TW202212813A - Method for defect review measurement on a substrate, apparatus for imaging a substrate, and method of operating thereof - Google Patents

Abstract

A method for a defect review measurement on a substrate is described. The method includes generating a defect image of a substrate portion including a defect, generating a reference image corresponding to the defect image, determining a mask pattern based on the reference image, and comparing the defect image and the reference image in regions outside the mask pattern to detect the defect.

Description

Method for defect inspection measurement of substrate, apparatus for imaging substrate and method of operation thereof

The present disclosure relates to an apparatus and method for imaging a substrate. More particularly, embodiments described herein relate to a method for defect review (DR) measurement of substrates, particularly for display manufacturing, such as large area substrates. In particular, embodiments relate to a method for defect inspection metrology of a substrate, an apparatus for imaging a substrate, and a method of operation thereof.

In many applications, it is beneficial to inspect substrates to monitor the quality of the substrates. For example, glass substrates on which layers of coating materials are deposited are manufactured for the display market. Since defects may occur, for example, during substrate processing, such as during substrate coating, it is beneficial to inspect the substrate to check for defects and monitor the quality of the display.

Displays tend to be fabricated on large-area substrates with ever-increasing substrate sizes. In addition, displays, such as TFT displays, are undergoing continuous improvement. Inspection of the substrate can be performed by an optical system. However, defect review (DR) measurements, such as the measurement of the DR of TFT arrays, require the use of resolution that optical inspection cannot provide. DR measurements can, for example, characterize defects that have been previously detected. Therefore, DR measurement is valuable for process control because countermeasures can be taken to prevent or reduce the probability of defects.

Defect detection or re-detection in a "defect inspection system" can be provided by comparing the reference image with the defect image, ie the image to be inspected. Defects are considered as deviations between the reference image and the defective image that exceed a given threshold.

Substrates for display fabrication are typically glass substrates with an area of eg 1 m ² or more. High-resolution images on such large substrates are inherently challenging, and most findings from the wafer industry are not applicable. Furthermore, the options for DR metrology exemplarily described above may not be applicable to large area substrates.

In the display industry, the variation between images of a particular location of a display product exhibits significant variation due to process variations based on the manufacturing tolerances of display manufacturing. Display manufacturing may have higher manufacturing tolerances than semiconductor manufacturing on wafers due to the much larger area compared to semiconductor manufacturing. In particular, the edge roughness of the patterned structures may lead to the fact that defect inspection procedures from the wafer industry may not provide the expected results. Such deviations can lead to false defect detections, or low threshold settings, which in turn can lead to low detection sensitivity. Often, manufacturing tolerances of the same or near order of magnitude as the defect size to be detected may result in erroneous defect detection or low threshold settings.

Therefore, in view of, for example, the increasing demand for defect inspection quality, there is a need for an improved apparatus and method for imaging substrates, eg, without mashing the substrate into smaller samples and allowing the continuation of the substrate's characterization after DR measurement. manufacturing process.

In view of the foregoing, a method for defect inspection metrology of a substrate, an apparatus for imaging at least a portion of a substrate, and a method of operating the apparatus are provided. Other aspects, advantages and features of the present disclosure are apparent from the description and drawings.

According to one embodiment, a method for defect inspection metrology of a substrate is provided. The method includes generating a defect image of a portion of the substrate including the defect; generating a reference image corresponding to the defect image; determining a mask pattern based on the reference image; and comparing the defect image to the reference in an area outside the mask pattern image to detect defects.

According to one embodiment, an apparatus for imaging a portion of a substrate is provided. The apparatus includes a vacuum chamber, a substrate support disposed in the vacuum chamber, and a first imaging charged particle beam microscope. The controller includes a processor and memory storing instructions that, when executed by the processor, cause an apparatus to perform a method according to any of the embodiments described herein.

According to one embodiment, there is provided a method of operating an apparatus according to any of the embodiments described herein. The method includes matching a first coordinate system on a substrate of a first imaging charged particle beam microscope with a second coordinate system on a substrate of a second imaging charged particle beam microscope.

Reference will now be made in detail to various illustrative embodiments, one or more examples of which are illustrated in the accompanying drawings of the present disclosure. Each example is provided by way of explanation and is not meant to be limiting. For example, features illustrated or described as part of one embodiment can be used on or in combination with other embodiments to yield further embodiments. It is intended that this disclosure includes such modifications and variations.

In the following description of the drawings, the same reference numerals refer to the same components. Only the differences with respect to the various embodiments are described. The structures shown in the drawings are not necessarily true to scale, but are provided for a better understanding of the embodiments.

Electron beam review (EBR) is a relatively young technology, especially for large-area substrates, where the entire substrate or an area distributed over the entire substrate is measured, allowing for example the display to be fabricated during the inspection process Or not broken when used for inspection process. For example, resolutions of 20 nm or lower, such as 10 nm or lower, are very difficult to achieve and previous findings from wafer imaging may not be suitable given the significant differences in substrate size. For example, the stage, ie the substrate stage, may be advantageously adapted to be positioned in any area of the entire substrate under the electron beam, and the positioning must be very precise over large areas. For large area substrates, eg compared to wafer imaging equipment, the area to be measured is larger and the various areas can be farther apart from each other. Therefore, simple scaling up cannot succeed, for example due to different production volume requirements. In addition, the process and equipment are beneficially adapted to reduce vibration on large dimensions below the desired resolution. Also, manual or semi-automatic processes may not be suitable given the required throughput and repeatability of measurement locations distributed over the area of a large area substrate.

Additionally, display fabrication on large area substrates has greater manufacturing tolerances than semiconductor fabrication on wafers. Therefore, the acceptable deviation of the image at the first location relative to the image at the second location having the same pattern is greater than in semiconductor manufacturing. Thus, the size of the defect can be within the same order of magnitude as the acceptable deviation, or only one or two orders of magnitude larger than the acceptable deviation. Typically, for display manufacturing and in the semiconductor industry, defect inspection can be based on image comparisons and thresholds for image deviation. Such comparisons have limitations as long as the defect size is close to the size of acceptable deviations, such as those based on manufacturing tolerances. Accordingly, embodiments of the present disclosure are particularly related to defect inspection for display manufacturing, eg, to inspect large area substrates for defects. Furthermore, embodiments of the present disclosure may also relate to the semiconductor industry, where defects compared to manufacturing tolerances are small, in particular of the same order of magnitude or only one or two orders of magnitude larger. Embodiments of the present disclosure provide an improved defect inspection metrology.

Embodiments of the present disclosure relate to image-based comparisons (such as a comparison of a defect image including a defect at one pixel of a display (eg, a transistor of a TFT display) with a reference image at an adjacent pixel) or based on a crystal Defect inspection for comparison of die to neighboring die. The term "adjacent" may refer to an immediately adjacent structure or an immediately adjacent structure having the same pattern of the patterned film. Immediately adjacent structures may also be referred to as structures adjacent to defective structures. Within the array area (display area), the feature (pixel) structure is repeated or repeated for unit cells. A unit cell is the smallest group of structures that repeat periodically in the display array area. For example, a unit cell is a group of red, green and blue (RGB) pixel structures, or N×RGB. A structure within a unit cell is equal to an equivalent structure within any other unit cell. The structure of any unit cell can be used as a reference for comparison with the unit cell including the defect candidates to be detected and inspected. According to some embodiments, which may be combined with other embodiments described herein, the defect image may be generated at one unit cell and the reference image may be generated at another unit cell. For example, another unit cell of the reference image may be an adjacent unit cell (including second, third, fourth, etc. adjacent unit cells) or a directly adjacent unit cell.

According to an embodiment of the present disclosure, the pattern edges in the reference image are utilized to create a mask, ie, a mask pattern, which is formed as a pattern edge having a defined size. Compare the reference image and the defect image. For example, the difference in brightness can be calculated. The mask pattern is overlaid on the pattern edge, ie the masked area is ignored by defect detection. Defect candidates for defect images are selected. For example, the best defect candidate or one or more defect candidates, ie the deviation of the structure outside the mask pattern, may be selected. Without the mask pattern, regions of one or more defect candidates are re-evaluated for defect detection.

1A-1C illustrate an exemplary embodiment of a method for defect inspection metrology. Corresponding pictures of Figures 1A to 1C are illustrated in Figures 7A to 7C, wherein some of the features are additionally labeled with reference numerals A, B, and C. FIG. 1A illustrates a reference image 10 . For example, the image may include a portion of a thin film transistor of a pixel of the display. The image may be a scanning electron microscope image. For example, the signal strength can be measured by measuring the signal electrons generated when the primary electron hits the substrate. The intensity signal of the signal electrons can be displayed to generate an image. Reference image 10 illustrates structure 14 . Structures 14 correspond to structures fabricated during display fabrication. According to some embodiments, which may be combined with other embodiments described herein, the reference image 10 may also include features 12 (see also reference C in Figure 7A). The feature 12 may be an undesired feature or an odd feature that may not cause a defect but is not intended for a perfectly fabricated structure 14 .

Figure 1B illustrates a defect image. The defect image includes defect 22 . Some operations of a method for defect inspection measurement of a substrate according to embodiments of the present disclosure are illustrated in FIG. 1C. A comparison between the reference image 10 and the defect image 20 is calculated. For example, the comparison image 30 is generated by calculating the luminance difference between the reference image 10 and the defect image 20 . For example, a perfectly matched defect image and a reference image will result in a black comparison image, ie an image without bias. Differences between the reference image and the defective image appear as bright spots, ie brightness deviations. For example, the absolute value of the difference between the reference image and the defective image may be calculated and/or the absolute value of the difference between the reference image and the defective image may be plotted. The greater the deviation of the intensity signal, the greater the absolute difference and therefore the brighter the area in the comparison image. According to some embodiments, which may be combined with other embodiments described herein, the comparison image may additionally or alternatively be generated by a filter and further image processing routines, wherein the defect image is compared with the reference image.

A mask pattern 32 is overlaid on the comparison image 30 . The mask pattern 32 is generated from the structure 14 of the reference image 10 . According to embodiments of the present disclosure, the structure may include one or more features selected from the group consisting of vias, lines, trenches, connections, material boundaries, etched layer structures, and the like. According to some embodiments, which may be combined with other embodiments described herein, the structure may be part of a thin film transistor or another transistor used to operate a pixel of a display.

According to some embodiments, which may be combined with other embodiments described herein, the mask pattern 32 is generated by a pattern recognition method.

According to some embodiments, which may be combined with other embodiments described herein, the mask pattern 32 may include features 12 , ie odd features of the reference image 10 . Because feature 12 is not intentional, it may result in a difference in brightness between the reference image and the defective image. However, since the reference image does not include defects, differences in brightness corresponding to features 12 may result in incorrect defect detection. The comparison image 30 is masked by the mask pattern 32, and the regions of the mask pattern are ignored. Thus, the mask pattern including features 12 prevents false defect detection of strange features.

Additionally or alternatively, brightness differences 24 (see also reference number B in Figure 7B) caused by manufacturing tolerances (such as edge roughness or other manufacturing tolerances) that may generate false defect detections in the comparison image 30 . Masked by mask pattern 32 . Thus, an acceptable deviation of an image at a first location (eg, reference image 10 ) relative to an image at a second location (eg, defect image 20 having the same pattern) may not result in a defect alarm, as acceptable Deviations are masked by mask pattern 32 .

As shown in FIG. 1C , defect 22 (see also reference A in FIG. 7C ) illustrates the difference in brightness between reference image 10 and defect image 20 . The defect 22 is outside the mask pattern 32 . A comparison of the defect image in the area outside the mask pattern with the reference image is used to detect defects 22 . According to some embodiments, which may be combined with other embodiments described herein, the comparison image 30 is searched for one or more optimal defect candidates outside the mask pattern. After detection of one or more defects, such as defect 22 in FIG. 1C , defect detection at the location of the defect may be further provided without mask pattern 32 .

The multi-step approach includes use of a mask pattern for defect selection and further defect re-detection of selected defects without the mask pattern, as several advantages. Such advantages can be tailored according to the manufacturing conditions of the display. The more pronounced pattern edge roughness in display manufacturing does not lead to false defects. Due to the shading, the remaining regions of the image, ie the unshaded regions (regions/area), can be searched for defects with higher sensitivity. By the second localized defect detection operation, ie the second defect detection without the mask pattern, the defect candidates partially covered by the mask or separated by the mask are corrected on the contour. Therefore, correct defect contours, ie defect contours without masks, can be provided, which facilitates defect type classification. Correct defect contours, such as defect detection without mask patterns, allow determination of true defect area and true defect size.

Figure 2 illustrates a portion of an apparatus for imaging a substrate, in particular for imaging with a scanning charged particle beam microscope for large area displays, such as for display fabrication, in accordance with embodiments described herein side view. The apparatus 100 includes a vacuum chamber 120 . The apparatus 100 also includes a substrate support 110 on which the substrate 160 may be supported. Apparatus 100 includes a first imaging charged particle beam microscope 130 . Additionally, the apparatus may include a second imaging charged particle beam microscope 140 . In the example shown in FIG. 2 , the first imaging charged particle beam microscope 130 and the second imaging charged particle beam microscope 140 are arranged above the substrate support 110 .

As further shown in FIG. 2 , the substrate support 110 extends along the x-direction 150 . In the drawing plane of FIG. 2, the x-direction 150 is the left-right direction. The substrate 160 is disposed on the substrate supporter 110 . The substrate support 110 is movable in the x-direction 150 to displace the substrate 160 in the vacuum chamber 120 relative to the first imaging charged particle beam microscope 130 and the second imaging charged particle beam microscope 140 . Thus, the area of the substrate 160 may be located under the first imaging charged particle beam microscope 130 or under the second imaging charged particle beam microscope 140 for DR measurements. The region may include structures for DR measurements contained in or on the coating on the substrate. The substrate support 110 can also be moved in the y-direction (not shown) so that the substrate 160 can be moved in the y-direction, as described below. By appropriately displacing the substrate support 110 that holds the substrate 160 within the vacuum chamber 120 , a portion along the entire extent of the substrate 160 can be measured within the vacuum chamber 120 .

The first imaging charged particle beam microscope 130 is a distance 135 along the x-direction 150 from the second imaging charged particle beam microscope 140 . In the embodiment shown in FIG. 2 , distance 135 is the distance between the center of first imaging charged particle beam microscope 130 and the center of second imaging charged particle beam microscope 140 . In particular, the distance 135 is the distance along the x-direction 150 between the first optical axis 131 defined by the first imaging charged particle beam microscope and the second optical axis 141 defined by the second imaging charged particle beam microscope 140 . The first optical axis 131 and the second optical axis 141 extend along the z direction 151 . The first optical axis 131 may be defined, for example, by the objective of the first imaging charged particle beam microscope 130 . Similarly, the second optical axis 141 may be defined, for example, by the objective lens of the second imaging charged particle beam microscope 140 .

As further shown in FIG. 2 , the vacuum chamber 120 has an interior width 121 along the x-direction 150 . The inner width 121 may be the distance obtained when passing through the vacuum chamber 120 in the x-direction from the left hand wall 123 of the vacuum chamber 120 to the right hand wall 122 of the vacuum chamber 120 . One aspect of the present disclosure pertains to the dimensions of device 100 relative to, for example, the x-direction 150 . According to an embodiment, the distance 135 along the x-direction 150 between the first imaging charged particle beam microscope 130 and the second imaging charged particle beam microscope 140 may be at least 30 cm, such as at least 40 cm. According to other embodiments, which may be combined with other embodiments described herein, the interior width 121 of the vacuum chamber 120 may be located at 250 of the distance 135 between the first imaging charged particle beam microscope 130 and the second imaging charged particle beam microscope 140 % to 450%. Further details, aspects and features will be described below with respect to Figures 2 and 3.

Accordingly, embodiments described herein may provide an apparatus for imaging substrates, particularly portions of large area substrates, in a vacuum chamber using two imaging charged particle beam microscopes remote from each other. The substrate is processed as a whole in a vacuum chamber. In particular, the embodiments described herein do not require damaging the substrate or etching the surface of the substrate. Therefore, high-resolution images for defect inspection measurement can be provided.

An advantage of having a vacuum chamber of reduced size, as provided by some embodiments described herein, is that one or more vibrations of the vacuum chamber may be reduced because the vibration level increases depending on the size of the vacuum chamber. Therefore, the vibration amplitude of the substrate can also be advantageously reduced.

Exemplary first imaging charged particle beam microscope and second imaging charged particle beam microscope distances along the first direction are in the range of 30% to 70% of the size of the first receiving area of the substrate receiving area. More particularly, the distance along the first direction may be in the range of 40% to 60% of the size of the first receiving area, eg, about 50% of the size of the first receiving area. For example, referring to the embodiment shown in FIG. 2 , the distance along the first direction may refer to the distance 135 between the first imaging charged particle beam microscope 130 and the second imaging charged particle beam microscope 140 . In the exemplary embodiment shown in FIG. 2 , the distance 135 is about 50% of the width 220 of the substrate receiving area 210 .

The substrate support can be moved relative to the first imaging charged particle beam microscope and/or relative to the second imaging charged particle beam microscope in the vacuum chamber. According to an embodiment that can be combined with other embodiments described herein, the second imaging charged particle beam microscope is at a distance of at least 30 cm, more particularly at least 40 cm, from the first imaging charged particle beam microscope, such as the first receiving About 50% of the area size. There is a minimum distance between the first imaging charged particle beam microscope and the second imaging charged particle beam microscope (ie, greater than just repeating two imaging charged particle beam microscopes next to each other for redundancy, such as two adjacent to each other The SEMS distance) has the advantage of reducing the distance traveled by the substrate inspected by the equipment. This allows to reduce the size of the vacuum chamber, so that the vibration of the vacuum chamber can also be advantageously reduced.

According to some embodiments, which may be combined with other embodiments described herein, the apparatus for imaging portions of a large area substrate may also include a controller 180 . The controller 180 may be connected (see reference numeral 182) to the substrate support 110, and in particular to the displacement unit of the substrate support. Additionally, the controller 180 may be connected to a scanning deflector assembly 184 of an imaging charged particle beam microscope, such as the first imaging charged particle beam microscope 130 and the imaging second charged particle beam microscope 140 .

The controller 180 includes a central processing unit (CPU), memory and, for example, support circuits. To facilitate control of equipment for inspecting large area substrates, the CPU may be one of any form of general purpose computer processor that may be used in an industrial environment to control various chambers and sub-processors. The memory is coupled to the CPU. The memory or computer-readable medium can be one or more readily available memory devices such as random access memory, read-only memory, floppy disk, hard disk, or any other form of local or remote digital storage device. Support circuitry may be coupled to the CPU for supporting the processor in a conventional manner. Such circuits include caches, power supplies, clock circuits, input/output circuitry, and related subsystems, among others. Inspection process instructions are typically stored in memory as software routines (often called recipes). Software routines may also be stored and/or executed by a second CPU (not shown) located remotely from the hardware controlled by the CPU. Software routines, when executed by the CPU, convert a general purpose computer into a special purpose computer (controller) that controls device operations, such as for controlling substrate support positioning and charged particle beam scanning during the imaging process. Although the methods and/or processes of the present disclosure are discussed as being implemented as a software routine, some of the method steps disclosed therein may be performed in hardware as well as by a software controller. As such, the present invention may be implemented in software executing on a computer system, and may be implemented in hardware or other types of hardware implementations as application-specific integrated circuits, or in a combination of software and hardware.

According to embodiments of the present disclosure, and as exemplarily described with reference to FIGS. 1A-1C, 5, and 6A-6E, a controller may make or perform measurements for defect inspection of substrates methods, such as for display manufacturing.

According to one embodiment, an apparatus for imaging a portion of a substrate is provided. The apparatus includes a vacuum chamber and a substrate support disposed in the vacuum chamber. According to some embodiments, which may be combined with other embodiments described herein, the substrate support may optionally provide a substrate receiving area of at least 1.2 m ² . The apparatus also includes a first imaging charged particle beam microscope and a controller having a processor and memory storing instructions that, when executed by the processor, cause the apparatus to perform an embodiment in accordance with the present disclosure. The method of any embodiment.

According to one embodiment, a method for defect inspection metrology of a substrate is provided. The method includes generating a defect image of the portion of the substrate including the defect, and generating a reference image corresponding to the defect image. The mask pattern is determined based on the reference image. The defect image and the reference image are compared in areas outside the mask pattern to detect defects. According to some embodiments, which may be combined with other embodiments described herein, defects are redetected without a mask pattern. For example, the defect contour of the defect can be determined. According to yet another optional implementation, an image-like view of defects can be generated.

Figure 3 illustrates a side view of another apparatus for imaging a portion of a substrate in accordance with embodiments described herein. The apparatus 100 includes a vacuum chamber 120 . The apparatus 100 also includes a substrate support 110 on which the substrate 160 may be supported. Apparatus 100 includes a first imaging charged particle beam microscope 130 . In contrast to Figure 2, Figure 3 illustrates a single imaging charged particle beam microscope disposed above a substrate support 110. Even though this may result in a reduction in imaging capability, eg, resolution, the resulting resolution may be sufficient for some DR measurements. Furthermore, for semiconductor wafer applications where the defect size of the defects to be detected is small compared to acceptable manufacturing tolerances, an apparatus for imaging portions of substrates with a single imaging charged particle beam microscope may be provided. Similar to Figure 2, the apparatus shown in Figure 3 may include a controller and a deflection assembly. The controller may be connected to the substrate support, and in particular the displacement unit of the substrate support. Additionally, the controller can be connected to the deflection assembly of the imaging charged particle beam microscope.

Defect inspection measurements are typically provided on various areas of substrates, such as wafers in semiconductor manufacturing or large area glass substrates such as used in display manufacturing. Thus, statistical analysis of defect inspection of structures can be performed over the entire substrate area and across multiple processed substrates. For small substrates, such as wafers, this can be done using methods known in the semiconductor industry with sufficient throughput. In the semiconductor industry, tool-to-tool matching provides metrology capabilities. For electron beam inspection (EBR) of display substrates, two imaging charged particle beam microscopes (see Figure 2) in one device can be matched relative to each other. This is about relative position and measurement capability. Single-column setups (see Figure 3) can avoid column matching in one system while accepting reduced resolution. Multi-column devices may advantageously include column matching and have increased resolution.

According to some embodiments, which may be combined with other embodiments described herein, a method of operating an apparatus for imaging of the present disclosure may include comparing a first coordinate system on a large area substrate of a first imaging charged particle beam microscope with The second coordinate system is matched on the large area substrate of the second imaging charged particle beam microscope.

Both options, namely the single-column method and the multi-column method, allow for the improved DR measurement process described herein, which provides sufficient detection sensitivity and sufficient throughput, especially also on large area substrates. According to embodiments of the present disclosure, DR measurements as described herein may be provided in various regions of a large area substrate. For example, two or more regions, such as 5 regions to 100 regions, may be distributed over the substrate.

Imaging charged particle beam microscopy as used herein can be adapted to generate low energy charged particle beams with landing energies of 2 keV or less, particularly 1 keV or less. In contrast to high energy beams, low energy beams do not affect or damage display backplane structures during defect inspection measurements. According to other embodiments, which may be combined with other embodiments described herein, the charged particle energy, eg electron energy, may be increased to 5 keV or higher, such as 10 keV or higher, between the particle beam source and the substrate. Accelerating charged particles within the column reduces interactions between charged particles, reduces aberrations in electro-optical components, and thus increases the resolution of imaging scanning charged particle beam microscopy.

According to yet another embodiment, which may be combined with other embodiments described herein, the term "substrate" as used herein includes non-flexible substrates, such as glass substrates or glass sheets, and flexible substrates, such as webs or foils. The substrate may be a coated substrate in which one or more materials are applied or deposited on the substrate, for example, by a physical vapor deposition (PVD) process or a chemical vapor deposition (CVD) process thin layer. Substrates used in the manufacture of displays often contain insulating materials such as glass. Thus, in contrast to semiconductor wafer SEMs, equipment used to image portions of large area substrates does not allow for biasing of the substrates. According to the embodiments described herein, which may be combined with other embodiments described herein, the substrate is grounded. The substrate cannot be biased to a potential that affects the landing energy or other electro-optical aspects of scanning electron beam microscopy. This is another example of the difference between EBR systems for large area substrates and SEM inspection of semiconductor wafers. This may further lead to electrostatic discharge (ESD) problems during substrate processing on the substrate support. Therefore, it can be seen that the wafer inspection scheme may not be easily applicable to DR metrology of substrates for display fabrication.

According to other embodiments, which may be combined with other embodiments described herein, defect inspection metrology for large area displays for display manufacturing may further differentiate semiconductor wafer DR based on scanning techniques. In general, a distinction can be made between analog scanning techniques and digital scanning techniques. The analog scanning technique may include an analog sawtooth signal provided to the scanning deflector assembly at a predetermined frequency. The sawtooth signal can be combined with continuous or quasi-continuous substrate movement to the substrate scanning area. Digital scanning techniques provide discrete values for the x- and y-positioning of the charged particle beam on the substrate, and the individual pixels of the scanned image are addressed pixel-by-pixel, ie, digitally, by coordinate values. Due to the scanning speed and reduced complexity, the analog scanning technique ("flight phase") may be considered better for SEM inspection of semiconductor wafers, but it is not beneficial for DR measurement of large area substrates. Due to the size of the substrate, the area to be scanned is scanned digitally, ie by providing a list of desired beam position coordinates. That is, the image is scanned using digital scanning technology, that is, a digital scanner. Such scanning processes provide better throughput and accuracy due to the size of the substrate.

According to some embodiments, which may be combined with other embodiments described herein, the field of view of an imaging charged particle beam microscope for use in methods and apparatus according to the present disclosure may have dimensions of 500 μm or less and/or 5 μm or larger size. The resolution of the image may be about 100 nm or less, such as 20 nm or less, eg 10 nm or less.

The method for defect inspection of an image may receive a list of defects or defect candidates from a controller or interface of a display manufacturing plant. For example, the pixels of a display can be tested using a display test method. Pixel defects, line defects, driver defects or other defects can be tested with e-beam test systems and optical test systems or other measurements such as electrical measurements. Thus, defective pixels may be provided for defect inspection measurement and/or may be provided to an apparatus for defect inspection measurement. The area of defective pixels is an image used to provide a defective image. Measure areas, such as corresponding areas of adjacent pixels, to provide a reference image. DR metrology can be used to evaluate defect inspections for defects from previous metrology tools. Due to the size of the substrates used for display fabrication and the resulting fabrication process challenges, locations for defect inspection measurements on large area substrates as described with respect to embodiments of the present disclosure may be distributed over the large area substrates. For example, a display may have 5 million or higher pixels, such as about 8 million pixels. Larger displays may include higher numbers of pixels. For each pixel, at least an electrode for red, an electrode for green, and an electrode for blue are provided. As a result, defects considered critical to the manufacturing process can appear over very large areas. As described above, embodiments of the present disclosure include providing DR measurements based on a first operation using a mask pattern and a subsequent second operation without the mask pattern. DR measurements are provided at the structure of the defect image using a reference image.

According to some embodiments, which may be combined with other embodiments described herein, the defective image is generated at the defective pixel on the substrate, and the reference image is generated at the pixel adjacent to the defective pixel, in particular adjacent to the defective pixel generated at pixels. Additionally or alternatively, the defect inspection measurements may be repeated over one or more regions of the substrate, the regions being distributed over at least 1.2 m ² .

According to some embodiments, which may be combined with other embodiments described herein, the substrates described herein relate to large area substrates, particularly for the display market. According to some embodiments, the large area substrate or corresponding substrate support may have a size of at least 1 m ² , such as at least 1.375 m ² . The size may be from about 1.375 m ² (1100 mm x 1250 mm - Gen 5) to about 9 m ² , more particularly from about 2 m ² to about 9 m ² , or even as high as 12 m ² . The substrate or substrate receiving area for which structures, apparatus and methods according to embodiments described herein are provided may be a large area substrate as described herein. For example, a large area substrate or carrier may be GEN 5 corresponding to about 1.375 ^m2 substrate (1.1 m x 1.25 m), GEN 7.5 corresponding to about 4.39 ^m2 substrate (1.95 m x 2.25 m), GEN 7.5 corresponding to about 5.7 m2 GEN 8.5 for ² substrates (2.2 m x 2.5 m), or even GEN 10 corresponding to about ⁹ m substrates (2.88 m x 3130 m). Even larger generations such as GEN 11 and GEN 12 and corresponding substrate areas can be implemented similarly. It must be considered that the substrate size generation provides a fixed industry standard, even though the size of the GEN 5 substrate may vary slightly from one display manufacturer to another. Embodiments of the apparatus for testing may, for example, have a GEN 5 substrate support or a GEN 5 substrate receiving area such that many display manufacturers' GEN 5 substrates may be supported by the support. The same applies to other substrate size generations.

Figure 4 illustrates an imaging charged particle beam microscope, ie, a charged particle beam apparatus 500, such as a first imaging charged particle beam microscope and/or a second imaging charged particle beam microscope as described herein. The charged particle beam apparatus 500 includes an electron beam column 420 providing, for example, a first chamber 421 , a second chamber 422 and a third chamber 423 . The first chamber, which may also be referred to as the gun chamber, includes an electron beam source 430 having an emitter 31 and a suppressor 432 .

The transmitter 431 is connected to a power source 531 for supplying an electrical potential to the transmitter. The potential supplied to the emitter may cause the electron beam to be accelerated to energies of, for example, 20 keV or higher. Thus, the transmitter can be biased to a potential of -1 kV voltage to provide a landing energy of 1 keV to the grounded substrate. The upper electrode 562 is set at a higher potential for guiding electrons through the column with higher energy.

Using the apparatus shown in FIG. 5, electron beam source 430 may generate an electron beam (not shown). The beam may be aligned with a beam confinement aperture 550 sized to shape the beam, ie, block a portion of the beam. Thereafter, the beam may pass through a beam splitter 580, which separates the primary electron beam from the signal electron beam, ie, from the signal electrons. The primary electron beam can be focused on the substrate 460 by the objective lens. The substrate 460 is located in the substrate position on the substrate support 410 . When the electron beam impinges on the substrate 460, signal electrons, such as secondary and/or backscattered electrons or x-rays, are released from the substrate 460, which can be detected by the detector 598.

In the exemplary embodiment shown in Figure 4, a focusing lens 520 and a beam shaping or beam limiting aperture 550 are provided. A two-stage deflection system 540 is disposed between the focusing lens and a beam-limiting aperture 550 (eg, a beam-shaping aperture) for directing the beam to the aperture. Electrons can be accelerated by the extractor or anode to a voltage in the column. The extractor may be provided, for example, by the upper electrode of the focusing lens 520 or by another electrode (not shown).

As shown in FIG. 4 , the objective lens has a magnetic lens member 561 having pole pieces 464 and 463 and a coil 462 that focuses the primary electron beam on a substrate 460 . The substrate 460 may be positioned on the substrate support 410 . The objective lens shown in FIG. 4 includes an upper pole piece 463, a lower pole piece 464, and a coil 462, thereby forming a magnetic lens member 461 of the objective lens. Further, the upper electrode 562 and the lower electrode 530 form an electrostatic lens part of the objective lens.

Additionally, in the embodiment shown in Figure 4, a scanning deflector assembly 570 is provided. Scanning deflector assembly 570 (see also scanning deflector assembly 184 in Figure 2) may be magnetic, for example, but is preferably an electrostatic scanning deflector assembly configured for high pixel rates. Scanning deflector assembly 570 may be a single stage assembly, as shown in FIG. 4 . Alternatively, two-stage or even three-stage deflector assemblies can also be provided. The respective tables are arranged at different positions along the optical axis 2 .

The lower electrode 530 is connected to a voltage source (not shown). The embodiment shown in FIG. 4 illustrates the lower electrode 530 below the lower pole piece 464 . The lower electrode is the deceleration electrode of the objective's immersion lens component (ie, the retarded field lens component), and is typically at a potential to provide a charged particle landing energy of 2 keV or less, eg, 500 V or 1 keV, on the substrate.

The beam splitter 580 is adapted to separate primary electrons and signal electrons. The beam splitter may be a Wien filter and/or may be at least one magnetic deflector so that the signal electrons are offset from the optical axis 402 . The signal electrons are then directed to detector 598 by beam bender 591 (eg, a hemispherical beam bender) and lens 595 . Other elements like filter 596 may be provided. According to a further modification, the detector may be a segmented detector configured to detect the signal electrons depending on the starting angle at the sample.

The first imaging charged particle beam microscope and the second imaging charged particle beam microscope may be an imaging charged particle beam microscope type charged particle beam apparatus, such as the charged particle beam apparatus 500 shown in FIG. 4 .

FIG. 5 illustrates a flow chart illustrating a method for performing defect inspection metrology on a substrate. At operation 510, a reference image is generated. As described with reference to FIGS. 1A-1C, at operation 511, a mask pattern is generated from a reference image. Further, a defect image is generated at operation 512 . An image of the portion of the substrate that includes defects, such as known defects, is generated. For example, a defect image may be provided at the portion of the substrate where the defect of the pixel has been previously reported by the metrology process.

As shown in FIG. 6A, a comparison image 30, such as a difference image, is generated. The comparison image is covered by the mask pattern 32 . Defect selection is provided outside the area of the mask pattern 32 within the comparison image.

According to some embodiments, which may be combined with other embodiments described herein, the comparison image may be a differential image or another comparison image. The intensity signals of the reference image and the defect image can be calculated and/or determined for each pixel of the image. For example, the reference image and the defect image may be aligned relative to each other to align the pixels of the images. The difference in intensity signals can be provided by the absolute value of the difference in intensity signals. Alternatively, the relevant structures (edges) of the reference image can be extracted from the display layout design data (CAD data). The reference structure can be extracted from the same unit cell location where the defect image was acquired. Additionally or alternatively, reference images may be stored. Therefore, acquiring a reference image for each defect location can be omitted. References to layout CAD data and/or stored reference images can increase throughput for defect inspection. No new reference images were acquired for each DR measurement.

Figure 6B illustrates an enlarged view of Figure 6A. Defects 22 outside the mask pattern 32 may be selected as shown in Figure 6B. Defects illustrate the deviation between the reference image and the defect image in areas outside the mask pattern 32, ie, bright spots in the comparison image. Accordingly, at operation 513, defects may be selected based on the masked comparison image. Defects may be re-detected in region 62 of comparison image 30 as shown in FIG. 6C. Additionally or alternatively, defects may be re-detected in the defect image in region 62 . According to operation 514, local redetection of this defect may be provided without the mask pattern.

Figure 6D illustrates a defect image. According to some embodiments, which may be combined with other embodiments described herein, a partial image 60 of the region of the selected defect may be provided. For example, defects can be redetected within the comparison image (ie, a portion of the comparison image). Additionally or alternatively, contours 64 may be determined in defect image 60 . For automatic defect classification (ADC), it is beneficial to see defects in larger FOVs. The relationship to adjacent pattern structures can be assessed (see Fig. 6D). Higher zoom images illustrating more defect detail can be provided, as shown, for example, in Figure 6E. The partial image may be a digital zoom of the defect image. Additionally or alternatively, another defect image may be generated at a different resolution than the defect image, eg as measured with imaging charged particle microscopy. In particular, the other defect image may have a higher resolution than the defect image, ie the original defect image.

As shown in FIG. 6D, in the absence of mask pattern 32, defect outline 64 may be provided by local re-detection of the defect (see eg, operation 515). This may be provided in the comparison image 30 or the defect image 60 . For classification of images, a class image view 80 may be provided (see Figure 6E). According to some embodiments, which may be combined with other embodiments, the image-like view may have increased resolution, eg by rescanning the desired FOV with an imaging charged particle beam microscope. The image-like view may in particular be based on the determined defect contour. Depending on the size of the defect contour, the image-like or image-like view may illustrate an area that includes the defect and has a size of a predetermined ratio compared to the size of the defect contour.

Due to the use of a two-step method for defect selection and re-detection, especially local re-detection, on the masked comparison image, without mask pattern, can provide higher sensitivity, improved edge suppression basis / or large and small defect contour detection.

Although the foregoing has been directed to some embodiments, other and further embodiments can be devised without departing from the essential scope of the present disclosure, which is to be determined by the scope of the appended claims.

10: Reference Image 12: Features 14: Structure 20: Defect image 22: Defects 24: Brightness difference 30: Compare Images 32: Mask Pattern 60: Partial image 62: Area 64: Defect outline 80: class image view 100: Equipment 110: Substrate support 120: Vacuum chamber 121: Internal width 122: Right hand wall 123: Left hand wall 130: First Imaging Charged Particle Beam Microscopy 131: The first optical axis 135: Distance 140: Second Imaging Charged Particle Beam Microscopy 141: Second optical axis 150:x direction 151: z direction 160: Substrate 180: Controller 182: connect 184: Scanning Deflector Assembly 402: Optical axis 410: Substrate support 420: electron beam column 421: First Chamber 422: Second Chamber 423: Third Chamber 430: Electron beam source 431: Launcher 432: Suppressor 460: Substrate 461: Magnetic Lens Components 462: Coil 463: Upper pole piece 464: Lower pole piece 500: Charged Particle Beam Device 510: Operation 511: Operation 512: Operation 513: Operation 514: Operation 515: Operation 520: Focusing Lens 530: Lower electrode 531: Power 540: Two-stage deflection system 550: Beam Confinement Aperture 561: Magnetic Lens Components 562: Upper electrode 570: Scanning Deflector Assembly 580: Beam Splitter 591: Beam bender 595: Lens 596: Filter 598: Detector

In order to enable a detailed understanding of the above-described features of the present disclosure, the present disclosure, briefly summarized above, may be more particularly described with reference to embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, for other equally effective embodiments may be admitted.

FIGS. 1A-1C illustrate images for illustrating defect inspection measurements according to embodiments of the present disclosure.

Figure 2 illustrates a side view of an apparatus for imaging a portion of a substrate in accordance with embodiments described herein.

Figure 3 illustrates a side view of another apparatus for imaging a portion of a substrate in accordance with embodiments described herein.

4 illustrates a side view of an imaging charged particle beam microscope, ie, an exemplary apparatus for examining imaging of a portion of a substrate, in accordance with embodiments described herein.

5 illustrates a flow diagram illustrating a method for defect inspection measurement, particularly for large area substrates, such as for display fabrication, in accordance with an embodiment of the present disclosure.

6A-6E illustrate exemplary images of defect inspection measurements in accordance with embodiments of the present disclosure.

FIGS. 7A to 7C illustrate pictures for explaining images of defect inspection measurement corresponding to FIGS. 1A to 1C .

To facilitate understanding, where possible, the same reference numbers have been used to refer to elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially combined in other embodiments without further recitation.

Domestic storage information (please note in the order of storage institution, date and number) none Foreign deposit information (please note in the order of deposit country, institution, date and number) none

22: Defects

24: Brightness difference

30: Compare Images

32: Mask Pattern

Claims (20)

A method for defect inspection and measurement of a substrate, comprising the steps of: generating a defect image of a substrate portion including a defect; generating a reference image corresponding to the defective image; determining a mask pattern based on the reference image; and The defect image and the reference image in the area outside the mask pattern are compared to detect the defect. The method of claim 1, further comprising the steps of: The defect is redetected without the mask pattern. The method of claim 1, further comprising at least one of the following steps: redetecting the defect without the mask pattern with a reduced search area, and The defect is re-detected without the mask pattern using a field of view around the detected defect location. The method of claim 2, further comprising: A defect profile of the defect is determined. The method of claim 4, further comprising: Generate a one-class image view of the defect. The method of claim 2, wherein the defect is re-detected using the defect image, or wherein the defect is re-detected using another defect image generated at a resolution different from the defect image. The method of claim 3, wherein the defect is re-detected using the defect image, or wherein the defect is re-detected using another defect image generated at a resolution different from the defect image. The method of claim 4, wherein the defect is re-detected using the defect image, or wherein the defect is re-detected using another defect image generated at a resolution different from the defect image. The method of claim 5, wherein the defect is re-detected using the defect image, or wherein the defect is re-detected using another defect image generated at a resolution different from the defect image. The method of any one of claims 1 to 9, wherein the defective image is generated at a defective pixel on the substrate, and wherein the reference image is generated at a pixel adjacent to the defective pixel. The method of any one of claims 1 to 9, wherein the defective image is generated at a defective pixel on the substrate, and wherein the reference image is generated at a pixel adjacent to the defective pixel. The method of any one of claims 1 to 9, wherein the defect image and the reference image are generated by a scanning electron beam. The method of any one of claims 1 to 9, wherein the defect image is measured by an intensity signal of signal electrons of a charged particle beam device. The method of any one of claims 1 to 9, wherein a field of view is measured with a digital scanner. The method of claim 14, wherein the field of view has at least one of a dimension of 200 μm or less and a dimension of 5 μm or greater. The method of any one of claims 1 to 9, further comprising the step of: repeating the defect inspection measurement on one or more additional areas of the substrate, the areas being distributed over at least 1.2 m ² . An apparatus for imaging a portion of a substrate, the apparatus comprising: a vacuum chamber; a substrate support disposed in the vacuum chamber; a first imaging charged particle beam microscope; and A controller includes: a processor and a memory that stores instructions that, when executed by the processor, cause the apparatus to perform the method of any one of claims 1-9. The apparatus for imaging a portion of a substrate of claim 17, wherein the substrate receiving area has a first receiving area size along a first direction, the apparatus further comprising: A second imaging charged particle beam microscope, wherein the first imaging charged particle beam microscope and the second imaging charged particle beam microscope have a distance along the first direction that is 30% to 70% of the size of the first receiving area . The apparatus for imaging a portion of a substrate of claim 18, wherein the second imaging charged particle beam microscope is at a distance of at least 30 cm from the first imaging charged particle beam microscope along the first direction . A method of operating a device as claimed in any one of claims 18 to 19, comprising the steps of: A first coordinate system on the substrate of the first imaging charged particle beam microscope is matched with a second coordinate system on the substrate of the second imaging charged particle beam microscope.

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