Method for implementing topography, and topography measuring instrument

Abstract

To provide a method for implementing a topography measurement presenting better results than a conventional art.SOLUTION: A topographic measurement method includes provision of a sample including first surface provided with plurality of salient patterns (2). A first surface of a sample (1) is illuminated by structured light that defines several repetitive patterns. The structured light is emitted at a first angle (α) with respect to the first surface. A first image of the first surface of the sample (1) illuminated by the structured light is acquired. The first image is acquired at a second angle (β) with respect to the first surface. A second image of the illuminated sample (1) is acquired. The second image differs in a value of an exposure time from the first image. The first image is compared with the second image so as to determine existence of at least one artifact on the first image. A reference image is formed from the first image and second image. The reference image does not have any artifact. A quantity representing the first surface is calculated from the reference image.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for performing topography measurement and a topography measuring instrument.

Background Art

[0002] In many technical fields, components protruding from a main surface are used. To grasp the shape and dimensions of these protruding parts, meticulous attention must be paid. The protruding parts are, for example, conductive pads that will function as electrical contacts for an electronic chip or any other electronic device. By appropriately grasping the dimensions of the protruding parts, it becomes possible to achieve high-performance electrical contacts.

[0003] It is important to be able to measure the shapes and dimensions of a plurality of protruding parts as accurately and quickly as possible.

[0004] It is known to perform measurement of the dimensions of protruding parts using an optical method. The surface of a sample having a plurality of protruding parts is irradiated with texture light. The texture light defines a plurality of repeated patterns irradiated on the surface of the sample.

[0005] Some images of the surface of the sample illuminated by the texture light are acquired. By analyzing different images, the dimensions and shape of the protruding parts can be calculated.

[0006] The quality of the measurement greatly depends on the quality of the acquired images. Therefore, there is a need to improve the quality of the images used in the step of calculating the dimensions and shape of the protruding parts.

Summary of the Invention

Problems to be Solved by the Invention

[0007] One object of the present invention consists of providing a method for performing topography measurement that presents better results than the methods of the prior art. [Means for solving the problem]

[0008] This result tends to be achieved by the method used to perform the topographic measurement, and the method is - To provide a sample having a first surface provided with multiple protruding patterns, - To acquire multiple images of a first surface of a sample, wherein the multiple images include a reference image of the sample, each reference image corresponds to a sample illuminated with structured light, and the structured light of each reference image defines several repeating patterns, and the images are different from each other in terms of the phase and / or frequency of the repeating patterns. The method includes a plurality of images comprising at least a first series of images of a first surface of a sample, the first series of images being acquired when the first surface of the sample is illuminated by a first structured light, the first structured light defining several repeating patterns, and the images of the first series of images differ from each other depending on the angle of illumination of the first structured light to the first surface. -Comparing images of a first set of images to determine the presence of at least one artifact on at least one image of the first set of images, - Forming at least one processed image from at least a first series of images, wherein the at least one processed image is devoid of the at least one artifact or the degree of the at least one artifact is reduced. -Calculate at least one quantity representing a sample from at least one processed image and a reference image. It is noteworthy in that respect.

[0009] Preferentially, the first series of images includes the reference image, and at least one processed image replaces that reference image.

[0010] Preferably, multiple images have a first set of images, each containing an image of a reference image. Each first set of images is used to form a processed image that lacks or has reduced artifacts to at least one. Each processed image replaces one of the reference images.

[0011] Preferably, the multiple images include at least a second series of images of a first surface of the sample, the second series of images being acquired when the first surface of the sample is illuminated by a first structured light, the images in the second series differ from each other by the exposure time of the images in the second series, and the illumination angle of the first structured light is constant with respect to the second series of images and corresponds to one of the angles of the first series of images. The measurement method is, -Comparing images in a second set of images to determine the presence of at least one artifact in at least one image of the second set of images, - Forming at least one processed image from at least a second series of images, wherein the at least one processed image is devoid of or has a reduced degree of the artifact. Includes.

[0012] Preferentially, the second set of images includes the reference image. At least one processed image formed from the second set of images replaces the reference image.

[0013] Prioritizing the reference image, the image belongs to the first series of images and the second series of images. The first series of images and the second series of images are used to form a processed image that replaces the reference image.

[0014] Preferably, multiple images have several second sets of images, each containing an image of the reference image. Each second set of images is used to form a processed image that lacks or has reduced artifacts to at least one. Each processed image replaces an image of the reference image.

[0015] Preferably, the multiple images include at least a third series of images of the first surface of the sample, the third series of images being acquired when the first surface of the sample is illuminated by a second structured light, the images in the third series of images differ from each other by the color of the structured light, and the illumination angle of the second structured light is constant with respect to the third series of images and corresponds to one of the angles of the first series of images. The measurement method is, -Comparing images of a third set of images to determine the presence of at least one artifact on at least one image of the third set of images, - Forming at least one processed image from at least a third series of images, wherein the at least one processed image is devoid of or has a reduced degree of the artifact. Includes.

[0016] The preferred method involves comparing the images of a first series of images to identify displacements of areas that exhibit a greater luminosity than the average luminosity of the first series of images, depending on the illumination angle of the first structured light, and the artifact is a spurious reflection.

[0017] Prioritizing the comparison of the first series of images, this involves identifying the degree of correction in areas that present a lower luminosity than the average luminosity of the first series of images, depending on the illumination angle of the first structured light, and the artifact is a shadow.

[0018] Prioritizing the comparison of images from a first series of images, this includes extracting repeating patterns of light intensity modifications resulting from structured light and comparing said light intensity modifications.

[0019] A further object of the present invention is to provide a topographic measuring device that presents improved performance compared to prior art machines and enables more accurate calculation of the amount of sample.

[0020] This result tends to be achieved by a topographical measuring device, which - a support having a surface designed to support a sample, <000008^>- projection means configured to emit different structured light, each structured light defining several repetition patterns and being different from each other by the phase and / or degree of the repetition pattern, - image capture means configured to acquire an image of a sample illuminated by one of the different structured lights, - a control circuit configured to acquire several reference images of a sample illuminated by different structured lights, each structured light of the reference images defining several repetition patterns and being different from each other by the phase and / or degree of the repetition pattern, comprises.

[0021] The topographic measuring device - the projection means is configured to define several irradiation angles of the structured light with respect to the surface of the support, - the control circuit is configured to acquire a first series of images of a sample illuminated by a first structured light, the first structured light defining several repetition patterns, and the images of the first series of images being different from each other by the irradiation angle of the first structured light with respect to the surface of the support, - the control circuit is configured to compare the images of the first series of images so as to determine the presence of at least one artifact on at least one image of the first series of images, - The processing circuit is configured to form at least one processed image from at least a first series of images, and the at least one processed image lacks the at least one artifact or has a reduced degree of the at least one artifact. - The processing circuit is configured to calculate at least one quantity representative of a sample from the at least one processed image and a reference image. This is worthy of note.

[0022] Other advantages and features are given for illustrative purposes only and will become more clearly apparent from the following description of specific embodiments and implementation modes of the invention, which are represented in the accompanying drawings.

Brief Description of the Drawings

[0023] [Figure 1] A topographic measuring instrument is schematically shown. [Figure 2] It is a photograph of a sample having a protruding pattern in the form of a hemisphere illuminated by uniform light. [Figure 3] A method for performing topographic measurement is schematically shown.

Modes for Carrying Out the Invention

[0024] When the sample has one or more protruding parts arranged to protrude from the first surface of the substrate, it is effective to characterize the sample, preferably the protruding part or the plurality of protruding parts, that is, to calculate the quantity representing the sample, and more preferably, to calculate the quantity representing the protruding part or the plurality of protruding parts. A rapid way to do this is to use optical property evaluation to take several images of the sample. Therefore, it is important to obtain high-quality images and accurately estimate the quantity of the sample, more specifically, the quantity of the protruding part, as accurately as possible.

[0025] In the first step S1 shown in Figure 3, a sample 1 is provided, which has a first surface on which a plurality of protrusion patterns 2 (see Figure 1) are provided. The sample 1 is placed on a support 3. The protrusion patterns 2 can be of any shape. However, it is particularly useful if the protrusion patterns 2 are spherical or hemispherical, conical, linear pads, or other simple shapes that facilitate the calculation of the shape of the protrusion patterns 2 and the calculation of the lateral dimensions. The lateral dimensions are dimensions measured perpendicular to the axis of the perpendicular to the support 3 supporting the sample 1, which also represents the perpendicular to the first surface. The perpendicular to the first surface is represented by line A shown in Figure 1, which indicates that a topographic measuring instrument can perform the measurement method.

[0026] The protruding pattern 2 can be fabricated from any possible material. However, this method has been found to be particularly effective when the protruding pattern 2 is fabricated from a metallic material, or more generally, from a light-reflecting material. Patterns fabricated from metallic materials have been observed to reflect light, which has the effect of producing artifacts. Furthermore, when texture light is emitted from the projection means 4 onto the protruding pattern 2, a shadowing phenomenon has been observed in which one surface of the protruding pattern 2 is illuminated better than the other surface. This phenomenon is exacerbated as the distance from the perpendicular to the first surface increases.

[0027] The topographic measurement method includes illuminating a first surface of sample 1 with structured light. The structured light defines several repeating patterns, such as several stripes. The illumination of the first surface is performed by projection means 4. The structured light may be a grayscale image or other color hues, and possibly black and white. The structured light defines a pattern that is repeated at a predetermined frequency and phase. The projection means 4 preferably comprises a projector configured to project structured light, preferably within the visible range.

[0028] The structured light preferably forms a striped pattern of the moiré or "shadow moiré" type, for example. In one embodiment, the projector directly emits the striped pattern. In an alternative embodiment, the structured light is formed by a mask through which the light emitted from the projector passes. The mask comprises, for example, openings and opaque areas in the form of a Ronchi grid. It is also possible to combine these two techniques.

[0029] The measurement method includes acquiring multiple images of the first surface of sample 1 in step S2, and in particular multiple reference images in step S2a.

[0030] The reference image includes deformation of the repeating pattern of structured light on the surface of the sample. The irradiation angle of the structured light is known as the repeating pitch of the repeating pattern, from which the deformation of the repeating pattern can be estimated, and therefore information about the quantity on the sample can be estimated. By using several repeating patterns that differ from each other in terms of repeating pitch and phase (and sometimes using the size of the repeating patterns), the quantity on the sample can be calculated.

[0031] In step S4, the reference image is used to calculate at least one quantity of the sample, preferably a quantity representing multiple protrusion patterns 2. In the preferred mode, the reference image is used to calculate at least one quantity selected from the coplanarity of the protruding part, the shape of the protruding part in the cross-sectional plane, i.e., perpendicular to line A, the repeating pitch of the protruding part in one or more directions perpendicular to line A, the lateral dimension of at least one of the protruding patterns, i.e., perpendicular to line A, and the height of one or more protruding patterns, i.e., the dimension along line A.

[0032] To acquire an image, it is effective to use an image acquisition means 5 configured to acquire an image of the first surface of sample 1. The image acquisition means 5 preferably comprises a camera positioned to capture structured light irradiated onto the surface of sample 1. The camera is designed to provide topographic measurements of the system surface from the captured structured light. In the illustrated embodiment, the optical axis of the image acquisition means 5 coincides with a perpendicular A to the surface of the support 3.

[0033] To characterize a sample, it is effective to irradiate it with different structured light in succession. The structured light defines a repeating pattern, preferably a fringe. To perform characterization of the sample, multiple reference images of the first surface of sample 1 will be acquired in step S2a. Each reference image is acquired using a different structured light. The structured light has different phases and / or frequencies of repeating patterns. By changing the frequency, it is also effective to change the repeating pitch of the repeating pattern, and to change the width of the pattern, especially the width of the fringes. By changing the phase, the position of the fringes on the sample is changed, and white areas become black areas or grayscale areas. By changing the phase and frequency of the pattern, a person skilled in the art can characterize sample 1. The change in intensity representing the transition from white areas to black areas may be sinusoidal, triangular, stepped, or any other preferred form.

[0034] By acquiring several reference images that differ from each other based on repeating patterns, preferably the phase and frequency of the stripes, a quantity representing the sample can be calculated.

[0035] Different reference images are analyzed together to determine the sample's topography using known techniques. Deformations of stripes on the sample's surface are observed to estimate the sample's characteristics, and preferably the characteristics of protruding patterns from them.

[0036] The distance between two protruding patterns 2, the height of each protruding pattern 2, the lateral dimension of each protruding pattern 2, the shape of each protruding pattern 2, and the planarity of the surface receiving each protruding pattern 2 can be calculated. For each protruding part 2, the mathematical surface passing through the highest point of the protruding pattern (along line A) can also be calculated. Furthermore, the coplanarity of the peaks of the protruding patterns 2 can be calculated, i.e., whether the peaks of the protruding patterns 2 belong to the same plane, and, if applicable, the amplitude (along line A) of the surface passing through all the peaks of the protruding patterns 2 can be determined. The properties of the surface passing through the peaks of the protruding patterns 2 and / or the properties of the substrate surface supporting the protruding patterns 2 can also be calculated. The property calculations can be of the bowing and torsion type.

[0037] However, these images present artifacts that hinder a more accurate characterization of Sample 1; therefore, it is important to perform the acquisition of additional images to achieve a finer characterization of the sample and, preferentially, the amount representing the protruding pattern.

[0038] The structured light is emitted at a first angle α with respect to the first surface. The projection means 4 projects structured light having a first angle α with respect to the first surface of the sample 1, also called the irradiation angle α. The first angle α is measured with respect to the perpendicular to the surface of the support 3 that supports the sample, which substantially corresponds to the perpendicular to the first surface of the substrate that receives the protruding pattern. Other configurations are also possible.

[0039] To improve the quality of characterization, it is useful to acquire several images under different conditions so that the presence of artifacts can be determined and these artifacts can be eliminated or at least their severity reduced. The additional images taken can be used to replace a reference image with another calculated reference image to reduce the degree of at least one artifact, or even eliminate at least one artifact, or to add a reference image to an already taken reference image to reduce the weight of artifacts. This allows for a more accurate calculation of the quantitative characteristics of the sample.

[0040] In step S2b, it is useful to acquire at least a first series of images of the first surface of sample 1. The first series of images is acquired when the first surface of sample 1 is illuminated by first structured light. The first structured light defines several predetermined repeating patterns, and the images in the first series of images differ from each other depending on the irradiation angle α of the first structured light on the first surface.

[0041] The projection means 4 is configured to irradiate the same first structured light having a first angle α of different values. The first angle α is preferably measured between the optical axis of the projection means 4 and a perpendicular to the plane of the support 3 receiving the sample. Depending on the configuration, the projection means 4 includes a mobile projector that moves to define multiple angles α. It is also possible to have several projectors, each projector associated with a predetermined angle. Furthermore, it is possible to have several mobile projectors.

[0042] The first angle α is effectively comprised of 5° to 175°, preferably 10° to 170°, more preferably 25° to 155°, and even more preferably 25° to 55° and 115° to 155°. Angle comprised of 0° to 90° corresponds to one side of the sample, i.e., one side of the support, and therefore one side of the image acquisition means 5, for example, the projection means 4 located on the right side of Figure 1. On the other hand, angle comprised of 90° to 180° corresponds to the other side of the sample, i.e., the other side of the support, and therefore the other side of the image acquisition means 5, for example, the projection means 4 located on the left side of Figure 1. For example, by using two projections, the projection means 4 can continuously illuminate two opposing surfaces of the protruding pattern 2, making it easier to better define the contour of the protruding pattern 2.

[0043] Of the multiple images, a first series of images of at least the first surface of sample 1 is acquired. The first series of images is acquired when the first surface of sample 1 is illuminated by first structured light. The first structured light defines several repeating patterns.

[0044] When light emission reflection occurs between the protruding patterns 2, it has been observed that some of the emitted structured light is reflected back toward the acquisition means 5 in the form of specular reflection, creating the appearance of a very bright area on at least a portion of the image. The very bright area is an area with a luminosity higher than the average luminosity of the image. The very bright area is a low-contrast area that makes it more difficult or hinders the observation of the characteristics of the structured light pattern, particularly the changes in light intensity. Spurious reflection, more specifically specular reflection, produces insufficient local contrast of the projected repeating pattern. Low contrast introduces artifacts, reducing the accuracy of topographic reconstruction calculations. Therefore, it becomes more difficult to characterize the sample, for example, the features of the protruding pattern, more specifically, the edges of the protruding pattern 2, the shape of the protruding pattern 2, or the raised areas. This very bright area creates artifacts that make it more difficult to measure the quantity representing the protruding pattern 2. By modifying the illumination angle α, the reflection points of the emitted structured light can be displaced, and therefore the position of the very bright area between the first series of images can be displaced. By comparing the positions of very bright areas on a first series of different images according to the value of the illumination angle α, it is possible to identify the displacement of the very bright areas according to the illumination angle α, thereby enabling the determination of the presence of artifacts, in this case spurious reflection or refraction.

[0045] By adjusting the irradiation angle α, it becomes possible to correct the shadow phenomenon, thereby enabling the determination of the edges of the protrusion pattern 2 while maintaining the structured light emitted from the same side of the support, and therefore the sample. The shadow results in the appearance of low-luminosity areas, i.e., low-contrast areas. Due to the low contrast, it is difficult to observe the repeating pattern of structured light, and therefore it is difficult to preferentially calculate the protrusion pattern 2 to obtain relevant information about the sample.

[0046] Furthermore, by adjusting the irradiation angle α, the effect of multiple reflections between protruding patterns can be reduced. Multiple reflections involve the reflection of projected intensity from another location on the sample to the image acquisition means 5. This causes localized distortion in the reconstruction calculation. To reduce the effect of multiple reflections, it is also effective to modify the frequency and / or pitch of the texture light.

[0047] For illustrative purposes, Figure 2 shows Sample 1, which has a substrate covered with a substantially hemispherical projection pattern. The sample is illuminated by uniform white light shining at an angle equal to 45°. It is clear that not all projection patterns reflect light in the same way, and that all projection patterns present both specular and shaded areas. It is also clear that the central projection pattern presents several reflection points representing reflections from adjacent projection patterns.

[0048] In a typical configuration, adjusting the irradiation angle α makes it possible to determine the presence of at least one artifact that appears as a high-luminosity or low-luminosity area as a result of reflection and refraction phenomena.

[0049] By adjusting the illumination angle α, it becomes possible to acquire multiple images, making it easier to determine the characteristics of repeating patterns, thereby reducing the degree of artifacts and / or displacing artifacts, which allows for better determination of the quantity representing the sample and provides sufficient contrast to identify the presence of at least a portion of the repeating pattern of the texture light.

[0050] The images in the first series differ from one another depending on the value of the irradiation angle α of the first structured light onto the first surface. By adjusting the irradiation angle α, the interaction between the sample and the structured light is modified. Each image corresponds to a known value of the irradiation angle α. By adjusting the irradiation angle α of the first light, the size of the shadow area and the angle of projection of the structured light onto the sidewall of the protruding pattern 2, and therefore the reflection and refraction, are modified.

[0051] By acquiring several images to form a first series of images, it becomes possible to observe the repeating pattern of structured light more effectively, thereby allowing for preferential and better identification of the dimensional characteristics of the protruding pattern 2 when the first series of images includes images emitted by projection means 4 positioned in opposite directions, i.e., at angles with positive and negative values, i.e., on one side or the other side of sample 1.

[0052] It is particularly effective to have images of a first series of images corresponding to different values ​​of the irradiation angle α, emitted from the same side of the sample and / or from the same side of the image acquisition means 5. For example, when the first light is irradiated onto the sample 1, at least two or at least three images are acquired, the images differ from each other depending on the value of the irradiation angle α, and the first light is emitted from the same side of the support 3. For example, the three images are acquired for three different values ​​of angle α that differ from each other by at least 10°. For example, the three images are acquired for angles α consisting of 80° to 10°, preferably 70° to 20°, and more preferably 60° to 30°, for example, 55°, 45° and 35°.

[0053] The use of several images associated with an angle α value having a difference of preferably less than 30°, preferably less than 20°, and even more preferably 15° or 10°, makes it easier to monitor artifact displacement due to the illumination angle α. The difference in angle α between images is preferably greater than 1°, and more preferably greater than 5°.

[0054] Furthermore, it is also beneficial that the first series of images includes images at different angles α relative to the structured light emitted from one side of the sample, and several images at different angles α relative to the structured light emitted from the other side of sample 1. The two sides of sample 1 are illuminated under several different conditions to improve the quality of the quantitative property calculations of sample 1.

[0055] In step S3a, the images of the first series of images are used to form a processed image that will either form an additional reference image or replace one of the reference images.

[0056] In step S3a, it is useful to compare the images of the first set of images to identify the presence of one or more artifacts corresponding to areas with low luminosity or areas with high luminosity, i.e., low-contrast areas.

[0057] When artifacts or multiple artifacts are identified, the first set of images is used to form a processed image that represents the sample and lacks at least one of the identified artifacts or the degree to which the artifacts are reduced.

[0058] The first series of images can be used in various ways. To form a processed image, corresponding to a stack of multiple first images that form the first series of images and are added to each other in the form of traces having areas with different weights, for example, it is possible to identify areas representing artifacts on the images and search for the same areas without artifacts in other images.

[0059] In a particularly effective manner, it is beneficial to process the images of a first series of images to identify the first structured light pattern and extract modifications of the structured light that preferentially define repeating patterns. For example, if the structured light defines grayscale fringes represented by sinusoidal fluctuations in intensity, it is effective to search for these sinusoidal fluctuations in the images. As the fringes are deformed by the sample, the fluctuations become more necessarily sinusoidal, but the fluctuations are transmissible between images since the degree is known as the illumination angle α. It is then possible to compare the images by comparing the fluctuations in the intensity of the structured light to estimate the deformation of the pattern on the surface of the sample, since the illumination angle α is known. This configuration is particularly effective because it allows for disregarding the fluctuations in light intensity on the protruding pattern 2 caused by fluctuations in the illumination angle α. The processed image is represented by the fluctuations in light intensity on the sample. This processed image is used together with a reference image that also contains the fluctuations in light intensity on the sample to provide a better quality characterization.

[0060] In a valid format, the first series of images is one of the reference images. Next, a processed image is formed to replace the reference image in the first series of images. The processed image is of better quality than the reference image it replaces because artifacts have been eliminated or reduced.

[0061] In a more effective approach, several first sets of images are acquired, each containing one of the reference images. Each first set of images allows for the creation of a processed image designed to replace the reference image, thereby improving the calculation of features for sample 1.

[0062] Prioritizing this approach, several initial series of images will use the same illumination angle α value.

[0063] In a particularly effective configuration, the first series of images are acquired simply by changing the illumination angle α to facilitate comparison between high-luminosity and low-luminosity areas. For example, the first series of images are acquired without changing the exposure time, the texture light pattern, the color of the texture light, or the angle of the acquisition means. It is also effective that the sample is at the same temperature for different images in the first series of images. Thus, comparison of the images in the first series is performed more easily.

[0064] To further improve the characterization of the sample, it is beneficial to acquire at least a second series of images in step S2c. Of the multiple images, at least a second series of images of the first surface of sample 1 are acquired. The second series of images are acquired when the first surface of sample 1 is illuminated by the first structured light.

[0065] The images in the second series differ from each other due to different exposure time values ​​of the image acquisition means 5. Strongly illuminated areas correspond to overexposed areas of the image. Conversely, weakly illuminated areas correspond to underexposed areas. By correcting the exposure time between images in the second series, an image is obtained that presents artifacts with surfaces that change depending on the exposure time.

[0066] By reducing the exposure time, the surface area of ​​the overexposed area is reduced, thereby limiting the degree of artifacts and thus the amount of unusable information. By increasing the exposure time, the surface area of ​​the underexposed area is reduced, thereby limiting the degree of artifacts and thus the amount of unusable information. By adjusting the exposure time between multiple images in a second series of images, it becomes easier to monitor variations in the intensity of the repeating pattern of the first texture light.

[0067] By processing a second series of images, it becomes possible to more accurately calculate the light intensity fluctuations representing the repeating pattern of structured light. Therefore, it is possible to form a processed image in which the repeating pattern of structured light is better defined. In the effective method, the light intensity fluctuations of the structured light on the sample are extracted from the second series of images. The light intensity fluctuations are used to define a new image free of at least one artifact. In the preferred method, at least four images with four different exposure time values ​​are acquired and used to form the processed image.

[0068] In step S3b, the images of the second series of images are used to form at least one processed image designed to form an additional reference image or to replace a reference image.

[0069] In the preferred configuration, the second set of images includes at least one of the reference images, and preferably, the reference image of the second set of images may also be common to the first set of images. This makes it possible to use the first and second sets of images to form a higher quality processed image by reducing the number and / or degree of artifacts.

[0070] In this case, it is particularly effective to obtain a second set of images, each having a reference image, and, more preferably, a reference image common to one of the first sets. In this way, it is possible to significantly improve the quality of some of the reference images, thereby improving the quality of calculations of the quantities representing the samples.

[0071] In the preferred configuration, the exposure time is shortened with respect to the time used for the reference image, to facilitate the measurement of the repeating pattern of structured light on the surface of the substrate receiving the protrusion pattern 2. This image allows for improved measurements of the flatness of the surface receiving the protrusion pattern 2.

[0072] In the preferred configuration, the exposure time ratio between the shortest time and the longest time is equal to at least 1.3, preferably at least 1.6, more preferably at least 2, and even more preferably at least 5. A larger exposure time ratio makes it easier to distinguish between very bright areas and dimly bright areas, which generally correspond to information from the substrate supporting the protruding pattern 2 and information from the reflective area of ​​the protruding pattern 2.

[0073] When the acquisition of the second series of images is performed, it is particularly effective to preferentially keep other parameters, especially those related to structured light, illumination angle, and observation angle constant.

[0074] In yet another preferred embodiment, at least a third series of images are acquired. The method includes step S2d, which comprises acquiring at least one image of a sample illuminated by a second structured light. The second structured light differs from the structured light used to acquire a reference image, preferably one of the first series, by the color of the emitted light. The repeating pattern is identical to that of the structured light of at least one reference image, i.e., identical in phase and frequency. Color correction can be used to improve the contrast depending on the material used to form the protruding pattern 2 and / or the substrate receiving the protruding pattern 2.

[0075] In step S3c, the image of the third set of images is used to form an image that lacks at least one artifact. It is effective that the third set of images has one of the reference images. The image of the third set of images is then used to form a processed image that is designed to form an additional reference image or to replace one of the reference images.

[0076] It may be effective to obtain several third sets of images, each containing one of the reference images. These third sets of images are used to replace the reference images.

[0077] The projection means 4 may be configured to modify the color of the structured light. It is effective for the projection means 4 to be configured to deliver white light in a black or grayscale pattern. It is also effective for the projection means 4 to be configured to deliver light of another color, such as red, blue, green, yellow, orange, or violet light, in a black or grayscale pattern or multiple patterns of another color.

[0078] In yet another embodiment, at least a fourth series of images are acquired. The method includes step S2e, which comprises acquiring at least one image of a sample illuminated by a first structured light. The images of the fourth series of images differ from the reference image by using a different acquisition angle than that used by the image acquisition means 5.

[0079] The image acquisition means 5 is positioned to acquire at least one image at a second angle β, also called the acquisition angle, which is different from the first angle. The second angle β is the angle between the optical axis of the image acquisition means 5 and an axis perpendicular to the support 3 designed to support the sample. The image acquisition means is then mounted on a mobile device and / or several acquisition means are used. By correcting the acquisition angle, it becomes possible to correct the position of overexposed and underexposed areas.

[0080] In step S3d, the images of the fourth set of images are used to form an image that lacks at least one of the artifacts. It is useful that the fourth set of images has one of the reference images. The images of the fourth set of images are then used to form a processed image that is designed to form an additional reference image or to replace one of the reference images. Defining pairs of acquisition angle and illumination angle makes it possible to define the sensitivity of measurement in direction A. By modifying either the acquisition angle or the illumination angle, or both, it is possible to determine pairs of angles that achieve a sensitivity of measurement in direction A that is greater than the threshold, or even the best threshold. However, one drawback of this embodiment is that superimposing images becomes more difficult because it requires additional calculations aimed at deforming the acquired image to make it closer to the previous image. In the fourth set of images, it is useful to acquire another first set of images, or yet another second set of images or another third set of images, in order to calculate another surface of the protruding part. Thus, in order to improve the accuracy of the calculation, it is possible to use two surfaces calculated for the same protruding element under different conditions.

[0081] In a general form, the measurement method includes step S3, which comprises forming at least one processed image using a first series of images and preferably at least one of a second, third, and fourth series of images.

[0082] It is effective to generate a second series of images for different conditions present in the first series of images, i.e., for different values ​​of the irradiation angle α. Multiple second series of images make it possible to improve the image quality of the first series of images, thereby making it possible to form a higher quality processed image using only the first series of images, or only the first series of images and a single second series of images.

[0083] By associating a first set of images with one or more second sets of images that share the same image, better artifact elimination and / or greater reduction of artifact surface can be achieved.

[0084] The reference images resulting from the first acquisition, the replacement by the processed image, and / or the added processed image are used, as is known to those skilled in the art, to identify the deformation of the repeating pattern of textured light in order to calculate at least one quantity representing the sample.

[0085] In the preferred method, the images of the first set of images are compared to identify the brightest and least bright pixels to determine the locations of reflection and / or refraction. The location of the brightest pixel is useful for determining the location of specular reflection.

[0086] The measuring instrument comprises a structured light-emitting element 4 configured to illuminate at least a first surface of sample 1 in a repeating pattern, and an image acquisition device 5 configured to capture multiple images of the first surface of sample 1.

[0087] The measuring instrument also includes a control circuit 6 configured to define conditions for acquiring multiple images by an image acquisition device 5 and to acquire at least a first image of the first surface of sample 1. The measuring instrument may also include a memory 7 configured to store multiple images.

[0088] Furthermore, the measuring instrument preferably includes a first moving device 8 configured to correct the inclination angle α of the light-emitting element 4 with respect to the first surface, and therefore with respect to the surface of the support 3. In a preferred configuration, the measuring instrument also includes a second moving device 9 configured to correct the inclination angle of the image acquisition device 5 with respect to the first surface, and therefore with respect to the surface of the support 3.

[0089] The control circuit 6 is configured to acquire several reference images of sample 1 illuminated by different structured light. Each of the structured light in the reference images defines several repeating patterns, which differ from one another by the phase and / or frequency of the repeating patterns. The control circuit is configured to acquire a first series of images of the sample illuminated by a first structured light. The first structured light defines several repeating patterns, and the images in the first series of images differ from one another by the irradiation angle α of the first structured light on the surface of the support 3.

[0090] The control circuit 6 is configured to compare the images of the first series of images to determine the presence of at least one artifact on at least one of the images in the first series of images.

[0091] The processing circuit 10 is configured to form at least one processed image from at least a first series of images, wherein the at least one processed image is devoid of the at least one artifact or has a reduced degree of the at least one artifact. The processing circuit 10 is configured to calculate at least one quantity representing a sample from the at least one processed image and a reference image.

[0092] In a privileged embodiment, sample 1 is placed within a housing located inside a topographic measuring instrument. The housing has a glossy first surface, and the projector is located outside the housing. Structured light passes through the transparent portion of the housing and reaches the first surface of sample 1. Image acquisition means 5 may include a camera, which, if present, is located outside the housing. The camera is positioned to capture structured light that is irradiated onto the surface of sample 1 and propagates through the transparent portion of the housing, more precisely through the glossy second surface of the housing.

Claims

1. To provide a sample (1) having a first surface on which multiple protruding patterns (2) are provided, Obtaining a plurality of images of the first surface of the sample (1) illuminated by structured light irradiated at an irradiation angle to the first surface of the sample (1), wherein each structured light defines a plurality of repeating patterns, each structured light is defined by the phase and frequency of the repeating patterns, and the plurality of images are A plurality of reference images of the sample (1), wherein each reference image corresponds to the sample (1) illuminated at the same first irradiation angle among the irradiation angles, and the reference images differ from each other in terms of the phase and / or frequency of the repeating pattern, A first series of images of the first surface of the sample (1), wherein the first series of images is obtained when the first surface of the sample (1) is illuminated by the first structured light of the structured light, and each image in the first series of images is different from one another depending on the irradiation angle (α) of the first structured light on the first surface. The acquisition of the aforementioned multiple images, The process involves comparing each of the first series of images with one another to determine the presence of at least one artifact in at least one of the images in the first series of images, Forming at least one processed image from the first series of images, wherein the at least one processed image lacks the at least one artifact or the degree of the at least one artifact is reduced. Calculating at least one quantity representing the sample from the at least one processed image and the reference image, A method for performing topographic measurements, including [specific details omitted].

2. A method for performing a topographic measurement according to claim 1, wherein the first series of images includes a first reference image among the plurality of reference images, and the at least one processed image replaces the first reference image in order to calculate the at least one quantity representing the sample.

3. A method for performing a topographic measurement according to claim 2, wherein the plurality of images include an additional first series of images, the additional first series of images is used to form an additional processed image having at least one artifact missing or reduced artifact, the additional processed image replaces the additional reference image, and the structured light of the additional first series of images is different from the structured light of the first series of images by the phase and / or frequency of the repeating pattern.

4. The plurality of images include at least a second series of images of the first surface of the sample (1), the second series of images are acquired when the first surface of the sample (1) is illuminated by the first structured light, the images of the second series of images differ from each other depending on the exposure time of the images of the second series of images, the irradiation angle (α) of the first structured light is constant with respect to the second series of images and corresponds to one of the angles of the first series of images, and the measurement method is Comparing the images in the second series of images to determine the presence of at least one artifact in at least one of the images in the second series of images, Forming at least one processed image from at least the second series of images, wherein the at least one processed image is devoid of or has a reduced degree of the at least one artifact. A method for performing a topographic measurement according to any one of claims 1 to 3, including the following:

5. A method for performing a topographic measurement according to claim 4, wherein the second series of images includes images of the plurality of reference images, and the at least one processed image formed from the second series of images replaces the images of the plurality of reference images.

6. A method for performing a topographic measurement according to claim 5, wherein the image among the plurality of reference images belongs to the first series of images and the second series of images, and the first series of images and the second series of images are used to form a processed image that replaces the image in the reference images.

7. A method for performing a topographic measurement according to claim 4, wherein the plurality of images each have a second set of images, each of which includes an image of the reference image, and each second set of images is used to form a processed image that lacks or has reduced artifacts to at least one artifact, and each processed image replaces each of the plurality of reference images.

8. The plurality of images include at least a third series of images of the first surface of the sample (1), the third series of images are obtained when the first surface of the sample (1) is illuminated by a second structured light, the images of the third series of images differ from each other by the color of the structured light, the irradiation angle (α) of the second structured light is constant with respect to the third series of images and corresponds to one of the angles of the first series of images, and the measurement method is Comparing the images of the third series of images to determine the presence of at least one artifact on at least one of the images of the third series of images, Forming at least one processed image from at least the third series of images, wherein the at least one processed image is devoid of or has a reduced degree of the at least one artifact. A method for performing a topographic measurement according to any one of claims 1 to 3, including the following:

9. A method for performing a topographic measurement according to any one of claims 1 to 3, comprising comparing the first series of images to identify the displacement of an area that exhibits a higher luminosity than the average luminosity of the first series of images, depending on the irradiation angle (α) of the first structured light, wherein the artifact is a spurious reflectance.

10. A method for performing a topographic measurement according to any one of claims 1 to 3, comprising comparing the first series of images to identify the degree of correction of areas that present a lower luminosity than the average luminosity of the first series of images, depending on the irradiation angle (α) of the first structured light, wherein the artifact is a shadow.

11. A method for performing a topographic measurement according to any one of claims 1 to 3, wherein the comparison of the first series of images includes extracting and comparing the light intensity modifications of the repeating patterns resulting from the structured light.

12. A support (3) having a surface designed to support a sample (1), A projection means (4) configured to emit structured light onto the surface of the support, wherein the structured light includes a plurality of repeating patterns defined by phase and / or frequency, Image acquisition means (5) configured to acquire an image of the sample (1) illuminated by the structured light, A control circuit (6) is configured to acquire several reference images of the sample (1) illuminated by the structured light, wherein the structured light of the reference images differs from one another in phase and / or frequency of the repeating pattern and has a predetermined irradiation angle. Equipped with, The control circuit (6) is configured to acquire a first series of images of the sample illuminated by the first structured light, wherein the images of the first series of images differ from each other depending on the different irradiation angles (α) of the first structured light on the surface of the support (3). The control circuit (6) is configured to compare the images of the first series of images in such a way that it determines the presence of at least one artifact in at least one of the images of the first series of images. A processing circuit (10) configured to form at least one processed image from at least the first series of images, wherein the at least one processed image is devoid of the at least one artifact or the degree of the at least one artifact is reduced. The processing circuit (10) is configured to calculate at least one quantity representing the sample from the at least one processed image and the reference image. Topography measuring instrument.

Images