Fused wafer bump three-dimensional shape measurement system

Abstract

The invention relates to a fused wafer bump three-dimensional shape measurement system. The fused wafer bump three-dimensional shape measurement system comprises an image acquisition module and a calculation module, the image acquisition module comprises a line scanning image acquisition module and a phase displacement image acquisition module; the line scanning image acquisition module comprises a line scanning projection unit and a plurality of line scanning imaging units, and the line scanning projection unit is used for projecting a first light beam onto a wafer bump; the line scanning imaging unit is used for scanning the part, projected with the first light beam, of the wafer bump to obtain a first image; the phase displacement image acquisition module comprises a pattern projection unit and a plurality of phase displacement imaging units; the pattern projection unit is used for projecting the stripe pattern onto the wafer bump through a second light beam; the phase shift imaging unit is used for acquiring a second image of the wafer bump containing the projected stripe pattern from a plurality of angles; and the calculation module is used for determining the morphology data of the wafer bump based on the plurality of first images and the plurality of second images, so that the accuracy of the morphology data of the whole wafer bump can be improved.

Description

Technical Field

[0001] The present disclosure relates to the field of measurement technology, and in particular to a fused wafer bump three-dimensional profile measurement system. Background Art

[0002] Wafer bumps are used for input / output (I / O) connections, and their topographical data, which characterizes the quality of their profile, is crucial for ensuring reliable connections. Therefore, wafer bump inspection has become an extremely important quality control step in chip manufacturing.

[0003] With the continuous advancement of advanced packaging technology, wafer bumps are becoming increasingly miniaturized in height, and achieving high-speed and high-precision detection required for production is facing increasingly severe challenges.

[0004] Currently, the two main methods used to determine wafer bump topography data are line scanning and phase shifting. However, each method has its own advantages and disadvantages. While the line scanning method can achieve high single-point measurement accuracy, it struggles to obtain a precise 3D topographic profile around the wafer bump apex, a key factor in process quality control. In contrast, the phase shifting method can obtain the entire 3D topographic profile of the wafer bump top area, but local measurement accuracy is difficult to guarantee.

[0005] Therefore, it has always been difficult to accurately obtain the three-dimensional topography data of the entire wafer bump. Summary of the Invention

[0006] In view of this, the present disclosure proposes a fused wafer bump 3D profile measurement system. The system includes:

[0007] Image acquisition module, calculation module;

[0008] The image acquisition module includes: a line scanning image acquisition module and a phase shift image acquisition module;

[0009] The line scanning image acquisition module includes: at least one line scanning projection unit and multiple line scanning imaging units,

[0010] The line scanning projection unit is used to project the first light beam onto the wafer bump;

[0011] The line scanning imaging unit is configured to scan the portion of the wafer bump onto which the first light beam is projected to obtain a first image;

[0012] The phase-shift image acquisition module includes: at least one pattern projection unit and a plurality of phase-shift imaging units;

[0013] The pattern projection unit is used to project a stripe pattern onto the wafer bump via a second light beam;

[0014] The phase shift imaging unit is used to obtain a second image of the wafer bump including the projected stripe pattern from multiple angles;

[0015] The calculation module is used to determine the topography data of the wafer bump based on a plurality of the first images and a plurality of the second images.

[0016] In a possible implementation, the line scanning projection unit includes: at least one light source and a first lens disposed between the light source and the wafer bump;

[0017] The line scan imaging unit includes: at least one first camera, and a second lens disposed between the first camera and the wafer bump;

[0018] The light source is used to emit the first light beam, which is emitted from the line scanning projection unit through the first lens, reaches the wafer bump, is refracted according to a first refraction angle, reaches the second lens, and reaches the first camera through the second lens;

[0019] The pattern projection unit includes: a projection device and a third lens disposed between the projection device and the wafer bump;

[0020] The phase shift imaging unit includes: a second camera and a fourth lens disposed between the second camera and the wafer bump;

[0021] The projection device is used to emit the second light beam, which passes through the third lens and emits the pattern projection unit, and projects the stripe pattern onto the wafer bump through the second light beam. The second light beam is refracted according to the second refraction angle and reaches the fourth lens, and then passes through the fourth lens to reach the second camera.

[0022] In one possible implementation, the light source includes an incoherent light source;

[0023] The line scanning projection unit includes: a first incoherent light source, a second incoherent light source, and a first beam splitter;

[0024] The first incoherent light source emits a first incoherent light beam, the second incoherent light source emits a second incoherent light beam, and the first beam splitter makes the first incoherent light beam and the second incoherent light beam overlap outside the line scanning projection unit.

[0025] In a possible implementation, the line scanning imaging unit includes: two first cameras and a second beam splitter, wherein the second beam splitter enables optical paths of the two first cameras to overlap outside the line scanning imaging unit.

[0026] In a possible implementation, the pattern projection unit enables the second light beam to be perpendicular to the plane where the wafer bump is located.

[0027] In a possible implementation, the pattern projection unit includes: a projection device, a third camera, a third beam splitter, a sixth lens disposed between the third beam splitter and the wafer bump, and a fifth lens disposed between the third camera and the third beam splitter;

[0028] The third beam splitter makes the optical paths of the projection device and the third camera overlap outside the pattern projection unit and are perpendicular to the plane where the wafer bump is located;

[0029] The pattern projection unit is further used to acquire the second image.

[0030] In one possible implementation, the system includes a control module;

[0031] The control module is used to control the image acquisition module to scan the wafer bumps line by line;

[0032] The control module controls the line scanning image acquisition module to acquire the first image during the movement of the image acquisition module;

[0033] The control module controls the image acquisition module to stop moving when the image acquisition module moves to the end of each row, and controls the phase-shifted image acquisition module to acquire the second image.

[0034] In a possible implementation, the calculation module is further configured to:

[0035] determining a first height of each physical point on the surface of the wafer bump based on the plurality of first images;

[0036] determining a second height of each of the entity points based on the plurality of second images;

[0037] For a single entity point, performing a first fusion on multiple first heights corresponding to the single entity point to obtain a first base height of the single entity point, and performing a second fusion on multiple second heights corresponding to the single entity point to obtain a second base height of the single entity point;

[0038] The first basic height and the second basic height of each entity point are subjected to a third fusion to obtain a target height of each entity point, and the target height is used to determine the topography data.

[0039] In a possible implementation, the calculation module is further configured to:

[0040] determining, based on the second image, a wrapping phase corresponding to each pixel in the second image;

[0041] Performing a first unwrapping process on each of the wrapped phases to obtain a second initial height of each of the entity points;

[0042] determining a quality indicator characterizing the quality of the wrapped phase;

[0043] When the quality indicator is greater than the quality threshold, taking the second initial height of the first entity point corresponding to the wrapped phase as the second height of the first entity point;

[0044] When the quality indicator is not greater than a quality threshold, determining a difference between a second initial height and a first base height of the first entity point;

[0045] When the difference is less than the first threshold, performing a fourth fusion on the second initial height and the first base height of the first entity point to obtain a second height of the first entity point;

[0046] When the difference is not less than a first threshold, determining surrounding pixels of the pixel corresponding to the wrapped phase;

[0047] Based on the first wrapped phase corresponding to each peripheral pixel, a second unwrapping process is performed on the wrapped phase to obtain a second height of the first entity point.

[0048] In a possible implementation, the calculation module is further configured to:

[0049] determining a spatial index according to a position of a pixel corresponding to the wrapping phase in a fringe period of the fringe pattern;

[0050] Determining the grayscale of the pixel corresponding to the wrapped phase;

[0051] Determining, based on the grayscale, a modulation index representing a pixel corresponding to the wrapped phase;

[0052] The quality index is determined according to the spatial index and the modulation index.

[0053] Using the integrated wafer bump three-dimensional topography measurement system disclosed in the present invention, the line scanning method and the phase shift method can be integrated. In one measurement process, the first image can be obtained by the line scanning method and the second image can be obtained by the phase shift method, thereby improving the measurement efficiency. In addition, the line scanning image acquisition module and the phase shift image acquisition module are in the same system, and their relative positions are fixed, so that in the process of determining the topography data, the data obtained by the two methods can be more accurately integrated, thereby improving the accuracy of the topography data. Moreover, the topography data determined by the first image and the second image can improve the accuracy of the local topography data on the premise of obtaining the entire three-dimensional topography contour of the wafer bump, thereby improving the accuracy of the topography data of the entire wafer bump.

[0054] Further features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.

[0056] Figure 1 A schematic structural diagram of a fused wafer bump three-dimensional profile measurement system provided in an embodiment of the present disclosure.

[0057] Figure 2 This is a structural diagram of the line scanning image acquisition module provided in an embodiment of the present disclosure.

[0058] Figure 3 A schematic structural diagram of a phase-shift image acquisition module provided in an embodiment of the present disclosure.

[0059] Figure 4 A schematic structural diagram of a line scanning projection unit provided in an embodiment of the present disclosure.

[0060] Figure 5 A schematic structural diagram of a line scanning imaging unit provided in an embodiment of the present disclosure.

[0061] Figure 6 A schematic structural diagram of a pattern projection unit provided in an embodiment of the present disclosure.

[0062] Figure 7 A schematic flow chart of a method for measuring the three-dimensional topography of wafer bumps provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0063] Various exemplary embodiments, features, and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0064] As used herein, the terms "comprises," "comprising," "having," or variations thereof are open ended and include one or more stated features, integers, elements, steps, parts, or functions, but do not preclude the presence or addition of one or more other features, integers, elements, steps, parts, functions, or groups thereof.

[0065] When an element is referred to as being "connected," "coupled," "responsive" or variations thereof to another element, it can be directly connected, coupled or responsive to the other element or intervening elements may be present.

[0066] Although the terms first, second, third, etc. may be used herein to describe various elements / operations, these elements / operations should not be limited by these terms. These terms are only used to distinguish one element / operation from another element / operation. Therefore, without departing from the teachings of the present invention, the first element / operation in some embodiments may be referred to as the second element / operation in other embodiments.

[0067] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0068] In addition, numerous specific details are provided in the following detailed description to better illustrate the present disclosure. Those skilled in the art will appreciate that the present disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art are not described in detail in order to highlight the main points of the present disclosure.

[0069] Figure 1 This is a schematic diagram of the structure of the integrated wafer bump three-dimensional shape measurement system provided by the embodiment of the present disclosure. Figure 1As shown, the system includes: an image acquisition module and a calculation module; the image acquisition module includes: a line scan image acquisition module and a phase shift image acquisition module; the line scan image acquisition module includes: at least one line scan projection unit and multiple line scan imaging units, the line scan projection unit is used to project a first light beam onto the wafer bump; the line scan imaging unit is used to scan the part of the wafer bump projected with the first light beam to obtain a first image; the phase shift image acquisition module includes: at least one pattern projection unit and multiple phase shift imaging units; the pattern projection unit is used to project a stripe pattern onto the wafer bump through a second light beam; the phase shift imaging unit is used to obtain a second image of the wafer bump containing the projected stripe pattern from multiple angles; the calculation module is used to determine the morphology data of the wafer bump based on multiple first images and multiple second images.

[0070] In an embodiment of the present disclosure, the line scan image acquisition module may include a line scan projection unit and a plurality of line scan imaging units. In another example, the line scan image acquisition module may include a plurality of line scan projection units and a plurality of line scan imaging units. A single line scan projection unit may correspond one-to-one with a single line scan imaging unit, or a single line scan projection unit may correspond to a plurality of line scan imaging units. Each line scan projection unit and the corresponding single line scan imaging unit may form a first combination. Each first combination may acquire a first image of the wafer bump at at least one angle.

[0071] The first light beam may be a coherent light beam or an incoherent light beam. The first light beam may be a first fused light beam obtained by fusion of two incoherent light beams. The coherent light beam may be a laser beam. The incoherent light beam may be a white light beam.

[0072] During a measurement of a wafer bump, the line scan projection unit and the corresponding line scan imaging unit can be fixed in position, so that the line scan projection unit can project a first light beam onto the wafer bump, and the line scan imaging unit corresponding to the line scan projection unit can image the portion of the wafer bump projected with the first light beam to obtain a first image. The first image can include a portion of the wafer bump and a portion of the background scenery surrounding the wafer bump.

[0073] In an embodiment of the present disclosure, the phase-shift image acquisition module may include a pattern projection unit and a plurality of phase-shift imaging units. In another example, the phase-shift image acquisition module may include a plurality of pattern projection units and a plurality of phase-shift imaging units. A single pattern projection unit may correspond one-to-one with a single phase-shift imaging unit, or a single pattern projection unit may correspond to a plurality of phase-shift imaging units. Each pattern projection unit and the corresponding single phase-shift imaging unit may form a second combination. Each second combination may acquire a second image of the wafer bump at at least one angle.

[0074] The pattern projection unit can emit a second light beam, and project the stripe pattern onto the wafer bump through the second light beam.

[0075] During a measurement of a wafer bump, the pattern projection unit and the corresponding phase-shift imaging unit can be fixed in position, allowing the pattern projection unit to project the second light beam onto the wafer bump, and the phase-shift imaging unit corresponding to the pattern projection unit to image the complete wafer bump with the projected stripe pattern and the background of the wafer bump to obtain a second image. The second image can include the entire wafer bump and the background of the wafer bump.

[0076] During the entire measurement process, the line scan image acquisition module can obtain a first image at multiple angles. The multiple first images corresponding to each angle can characterize the wafer bump at that angle. Moreover, during the entire measurement process, the phase shift image acquisition module can obtain a second image at multiple angles. The calculation module can determine the first height of each entity point on the wafer bump based on the first image. Moreover, the calculation module can determine the second height of each entity point on the wafer bump based on the second image. The process of determining the first height and the second height is not the focus of this disclosure, and the first height and the second height can be obtained using the methods in the relevant technology (line scan method, phase shift method). In the embodiment of the present disclosure, the first height and the second height corresponding to each entity point on the wafer bump can be fused to obtain the target height of each entity point. The spacing between the entity points can be pre-set, and combined with the target height, the three-dimensional morphology data of the wafer bump can be determined. The embodiment of this disclosure does not limit the fusion method of the first height and the second height corresponding to the entity point.

[0077] Using the integrated wafer bump three-dimensional topography measurement system disclosed in the present invention, the line scanning method and the phase shift method can be integrated. In one measurement process, the first image can be obtained by the line scanning method and the second image can be obtained by the phase shift method, thereby improving the measurement efficiency. In addition, the line scanning image acquisition module and the phase shift image acquisition module are in the same system, and their relative positions are fixed, so that in the process of determining the topography data, the data obtained by the two methods can be more accurately integrated, thereby improving the accuracy of the topography data. Moreover, the topography data determined by the first image and the second image can improve the accuracy of the local topography data on the premise of obtaining the entire three-dimensional topography contour of the wafer bump, thereby improving the accuracy of the topography data of the entire wafer bump.

[0078] In one possible implementation, the line scanning projection unit includes: at least one light source and a first lens arranged between the light source and the wafer bump; the line scanning imaging unit includes: at least one first camera and a second lens arranged between the first camera and the wafer bump; the light source is used to emit the first light beam, the first light beam is emitted from the line scanning projection unit through the first lens, reaches the wafer bump, and is refracted according to a first refraction angle, reaches the second lens, and reaches the first camera through the second lens; the pattern projection unit includes: a projection device and a third lens arranged between the projection device and the wafer bump; the phase shift imaging unit includes: a second camera and a fourth lens arranged between the second camera and the wafer bump; the projection device is used to emit the second light beam, the second light beam is emitted from the pattern projection unit through the third lens, and the stripe pattern is projected onto the wafer bump through the second light beam, the second light beam is refracted according to the second refraction angle, reaches the fourth lens, and reaches the second camera through the fourth lens.

[0079] Figure 2 This is a structural diagram of the line scanning image acquisition module provided in an embodiment of the present disclosure.

[0080] In the embodiment of the present disclosure, the line scan image acquisition module may include multiple line scan projection units 11 and multiple line scan imaging units 10. A single line scan projection unit 11 may include at least one light source 110, each light source 110 may be provided with a corresponding first lens 111, and the first lens 111 may be provided between the light source 110 and the wafer bump.

[0081] A single line scan imaging unit 10 may include at least one first camera 100. Each first camera 100 may be provided with a corresponding second lens 102, which may be positioned between the first camera 100 and the wafer bump. In one example, a Sham angle adjustment device 101 may be positioned between the first camera 100 and the second lens 102 to increase the information content of the first image, allowing the first image to accurately represent the portion of the wafer bump onto which the first light beam is projected.

[0082] Figure 3 A schematic structural diagram of a phase-shift image acquisition module provided in an embodiment of the present disclosure.

[0083] In the disclosed embodiment, the phase-shift image acquisition module may include multiple pattern projection units 33 and multiple phase-shift imaging units 30. A single pattern projection unit 33 may include a projection device 330. A third lens 331 may be disposed between the projection device 330 and the wafer bump. The projection device 330 may utilize a Ronchi grating or a sinusoidal grating combined with piezoelectric ceramics to achieve phase-shift projection. Alternatively, the projection device may utilize an optical engine to achieve phase-shift projection through pattern switching. The optical engine may include one or more of the following: a digital micromirror element optical engine, an off-axis optical projection system optical engine, an off-axis optical projection system, and the like.

[0084] The single phase-shift imaging unit 30 may include a second camera 300. A fourth lens 302 may be disposed between the second camera 300 and the wafer bump. In one example, a Sham angle adjustment device 301 may be disposed between the second camera 300 and the fourth lens 302 to increase the information content of the second image, allowing the second image to accurately represent the entire wafer bump.

[0085] In the embodiment of the present disclosure, the positions of the line scan projection unit and the line scan imaging unit are preset so that the first light beam can be refracted on the wafer bump according to the first refraction angle. In this way, the first light beam can reach the second lens, and the first image can accurately represent the portion of the wafer bump projected with the first light beam. In addition, the positions of the pattern projection unit and the phase shift imaging unit are preset so that the stripe pattern can be projected onto the wafer bump, and the second light beam can be refracted according to the second refraction angle. In this way, the second light beam can reach the fourth lens, and the second image can accurately represent the wafer bump as a whole.

[0086] In addition, the first lens 111 , the second lens 102 , the third lens 331 , and the fourth lens 302 may be telecentric lenses to increase the clarity of the first image and the second image and reduce distortion.

[0087] The integrated wafer bump 3D topography measurement system disclosed in the present invention can obtain first and second images from multiple angles during a single measurement, improving the efficiency of determining wafer bump topography data. Furthermore, it can minimize the negative impact of shadows on measurement results, reduce distortion, and improve measurement accuracy.

[0088] In one possible implementation, the light source includes an incoherent light source; the line scanning projection unit includes: a first incoherent light source, a second incoherent light source, and a first spectrometer; the first incoherent light source emits a first incoherent light beam, the second incoherent light source emits a second incoherent light beam, and the first spectrometer causes the first incoherent light beam and the second incoherent light beam to overlap outside the line scanning projection unit.

[0089] Figure 4 A schematic structural diagram of a line scanning projection unit provided in an embodiment of the present disclosure.

[0090] In the embodiment of the present disclosure, the line scanning projection unit 11 may include two incoherent light sources, namely: a first incoherent light source 110a and a second incoherent light source 110b. The line scanning projection unit 11 also includes a first spectrometer 112. The incoherent light beams emitted by the first incoherent light source 110a and the second incoherent light source 110b respectively overlap after passing through the first spectrometer 112 to form a first fused light beam. In the embodiment of the present disclosure, the first fused light beam can be used as the first light beam. The light beams provided by the first incoherent light source 110a and the second incoherent light source 110b can be: white, purple, blue, green, red, etc. In addition, the wavelengths of the light beams provided by the first incoherent light source and the second incoherent light source are different.

[0091] The line scanning projection unit in the disclosed embodiments can perform line scanning based on dual-wavelength differential incoherent light. This produces a narrow, bright projection line, minimizing the precision loss associated with incoherent light. This maintains accuracy even when using an incoherent light source.

[0092] In a possible implementation, the line scanning imaging unit includes: two first cameras and a second beam splitter, wherein the second beam splitter enables optical paths of the two first cameras to overlap outside the line scanning imaging unit.

[0093] Figure 5 A schematic structural diagram of a line scanning imaging unit provided in an embodiment of the present disclosure.

[0094] In the disclosed embodiment, the line scan imaging unit 10 includes two first cameras, namely, first camera 100a and first camera 100b. These two first cameras can be industrial black-and-white cameras. Compared to color cameras, they do not require interpolation processing, which improves the accuracy of determining the height of physical points on the wafer bumps from the first image. The line scan imaging unit 10 also includes a second beam splitter 103. The first light beam passes through the second beam splitter 103 and is split into two first light beams, allowing both first camera 100a and first camera 100b to receive the first light beam.

[0095] In this way, the line scan imaging unit in the embodiment of the present disclosure can break through the frame rate limit of a single first camera. The two first cameras can work alternately to improve the efficiency of first image acquisition.

[0096] In a possible implementation, the pattern projection unit enables the second light beam to be perpendicular to the plane where the wafer bump is located.

[0097] The pattern projection unit can emit a second light beam, which makes the second light beam perpendicular to the plane where the wafer bumps are located, and projects a stripe pattern onto the wafer bumps in a forward projection manner.

[0098] In this way, the phase-shift image acquisition module only needs to be equipped with one pattern projection unit to complete the synchronous imaging of the multi-angle cameras, thereby improving the efficiency of the second image acquisition.

[0099] In a possible implementation, the line scanning projection unit causes the first light beam to be disposed on the surface where the wafer bump is located.

[0100] The line scanning projection unit can emit a first light beam, which makes the first light beam perpendicular to the plane where the wafer bumps are located, and projects the first light beam perpendicularly onto the wafer bumps.

[0101] In this way, the line scanning image acquisition module only needs to be provided with one line scanning projection unit to complete the synchronous imaging of the multi-angle cameras, thereby improving the efficiency of the first image acquisition.

[0102] In one possible implementation, the pattern projection unit includes: a projection device, a third camera, a third beam splitter, a sixth lens arranged between the third beam splitter and the wafer bump, and a fifth lens arranged between the third camera and the third beam splitter; the third beam splitter makes the respective optical paths of the projection device and the third camera overlap outside the pattern projection unit and are perpendicular to the plane where the wafer bump is located; the pattern projection unit is also used to obtain the second image.

[0103] Figure 6 A schematic structural diagram of a pattern projection unit provided in an embodiment of the present disclosure.

[0104] In the embodiment of the present disclosure, the pattern projection unit 33 can project a stripe pattern onto the wafer bump in an orthographic projection manner; and the pattern projection unit 33 can also obtain a second image directly above the wafer bump. The pattern projection unit 33 includes: a third camera 332, a projection device 330, and a third beam splitter 334. It also includes a fifth lens 333 disposed between the third camera 332 and the third beam splitter 334, and a sixth lens 335 disposed between the third beam splitter 334 and the wafer bump. The fifth lens 333 and the sixth lens 334 can be telecentric lenses. Due to the provision of the third beam splitter 334, the optical path of the second light beam projected by the projection device 330 can overlap with the optical path of the third camera 332 between the pattern projection unit 33 and the wafer bump.

[0105] In this way, the pattern projection unit can not only project the stripe pattern onto the wafer bump, but also obtain a second image at an angle directly above the wafer bump, which better reduces the probability of shadow occlusion, improves the ability to suppress mirror reflection, and improves the accuracy of the second image in showing the wafer bump.

[0106] In one possible implementation, the system includes a control module; the control module is used to control the image acquisition module to scan the wafer bumps line by line; the control module controls the line scan image acquisition module to acquire the first image during the movement of the image acquisition module; the control module controls the image acquisition module to stop moving when the image acquisition module moves to the end of each row, and controls the phase shift image acquisition module to acquire the second image.

[0107] The control module can control the line scanning image acquisition module and the phase shift image acquisition module in the image acquisition module to work together to acquire the first image and the second image.

[0108] The control module can control the image acquisition module to move line by line, and the image acquisition module can scan the wafer bumps, that is, the line scanning image acquisition module in the image acquisition module can obtain the first image during the movement.

[0109] The motion trajectory of the image acquisition module can be pre-set, with each row having a starting position and an ending position. The end of each row can be the ending position of each row. When the image acquisition module reaches the end of each row, the control module can control the image acquisition module to stop moving and control the phase-shifted image acquisition module to acquire a second image of the wafer bump.

[0110] Furthermore, different magnifications can be set for each row to adjust the framing range of each row. In the column direction of the movement path, the framing range of each row can fully cover the corresponding column on the wafer bump. This allows for setting an appropriate framing range for each row based on actual needs, thereby adjusting the number of scan rows to improve scanning accuracy or efficiency.

[0111] In the embodiment of the present disclosure, the control module can enable the image acquisition module to alternately acquire the first image and the second image, thereby improving acquisition efficiency.

[0112] In one possible implementation, the calculation module is further used to: determine the first height of each entity point on the surface of the wafer bump based on multiple first images; determine the second height of each entity point based on multiple second images; for a single entity point, perform a first fusion of the multiple first heights corresponding to the single entity point to obtain the first base height of the single entity point, and perform a second fusion of the multiple second heights corresponding to the single entity point to obtain the second base height of the single entity point; perform a third fusion of the first base height and the second base height of each entity point to obtain the target height of each entity point, and the target height is used to determine the morphology data.

[0113] As mentioned above, the line scanning image acquisition module can acquire first images at different angles. For a single angle, multiple first images can be obtained. The multiple first images acquired at a single angle can jointly show the wafer bump. Using the line scanning method, the first height of each entity point on the wafer bump can be determined based on the first image corresponding to a single angle. For example: when the light source is a coherent light source, the scanning center line can be extracted from the first image, and the triangulation method can be used to determine the first height of the entity point corresponding to the first image. For another example: if only the height of the vertex of the wafer bump needs to be measured, then even if the light source is an incoherent light source, the first height corresponding to the vertex can be determined by the projection method. This can reduce the error caused by the incoherent light projection line being thicker than the coherent light projection line, and improve the accuracy of the first height of the vertex.

[0114] For a single entity point, based on the first images corresponding to each of the multiple angles, multiple first heights of the entity point can be determined respectively. In this way, each entity point can correspond to multiple first heights. The multiple first heights corresponding to each entity point can be first fused to obtain the first base height corresponding to each entity point. The embodiment of the present disclosure does not limit the specific method of the first fusion. For example: the first fusion can be to determine the average value or median of multiple first heights. Alternatively, a weight can be set for each angle, and the first fusion can use the weight to perform a weighted average of the first heights.

[0115] Each time the image acquisition module stops moving, the phase shift image acquisition module can acquire multiple second images of the wafer bump from multiple angles. Using the phase shift method, based on a single second image, the second height of each entity point of the wafer bump can be determined. In this way, each entity point can correspond to multiple second heights. The multiple second heights corresponding to each entity point can be second-fused to obtain the second base height corresponding to each entity point. The embodiment of the present disclosure does not limit the specific method of the second fusion. For example: the second fusion can be to determine the average value or median of multiple second heights. Alternatively, a weight can be set for each angle, and the second fusion can use the weight to perform a weighted average of the second heights.

[0116] A single entity point can correspond to two heights determined using the line scanning method and the phase shift method, namely the first base height and the second base height. The first base height can be assigned a first weight, and the second base height can be assigned a second weight. Since the accuracy of the line scanning method is better than the phase shift method, the first weight can be greater than the second weight. The third fusion can be to weight the first base height using the first weight and to weight the second base height using the second weight. In addition, the average value of the weighted first base height and the weighted second base height is determined, and the average value is used as the target height of the entity point. Based on related technology, the target height can be used to determine the morphological data of the wafer bump.

[0117] The calculation unit in the embodiment of the present disclosure can improve the accuracy of the height of each entity point of the wafer bump determined by the line scan method through the first fusion; improve the accuracy of the height of each entity point of the wafer bump determined by the phase shift method through the second fusion; and fuse the heights of each entity point determined by the line scan method and the phase shift method through the third fusion. In this way, the target height reflects the respective advantages of the line scan method and the phase shift method. Not only is the target height of each entity point on the overall outline of the wafer bump obtained, but the accuracy and precision of the target height are also improved.

[0118] In one possible implementation, the calculation module is further used to: determine the wrapping phase corresponding to each pixel in the second image based on the second image; perform a first unwrapping process on each of the wrapped phases to obtain the second initial height of each entity point; determine a quality index that characterizes the quality of the wrapped phase; when the quality index is greater than a quality threshold, use the second initial height of the first entity point corresponding to the wrapped phase as the second height of the first entity point; when the quality index is not greater than the quality threshold, determine the difference between the second initial height and the first base height of the first entity point; when the difference is less than the first threshold, perform a fourth fusion on the second initial height and the first base height of the first entity point to obtain the second height of the first entity point; when the difference is not less than the first threshold, determine the surrounding pixels that characterize the pixel corresponding to the wrapped phase; based on the first wrapping phase corresponding to each surrounding pixel, perform a second unwrapping process on the wrapped phase to obtain the second height of the first entity point.

[0119] In an embodiment of the present disclosure, a first mapping relationship between the first coordinate system of the first image and the world coordinate system can be established in advance, and a second mapping relationship between the second coordinate system of the second image and the world coordinate system can be established. The second coordinate system can be used to determine the first entity point on the wafer bump corresponding to the pixel in the second image in the real world. In this way, the first entity point corresponding to the wrapping phase corresponding to the pixel can be determined. The second initial height determined based on the wrapping phase can then be used as the initial height of the first entity point. Using the first mapping relationship and the second mapping relationship, the second initial height and the first base height corresponding to the first entity point can be determined, that is, the second initial height and the first base height of the same first entity point can be corresponded.

[0120] In the disclosed embodiments, relevant technologies, such as multi-frequency phase shift methods, can be utilized to determine the wrapping phase corresponding to each pixel in the second image based on the second image. The first unwrapping process can be a time-based unwrapping algorithm. After the first unwrapping process, a second initial height of each entity point can be obtained. The time-based unwrapping algorithm can save time in determining the second initial height. The quality of each wrapped phase can then be determined to obtain a quality indicator.

[0121] For example, a quality judgment model may be pre-trained, and the second image and each package phase may be input into the quality judgment model to obtain a quality index of each package phase.

[0122] For example, multiple phase threshold ranges may be experimentally set, each phase threshold range corresponds to a quality indicator, and it is determined which phase threshold range each package phase falls into, thereby obtaining the corresponding quality indicator.

[0123] The above is only an example, and the embodiments of the present disclosure do not limit the method for determining the quality indicator.

[0124] If the quality indicator is greater than the quality threshold, it indicates that the second initial height is reliable and can be used as the second height of the first entity point.

[0125] If the quality indicator is not greater than the quality threshold, the difference between the second initial height corresponding to the first physical point and the first base height must be determined. Generally, the line scan method is more accurate than the phase shift method. Therefore, the heights of the same physical point can be determined using these two methods, resulting in two heights. The difference between these two heights can then be used to determine whether the second initial height is acceptable.

[0126] If the difference is less than the first threshold, it indicates that the second initial height is available. Then, the second initial height and the first base height can be subjected to a fourth fusion. The fourth fusion can be performed by taking a weighted average of the second initial height and the first base height to obtain the second height of the first entity point. The weight of the first base height is higher than the weight of the second initial height.

[0127] If the difference is not less than the first threshold, it means that the second initial height is inaccurate and unusable. The second height needs to be re-determined based on the wrapping phase corresponding to the first entity point. The surrounding pixels of the pixel corresponding to the wrapping phase can be obtained, for example, the pixels representing the vertex of the wafer bump adjacent to the pixel corresponding to the wrapping phase can be obtained. For ease of description, the wrapping phase corresponding to the surrounding pixels is named the first wrapping phase. A second unwrapping process can be performed on each first wrapping phase. The second unwrapping process can be a path-independent unwrapping algorithm such as the Goldstein unwrapping algorithm, the Quality-Guided unwrapping algorithm, the Least Squares unwrapping algorithm, the Adaptive unwrapping algorithm, etc. In scenarios where computing speed is prioritized, the second unwrapping process can also be a path-dependent algorithm. Not only can computing efficiency be improved. In this way, the second height can be determined.

[0128] In addition, increasing the sampling frequency of line scans (reducing the scanning line spacing) can reduce the accumulated errors in the unwrapping process and compensate for the lack of accuracy when using incoherent light sources, thereby improving the unwrapping accuracy by narrowing the approximation range.

[0129] The calculation module in the embodiment of the present disclosure takes into account the quality of the wrapped phase corresponding to the entity point and the reliability of the second initial height value corresponding to the entity point (the difference between the second initial height and the first basic height), and uses different methods to determine the second height in different situations, thereby improving the accuracy of the second height determined by the phase shift method.

[0130] In one possible implementation, the calculation module is further used to: determine a spatial index based on the position of the pixel corresponding to the wrapping phase in the stripe period of the stripe pattern; determine the grayscale of the pixel corresponding to the wrapping phase; based on the grayscale, determine a modulation index characterizing the pixel corresponding to the wrapping phase; and determine the quality index based on the spatial index and the modulation index.

[0131] Phase loss and breakage are prone to occur at the junction of two fringe periods, which can easily lead to periodic errors. Moreover, the error is more serious in multi-frequency projection than in single-frequency projection. In view of this, in the embodiment of the present disclosure, the spatial index can be determined based on the position of the pixel corresponding to the wrapped phase in the fringe period. The closer the position is to the junction of the two fringe periods, the smaller the value of the spatial index can be. Conversely, the farther the position is from the junction of the two fringe periods, the larger the value of the spatial index. It is also possible to set corresponding coefficients for single-frequency projection and multi-frequency projection to weight the spatial index.

[0132] Modulation indexes can include the contrast between the fringe pattern and the background, the magnitude of brightness variation within a cycle, and other factors. Therefore, the modulation index can be determined based on the grayscale of the pixel corresponding to the wrapped phase. The higher the contrast between the fringe pattern and the background, the larger the modulation index value. The greater the magnitude of brightness variation within a cycle, the larger the modulation index value. Conversely, the lower the contrast between the fringe pattern and the background, the smaller the modulation index value. The smaller the magnitude of brightness variation within a cycle, the smaller the modulation index value.

[0133] The quality index can be obtained by weighting the spatial index and the modulation index. To more effectively filter out pixels with phase discontinuity that seriously affect height measurement, the weight corresponding to the spatial index can be greater than the weight corresponding to the modulation index. A larger value of the quality index indicates better quality of the wrapped phase, while a smaller value indicates worse quality of the wrapped phase.

[0134] In the embodiment of the present disclosure, the calculation module can determine the spatial index and modulation index based on the position of the pixel corresponding to the wrapped phase in the stripe period and the grayscale of the pixel, thereby improving the reliability of the quality index and improving the accuracy and reliability of the quality evaluation of the wrapped phase.

[0135] Figure 7 The flowchart of the wafer bump three-dimensional morphology measurement method provided by the embodiment of the present disclosure is divided into two parts for ease of understanding: the line scanning part and the phase shift part. Figure 7As shown, multiple first images and multiple second images can be obtained. Line scanning can be performed at multiple angles. Multiple first images can be obtained at a single angle. Based on each first image, multiple first heights of each physical point on the wafer bump can be calculated. For each physical point, the corresponding multiple first heights are first fused to obtain the first base height of each physical point on the wafer bump.

[0136] The single second image can be an image obtained by phase shifting at a single angle. Based on the single second image, the wrapping phase corresponding to each pixel in the second image can be calculated. Based on the first and second mapping relationships, the second initial height and first base height of the same entity point can be determined.

[0137] A first unwrapping process is performed on each wrapping phase to obtain the second initial height of each entity point on the wafer bump. In addition, it is judged whether the quality of each wrapping phase is greater than the quality threshold. When the quality of the wrapping phase is greater than the quality threshold point, the second initial height is used as the second height. When the quality of the wrapping phase is not greater than the quality threshold, the difference between the second initial height of the entity point corresponding to the wrapping phase and the first base height is judged. It is judged whether the difference is less than the first threshold. When the difference is less than the first threshold, the second initial height of the entity point corresponding to the wrapping phase is fused with the first base height for the fourth time to obtain the second height. When the difference is not less than the first threshold, the surrounding pixels of the pixel corresponding to the wrapping phase are determined, for example, the surrounding pixels representing the vertices of the wafer bump can be used. Based on the first wrapping phase of the surrounding pixels, a second wrapping process is performed to obtain the second height.

[0138] There are three operations described above that can be used to obtain the second height. You can choose one of them based on the actual situation to obtain the second height. In this way, based on each second image, the second height of each physical point on the wafer bump can be obtained. Therefore, multiple second heights of each physical point on the wafer bump can be obtained. For each physical point, the corresponding multiple second heights are second-fused to obtain the second base height of each physical point on the wafer bump.

[0139] Furthermore, for each physical point, the corresponding first base height and second base height are subjected to a third fusion to obtain a target height of each physical point on the wafer bump. This target height can be used as the topography data of the wafer bump.

[0140] The flow charts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the systems, methods and computer program products according to multiple embodiments of the present disclosure. In this regard, each box in the flow chart or block diagram can represent a part of a module, program segment or instruction, and the part of the module, program segment or instruction contains one or more executable instructions for realizing the prescribed logical function. In some alternative implementations, the functions marked in the box can also occur in a sequence different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flow chart, and the combination of the boxes in the block diagram and / or flow chart can be implemented by a dedicated hardware-based system that performs the prescribed function or action, or can be implemented by a combination of dedicated hardware and computer instructions.

[0141] While various embodiments of the present disclosure have been described above, the foregoing description is intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A fused wafer bump three-dimensional profile measurement system, characterized in that: The system includes: an image acquisition module and a calculation module; The image acquisition module includes: a line scanning image acquisition module and a phase shift image acquisition module; The line scanning image acquisition module includes: at least one line scanning projection unit and multiple line scanning imaging units, The line scanning projection unit is used to project the first light beam onto the wafer bump; The line scanning imaging unit is configured to scan the portion of the wafer bump onto which the first light beam is projected to obtain a first image; The phase-shift image acquisition module includes: at least one pattern projection unit and a plurality of phase-shift imaging units; The pattern projection unit is used to project a stripe pattern onto the wafer bump via a second light beam; The phase shift imaging unit is used to obtain a second image of the wafer bump including the projected stripe pattern from multiple angles; The calculation module is used to determine the topography data of the wafer bump based on a plurality of the first images and a plurality of the second images.

2. The system according to claim 1, wherein: The line scanning projection unit includes: at least one light source and a first lens disposed between the light source and the wafer bump; The line scan imaging unit includes: at least one first camera, and a second lens disposed between the first camera and the wafer bump; The light source is used to emit the first light beam, which is emitted from the line scanning projection unit through the first lens, reaches the wafer bump, is refracted according to a first refraction angle, reaches the second lens, and reaches the first camera through the second lens; The pattern projection unit includes: a projection device and a third lens disposed between the projection device and the wafer bump; The phase shift imaging unit includes: a second camera and a fourth lens disposed between the second camera and the wafer bump; The projection device is used to emit the second light beam, which passes through the third lens and emits the pattern projection unit, and projects the stripe pattern onto the wafer bump through the second light beam. The second light beam is refracted according to the second refraction angle and reaches the fourth lens, and then passes through the fourth lens to reach the second camera.

3. The system according to claim 2, characterized in that The light source includes an incoherent light source; The line scanning projection unit includes: a first incoherent light source, a second incoherent light source, and a first beam splitter; The first incoherent light source emits a first incoherent light beam, the second incoherent light source emits a second incoherent light beam, and the first beam splitter makes the first incoherent light beam and the second incoherent light beam overlap outside the line scanning projection unit.

4. The system according to claim 2, wherein: The line scanning imaging unit includes: two first cameras and a second beam splitter, wherein the second beam splitter enables the optical paths of the two first cameras to overlap outside the line scanning imaging unit.

5. The system according to claim 2, wherein: The pattern projection unit makes the second light beam perpendicular to the plane where the wafer bump is located.

6. The system according to claim 5, characterized in that The pattern projection unit includes: a projection device, a third camera, a third beam splitter, a sixth lens disposed between the third beam splitter and the wafer bump, and a fifth lens disposed between the third camera and the third beam splitter; The third beam splitter makes the optical paths of the projection device and the third camera overlap outside the pattern projection unit and are perpendicular to the plane where the wafer bump is located; The pattern projection unit is further used to acquire the second image.

7. The system according to claim 1, wherein: The system includes a control module; The control module is used to control the image acquisition module to scan the wafer bumps line by line; The control module controls the line scanning image acquisition module to acquire the first image during the movement of the image acquisition module; The control module controls the image acquisition module to stop moving when the image acquisition module moves to the end of each row, and controls the phase-shifted image acquisition module to acquire the second image.

8. The system according to claim 1, wherein: The computing module is further configured to: determining a first height of each physical point on the surface of the wafer bump based on the plurality of first images; determining a second height of each of the entity points based on the plurality of second images; For a single entity point, performing a first fusion on multiple first heights corresponding to the single entity point to obtain a first base height of the single entity point, and performing a second fusion on multiple second heights corresponding to the single entity point to obtain a second base height of the single entity point; The first basic height and the second basic height of each entity point are subjected to a third fusion to obtain a target height of each entity point, and the target height is used to determine the topography data.

9. The system according to claim 8, characterized in that The computing module is further configured to: determining, based on the second image, a wrapping phase corresponding to each pixel in the second image; Performing a first unwrapping process on each of the wrapped phases to obtain a second initial height of each of the entity points; determining a quality indicator characterizing the quality of the wrapped phase; When the quality indicator is greater than the quality threshold, taking the second initial height of the first entity point corresponding to the wrapped phase as the second height of the first entity point; When the quality indicator is not greater than a quality threshold, determining a difference between a second initial height and a first base height of the first entity point; When the difference is less than the first threshold, performing a fourth fusion on the second initial height and the first base height of the first entity point to obtain a second height of the first entity point; When the difference is not less than a first threshold, determining surrounding pixels of the pixel corresponding to the wrapped phase; Based on the first wrapped phase corresponding to each peripheral pixel, a second unwrapping process is performed on the wrapped phase to obtain a second height of the first entity point.

10. The system according to claim 9, characterized in that The calculation module is further configured to: determining a spatial index according to a position of a pixel corresponding to the wrapping phase in a fringe period of the fringe pattern; Determining the grayscale of the pixel corresponding to the wrapped phase; Determining, based on the grayscale, a modulation index representing a pixel corresponding to the wrapped phase; The quality index is determined according to the spatial index and the modulation index.

Images