBeans, Microsoft Foundation Classes (MFC) Techniques or methods described herein.

The computer system 14 may take various forms, including a personal computer system, a mainframe computer system, a workstation, a system computer, an image computer, a programmable image computer, a parallel processor, or any other device known in the art . In general, the term "computer system" can be broadly defined to include any device having one or more processors executing instructions from a memory medium.

A further embodiment relates to a system configured to detect defects on a wafer. One embodiment of such a system is shown in FIG. As shown in FIG. 2, the system 16 includes an inspection subsystem 18 and a computer subsystem 20. The inspection system is configured to generate a raw output for the wafer by scanning the wafer. For example, as shown in FIG. 2, the inspection subsystem includes a light source 22, such as a laser. Light source 22 is configured to direct light to polarizing component 24. In addition, the inspection subsystem may include more than one polarization component (not shown), each of which may be positioned independently in the path of light from the light source. Each of the polarization components can be configured to change the polarization of light from the light source in different ways. The inspection subsystem may be configured to move the polarization components either into or out of the path of light from the light source in any suitable manner depending on which polarization setting is selected for illumination of the wafer during the scan. The polarization set point used for illumination of the wafer during a scan may include p-polarized light (P), s-polarized light (S), or circular polarized light (C).

The light exiting the polarization component 24 is directed to the wafer 26 at an oblique incidence angle that may include any suitable oblique incidence angle. The inspection subsystem may also include one or more optical components (not shown) configured to direct light from the light source 22 to the polarization component 24 or from the polarization component 24 to the wafer 26. The optical components may include any suitable optical components known in the art, such as, but not limited to, reflective optical components. Further, the light source, polarization component, and / or one or more optical components may be configured to direct light to the wafer at one or more incident angles (e.g., a beveled incident angle and / or a normal angle to the incident portion) have. The inspection subsystem may be configured to perform scanning by scanning light onto the wafer in any suitable manner.

Light scattered from the wafer 26 may be collected and detected by multiple channels of the die inspection subsystem during scanning. For example, light that is scattered from the wafer 26 at relatively close angles to the normal may be collected by the lens 28. The lens 28 may comprise a refractive optical element as shown in Fig. The lens 28 may also include one or more refractive optical elements and / or one or more reflective optical elements. The light collected by the lens 28 may be directed to a polarization component 30 that may include any suitable polarization component known in the art. In addition, the inspection subsystem may include more than one polarization component (not shown), each of which may be positioned independently of the path of light collected by the lens. Each of the polarization components can be configured to alter the polarization of light collected by the lens in a different manner. The inspection subsystem moves the polarization components out of the path of the light and into the path of light collected by the lens in any suitable manner depending on which polarization setting is selected for detection of light collected by the lens 28 during scanning . The polarization setpoints used for detection of light collected by the lens 28 during scanning may include any of the polarization settings disclosed herein (such as P, S, and unpolarized (N)).

Light exiting the polarization component 30 is directed to the detector 32. Detector 32 may comprise any suitable detector known in the art, such as a charge coupled device (CCD) or other type of imaging detector. The detector 32 is configured to respond to the scattered light collected by the lens 28 and to produce an unprocessed output transmitted by the polarization component 30 when located in the path of the collected scattered light. Thus, the polarizing component 30 and the detector 32 when placed in the path of the light collected by the lens 28, lens 28, and detector 32 form one channel of the inspection subsystem. Such channels of the inspection subsystem may include any other suitable optical components (not shown) known in the art, such as Fourier filtering components.

The light scattered from the wafer 26 at different angles can be collected by the lens 34. [ The lens 34 may be configured as described above. The light collected by the lens 34 may be directed to a polarization component 36 that may comprise any suitable polarization component known in the art. In addition, the inspection subsystem may include more than one polarization component (not shown), each of which may be positioned independently of the path of light collected by the lens. Each of the polarization components can be configured to alter the polarization of the die light collected by the lens in a different manner. The inspection subsystem moves the polarization components out of the path of the light collected by the lens in any suitable manner and along the path of the light, depending on which polarization setting is selected for detection of the light collected by the lens 34 during scanning . The polarization set point used for detection of the light collected by the lens 34 during scanning may include P, S, or N. [

The light exiting the polarization component 36 is directed to a detector 38 that can be configured as described above. The detector 38 is also configured to generate a raw output responsive to the collected scattered light passing through the polarizing component 36 when positioned in the path of the scattered light. Thus, when present in the path of the light collected by lens 34, lens 34, polarizing component 36, and detector 38 can form different channels of the inspection subsystem. This channel may include any other optical component (not shown) previously disclosed. In some embodiments, lens 34 may be configured to collect light scattered from the wafer at polar angles of about 20 degrees to about 70 degrees. In addition, the lens 34 may be comprised of a reflective optical component (not shown) configured to collect light scattered from the wafer at an azimuth angle of about 360 degrees.

The inspection subsystem shown in FIG. 2 may include one or more other channels (not shown). For example, the inspection subsystem may include additional channels that may include any of the optical components disclosed herein, such as a detector, a lens, and one or more polarization components configured as side channels. The lens, the one or more polarization components, and the detector may be further configured as disclosed herein. In this example, the side channel may be configured to collect and detect light scattered from the incident plane (e.g., A lens that is substantially centered in a plane that is orthogonal to the plane of incidence, and a detector that is configured to detect light collected by the lens).

If the inspection of the wafer includes more than one pass, the values of any optical parameter (s) of the inspection subsystem may be changed in any suitable manner between the passes as needed. For example, to change the illumination polarization states between passes, the polarization component 24 may be removed and / or replaced as described herein using different polarization components. In another example, the position of the light source and / or any other optical component (e.g., polarizing component 24) used to direct light to the wafer, to change illumination angles between passes, Lt; / RTI > can be changed between paths.

The computer subsystem 20 is configured to obtain the raw output generated by the inspection subsystem. For example, the raw output generated by the detectors during scanning can be provided to the computer subsystem 20. In particular, the computer subsystem may be configured to receive the raw output generated by the detectors by a computer subsystem (e. G., Shown in phantom in FIG. 2, which may include any suitable transmission medium known in the art) (E.g., by one or more transmission media). The computer subsystem may be coupled to each of the detectors in any suitable manner. The raw output generated by the detectors during scanning of the wafers may include any raw output disclosed herein.

The computer subsystem is configured to identify one or more features of the raw output corresponding to one or more geometric features of the patterned features formed on the wafer in accordance with any of the embodiments disclosed herein. One or more features of the raw output may include any of these features disclosed herein. One or more geometric features may include any of these features disclosed herein. Patterned features may include any of the patterned features disclosed herein.

The computer subsystem may also be configured to assign each output of the raw output to different segments based on the identified one or more features of the raw output such that the one or more geometric features of the patterned features corresponding to each of the different segments are different . The computer subsystem may be configured to assign each of the outputs to different segments according to any of the embodiments disclosed herein. Each output may comprise any of the outputs described herein. The different segments may be configured as disclosed herein. One or more of the identified features of the raw output may include any of these features disclosed herein.

The computer subsystem is further configured to individually allocate one or more fault detection parameters to different segments according to any of the embodiments disclosed herein. The one or more defect detection parameters may include any of the defect detection parameters disclosed herein. The computer subsystem is also configured to apply one or more defect detection parameters assigned to each output assigned to different segments to detect defects on the wafer, which may be performed in accordance with any of the embodiments disclosed herein . The assigned one or more defect detection parameters may include any of these parameters disclosed herein.

The computer subsystem may be configured to perform any other step (s) of any method embodiment (s) disclosed herein. The computer subsystem, the inspection subsystem, and the system may be further configured as disclosed herein.

It is noted that Figure 2 is provided herein to generally illustrate one configuration of the inspection subsystem that may be included in the system embodiments disclosed herein. Obviously, the inspection subsystem configuration disclosed herein can be modified to optimize the performance of the inspection subsystem as is typically done when designing a commercial inspection system. In addition, the systems described herein may be used with any of the Puma 90xx, 91 xx, and 93xx series tools commercially available from KL-Ten Core of Milpitas, Calif., By adding the functionality described herein to existing inspection systems , ≪ / RTI > For some such systems, the methods disclosed herein may be provided as optional functions of the system (in addition to other functions of the system, for example). Alternatively, the system described herein may be designed "from scratch" to provide a completely new system.

Additional modifications and alternative embodiments to various aspects of the present invention will be apparent to those skilled in the art with reference to this disclosure. For example, methods and systems are provided for detecting defects on a wafer.

Accordingly, the description is to be construed as exemplary only and is intended to provide further explanation as would occur to those skilled in the art in practicing the invention in the generic sense. It will be appreciated that aspects of the invention shown and described herein are contemplated as presently preferred embodiments. It will be appreciated that elements and materials may be substituted for those illustrated and described herein, and parts and processes may be reversed, and certain features of the present invention may be utilized independently, And will be apparent to those skilled in the art. Changes may be made in the elements disclosed herein without departing from the scope and spirit of the invention as set forth in the following claims.

Claims (19)

A computer-implemented method for detecting defects on a wafer,
Obtaining a raw output for a wafer produced by the inspection system;
Identifying one or more features of the raw output corresponding to one or more geometrical characteristics of the patterned features formed on the wafer;
Assigning each output of the raw output to different segments based on the identified one or more features of the raw output such that the one or more geometric features of the patterned features corresponding to each of the different segments are different, Wherein the one or more geometric features corresponding to one of the different segments comprise one or more geometric features of page breaks and wherein the one or more geometric features corresponding to another of the different segments The one or more geometric features of the one or more of the plurality of geometric features;
Individually assigning one or more fault detection parameters to the different segments; And
Applying the assigned one or more defect detection parameters to each output assigned to the different segments to detect defects on the wafer.
A computer implemented method for detecting defects on a wafer. The method according to claim 1,
Wherein the raw output is responsive to light scattered from the wafer.
A computer implemented method for detecting defects on a wafer. The method according to claim 1,
Wherein the identified one or more features of the raw output comprise projections along lines in the raw output.
A computer implemented method for detecting defects on a wafer. The method according to claim 1,
Wherein the one or more geometric features of the patterned features include mathematical calculations, edges, shapes, textures, or some combination thereof that define the geometry of the patterned features.
A computer implemented method for detecting defects on a wafer. The method according to claim 1,
Wherein the identifying step is performed based on how the design layout of the patterned features will affect one or more features of the raw output.
A computer implemented method for detecting defects on a wafer. The method according to claim 1,
Wherein the identifying step is performed while the obtaining step is performed.
A computer implemented method for detecting defects on a wafer. The method according to claim 1,
Wherein the identifying and assigning each output is performed automatically without user input.
A computer implemented method for detecting defects on a wafer. The method according to claim 1,
Wherein assigning each output is performed independently of designing data associated with the patterned features.
A computer implemented method for detecting defects on a wafer. The method according to claim 1,
Wherein the step of assigning each output is performed independently of the intensity of each output.
A computer implemented method for detecting defects on a wafer. The method according to claim 1,
Wherein assigning each of the outputs comprises analyzing one or more identified characteristics of the raw output and applying thresholds to each of the outputs.
A computer implemented method for detecting defects on a wafer. delete A computer-implemented method for detecting defects on a wafer,
Obtaining a raw output for a wafer produced by the inspection system;
Identifying one or more features of the raw output corresponding to one or more geometrical characteristics of the patterned features formed on the wafer;
Assigning each output of the raw output to different segments based on the identified one or more features of the raw output such that the one or more geometric features of the patterned features corresponding to each of the different segments are different;
Individually assigning one or more fault detection parameters to the different segments; And
Applying the assigned one or more defect detection parameters to each of the outputs assigned to the different segments to detect faults on the wafer,
Wherein the one or more features of the raw output corresponding to the one or more geometric features of some of the patterned features can not be suppressed by Fourier filtering.
A computer implemented method for detecting defects on a wafer. The method according to claim 1,
Wherein the one or more fault detection parameters include a threshold to be applied to a difference between each output and a reference.
A computer implemented method for detecting defects on a wafer. A computer-implemented method for detecting defects on a wafer,
Obtaining a raw output for a wafer produced by the inspection system;
Identifying one or more features of the raw output corresponding to one or more geometrical characteristics of the patterned features formed on the wafer;
Assigning each output of the raw output to different segments based on the identified one or more features of the raw output such that the one or more geometric features of the patterned features corresponding to each of the different segments are different;
Individually assigning one or more fault detection parameters to the different segments; And
Applying the assigned one or more defect detection parameters to each of the outputs assigned to the different segments to detect faults on the wafer,
Wherein separately allocating the one or more fault detection parameters is performed such that faults are detected using the respective outputs assigned to the different segments having different sensitivities.
A computer implemented method for detecting defects on a wafer. A computer-implemented method for detecting defects on a wafer,
Obtaining a raw output for a wafer produced by the inspection system;
Identifying one or more features of the raw output corresponding to one or more geometrical characteristics of the patterned features formed on the wafer;
Assigning each output of the raw output to different segments based on the identified one or more features of the raw output such that the one or more geometric features of the patterned features corresponding to each of the different segments are different;
Individually assigning one or more fault detection parameters to the different segments; And
Applying the assigned one or more defect detection parameters to each of the outputs assigned to the different segments to detect faults on the wafer,
Wherein the obtaining is performed in one pass of the multi-pass inspection of the wafer, and the computer implemented method is performed on the raw output obtained in the other pass of the multi-pass inspection That is,
A computer implemented method for detecting defects on a wafer. A computer-implemented method for detecting defects on a wafer,
Obtaining a raw output for a wafer produced by the inspection system;
Identifying one or more features of the raw output corresponding to one or more geometrical characteristics of the patterned features formed on the wafer;
Assigning each output of the raw output to different segments based on the identified one or more features of the raw output such that the one or more geometric features of the patterned features corresponding to each of the different segments are different;
Individually assigning one or more fault detection parameters to the different segments; And
Applying the assigned one or more defect detection parameters to each of the outputs assigned to the different segments to detect faults on the wafer,
Wherein the obtaining is performed in one pass of the multi-pass inspection of the wafer, the computer implemented method is not performed on the raw output obtained in the other pass of the multi-pass inspection, The method further comprising combining the defects and the additional defects to produce inspection results for the wafer, the method further comprising:
A computer implemented method for detecting defects on a wafer. A computer-implemented method for detecting defects on a wafer,
Obtaining a raw output for a wafer produced by the inspection system;
Identifying one or more features of the raw output corresponding to one or more geometrical characteristics of the patterned features formed on the wafer;
Assigning each output of the raw output to different segments based on the identified one or more features of the raw output such that the one or more geometric features of the patterned features corresponding to each of the different segments are different;
Individually assigning one or more fault detection parameters to the different segments;
Applying the assigned one or more defect detection parameters to each output assigned to the different segments to detect defects on the wafer; And
Applying one or more predetermined defect detection parameters to the raw output to detect further defects on the wafer; and combining the defects and the additional defects to produce inspection results for the wafer Including,
A computer implemented method for detecting defects on a wafer. 22. A computer-readable medium comprising program instructions executable on a computer system to perform a method for detecting defects on a wafer, the method comprising:
Obtaining an unprocessed output for a wafer produced by the inspection system;
Identifying one or more features of the raw output corresponding to one or more geometric features of the patterned features formed on the wafer;
Assigning each output of the raw output to different segments based on the identified one or more features of the raw output such that the one or more geometric features of the patterned features corresponding to each of the different segments are different The one or more geometric features corresponding to one of the different segments comprise one or more geometric features of page breaks and wherein the one or more geometric features corresponding to different ones of the different segments One or more geometric features of the zones;
Individually assigning one or more fault detection parameters to the different segments; And
Applying the assigned one or more defect detection parameters to each output assigned to the different segments to detect defects on the wafer.
Computer-readable medium. A system configured to detect defects on a wafer,
An inspection subsystem configured to generate a raw output for the wafer by scanning the wafer; And
Computer subsystem
Wherein the computer subsystem comprises:
Obtain the raw output;
Identify one or more features of the raw output corresponding to one or more geometric features of the patterned features formed on the wafer;
Assigning each output of the raw output to different segments based on the identified one or more features of the raw output such that the one or more geometric features of the patterned features corresponding to each of the different segments are different; Wherein the one or more geometric features corresponding to one of the different segments comprise one or more geometric features of page breaks and wherein the one or more geometric features corresponding to different ones of the different segments Comprising one or more geometric features;
Individually assigning one or more fault detection parameters to the different segments; And
And to apply the assigned one or more fault detection parameters to each output assigned to the different segments to detect faults on the wafer.

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