Topographic measuring device and topographic measurement method

Abstract

To provide a topographic measuring device.SOLUTION: A topographic measuring device comprises a sample holder 1 receiving a sample 2. A first projector 3 applies first textured light 4 to a first part of the sample. A second projector 5 applies second textured light 6 to a second part of the sample different from the first part. A first camera 7 observes the first textured light applied to the first part to acquire first images 8. A second camera 9 observes the second textured light applied to the second part to acquire second images 10. The second textured light has patterns with a second repetition pitch that is lower than a first repetition pitch of patterns of the first textured light.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a topography measurement apparatus and a topography measurement method.

Background Art

[0002] In many technical fields related to printed circuits, different materials are associated with specific patterns to form electrical or electronic functions. Since the volume of the printed circuit is not uniform, these patterns cause the printed circuit to deform anisotropically with temperature and time. Also, it is obvious that printed circuits generally have components protruding from the main surface. These protruding components must have the optimally acquired shape and size as much as possible. For example, a protruding component is a conductive pad that will function as an electrical contact for an electronic chip or any other electronic device. By knowing the dimensions of the protruding components, efficient electrical contact is ensured.

[0003] It is important to be able to measure the shapes and dimensions of a plurality of protruding components as accurately and quickly as possible. It is also important to know the general or specific deformations of the chip or printed circuit in order to predict the causes of malfunction.

[0004] Measurement of the dimensions of protruding components and the deformation of the chip is known to be performed using optical techniques. The surface of the sample is irradiated with texture light. The texture light forms a plurality of repeating patterns on the surface of the sample.

[0005] Some images of the surface of the sample irradiated with the texture light are acquired. By analyzing different images, the dimensions and shapes of the protruding components and / or the three-dimensional deformation of the chip can be calculated.

[0006] The quality of the measurement depends greatly on the quality of the acquired image and the characteristics of the texture light. The texture light defines several regions with color differences, generally black regions and white regions, and preferentially transitions through the middle tones. The resolution of the deformation measurement is determined by the distance between two black regions or two white regions. The measurement quality also depends on the resolution of the texture light, i.e., the distance between two white regions or two black regions. The resolution is limited by the technology for forming the texture light and also by physical limitations. Since the surface to be investigated is small, it is not possible to make the fringe density infinite.

[0007] Logically, the measurement quality is a function of the optical performance of the camera, i.e., the resolution of the image acquired by the camera, which corresponds to the number of pixels per unit length. For a given sample and a given camera, it is necessary to find a trade-off between the measurement resolution that can be established by the texture light and the measurement resolution of the camera. If the repeat pitch is much smaller than the resolution of the camera, it is meaningless to provide texture light with a very small repeat pitch. Conversely, a high-resolution camera will be limited by the resolution of the texture light with a coarse pitch.

[0008] To reasonably maintain the size and cost, it is not advantageous to have a camera with a large collection surface and a small resolution pitch. Also, it is non-productive to try to obtain texture light that is as fine as possible for measuring rough deformations of the sample. Depending on the type of deformation to be measured, it is necessary to match the characteristics of the texture light and the resolution of the camera. SUMMARY OF THE INVENTION

[0009] One object of the present invention is to provide a topography measurement device that presents a better trade-off between the ability to measure rough deformations and the ability to measure fine deformations.

[0010] This result tends to be achieved by a topography measurement device comprising the following.

[0011] - A sample holder designed to receive a sample, - A first projector designed to irradiate at least a first portion of the sample with a first texture light, - A second projector designed to irradiate at least a second portion of the sample with a second texture light, wherein the second portion is different from the first portion, - A first camera designed to observe the first texture light irradiated on the first portion of the sample to obtain a first series of images, - A second camera designed to observe the second texture light irradiated on the second portion of the sample to obtain a second series of images, - A control circuit connected to the first projector, the second projector, the first camera, and the second camera, configured such that the second texture light has a pattern with a second repetition pitch greater than a first repetition pitch of the pattern of the first texture light.

[0012] In an advantageous aspect, the second portion is adjacent to the first portion.

[0013] In a specific configuration, the second portion at least partially overlaps the first portion.

[0014] In an advantageous development, the first portion of the sample forms a ring around the second portion of the sample.

[0015] Preferably, the first projector defines a void area without a pattern. The second projector irradiates the void area without irradiating the pattern of the first texture light.

[0016] According to one embodiment, the control circuit is configured to simultaneously acquire images of the first series of images and the second series of images.

[0017] In an advantageous development, the control circuit is connected to at least one shutter configured to alternately block the transmission of the first texture light and the second texture light in the direction of the second part of the sample holder in order to prevent the overlap of the first texture light and the second texture light, or the control circuit is configured to alternately emit the first texture light and the second texture light.

[0018] Preferably, the control circuit is configured to acquire at least one image of the second series of images between two images of the first series of images within a certain period.

[0019] A further object of the present invention is to provide a method for performing topographic measurement of a sample, which can more easily perform measurement of rough deformation and fine deformation.

[0020] This result is - a step of placing a sample on a sample holder, - a step of applying a temperature lamp to the sample, - a step of irradiating a first texture light to a first part of the sample and a second texture light to a second part of the sample different from the first part of the sample, wherein the second texture light has a pattern with a second repetition pitch smaller than the first repetition pitch of the pattern of the first texture light, - a step of acquiring a first series of images of the first texture light irradiated to the first part of the sample during the temperature lamp, - a step of acquiring a second series of images of the second texture light irradiated to the second part of the sample during the temperature rise, - a step of processing the first series of images and the second series of images to measure a first deformation of the first part and a second deformation of the second part during the temperature lamp, is likely to be achieved by a method for performing topographic measurement of a sample including

[0021] In a preferred development, the second part is included in the first part. The first deformation is subtracted from the second deformation.

Brief Description of the Drawings

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

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DETAILED DESCRIPTION OF THE INVENTION

[0023] FIG. 1 shows a topography measurement apparatus having a sample holder 1 designed to support a sample 2. The topography measurement apparatus also includes a first projector 3 designed to irradiate at least a first portion 2a of the sample 2 with a first texture light 4, and a second projector 5 designed to irradiate at least a second portion 2b of the sample 2 with a second texture light 6. The second portion 2b is different from the first portion 2a.

[0024] The sample holder 1 has a first surface designed to receive the sample 2. The Z direction is the normal direction of the first surface.

[0025] Each of the first texture light 4 and the second texture light 6 forms several repeating patterns, for example, several stripes. The illumination of the surface of the sample 2 is performed by the first projector 3 and the second projector 5. The texture light can be an image with a gray shade or a shade of other colors, and in some cases, a black and white image. The texture light forms a pattern that repeats at a predetermined frequency and a predetermined phase. The projector is preferably projection means configured to project texture light in the visible range.

[0026] The texture light preferably forms a stripe pattern such as a moiré or shadow moiré pattern. In one embodiment, the projector directly emits the stripe pattern. In another embodiment, the texture light is formed by a mask through which the light coming from the projector passes. The mask includes, for example, apertures and opaque regions in the form of Ronchi rulings. It is also possible to combine these two techniques.

[0027] A predetermined pattern is irradiated onto the surface of the sample, and the shape of the irradiation pattern will change due to the topography of the sample. By analyzing the change in the shape of the pattern, the three-dimensional deformation of the sample can be calculated.

[0028] The topography measuring device includes a first camera 7 designed to observe the first texture light 4 irradiated on the first part 2a of the sample 2 and acquire at least a first series of images 8, and a second camera 9 designed to observe the second texture light 6 irradiated on the second part 2b of the sample 2 and acquire at least a second series of images 10. The second camera 9 is different from the first camera 7. Alternatively, the first camera 7 and the second camera 9 share the same detection sensor, but the images reach through two different paths by means of lenses and / or prisms so as to observe two different parts of the sample 2 placed on the sample holder 1.

[0029] The first camera 7 and the second camera 9 are imaging means for acquiring a series of images of the surface of the sample 2. The first camera 7 and the second camera 9 are arranged to capture the texture light irradiated on the surface of the sample 2. Preferably, the optical axes of the first camera 7 and the second camera 9 are parallel to the Z direction perpendicular to the surface of the sample holder 1 or exhibit a slight offset with respect to the Z direction.

[0030] Each camera acquires a series of images. Each series of images is compared with each other or with a reference in order to observe the deformation of the texture light and estimate the deformation of the sample 2 therefrom.

[0031] The images are sent to a calculation circuit A configured to calculate the deformation between the images and calculate the three-dimensional deformation of the sample 2.

[0032] The topography measuring device includes a control circuit 16 connected to the first projector 3, the second projector 5, the first camera 7, and the second camera 9. The control circuit 16 is configured such that the second texture light 6 has a pattern having a second repetition pitch smaller than the first repetition pitch of the pattern of the first texture light 4. Since the second texture light 6 has a pattern having a second repetition pitch smaller than the first repetition pitch of the pattern of the first texture light 4, the second texture light 6 can measure a finer deformation than the first texture light 4.

[0033] During the deformation of the sample 2, the first camera 7 will acquire a series of images of the first portion 2a of the sample 2 irradiated with the first texture light 4 having the first repetition pitch. To measure the relevant information, the resolution of the first camera 7 is adjusted according to the surface of the first portion 2a and the amount of information provided by the first texture light 4. The larger the surface of the first portion 2a, the more information is processed. The smaller the repetition pitch of the first texture light 4, the more information is processed. Due to the performance of the first camera 7, a pair of the surface of the first portion / the repetition pitch of the first texture light 4 is established. It is advantageous for the first camera 7 to have an adjustable magnification so that the measurement performance can be adjusted according to the requirements. Preferably, the first projector 3 is provided with magnifying means, for example, a plurality of movable lenses, configured to increase or decrease the magnification of the repetition pitch of the first texture light 4. Preferably, the repetition pitch is adjusted to match the range of the surface of the first portion 2a and / or the required measurement resolution. Alternatively, the first projector 3 can irradiate different first texture lights 4 having different repetition pitches.

[0034] During the deformation of the sample 2, the second camera 9 will acquire a series of images of the second portion 2b of the sample 2 irradiated with the second texture light 6 having the second repetition pitch. The resolution of the second camera 9 is adjusted according to the resolution provided by the second texture light 6 and the size of the second portion 2b for measuring the relevant information. It is advantageous for the second camera 9 to have an adjustable magnification so that the measurement performance can be adjusted to meet the requirements. Preferably, the second projector 5 is provided with magnifying means, for example, a plurality of movable lenses, configured to increase or decrease the magnification of the repetition pitch of the second texture light 6. Preferably, the repetition pitch is adjusted to match the range of the surface of the second portion 2b and / or the required measurement resolution. Alternatively, the second projector 5 can irradiate different second texture lights 6 with different repetition pitches.

[0035] Since the second repeating pitch is smaller than the first repeating pitch, it is advantageous for the resolution of the second camera 9 to be higher than the resolution of the first camera 7. Preferably, when the sensors of the two cameras have the same resolution, during deformation measurement, the magnification of the second camera 9 is larger than the magnification of the first camera 7. For example, the first camera 7 and the second camera 9 are identical, and the adjustment of the resolution of the images taken by the two cameras is established by the magnification of the lenses arranged in alignment from the sensor along the optical path.

[0036] The topography measuring device comprises heating means 12 and / or cooling means 13 connected to the control circuit 16. The heating means 12 and / or cooling means 13 are arranged to heat or cool the sample 2 so that the sample 2 follows a predetermined temperature profile. Preferably, the heating means 12 includes heating by infrared radiation. Advantageously, the cooling means 13 includes the application of a fluid flowing within the sample holder 1 or in direct contact with the sample holder 1. Depending on the requirements, the fluid can be a gas or a liquid. The nature of the fluid depends on the lowest temperature of the sample holder 1 to be reached.

[0037] The control circuit 16 applies a temperature ramp to the sample 2. During the temperature ramp, the temperature value of the sample 2 changes and the sample 2 deforms. During the temperature ramp, the first texture light 4 is irradiated onto the first portion 2a of the sample 2, and the second texture light 6 is irradiated onto the second portion 2b of the sample 2. During the temperature ramp, the first series of images 8 and the second series of images 10 are acquired. The images of the first series of images 8 are used, for example, to measure the deformation of the first portion 2a during the temperature ramp. The images of the second series of images 10 are used, for example, to measure the deformation of the second portion 2b during the temperature ramp.

[0038] In the same temperature lamp, the second series of images 10 enables more precise deformation measurement in the second part 2b than the deformation measurement in the first part 2a performed by the first series of images 8. The two series of images are acquired in the same temperature lamp and can characterize the behavior of the sample 2 better compared to two measurements performed in two consecutive temperature lamps to prevent the influence of the change of the sample 2 over time.

[0039] It is particularly advantageous to calculate more accurate deformation data for the second part 2b using the deformation data obtained for the first part 2a. For the deformation data for the first part 2a to be optimal for examining the deformation of the second part 2b, it is preferable that the second part 2b is as close as possible to the first part 2a. Advantageously, the second part 2b is adjacent to the first part 2a, i.e., the first part 2a has an interface with the second part 2b.

[0040] Advantageously, at least a part of the second part 2b is included in the first part 2a. The first part 2a can be considered as a non-convex non-self-intersecting polygon, for example, a rectangle with the intersection with a smaller rectangle removed. The second part 2b penetrates into the interior of the first part 2a. Depending on the configuration, the part occupied by the second part 2b is measured or not measured by the first texture light 4 and the first camera 7. Preferably, at least 50% of the surface of the second part 2b is included in the surface of the first part 2a. More advantageously, the second part 2b is entirely included in the first part 2a, i.e., the first part 2a forms a ring around the second part 2b.

[0041] The irradiation of the first texture light 4 and the second texture light 6 onto the first part 2a and the second part 2b can be performed in different ways. In one particular case, the first texture light 4 and the second texture light 6 are irradiated simultaneously in the temperature lamp. This embodiment is advantageous when the first camera 7 and the second camera 9 respectively perform the acquisition of the first series of images 8 and the second series of images 10 simultaneously. Preferably, simultaneously means acquiring at the same time.

[0042] If the first part 2a and the second part 2b are slightly offset or have a side as an interface, it is possible to easily irradiate the two texture lights. When the first part 2a and the second part 2b overlap partially or entirely, it is important that the first texture light 4 does not overlap the second texture light 6. The first texture light 4 will define a void region, i.e., an area without a pattern which is preferably a non-irradiated region. This void region will correspond entirely or partially to the second part 2b.

[0043] The void region can result from a part of the lighting device of the first projector 3 that is not activated, or from a shutter 11 arranged along the optical path between the first projector 3 and the sample 2. The void region preferably corresponds as accurately as possible to the second part 2b. The second texture light 6 is irradiated onto the void region defined at least partially by the first texture light 4. The shutter 11 can also be provided along the optical path of the second projector 5, i.e., to form a void region without illumination by the second projector 5. By operating and stopping the shutter 11, the range of the irradiation region can be changed. Preferably, the shutter 11 associated with the first projector 3 operates independently of the shutter 11 of the second projector 5.

[0044] It is advantageous to utilize the void region, which is a non-irradiated region, so as to be able to utilize a wider range in the resolution of the pattern, particularly when the pattern is represented in black and white or in grayscale. Alternatively, the first texture light 4 and the second texture light 6 use different wavelengths, for example, to establish different colors, and are simultaneously projected over the entire regions of these texture lights respectively. The first camera 7 or the control circuit 16 selects the first texture light 4 by colorimetric analysis or, preferably, by the first optical filter 14. The second camera 9 selects the second texture light 6 by colorimetric analysis or, preferably, by the second optical filter 15. FIG. 2 shows an embodiment in which the first portion 2a completely surrounds the second portion 2b and the two texture lights are simultaneously irradiated, and the second portion 2b is located inside the ring formed by the first portion 2a. FIG. 3 shows an embodiment in which the first portion 2a and the second portion 2b are adjacent to each other and offset. The interface appears in a straight line form.

[0045] In a preferred embodiment, the control circuit 16 is configured to simultaneously acquire images of the first series of images 8 and the second series of images 10 within a certain period. The first texture light 4 is irradiated at a first wavelength, and the second texture light 6 is irradiated at a second wavelength different from the first wavelength. The control circuit 16 separates the first texture light 4 and the second texture light 6 by colorimetric analysis, or the first camera 7 and the second camera 9 are provided with optical filters.

[0046] In alternative embodiments shown in FIGS. 4, 5, and 6, the first texture light 4 is alternately irradiated with the second texture light 6 in a temperature lamp. This embodiment is advantageous when the second portion 2b is at least partially included in the first portion 2a.

[0047] The first projector 3 and the second projector 5 can each alternately irradiate the first part 2a and the second part 2b with the first texture light 4 and the second texture light 6. FIGS. 4 and 5 show the irradiation of the first texture light 4, and the second part 2b is shown by a dashed line. FIG. 6 shows the irradiation of the second texture light 6, and the first part 2a is shown by a dashed line.

[0048] Alternatively, at least one shutter 11 is connected to the control circuit 16 and is movably installed so as to alternately block the first texture light 4 and the second texture light 6, thereby alternately illuminating the sample 2. Using the shutter 11 is particularly advantageous because it can be moved quickly to block at least a part of the first texture light 4. This eliminates the need to switch the first projector 3 and / or the second projector 5 on and off at regular intervals. The control circuit 16 can be configured so that no part of the sample 2 is simultaneously illuminated by the first texture light 4 and the second texture light 6.

[0049] When the first part 2a and the second part 2b overlap, more preferably when they completely overlap, it becomes possible to measure two different deformations on the second part 2b by alternately irradiating the first texture light 4 and the second texture light 6.

[0050] The deformation of the first part 2a can be measured by the first series of images 8. The deformation of the second part 2b can be measured by the second series of images 10. When the second part 2b overlaps with the first part 2a, in order to measure the specific deformation of the second part 2b, it is advantageous to subtract the overall deformation of the first part 2a from what has been measured for the second part 2b. If the first series of images corresponds to a larger measurement area than the second series of images and the first area completely surrounds the second area or overlaps the second area over at least 50% of its surface, it is particularly advantageous to have the first series of images 8 with a lower resolution than the second series of images 10, for example, at least 20% lower resolution, in order to limit the amount of information to be processed.

[0051] As an alternative to the subtraction of deformations, it is possible to compare the deformation of the second part 2b with the deformation of the first part 2a. If the difference between the deformations is less than a threshold value, one or more layers of the second part 2b correspond to one or more layers of the first part 2a. For example, the second part 2b corresponds to all or part of a component arranged on a support. The first part 2a extends over the support. By comparing the deformations, it is possible to detect whether the deformation of the component corresponds to the deformation of the support. As an alternative, the second part 2b extends into a hole in the support and it is detected whether the deformation of the support changes due to the hole formed in the support. For example, the hole formed in the support means comparing two different laminates.

[0052] In another alternative form, the first series of images 8 is analyzed and the topography interpolated on the second part 2b is calculated from the measured values of the first part 2a. Then, the interpolated deformation measurement value of the first part 2a is subtracted from the deformation measurement value of the second part 2b to analyze only the local deformation of the second part 2b. If the second part 2b has a different laminate from the first part 2a, interpolation makes it possible to estimate the deformation component corresponding to the stack of the first part 2a as compared with the deformation calculated from the second series of images 10.

[0053] Preferably, the second part 2b is included in the first part 2a. Subtract the first deformation from the second deformation, or compare the first deformation with the second deformation, or subtract the interpolated topography of the second part 2b calculated from the first deformation from the first deformation to calculate the local deformation of the second part 2b.

[0054] The control circuit 16 comprises one or more processors and one or more memories designed to store information. The control circuit 16 may be included in a computer.

[0055] It is particularly advantageous that the images of the first series of images 8 are acquired simultaneously with, i.e., simultaneously or almost simultaneously with, the images of the second series of images 10, whereby the two images represent the same deformed state. By using two projectors and two cameras, the measurement is faster compared to the case of irradiating two different sets of texture light with one projector and / or performing two different acquisitions with one camera. By adjusting the resolution of the images generated by the camera to match the resolution of the texture light pattern provided by the projector, the amount of relevant data provided by the camera is increased. This avoids the provision of data that is not sufficiently accurate due to the camera being underperforming with respect to the texture light, and also prevents the control circuit 16 from being saturated with unusable data due to the pitch of the texture light being too coarse.

[0056] In a particular embodiment, the control circuit 16 controls the first camera 7 and the second camera 9 to acquire pairs of images corresponding to the same deformed state. The deformed state changes with the temperature lamp. The control circuit 16 acts on the first projector 3 and the second projector 5 to irradiate texture light continuously, for example, during the acquisition.

[0057] In another embodiment, the control circuit 16 controls the first camera 7 and the second camera 9 to obtain images representing different deformed states between the first camera 7 and the second camera 9. Further, the control circuit 16 controls the first camera 7 and the second camera 9 to obtain a pair of images corresponding to the same deformed state, or a plurality of pairs of images corresponding to the same deformed state. The deformed state changes together with the temperature lamp.

[0058] In each series of images, the images are compared with each other or with a reference image in order to calculate the deformation of at least a part of the sample. A pair or a plurality of pairs of images acquired simultaneously are used as a reference for clarifying one or more deformed states common to both series of images. Thereby, the deformed states can be compared.

[0059] Acquired in the same deformed state means that the images are acquired at the same or similar times. The time lag between image acquisitions can be a function of the measured sample or the applied temperature lamp. The time difference between two images representing the same deformed state can be several seconds, for example, 5 seconds or more. This difference makes it possible to acquire a large amount of data without using computing resources that can manage all this data simultaneously.

[0060] Preferably, the two projectors are movably installed with respect to the sample holder 1. In one embodiment, the two projectors are movably installed in the X direction and the Y direction, and the sample holder 1 is fixedly installed in these two directions. In another embodiment, the two projectors are fixedly installed in the X direction and the Y direction, and the sample holder 1 is movably installed in these two directions. In the last embodiment, the two projectors are movably installed in the X direction and the Y direction, and the sample holder 1 is also movably installed in these two directions. The two projectors can be movably installed independently of each other in the X direction and / or the Y direction. The X direction and the Y direction are perpendicular to each other and perpendicular to the Z direction.

[0061] It is also possible to install the first camera 7 and / or the second camera 9 so as to be movable in the X and Y directions with respect to the sample holder 1.

[0062] Alternatively or complementarily, the control circuit 16 is also configured to move the first part 2a along the sample 2 during deformation to calculate a surface deformation of at least twice the size of the surface of the first part 2a, preferably to calculate a surface deformation of more than 80% of the surface of the sample 2. More preferably, the control circuit 16 is configured to irradiate the first texture light 4 and the second texture light 6 with the first projector 3 and the second projector 5 showing the same repetition pitch. The control circuit 16 advantageously moves the two projectors and the two cameras so that the first part 2a and the second part 2b move independently of each other to characterize at least 80% of the surface of the sample 2. By using two separate pairs of projectors and cameras, the surface of the sample 2 can be measured twice as fast.

Claims

1. 1. A topography measurement apparatus comprising: - a sample holder (1) designed to receive a sample (2), a first projector (3) designed to project a first texture light (4) onto at least a first portion (2a) of said sample (2); a second projector (5) designed to project a second texture light (6) onto at least a second portion (2b) of said sample (2), said second portion (2b) being different from said first portion (2a); and a first camera (7) designed to observe the first texture light (4) irradiated onto the first portion (2a) of the sample (2) in order to obtain a first series of images (8); a second camera (9) designed to observe the second texture light (6) irradiated onto the second portion (2b) of the sample (2) in order to obtain a second series of images (10); - heating means (12) and / or cooling means (13) configured to heat or cool said sample (2) and to deform said sample (2); a control circuit (16) connected to the first projector (3), the second projector (5), the first camera (7) and the second camera (9), configured so that the second texture light (6) has a pattern with a second repeat pitch that is smaller than the first repeat pitch of the pattern of the first texture light (4), the control circuit (16) is connected to the heating means (12) and / or the cooling means (13) for applying a temperature ramp to the sample (2); the control circuitry (16) compares images of the first series of images with each other or with a reference to estimate deformation of the first portion from the first series of images, and compares images of the second series of images with each other or with a reference to estimate deformation of the second portion from the second series of images; During the temperature ramp, the first texture light (4) is irradiated onto the first portion (2a) of the sample (2) and the second texture light (6) is irradiated onto the second portion (2b) of the sample (2), and the first series of images (8) and the second series of images (10) are acquired; The second portion (2b) is adjacent to the first portion (2a), a control circuit (16) configured to acquire, during the temperature ramp, images of the first series of images (8) and the second series of images (10) in the same deformation state, or to acquire images representing different deformation states and at least one image of the first series of images and at least one image of the second series of images representing the same deformation state.

2. 2. The topography measurement device of claim 1, wherein the second portion (2b) at least partially overlaps the first portion (2a).

3. 3. The topography measurement apparatus of claim 2, wherein the first portion (2a) of the sample (2) forms a ring around the second portion (2b) of the sample (2).

4. 4. The topography measurement apparatus of claim 3, wherein the first projector (3) defines a void area without a pattern and the second projector (5) illuminates the void area without illuminating the pattern of the first texture light.

5. 5. The topography measurement device of claim 1, wherein the control circuit (16) is configured to simultaneously irradiate the first texture light and the second texture light and to simultaneously acquire the first series of images (8) and the second series of images (10) during the temperature ramp.

6. 6. The topography measurement device of claim 5, wherein the first texture light (4) is illuminated at a first wavelength and the second texture light (6) is illuminated at a second wavelength different from the first wavelength, and the control circuit (16) separates the first texture light (4) and the second texture light (6) by colorimetric analysis, or the first camera (7) and the second camera (9) are equipped with optical filters.

7. 4. A topography measurement device as described in claim 2 or 3, wherein the control circuit (16) is connected to at least one shutter (11) configured to alternately block transmission of the first texture light (4) and the second texture light (6) in the direction of the sample holder (1) of the second part (2b) to prevent overlapping of the first texture light (4) and the second texture light (6), or the control circuit (16) is configured to alternately emit the first texture light (4) and the second texture light (6).

8. 8. The topography measurement device of claim 7, wherein the control circuit (16) is configured to acquire at least one image of the second series of images (10) between two images of the first series of images (8) within a period of time.

9. A method for performing a topographical measurement of a sample (2), comprising the steps of: - placing a sample (2) on a sample holder (1); - applying a temperature ramp to said sample (2); - irradiating a first portion (2a) of the sample (2) with a first texture light (4) and a second portion (2b) of the sample (2) different from the first portion (2a) of the sample (2) with a second texture light (6), the second texture light (6) having a pattern with a second repeat pitch smaller than the first repeat pitch of the pattern of the first texture light (4); - acquiring a first series of images (8) of the first texture light (4) irradiated onto the first portion (2a) of the sample (2) during the temperature ramp; - acquiring a second series of images (10) of the second texture light (6) irradiated onto the second portion (2b) of the sample (2) during the temperature ramp; - processing said first series of images (8) and said second series of images (10) to measure a first deformation of said first portion (2a) and a second deformation of said second portion (2b) during said temperature ramp; A method comprising:

10. 10. The method for performing a topography measurement of a sample (2) according to claim 9, wherein the second portion (2b) is included in the first portion (2a) and the first deformation is subtracted from the second deformation, or the first deformation and the second deformation are compared, or an interpolated topography of the second portion (2b) calculated from the first deformation is subtracted from the first deformation to calculate the local deformation of the second portion (2b).

Images