Wafer alignment improvement by design alignment through image projection based repair

Abstract

Image alignment or image pair design alignment can be improved using normalized cross correlation. An alignment sets up an image and a run-time image and determines a normalized cross correlation score. Image projections of the images can be determined and aligned in perpendicular x and y directions. The alignment of the image projections can include finding a projection peak position and adjusting the projection peak position in the x and y directions.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to imaging semiconductor wafers. BACKGROUND

[0002] The development of the semiconductor manufacturing industry places ever- increasing demands on yield management and, in particular, on metrology and inspection systems. Critical dimensions continue to shrink, but industry demands continue to shorten the time for achieving high-yield, high-value production. Minimizing the total time from detecting a yield problem to solving it maximizes the return on investment for semiconductor manufacturers.

[0003] Manufacturing semiconductor devices, such as logic and memory devices, typically includes processing semiconductor wafers using a large number of manufacturing processes to form various features and multiple levels of the semiconductor devices. For example, lithography is a semiconductor manufacturing process that involves transferring a pattern from a photomask to a photoresist disposed on a semiconductor wafer. Other examples of semiconductor manufacturing processes include, but are not limited to, chemical-mechanical polishing (CMP), etch, deposition, and ion implantation. The layout of multiple semiconductor devices manufactured on a single semiconductor wafer can be separated into individual semiconductor devices.

[0004] Inspection processes are used at various steps during semiconductor manufacturing to detect defects on wafers to promote higher yield in the manufacturing process, and thus higher profits. Inspection has always been an important part of fabricating semiconductor devices such as integrated circuits (ICs). However, as the dimensions of semiconductor devices decrease, inspection becomes even more important to successfully fabricate acceptable semiconductor devices because smaller defects can cause devices to fail. For example, as the dimensions of semiconductor devices decrease, it becomes necessary to detect defects that are smaller in size because even relatively smaller defects can cause undesirable variations in the semiconductor devices.

[0005] A patch design alignment (PDA) can be used during inspection. The entire wafer can be scanned during setup to find 2D unique targets that are uniformly distributed across the dies. A design is acquired for each of these targets. Image rendering parameters can be learned from example targets and an image can be rendered from the design at each target. This rendered image can be aligned with the optical image at each target. A design and image offset can be determined from the targets of each inspection frame. The targets and offsets are saved to a database.

[0006] During runtime, the setup image is aligned with the runtime image at each target because aligning a real optical image with another optical image is more accurate. An offset between the setup image and the runtime image is determined for each inspection frame. An offset between the design and the runtime image is determined for each inspection frame. The placement of interest regions can then be corrected according to the offsets.

[0007] The alignment or other aspects of PDA can be negatively impacted by process variations, which can degrade PDA performance. Improved techniques and systems are needed. SUMMARY

[0008] A method is provided in a first embodiment. The method includes aligning, using a processor, a setup image with a runtime image at a target, thereby producing an aligned image. A normalized cross-correlation score of the aligned image is determined using the processor. The normalized cross-correlation score of the aligned image can be below a threshold. Image projections in perpendicular x and y directions for a polygon in the aligned image are determined using the processor. The image projections of the setup image and the runtime image are aligned using the processor.

[0009] The method can further include, after aligning the image projections, determining an offset between the setup image and the runtime image of an inspection frame. An offset between a design of the inspection frame and the runtime image can also be determined. An area of interest can be placed based on an offset correction.

[0010] Aligning the image projections can include determining a projection peak position along the x direction for the polygon in the aligned image, adjusting the runtime image and / or the setup image such that the projection peak positions overlap along the x direction, determining a projection peak position along the y direction for the polygon in the aligned image, and adjusting the runtime image and / or the setup image such that the projection peak positions overlap along the y direction.

[0011] A system is provided in a second embodiment. The system includes a stage configured to hold a semiconductor wafer, an energy source configured to direct a beam at the semiconductor wafer on the stage, a detector configured to receive the beam reflected from the semiconductor wafer on the stage, and a processor in electronic communication with the detector. The energy source can be a light source. The beam can be a light beam. The processor is configured to align a setup image with a runtime image at a target, thereby producing an aligned image, determine a normalized cross-correlation score of the aligned image, determine image projections in perpendicular x and y directions for a polygon in the aligned image, and align the image projections of the setup image and the runtime image. The normalized cross-correlation score of the aligned image can be below a threshold.

[0012] The processor can be further configured to determine an offset between the setup image and the runtime image of an inspection frame after aligning the image projections. The processor can be further configured to determine an offset between a design of the inspection frame and the runtime image. The processor can be further configured to place an area of interest based on an offset correction.

[0013] Aligning the image projections can include determining a projection peak position for the polygon in the aligned image along the x-direction, adjusting the runtime image and / or the setup image so the projection peak positions overlap along the x-direction, determining a projection peak position for the polygon in the aligned image along the y-direction, and adjusting the runtime image and / or the setup image so the projection peak positions overlap along the y-direction.

[0014] A non-transitory computer-readable storage medium is provided in a third embodiment. The non-transitory computer-readable storage medium comprises one or more programs for executing the following steps on one or more computing devices. The steps include aligning a setup image with a runtime image at a target, thereby producing an aligned image, determining a normalized cross-correlation score of the aligned image, determining image projections of a polygon in the aligned image in perpendicular x and y directions, and aligning the image projections of the setup image and the runtime image. The normalized cross-correlation score of the aligned image can be below a threshold value.

[0015] The steps can further include determining an offset between the setup image and the runtime image of a test frame after aligning the image projections. The steps can further include determining an offset between a design of the test frame and the runtime image. The steps can further include placing a region of interest using the processor based on an offset correction.

[0016] The steps can further include determining a projection peak position for the polygon in the aligned image along the x-direction, adjusting the runtime image and / or the setup image so the projection peak positions overlap along the x-direction, determining a projection peak position for the polygon in the aligned image along the y-direction, and adjusting the runtime image and / or the setup image so the projection peak positions overlap along the y-direction. BRIEF DESCRIPTION OF DRAWINGS

[0017] For a more complete understanding of the nature and objects of this disclosure, reference should be made to the following detailed description taken in connection with the accompanying drawings in which:

[0018] Figure 1 is a flowchart of a method according to the present disclosure;

[0019] Figure 2 is a flowchart of an embodiment of a method according to the present disclosure Figure 1 is a flowchart of an embodiment of a method according to the present disclosure

[0020] Figure 3 is an example of adjusting polygon positions; and

[0021] Figure 4is an embodiment of a system according to the disclosure. DETAILED DESCRIPTION

[0022] Although the claimed subject matter will be described in terms of certain embodiments, other embodiments, including embodiments that do not provide all of the benefits and features set forth herein, are within the scope of the disclosure. Various structural, logical, process steps, and electronic changes can be made without departing from the scope of the disclosure. Accordingly, the scope of the disclosure is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0023] Embodiments disclosed herein improve the stability of PDA by adding a projection-based alignment step during run-time. With the techniques disclosed herein, fewer PDA alignment targets can cause alignment to fail. This can also avoid making false processing decisions due to poor alignment. Embodiments disclosed herein are particularly useful for low-contrast images or images that are difficult to align, for example, with memory devices.

[0024] Figure 1 is a flowchart of a method 100. Some or all of the steps of method 100 can be performed by a processor.

[0025] At 101, a setup image is aligned to a run-time image at a target. Subsequent steps, such as defect attribute determination, can use the aligned image. Alignment also affects defect location accuracy. The target in step 101 can be a target image printed on a wafer or other structure. The image can be from 128x128 pixels to 1024x1024 pixels, but other sizes are possible. The aligned image can be overlaid in examples.

[0026] In an example, the setup image is a golden image from a golden wafer or another reference image. The run-time image is an image generated during inspection. This produces an aligned image. An example of a setup image aligned to a run-time image is shown in the left-hand example of Figure 3 . Figure 3 The polygons of the two images are shown in black and gray, respectively. Note that Figure 3 the polygons in the left-hand example of are not properly aligned.

[0027] Returning to Figure 1 , at 102, a normalized cross-correlation (NCC) score is determined for the aligned image. Cross-correlation is a measure of similarity of two types of data, as a function of the displacement of one relative to the other. NCC is a technique that can be used to compare two images. A low NCC score indicates poor alignment between the two images.

[0028] For continuous functions f and g, cross-correlation can be defined as follows.

[0029]

[0030] denotes the complex conjugate of f(t). τ is a shift (or lag) that shows that a feature in f at t appears in g at t + τ.

[0031] If the NCC score of the aligned images is above a threshold, steps 103 and 104 are not performed. The threshold can be determined from experimental data, such that the threshold can provide a required NCC score for a type of image. If the NCC score of the aligned images is below the threshold, the image projections are determined at 103. The image projections can be in the perpendicular x and y directions for the polygons on the aligned images.

[0032] The images used in the NCC score are independent of each other (i.e., not merged). Cross-correlation is used to measure similarity. If the images are not similar enough for subsequent processing, projection techniques can be used.

[0033] An image projection is a sum of gray scale values along a column or row of an image. This can be using the following formula.

[0034]

[0035] a ij is the i,jth element of the image matrix. The projection adds all pixels along a particular row or column and divides it by the number of pixels in this row or column, respectively. The projection value p j is plotted over the number of pixels. This provides a projection plot of all rows j. A similar procedure can be performed for all columns i.

[0036] For example, the image projection sum is shown in Figure 3 in the plot below the example images in Figure 3 In

[0037] The potential image rotation angle between two images is typically low (e.g., below 1 degree). Such a rotation can manifest itself as a vertical shift. The actual rotation of an image can not be relevant as it is typically less than 1 degree.

[0038] Turning back to Figure 1 , the image projections of the setup image and the runtime image are aligned at 104. This can include determining the projection peak positions of the polygons in the images along the x direction and along the y direction. The images can be adjusted such that the projection peak positions overlap along the x direction and / or the y direction. This offset correction is shown at the bottom of Figure 3 , which aligns the two projection maxima and minima. In Figure 3The maximum and minimum of the projected peaks at the bottom of the image correspond to the misaligned polygon and the aligned polygon above it. Figure 3 The solid line in the center is the projection of the black shaded structure. The dashed line is the center of the projection of the gray shaded structure.

[0039] Typically, a moving row can be equivalent to moving a pixel. A row can be equal to a pixel or the row can be configured to correspond to a group of pixels. This is illustrated in Figure 3 Figure 3 Only the x projection is illustrated in but the same technique can be performed in the vertical y projection. The offset correction can be used in the x direction or the y direction to shift the polygon by adjusting the image so that the maximum and / or minimum in the image projection overlap. If the overlap is not possible, the polygon can be shifted to align as close as possible to the maximum and / or minimum in the image projection.

[0040] After step 104, the offset between the setup image and the runtime image of the test frame can be determined. The size of the test frame and the runtime image can be the same (e.g., 128x128 pixels or larger). The offset between the design of the test frame and the runtime image can also be determined. The region of interest can be placed on the runtime image based on the offset correction. The placement of the region of interest can be adjusted based on the compensation during the offset correction. The offset correction can be based on the offset between the setup image and the runtime image and / or the offset between the design and the runtime image.

[0041] An embodiment of this PDA process is shown in Figure 2 The setup process can remain the same. The NCC score is calculated after the initial PDA alignment is performed. The setup and runtime images can be aligned at each target. If the NCC score is too low, the image projections in the x and y directions are calculated for the design polygon of the optical image or the setup optical image and the runtime optical image. The projected peak locations of the two image projections are used to align the optical repair image (e.g., the runtime image) to the design or to align the setup optical image to the runtime optical image.

[0042] A zero region of interest boundary can be used for the placed region of interest in the x and y directions. The region of interest boundary can be a way to expand the current region of interest to compensate for alignment errors. The zero region of interest boundary indicates a high confidence that the alignment error is much smaller than a pixel size, which can be a result of the offset correction. If the region of interest alignment is not too far off, the region of interest boundary can be set to zero.

[0043] The offset between the setup and runtime images and / or the design and runtime images can be determined at each test frame.

[0044] The method 100 can be used to align an image to a design or to align two images. The images can be a golden image, a rendered image, or other runtime or setup images.

[0045] ​One embodiment of system 200 is shown in Figure 4 System 200 includes an optical-based subsystem 201. In general, optical-based subsystem 201 is configured for generating an optical-based output for a sample 202 by directing light to (or scanning light over) sample 202 and detecting light from sample 202. In one embodiment, sample 202 includes a wafer. The wafer can include any wafer known in the art. In another embodiment, sample 202 includes a reticle. The reticle can include any reticle known in the art.

[0046] In the embodiment of system 200 shown in Figure 4 In the embodiment of system 200 shown in Figure 4 In the embodiment of system 200 shown in Figure 4 In the embodiment of system 200 shown in

[0047] Optical-based subsystem 201 can be configured to direct light to sample 202 at different angles of incidence at different times. For example, optical-based subsystem 201 can be configured to change one or more properties of one or more elements of the illumination subsystem such that light can be directed to sample 202 at different angles of incidence than shown in Figure 4 In one such example, optical-based subsystem 201 can be configured to move light source 203, optical element 204, and lens 205 such that light is directed to sample 202 at different oblique angles of incidence or normal (or near-normal) angles of incidence.

[0048] In some instances, optical-based subsystem 201 can be configured to direct light to sample 202 at more than one angle of incidence at the same time. For example, the illumination subsystem can include more than one illumination channel, one of which can include a light source and a lens as shown in Figure 4The light source 203, optical element 204, and lens 205 shown herein, and another element in the illumination channel (not shown), may contain similar elements, which may be configured differently or identically, or may contain at least one light source and possibly one or more other components, such as those further described herein. If this 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 incident angles may be different, such that the light generated by illuminating the sample 202 at different incident angles can be distinguished from each other at the detector.

[0049] In another example, the lighting subsystem may contain only one light source (e.g., Figure 4 The light source 203 shown in the diagram can be split into different optical paths (e.g., based on wavelength, polarization, etc.) by one or more optical elements (not shown) of the illumination subsystem. Light from each of these different optical paths can then be directed to sample 202. Multiple illumination channels can be configured to direct light to 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 can be configured to direct light to sample 202 with different characteristics at different times. For example, in some examples, optical element 204 can be configured as a spectral filter, and the properties of the spectral filter can be changed in various different ways (e.g., by changing the spectral filter) so that light of different wavelengths can be directed to sample 202 at different times. The illumination subsystem can have any other suitable configuration known in the art for sequentially or simultaneously directing light with different or the same characteristics to sample 202 at different or the same incident angles.

[0050] In one embodiment, light source 203 may comprise a broadband plasma (BBP) source. In this way, the light generated by light source 203 and guided to sample 202 may comprise broadband light. However, the light source may comprise any other suitable light source, such as a laser. The laser may comprise any suitable laser known in the art and may be configured to produce light of any suitable wavelength known in the art. Additionally, the laser may be configured to produce monochromatic or near-monochromatic light. In this way, the laser may be a narrowband laser. Light source 203 may also comprise a multicolor light source that produces light of multiple discrete wavelengths or bands.

[0051] Light from optical element 204 can be focused onto sample 202 by lens 205. Although lens 205... Figure 4 While shown as a single refractive optical element, it should be understood that, in practice, lens 205 may comprise several refractive and / or reflective optical elements that combine to focus light from the optical element onto the sample. Figure 4The illumination subsystem shown in and described herein can include any other suitable optical elements (not shown). Examples of such optical elements include, but are not limited to, polarization components, spectral filters, spatial filters, reflective optical elements, apodizers, beam splitters (such as beam splitter 213), apertures, and the like, which can include any such suitable optical elements known in the art. Additionally, the optical-based subsystem 201 can be configured to change one or more of the elements of the illumination subsystem based on the type of illumination to be used to generate the optical-based output.

[0052] The optical-based subsystem 201 can also include a scanning subsystem configured to scan light across the sample 202. For example, the optical-based subsystem 201 can include a stage 206 on which the sample 202 is disposed during generation of the optical-based output. The scanning subsystem can include any suitable mechanical and / or robotic assembly (including the stage 206) that can be configured to move the sample 202 so that light can be scanned across the sample 202. Additionally or alternatively, the optical-based subsystem 201 can be configured so that one or more optical elements of the optical-based subsystem 201 perform some scanning of light across the sample 202. The light can be scanned across the sample 202 in any suitable manner, such as in a serpentine path or in a spiral path.

[0053] 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 as a result of illumination of the sample 202 by the subsystem and generate an output in response to the detected light. For example, Figure 4 The optical-based subsystem 201 shown in includes two detection channels, one formed by the collector 207, element 208, and detector 209 and the other formed by the collector 210, element 211, and detector 212. As Figure 4 As shown in, the two detection channels are configured to collect and detect light at different collection angles. In some examples, the two 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 of the detection channels can be configured to detect another type of light (such as reflected light) from the sample 202.

[0054] As Figure 4As further shown in FIG. 2, the two detection channels are shown as being positioned in the plane of the paper and the illumination subsystem is also shown as being 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 can be positioned out of the plane of incidence. For example, the detection channel formed by the collector 210, the element 211, and the detector 212 can be configured to collect and detect light scattered out of the plane of incidence. Thus, this detection channel can generally be referred to as a "side" channel and this side channel can be centered in a plane that is substantially perpendicular to the plane of incidence.

[0055] Although Figure 4 Although an embodiment of the optical-based subsystem 201 including two detection channels is shown, the optical-based subsystem 201 can include a different number of detection channels (e.g., only one detection channel or two or more detection channels). In one such example, the detection channel formed by the collector 210, the element 211, and the detector 212 can form one side channel as described above, and the optical-based subsystem 201 can include an additional detection channel (not shown) formed as another side channel positioned on an opposite side of the plane of incidence. Thus, the optical-based subsystem 201 can include a detection channel including the collector 207, the element 208, and the detector 209 and centered in the plane of incidence and configured to collect and detect light at or near the scattering angle normal to the surface of the sample 202. Thus, this detection channel can generally be referred to as a "top" channel, and the optical-based subsystem 201 can also include two or more side channels configured as described above. As such, the optical-based subsystem 201 can include at least three channels (i.e., one top channel and two side channels), and each of the at least three channels has its own collector, each of which is configured to collect light at a different scattering angle than each of the other collectors.

[0056] As further described above, each of the detection channels included in the optical-based subsystem 201 can be configured to detect scattered light. Thus, Figure 4 The optical-based subsystem 201 shown in FIG. 2 can be configured for dark-field (DF) output generation of the sample 202. However, the optical-based subsystem 201 can also or instead include a detection channel configured for bright-field (BF) output generation of the sample 202. In other words, the optical-based subsystem 201 can include at least one detection channel configured to detect light specularly reflected from the sample 202. Thus, the optical-based subsystem 201 described herein can be configured for DF imaging only, BF imaging only, or both DF and BF imaging. Although each of the collectors is in the plane of incidence in the embodiment shown in FIG. 2, one or more of the collectors can be positioned out of the plane of incidence. For example, the collector 207 can be positioned out of the plane of incidence and configured to collect light at a scattering angle that is different than the scattering angle of the collector 210. Figure 4The collection optics are shown as single refractive optical elements, but it should be understood that each of the collection optics can include one or more refractive optical dies and / or one or more reflective optical elements.

[0057] The one or more detection channels can include any suitable detector known in the art. For example, the detectors can include photomultiplier tubes (PMTs), charge-coupled devices (CCDs), time delay integration (TDI) cameras, and any other suitable detector known in the art. The detectors can also include non-imaging detectors or imaging detectors. In this way, if the detectors are non-imaging detectors, each of the detectors can be configured to detect a particular characteristic of the scattered light (e.g., intensity), but can not be configured to detect such a characteristic as a function of position within an imaging plane. As such, the output generated by each of the detectors included in each of the detection channels of the optical-based subsystem can be a signal or data, but not an image signal or image data. In such examples, the processor (e.g., processor 214) can be configured to generate an image of the sample 202 from the non-imaging output of the detectors. However, in other examples, the detectors can be configured as imaging detectors configured to generate imaging signals or image data. Thus, the optical-based subsystem can be configured to generate the optical images or other optical-based outputs described herein in a variety of ways.

[0058] It should be noted that the systems described herein Figure 4 To generally illustrate the configuration of the optical-based subsystem 201, which can be included in or can generate optical-based outputs used by the system embodiments described herein. The optical-based subsystem 201 configuration described herein can be varied to optimize the performance of the optical-based subsystem 201, as is typically performed when designing a commercial output acquisition system. Additionally, the systems described herein can be implemented using existing systems (e.g., by adding the functionality described herein to an existing system). For some such systems, the methods described herein can be provided as optional functionality of the system (e.g., in addition to other functionality of the system). Alternatively, the systems described herein can be designed as a brand new system.

[0059] The processor 214 can be coupled to the components of the system 200 in any suitable manner (e.g., via one or more transmission media, which can include wired and / or wireless transmission media) so that the processor 214 can receive outputs. The processor 214 can be configured to perform a number of functions using the outputs. The system 200 can receive instructions or other information from the processor 214. The processor 214 and / or the electronic data storage unit 215 optionally can be in electronic communication with a wafer inspection tool, a wafer metrology tool, or a wafer review tool (not illustrated) to receive additional information or send instructions. For example, the processor 214 and / or the electronic data storage unit 215 can be in electronic communication with a scanning electron microscope.

[0060] The processor 214, other systems, or other subsystems described herein can be part of various systems, including a personal computer system, image computer, mainframe computer system, workstation, network appliance, Internet appliance, or other device. The subsystems or systems can also include any suitable processor known in the art, such as a parallel processor. In addition, the subsystems or systems can include a platform with high speed processing and software, either as a standalone or networked tool.

[0061] The processor 214 and the electronic data storage unit 215 can be disposed in or otherwise part of the system 200 or another device. In an example, the processor 214 and the electronic data storage unit 215 can be part of a standalone control unit or in a centralized quality control unit. Multiple processors 214 or electronic data storage units 215 can be used.

[0062] The processor 214 can be implemented in practice by any combination of hardware, software, and firmware. Moreover, its functions as described herein can be performed by one unit, or divided up among different components, each of which can again be implemented by any combination of hardware, software, and firmware. Program code or instructions for the processor 214 to implement various methods and functions can be stored in a readable storage medium, such as a memory or other memory in the electronic data storage unit 215.

[0063] If the system 200 includes more than one processor 214, the different subsystems can be coupled to one another so that images, data, information, instructions, etc. can be sent between the subsystems. For example, one subsystem can be coupled to an additional subsystem by any suitable transmission media, which can include any suitable wired and / or wireless transmission media known in the art. Two or more of such subsystems can also be effectively coupled by a shared computer readable storage medium (not shown).

[0064] The processor 214 can be configured to perform a number of functions using the output of the system 200 or other output. For example, the processor 214 can be configured to send the output to the electronic data storage unit 215 or another storage medium. The processor 214 can be configured according to any of the embodiments described herein. The processor 214 can 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.

[0065] The various steps, functions, and / or operations of the system 200 and the methods disclosed herein are carried out by one or more of: electronic circuits, logic gates, multiplexers, programmable logic devices, ASICs, analog or digital controls / switches, microcontrollers, or computing systems. Program instructions implementing a method, such as the methods described herein, can be transmitted over or stored on carrier media. The carrier media can include storage media (e.g., read-only memory, random-access memory, magnetic or optical disks, nonvolatile memory, solid state memory, magnetic tape, and the like). The carrier media can include transmission media, such as electrical wires, cables, or wireless transmission links. For example, the various steps described throughout the present disclosure can be carried out by a single processor 214 or, alternatively, multiple processors 214. Moreover, different subsystems of the system 200 can include one or more computing or logic systems. Accordingly, the above description should not be interpreted as a limitation on the present disclosure but merely an illustration.

[0066] In an 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 align a setup image with a runtime image at a target to form an aligned image; determine a normalized cross-correlation score of the aligned image; determine image projections of the setup image in perpendicular x and y directions for a design polygon; and align the image projections of the setup image and the runtime image. The system 200 can be used to provide the setup image and the runtime image. In another example, the system 200 can be used to provide the runtime image and the setup image is provided by another inspection system.

[0067] Additional embodiments relate to a non-transitory computer readable medium storing program instructions executable on a controller for performing a computer-implemented method for classifying wafer maps as disclosed herein. In particular, as shown in Figure 4 As shown in FIG. 1, the electronic data storage unit 215 or other storage medium can contain a non-transitory computer readable medium including program instructions executable on the processor 214. The computer-implemented method can include any step of any method described herein, including the method 100.

[0068] The program instructions can be implemented in any of various ways, including procedure-based techniques, component-based techniques, and / or object-oriented techniques, among others. For example, the program instructions can be implemented using ActiveX controls, C++ objects, JavaBeans, Microsoft Foundation Classes (MFC), a Streamed SIMD Extensions (SSE), or other technologies or methodologies, as desired.

[0069] Although system 200 uses light, method 100 can be performed using different semiconductor inspection systems. For example, method 100 can be performed using results from systems that use electron beams (e.g., scanning electron microscopes) or ion beams. Thus, a system can have an electron beam source or an ion beam source instead of a light source as the energy source.

[0070] Although the present disclosure has been described in relation to one or more particular embodiments, those skilled in the art will realize that other embodiments of the present disclosure can be made without deviating from the scope of the present disclosure. Accordingly, the present disclosure is considered to be limited only by the following claims, with the full scope thereof intended to be encompassed thereby.

Claims

1. A method comprising: The processor aligns the setup image with the runtime image at the target location, thereby generating an aligned image using polygons from the setup image and the runtime image; The processor is used to determine the normalized cross-correlation score of the aligned image; The processor uses the normalized cross-correlation score to determine the image projection of the polygon in the aligned image in the vertical x and y directions based on whether the score exceeds a threshold. and The processor is used to align the image projection of the setup image and the runtime image.

2. The method of claim 1, further comprising, after aligning the image projection, using the processor to determine the offset between the setup image and the runtime image of the inspection frame.

3. The method of claim 2, further comprising using the processor to determine the offset between the design of the inspection frame and the runtime image.

4. The method of claim 3, further comprising using the processor to place the region of interest based on offset correction.

5. The method of claim 1, wherein aligning the image projection comprises: Determine the position of the projection peak along the x-direction for the polygon in the aligned image; Adjust the runtime image and / or the setting image so that the projection peak positions overlap along the x-direction; Determine the position of the projection peak along the y-direction for the polygon in the aligned image; and Adjust the runtime image and / or the setting image so that the projection peak positions overlap along the y-direction.

6. A system comprising: A stage configured to hold a semiconductor wafer; An energy source configured to direct a beam toward the semiconductor wafer on the stage; A detector configured to receive the beam reflected from the semiconductor wafer on the stage; and A processor that communicates electronically with the detector, wherein the processor is configured to: Align the setup image with the runtime image at the target location, thereby generating an aligned image using polygons from the setup image and the runtime image; Determine the normalized cross-correlation score of the aligned image; The image projection of the polygon in the aligned image in the vertical x and y directions is determined based on whether the normalized cross-correlation score exceeds a threshold. and Align the image projection of the setting image and the runtime image.

7. The system of claim 6, wherein the energy source is a light source, and wherein the beam is a light beam.

8. The system of claim 6, wherein the processor is further configured to determine the offset between the setup image and the runtime image of the inspection frame after aligning the image projection.

9. The system of claim 8, wherein the processor is further configured to determine the offset between the design of the inspection frame and the runtime image.

10. The system of claim 9, wherein the processor is further configured to place the region of interest based on offset correction.

11. The system of claim 6, wherein aligning the image projection comprises: Determine the position of the projection peak along the x-direction for the polygon in the aligned image; Adjust the runtime image and / or the setting image so that the projection peak positions overlap along the x-direction; Determine the position of the projection peak along the y-direction for the polygon in the aligned image; and Adjust the runtime image and / or the setting image so that the projection peak positions overlap along the y-direction.

12. A non-transitory computer-readable storage medium comprising one or more programs for performing the following steps on one or more computing devices: Align the setup image with the runtime image at the target location to generate a polygon of the aligned image using the setup image and the runtime image; Determine the normalized cross-correlation score of the aligned image; The image projection of the polygon in the aligned image in the vertical x and y directions is determined based on whether the normalized cross-correlation score exceeds a threshold. and Align the image projection of the setting image and the runtime image.

13. The non-transitory computer-readable storage medium of claim 12, wherein the step further comprises determining an offset between the setup image and the runtime image of the inspection frame after aligning the image projection.

14. The non-transitory computer-readable storage medium of claim 13, wherein the step further comprises determining an offset between the design of the inspection frame and the runtime image.

15. The non-transitory computer-readable storage medium of claim 12, wherein the step further comprises: Determine the position of the projection peak along the x-direction for the polygon in the aligned image; Adjust the runtime image and / or the setting image so that the projection peak positions overlap along the x-direction; Determine the position of the projection peak along the y-direction for the polygon in the aligned image; and Adjust the runtime image and / or the setting image so that the projection peak positions overlap along the y-direction.

16. The non-transitory computer-readable storage medium of claim 14, wherein the step further comprises using a processor to place the region of interest based on offset correction.

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