Detection method and device, equipment and storage medium

Abstract

The invention discloses a detection method, device and equipment and a storage medium, which are used for bubble defect detection in a wafer bonding process and can be applied to the technical field of optics, and the method comprises the following steps: obtaining an interference fringe pattern of a to-be-detected bonding wafer; determining a three-dimensional shape graph corresponding to the to-be-detected bonding wafer based on the interference fringe graph; determining whether a bubble defect exists in the to-be-detected bonding wafer based on the interference fringe pattern; if yes, determining a target position area corresponding to the bubble defect; determining the size information of the bubble defect in combination with the three-dimensional morphology graph and the target position area; the size information comprises thickness information, length information and width information. Thus, the interference fringe pattern of the whole bonded wafer is collected by using the optical interference principle, then the three-dimensional morphology graph of the bonded wafer is calculated, then the possibly existing bubble defect and the size information of the bubble defect are visually detected through the interference fringe pattern and the three-dimensional morphology graph, the detection efficiency is improved, and the bubble size is accurately measured.

Description

Technical Field

[0001] The present application relates to the field of optical technologies, and in particular, to a method for detecting bubble defects in a wafer bonding process and related products. Background Art

[0002] Wafer bonding technology refers to the process of tightly bonding two mirror-polished homogeneous or heterogeneous wafers together through chemical or physical actions, achieving a strong bonding force.

[0003] During the bonding process, if the gas generated on the bonding surface is not completely released, bubble defects of different sizes will be formed on the bonding surface. If the size of the bubble defects exceeds a certain threshold, during subsequent processes such as high-temperature annealing and plasma etching, due to the action of thermal stress, mechanical stress, etc., the bubbles may burst. By clarifying the precise size of the bubbles, wafers with oversized bubble sizes can be screened out in advance, avoiding problems such as damage to the wafer surface and particle contamination caused by bubble rupture in subsequent processes, which affect the process stability and yield. Existing methods for detecting bubble defects usually use ultrasonic waves to scan and detect each area of the bonded wafer one by one, which leads to low detection efficiency. In addition, existing methods for detecting bubble defects usually can only be qualitative, but not quantitative, which also results in the problem that the method cannot accurately measure the bubble size, and thus cannot accurately screen out wafers with oversized bubble sizes.

[0004] Therefore, how to accurately measure the bubble size while ensuring the detection efficiency of bubble defect detection is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] Based on the above problems, the present application provides a method for detecting bubble defects in a wafer bonding process and related products. By using the principle of optical interference, an interference fringe pattern of the entire bonded wafer is collected, and then the three-dimensional topography map of the bonded wafer is calculated. Then, the possible bubble defects and the size information of the bubble defects are visually detected through the interference fringe pattern and the three-dimensional topography map, improving the detection efficiency and accurately measuring the bubble size.

[0006] In a first aspect, an embodiment of the present application provides a detection method, which is a method for detecting bubble defects in a wafer bonding process, including:

[0007] Obtain an interference fringe pattern of the bonded wafer to be measured;

[0008] Determine a three-dimensional topography map corresponding to the bonded wafer to be measured based on the interference fringe pattern;

[0009] Determine whether there are bubble defects in the bonded wafer to be measured based on the interference fringe pattern; if so, determine the target position area corresponding to the bubble defects;

[0010] Determine the size information of the bubble defect in combination with the three-dimensional topography map and the target position area; the size information includes thickness information, length information, and width information.

[0011] Optionally, before obtaining the interference fringe pattern of the bond wafer to be measured, it further includes:

[0012] Fix the bond wafer to be measured in the interference cavity, and determine the initial optical path difference between the reference light and the test light corresponding to the bond wafer to be measured;

[0013] Determine the target phase-shifting parameter based on the initial optical path difference.

[0014] Optionally, obtaining the interference fringe pattern of the bond wafer to be measured includes:

[0015] Adjust the initial optical path difference between the reference light and the test light based on the target phase-shifting parameter, collect the interference fringe patterns corresponding to the bond wafer to be measured during the phase-shifting process, and form an interference fringe pattern set;

[0016] The interference fringe pattern set includes at least two interference fringe patterns corresponding to the bond wafer to be measured.

[0017] Optionally, based on the interference fringe pattern, determining the three-dimensional topography map corresponding to the bond wafer to be measured includes:

[0018] Determine the wrapped phase according to the interference fringe pattern;

[0019] Determine the three-dimensional topography map corresponding to the bond wafer to be measured according to the wrapped phase.

[0020] Optionally, determining the three-dimensional topography map corresponding to the bond wafer to be measured according to the wrapped phase includes

[0021] Unwrap the wrapped phase and obtain the unwrapped phase value;

[0022] In combination with the phase value, determine the three-dimensional topography map corresponding to the bond wafer to be measured according to the surface profile height solution formula;

[0023] The surface profile height solution formula is:

[0024]

[0025] In the formula, H is the height value of the surface profile, is the unwrapped phase value, and λ is the wavelength of the test light.

[0026] Optionally, based on the interference fringe pattern, determining whether there is a bubble defect in the bond wafer to be measured includes:

[0027] Determine the gradient information of the interference fringe pattern;

[0028] If there is a gradient change in the gradient information, it is determined that there are bubble defects in the bond wafer to be measured;

[0029] If there is no gradient change in the gradient information, it is determined that there are no such bubble defects in the bond wafer to be measured.

[0030] Optionally, determining the target position area corresponding to the bubble defect includes:

[0031] Take the area with the gradient change as the target position area corresponding to the bubble defect, and determine the area coordinate information of the target position area.

[0032] Optionally, the method further includes:

[0033] Annotate the three-dimensional topography map according to the area coordinate information to distinguish the target position area and other areas;

[0034] Retain the three-dimensional topography map corresponding to the target position area from the three-dimensional topography map, and delete the three-dimensional topography map corresponding to the other areas.

[0035] Optionally, combining the three-dimensional topography map and the target position area to determine the size information of the bubble defect includes:

[0036] Combined with the three-dimensional topography map, determine the thickness information, length information and width information of the bubble defect according to the surface gradient of the target position area.

[0037] Optionally, determining the thickness information of the bubble defect according to the surface gradient of the target position area includes:

[0038] According to the surface gradient of the target position area, take the height values of the points with the largest change in gradient values on the left and right sides as the thickness information of the bubble defect.

[0039] Optionally, determining the length information and width information of the bubble defect according to the surface gradient of the target position area includes:

[0040] According to the surface gradient of the target position area, take the difference in the number of horizontal pixels between the two points with the largest change in horizontal gradient values as the horizontal width range of the bubble defect;

[0041] Determine the length information of the bubble defect based on the pixel resolution and the horizontal width range;

[0042] According to the surface gradient of the target position area, the longitudinal pixel number difference between the two points with the largest change in longitudinal gradient value is used as the longitudinal width range of the bubble defect;

[0043] Based on the pixel resolution and the longitudinal width range, the width information of the bubble defect is determined.

[0044] In a second aspect, an embodiment of the present application provides a detection device for detecting bubble defects in a wafer bonding process, including:

[0045] An acquisition module for acquiring an interference fringe pattern of a bonding wafer to be measured;

[0046] A first determination module for determining a three-dimensional topography map corresponding to the bonding wafer to be measured based on the interference fringe pattern;

[0047] A second determination module for determining whether there is a bubble defect in the bonding wafer to be measured based on the interference fringe pattern; if so, determining the target position area corresponding to the bubble defect;

[0048] A third determination module for determining the size information of the bubble defect by combining the three-dimensional topography map and the target position area; the size information includes thickness information, length information, and width information.

[0049] In a third aspect, an embodiment of the present application provides a detection device for detecting bubble defects in a wafer bonding process, including:

[0050] A memory for storing a computer program;

[0051] A processor for implementing the steps of the detection method as described above when executing the computer program.

[0052] In a fourth aspect, an embodiment of the present application provides a readable storage medium with a computer program stored thereon, and the computer program, when executed by a processor, implements the steps of the detection method as described above.

[0053] It can be seen from the above technical solutions that compared with the prior art, the present application has the following advantages:

[0054] This application first obtains the interference fringe pattern of the bonding wafer to be measured, and determines the three-dimensional topography map corresponding to the bonding wafer to be measured based on the interference fringe pattern. Then, it determines whether there are bubble defects in the bonding wafer to be measured based on the interference fringe pattern. If there are, it determines the target position area corresponding to the bubble defects. Finally, it determines the size information of the bubble defects by combining the three-dimensional topography map and the target position area. The size information includes thickness information, length information, and width information. In this way, using the principle of optical interference, the interference fringe pattern of the entire bonding wafer is collected, and then the three-dimensional topography map of the bonding wafer is calculated. Then, the possible bubble defects and the quantitative measurement results of the bubbles, that is, the size information of the bubble defects, can be intuitively detected through the interference fringe pattern and the three-dimensional topography map. In this way, the method provided by this application can accurately measure the bubble size while ensuring the detection efficiency of bubble defect detection. The quantitative bubble size can screen out the wafers with excessive bubble size in advance and accurately, avoiding problems such as surface damage of the wafer and particle contamination caused by bubble rupture in subsequent processes. In addition, clarifying the accurate size of the bubbles can also adjust the subsequent process parameters according to the actual situation. For example, when performing chemical mechanical polishing (CMP), the polishing pressure, time and other parameters can be adjusted according to the bubble size and distribution to prevent uneven polishing caused by the presence of bubbles and affect the surface flatness of the wafer, ensuring that the process is carried out under stable parameters. Furthermore, accurately mastering the bubble size, combined with information such as process parameters and equipment conditions, is also helpful for in-depth analysis of the root cause of bubble generation. After improving the process, by monitoring the accurate size change of the bubbles, the effect of process improvement can be intuitively evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 FIG. is a schematic structural diagram of a bilateral interferometer provided by an embodiment of the present application;

[0056] Figure 2 FIG. is a flowchart of a method for detecting bubble defects in a wafer bonding process provided by an embodiment of the present application;

[0057] Figure 3 FIG. is a schematic diagram of a bubble defect provided by an embodiment of the present application;

[0058] Figure 4 FIG. is a schematic structural diagram of a device for detecting bubble defects in a wafer bonding process provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0059] As described above, the existing bubble defect detection methods have the problem of low detection efficiency. Specifically, the existing methods for detecting bubble defects in bonded wafers mainly use ultrasonic waves for detection, and judge whether there are bubble defects in the bonded wafers by distinguishing the differences between the reflection signals of ultrasonic waves on gases and solids. However, this method requires scanning each piece and each area on the bonded wafer, which leads to the problem of low detection efficiency of bubble defect detection.

[0060] To solve the above problems, the embodiments of the present application provide a method for detecting bubble defects in a wafer bonding process. The method first obtains an interference fringe pattern of a to-be-detected bonded wafer, and determines a three-dimensional topography map corresponding to the to-be-detected bonded wafer based on the interference fringe pattern. Then, it is determined whether there are bubble defects in the to-be-detected bonded wafer based on the interference fringe pattern. If so, the target position area corresponding to the bubble defect is determined. Finally, the size information of the bubble defect is determined by combining the three-dimensional topography map and the target position area. The size information includes thickness information, length information, and width information.

[0061] In this way, by using the optical interference principle, the interference fringe pattern of the entire bonded wafer is collected, and then the three-dimensional topography map of the bonded wafer is calculated. Then, the possible bubble defects and the size information of the bubble defects are intuitively detected through the interference fringe pattern and the three-dimensional topography map, improving the detection efficiency.

[0062] It should be noted that a method for detecting bubble defects in a wafer bonding process and related products provided by the present application can be applied to the field of semiconductor devices. The above is only an example, and does not limit the application field of a method for detecting bubble defects in a wafer bonding process and related products provided by the present application.

[0063] In order to make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0064] Figure 1 The structural schematic diagram of a bilateral interferometer provided for the embodiments of the present application. In combination with Figure 1As shown in the figure, the double-sided interferometer includes a detection fixture and laser interferometers arranged on both sides. Each side's laser interferometer includes a reference mirror, a phase shifter, a collimator, a beam splitter, a detector, an optical fiber, and a laser. Among them, the detection fixture is used to fix the bonded wafer to be detected. The light emitted by the laser irradiates on the beam splitter through the optical fiber for beam splitting processing. The reflected split beam is directed to the collimator for collimation processing. The collimated reflected split beam is directed to the reference mirror and the bonded wafer to be detected, and reflected beams are formed on the surfaces of both. Among them, the reflected beam formed on the surface of the bonded wafer to be detected is the test light, and the reflected beam formed on the surface of the reference mirror is the reference light. The two overlap to form an interference light that is directed to the detector to realize bubble defect detection. The phase shifter can synchronously drive the reference mirror to move in the optical path, thereby changing the distance between the bonded wafer to be detected and the reference mirror, and further changing the optical path difference between the test light and the reference light for phase shifting. The double-sided interferometer can quickly and batchwise realize the detection of bubble defects in single-sided or double-sided bonded wafers. Using the principle of optical interference, it collects the interference fringe pattern of the entire bonded wafer, and then calculates the three-dimensional topography map of the bonded wafer. Then, the possible bubble defects and the size information of the bubble defects can be intuitively detected through the interference fringe pattern and the three-dimensional topography map, improving the detection efficiency.

[0065] Figure 2 The following is a flowchart of a method for detecting bubble defects in a wafer bonding process provided by an embodiment of the present application. In combination with Figure 2 As shown in the figure, a method for detecting bubble defects in a wafer bonding process provided by an embodiment of the present application may include:

[0066] S201: Obtain the interference fringe pattern of the bonded wafer to be detected.

[0067] In practical applications, the presence of bubble defects in the bonded wafer will change the surrounding topography distribution, and the change in topography will be intuitively shown in the interference fringes. Therefore, an embodiment of the present application provides a method for determining bubble defects and the size information of bubble defects based on the principle of optical interference, improving the detection efficiency. Specifically, in combination with the above double-sided interferometer, first, the bonded wafer to be detected needs to be fixed in the detection fixture, and then the phase is shifted by changing the parameters of the laser or adjusting the position of the reference mirror using the phase shifter. Then, the interference fringe pattern of the bonded wafer to be detected is obtained using the detector.

[0068] In addition, since the methods for obtaining the interference fringe pattern are not the same, an embodiment of the present application can illustrate one possible obtaining method.

[0069] In one case, before obtaining the interference fringe pattern of the bonded wafer to be detected, it further includes:

[0070] Fix the bonding wafer to be measured in the interference cavity, and determine the initial optical path difference between the reference light and the test light corresponding to the bonding wafer to be measured;

[0071] Determine the target phase-shifting parameter based on the initial optical path difference.

[0072] In practical applications, it is necessary to calculate the phase-shifting parameter before obtaining the interference fringe pattern. Specifically, use a detection fixture to fix the bonding wafer to be measured in the interference cavity. By measuring the distance between the bonding wafer to be measured and the reference mirror, the optical path difference (initial optical path difference) between the test light and the reference light can be determined. Given the wavelength of the light emitted by the laser, the phase difference between the test light and the reference light can be determined, and then the target phase-shifting parameter can be obtained through calculation.

[0073] The obtaining of the interference fringe pattern of the bonding wafer to be measured includes:

[0074] Adjust the initial optical path difference between the reference light and the test light based on the target phase-shifting parameter, collect the interference fringe patterns corresponding to the bonding wafer to be measured during the phase shift, and form an interference fringe pattern set;

[0075] The interference fringe pattern set includes at least two interference fringe patterns corresponding to the bonding wafer to be measured.

[0076] In practical applications, generally multiple interference fringe patterns are required to solve the wrapped phase. Therefore, in the embodiments of the present application, the target phase-shifting parameter is introduced. The phase shift is performed by changing the optical path difference between the reference mirror and the bonding wafer through a phase shifter, and then multiple interference fringe patterns during the phase shift are collected and form an interference fringe pattern set. In addition, if the wavelength of the laser is adjustable, wavelength phase shift can be achieved by changing the wavelength instead of using a phase shifter. In addition, when the bubble defect is small, a laser with a different wavelength can also be replaced, and the purpose is to obtain higher resolution.

[0077] S202: Determine the three-dimensional topography map corresponding to the bonding wafer to be measured based on the interference fringe pattern.

[0078] In practical applications, the bubble defect will change the surrounding topography distribution, and the change in topography will be intuitively shown in the interference fringes. Therefore, the three-dimensional topography map corresponding to the bonding wafer to be measured can be determined through the interference fringe pattern.

[0079] In addition, since the methods for determining the three-dimensional topography map are not the same, the embodiments of the present application can illustrate one possible determination method.

[0080] In one case, S202: Determine the three-dimensional topography map corresponding to the bonding wafer to be measured based on the interference fringe pattern, specifically including:

[0081] Determine the wrapped phase according to the interference fringe pattern;

[0082] Determine a three-dimensional topography map corresponding to the to-be-tested bonded wafer according to the wrapped phase.

[0083] In practical applications, the wrapped phase refers to the phase restricted within a specific range. During the process of the phase shifter moving from the initial position to the target position, the detector can collect a set of interference fringe patterns during the phase shift process, and then by analyzing these interference fringe patterns, the corresponding wrapped phase is solved. Among them, the target position of the phase shifter is determined based on the above-mentioned target phase shift parameters. Finally, a three-dimensional topography map corresponding to the to-be-tested bonded wafer is determined through the wrapped phase.

[0084] In addition, since the methods for determining the surface height in the three-dimensional topography map are not all the same, the embodiments of the present application can illustrate one possible determination method.

[0085] In one case, the determining a three-dimensional topography map corresponding to the to-be-tested bonded wafer according to the wrapped phase includes

[0086] Unwrap the wrapped phase and obtain the phase value after unwrapping;

[0087] Combined with the phase value, determine a three-dimensional topography map corresponding to the to-be-tested bonded wafer according to the surface height solving formula;

[0088] The surface height solving formula is:

[0089]

[0090] In the formula, H is the height value of the surface shape, is the phase value after unwrapping, and λ is the wavelength of the test light.

[0091] In practical applications, for a bonded wafer with bubble defects, the surface heights at different positions may be different. It can be understood that on the surface of the bonded wafer, the surface height of the area with bubble defects will be higher than other areas. Therefore, it is necessary to unwrap the wrapped phase and determine the phase value after unwrapping. There are many methods for phase unwrapping, such as the ltoh method, the least squares unwrapping algorithm, the multi-frequency method, etc. Different methods have their own characteristics and applicable scenarios. Combined with the wavelength λ of the test light, the surface height solving formula: can be used to determine the height value H of the surface shape, and then solve the three-dimensional topography map of the to-be-tested bonded wafer.

[0092] S203: Determine whether there are bubble defects in the to-be-tested bonded wafer based on the interference fringe pattern; if so, determine the target position area corresponding to the bubble defects.

[0093] In practical applications, bubble defects in a bonded wafer can cause changes in the surrounding topography distribution, and the changes in topography will be visually displayed in the interference fringe pattern. Therefore, it is possible to determine whether there are bubble defects in the to-be-tested bonded wafer through the interference fringe pattern, and the area where the interference fringes change in the interference fringe pattern can be used as the target position area where the bubble defects are located.

[0094] In addition, since the methods for determining whether there are bubble defects are not all the same, the embodiments of the present application can illustrate one possible determination method.

[0095] In one case, determining whether there are bubble defects in the to-be-tested bonded wafer based on the interference fringe pattern includes:

[0096] Determining the gradient information of the interference fringe pattern;

[0097] If there is a gradient change in the gradient information, it is determined that there are bubble defects in the to-be-tested bonded wafer;

[0098] If there is no gradient change in the gradient information, it is determined that there are no such bubble defects in the to-be-tested bonded wafer.

[0099] In practical applications, the changes in the interference fringe pattern are mainly reflected in the gradient changes of the interference fringes. It can be understood that for a bonded wafer with no change in surface height in the ideal state, the gradient of the interference fringes in its interference fringe pattern does not change. Therefore, the gradient information of the interference fringe pattern corresponding to the to-be-tested bonded wafer obtained can be calculated, and then it is determined whether the gradients in different regions in the gradient information are consistent, that is, whether there is a gradient change in the gradient information. If there is, it is determined that there are bubble defects in the to-be-tested bonded wafer; if not, it is determined that there are no such bubble defects in the to-be-tested bonded wafer. Generally, in the area with bubble defects, the distribution of the interference fringes will be denser.

[0100] In addition, since the methods for determining the target position area corresponding to the bubble defects are not all the same, the embodiments of the present application can illustrate one possible determination method.

[0101] In one case, determining the target position area corresponding to the bubble defects includes:

[0102] Taking the area with the gradient change as the target position area corresponding to the bubble defects, and determining the area coordinate information of the target position area.

[0103] In practical applications, a coordinate system can be established to correspond the interference fringe pattern to the three-dimensional topography map. For the corresponding interference fringe pattern and three-dimensional topography map, the coordinate information at the same position of the wafer to be bonded under test is the same. Thus, the position area where the bubble defect is located is determined in the interference fringe pattern through gradient change. This position area is used as the target position area, and the area coordinate information of this position area is recorded for marking in the three-dimensional topography map.

[0104] In addition, since the methods for distinguishing different position areas in the three-dimensional topography map are not all the same, the embodiments of the present application can illustrate one possible distinguishing method.

[0105] In one case, the method further includes:

[0106] Mark the three-dimensional topography map according to the area coordinate information to distinguish the target position area and other areas;

[0107] Retain the three-dimensional topography map corresponding to the target position area from the three-dimensional topography map, and delete the three-dimensional topography map corresponding to the other areas.

[0108] In practical applications, to conveniently and visually determine the position area where the bubble defect is located in the three-dimensional topography map, it can be marked in the three-dimensional topography map based on the area coordinate information of the position area where the bubble defect is located. Only the three-dimensional topography corresponding to the area coordinate information is retained, and the three-dimensional topographies of other areas are all assigned Nan, so as to achieve the marking purpose, distinguish the target position area (bubble defect area) and other areas. During the subsequent topography analysis process, the computer will ignore other areas (delete the three-dimensional topography map corresponding to other areas) and only actively analyze the three-dimensional topography of the target position area (retain the three-dimensional topography map corresponding to the target position area).

[0109] S204: Determine the size information of the bubble defect in combination with the three-dimensional topography map and the target position area; the size information includes thickness information, length information, and width information.

[0110] In practical applications, the surface height of each area on the surface of the bonding wafer to be measured is shown in the three-dimensional topography map. It can be understood that in the three-dimensional topography map, the surface height of the bubble defect area is higher than that of other areas, and the size of the bubble (thickness information, length information, and width information) will regularly affect the X-axis span, Y-axis span, and Z-axis span of the area coordinate information corresponding to the bubble defect area. For example, the thicker the bubble, the larger the Z-axis span of the area coordinate information; the longer the bubble, the larger the X-axis span of the area coordinate information; the wider the bubble, the larger the Y-axis span of the area coordinate information. In this way, accurately determining the size information of the bubble defect, and then evaluating the current bonding process through the size information of the bubble defect, is more convenient for process guidance or process improvement. Specifically, accurately grasping the bubble size and combining information such as process parameters and equipment conditions helps to deeply analyze the root cause of bubble generation. For example, if it is found that the bubble sizes in a batch of wafers are generally large and concentrated after a certain process step, it is possible to focus on checking whether there are problems with the parameter settings and equipment status of this process step, providing a basis for improving the process and optimizing the parameters, thereby reducing the generation of bubbles and improving the bonding quality. Furthermore, after the process is improved, by monitoring the precise size change of the bubbles, the effect of the process improvement can be intuitively evaluated. If the bubble size and quantity decrease significantly after the improvement, it indicates that the process improvement measures are effective; otherwise, further adjustment and optimization are required to continuously improve and enhance the process. In addition, clarifying the precise size of the bubbles is beneficial for improving process stability, enhancing product performance and quality, and reducing costs. Specifically, by clarifying the precise size of the bubbles, wafers with oversized bubble sizes can be screened out in advance, avoiding problems such as damage to the wafer surface and particle contamination caused by bubble rupture in subsequent processes. Moreover, bubbles of different sizes have different effects on the physical properties of the bonding wafers. Understanding the precise size of the bubbles can adjust the subsequent process parameters according to the actual situation, thereby ensuring that the process is carried out under stable parameters and improving process stability. Then, the presence of bubbles may change the electrical characteristics of the bonding interface. If the bubble size is large, it will cause problems such as an increase in the contact resistance of the bonding interface and unstable signal transmission. Therefore, by clarifying the precise size of the bubbles, more accurate parameter compensation and optimization can be carried out during circuit design, or targeted treatment can be performed on wafers with bubble sizes exceeding the allowable range to ensure that the electrical performance of the chip meets the design requirements and improve the performance and quality of the product. Then again, if the bubble size is not clear, it may be found at a certain stage of the subsequent process that the wafer cannot be used due to bubble problems, resulting in waste of materials, time, and costs invested previously. After clarifying the precise size of the bubbles, problematic wafers can be processed at an early stage, concentrating resources on wafers with bubble sizes meeting the requirements, improving material utilization rate, and reducing production costs.

[0111] In addition, since the methods for determining the size information of the bubble defect are not the same, the embodiments of the present application can illustrate one possible determination method.

[0112] In one case, determining the size information of the bubble defect by combining the three-dimensional topography map and the target position area includes:

[0113] Combining the three-dimensional topography map, and determining the thickness information, length information, and width information of the bubble defect according to the surface shape gradient of the target position area.

[0114] In practical applications, considering that the bubble defect will cause changes in the surrounding surface shape, the actual size of the bubble is smaller than the target position area. What can be intuitively determined through the surface shape characteristics of the position area (target position area) where the bubble defect is located in the three-dimensional topography map is the protrusion size on the surface of the bonded wafer caused by the bubble defect, rather than the size of the bubble. Therefore, it is necessary to analyze the protrusion on the surface of the bonded wafer and deduce it in combination with the surface shape gradient of the bonded wafer surface, so as to calculate the size information (thickness information, length information, and width information) of the bubble under the bonded wafer.

[0115] In addition, since the methods for determining the thickness information of the bubble defect are not the same, the embodiments of the present application can illustrate one possible determination method.

[0116] In one case, determining the thickness information of the bubble defect according to the surface shape gradient of the target position area includes:

[0117] According to the surface shape gradient of the target position area, taking the height values of the points with the largest change in gradient values on the left and right sides as the thickness information of the bubble defect.

[0118] Figure 3 This is a schematic diagram of a bubble defect provided by the embodiments of the present application. Combining Figure 3 As shown, the surface of the bonded wafer bulges due to the influence of the bubble, and the size of the bulge is larger than the bubble in the spans of X, Y, and Z. Therefore, the bubble defect can be approximated as an ellipsoidal shape, and the thickness of the bubble defect can be approximated as T = 2·(T1 + T2), where T1 and T2 are the height values of the bonded wafer at the points with the largest gradient changes on the left and right sides corresponding to the target position area of the bubble defect, respectively.

[0119] In addition, since the methods for determining the length information and width information of the bubble defect are not the same, the embodiments of the present application can illustrate one possible determination method.

[0120] In one case, determining the length information and width information of the bubble defect according to the surface shape gradient of the target position area includes:

[0121] According to the surface shape gradient of the target position area, the difference in the number of horizontal pixels between the two points with the largest change in the horizontal gradient value is used as the horizontal width range of the bubble defect;

[0122] Based on the pixel resolution and the horizontal width range, determine the length information of the bubble defect;

[0123] According to the surface shape gradient of the target position area, the difference in the number of vertical pixels between the two points with the largest change in the vertical gradient value is used as the vertical width range of the bubble defect;

[0124] Based on the pixel resolution and the vertical width range, determine the width information of the bubble defect.

[0125] In practical applications, continue to combine Figure 3 As shown, according to the surface shape gradient of the target position area corresponding to the bubble defect, the difference m in the number of horizontal pixels between the two points with the largest change in the horizontal (X-axis direction) gradient value is taken as the horizontal width range of the bubble, and then the length information of the bubble defect W = k·m is calculated in combination with the pixel resolution k (μm / pixel). Similarly, according to the surface shape gradient of the target position area corresponding to the bubble defect, the difference n in the number of vertical pixels between the two points with the largest change in the vertical (Y-axis direction) gradient value is taken as the vertical width range of the bubble, and then the width information of the bubble defect H = k·n is calculated in combination with the pixel resolution k (μm / pixel).

[0126] In summary, the present application first obtains the interference fringe pattern of the bonding wafer to be measured, and determines the three-dimensional topography map corresponding to the bonding wafer to be measured based on the interference fringe pattern. Then, based on the interference fringe pattern, it is determined whether there are bubble defects in the bonding wafer to be measured. If so, the target position area corresponding to the bubble defect is determined. Finally, the size information of the bubble defect is determined in combination with the three-dimensional topography map and the target position area. Among them, the size information includes thickness information, length information, and width information. In this way, by using the principle of optical interference, the interference fringe pattern of the entire bonding wafer is collected, and then the three-dimensional topography map of the bonding wafer is calculated. Then, the possible bubble defects and the quantitative measurement results of the bubbles, that is, the size information of the bubble defects, are visually detected through the interference fringe pattern and the three-dimensional topography map. In this way, the method provided by the present application can accurately measure the bubble size while ensuring the detection efficiency of bubble defect detection.

[0127] Based on the method for detecting bubble defects in a wafer bonding process provided in the above embodiments, the present application embodiment also provides a device for detecting bubble defects in a wafer bonding process. The device for detecting bubble defects in the wafer bonding process will be described below in combination with the embodiments and the drawings respectively.

[0128] Figure 4The structural schematic diagram of a bubble defect detection device in a wafer bonding process provided by an embodiment of the present application. In combination with Figure 4 As shown, the bubble defect detection device 400 provided by an embodiment of the present application includes:

[0129] An acquisition module 401, configured to acquire an interference fringe pattern of a bonding wafer to be measured;

[0130] A first determination module 402, configured to determine a three-dimensional topography map corresponding to the bonding wafer to be measured based on the interference fringe pattern;

[0131] A second determination module 403, configured to determine whether there is a bubble defect in the bonding wafer to be measured based on the interference fringe pattern; if so, determine the target position area corresponding to the bubble defect;

[0132] A third determination module 404, configured to determine the size information of the bubble defect by combining the three-dimensional topography map and the target position area; the size information includes thickness information, length information, and width information.

[0133] As an implementation manner, for how to calculate the target phase shift parameter, the above-mentioned bubble defect detection device 400 further includes: a first calculation module;

[0134] The first calculation module is configured to fix the bonding wafer to be measured in the interference cavity and determine the initial optical path difference between the reference light and the test light corresponding to the bonding wafer to be measured;

[0135] Determine the target phase shift parameter based on the initial optical path difference.

[0136] As an implementation manner, for how to acquire the interference fringe pattern of the bonding wafer to be measured, the above-mentioned acquisition module 401 is specifically configured to:

[0137] Adjust the initial optical path difference between the reference light and the test light based on the target phase shift parameter, collect the interference fringe patterns corresponding to the bonding wafer to be measured during the phase shift process, and form an interference fringe pattern set;

[0138] The interference fringe pattern set includes at least two interference fringe patterns corresponding to the bonding wafer to be measured.

[0139] As an implementation manner, for how to determine the three-dimensional topography map corresponding to the bonding wafer to be measured based on the interference fringe pattern, the above-mentioned first determination module 402 includes: a first determination sub-module and a second determination sub-module;

[0140] The first determination sub-module is configured to determine the wrapped phase according to the interference fringe pattern;

[0141] A second determination sub-module, configured to determine a three-dimensional topography map corresponding to the bond wafer to be measured according to the wrapped phase.

[0142] As an implementation manner, for how to calculate the surface height in the three-dimensional topography map, the above-mentioned second determination sub-module is specifically configured to:

[0143] Unwrap the wrapped phase and obtain the phase value after unwrapping;

[0144] Combine the phase value and determine a three-dimensional topography map corresponding to the bond wafer to be measured according to the surface height solving formula;

[0145] The surface height solving formula is:

[0146]

[0147] In the formula, H is the height value of the surface, is the phase value after unwrapping, and λ is the wavelength of the test light.

[0148] As an implementation manner, for how to determine whether there is a bubble defect, the above-mentioned second determination module 403 is specifically configured to:

[0149] Determine the gradient information of the interference fringe pattern;

[0150] If there is a gradient change in the gradient information, it is determined that there is a bubble defect in the bond wafer to be measured;

[0151] If there is no gradient change in the gradient information, it is determined that there is no such bubble defect in the bond wafer to be measured.

[0152] As an implementation manner, for how to determine the target position area corresponding to the bubble defect, the above-mentioned second determination module 403 is further specifically configured to:

[0153] Take the area where the gradient change exists as the target position area corresponding to the bubble defect, and determine the area coordinate information of the target position area.

[0154] As an implementation manner, for how to distinguish the target position area from other areas, the above-mentioned bubble defect detection device 400 further includes: a marking module;

[0155] The marking module is configured to mark the three-dimensional topography map according to the area coordinate information to distinguish the target position area and other areas;

[0156] Retain the three-dimensional topography map corresponding to the target position area from the three-dimensional topography map, and delete the three-dimensional topography map corresponding to the other areas.

[0157] As an implementation manner, regarding how to determine the size information of the bubble defect by combining the three-dimensional topography map and the target position area, the above-mentioned third determination module includes: a third determination sub-module and a fourth determination sub-module;

[0158] The third determination sub-module is used to combine the three-dimensional topography map and determine the thickness information of the bubble defect according to the surface shape gradient of the target position area;

[0159] The fourth determination sub-module is used to determine the length information and width information of the bubble defect according to the surface shape gradient of the target position area.

[0160] As an implementation manner, regarding how to determine the thickness information of the bubble defect, the above-mentioned third determination sub-module is specifically used for:

[0161] According to the surface shape gradient of the target position area, take the height value of the points with the largest change in gradient values on the left and right sides as the thickness information of the bubble defect.

[0162] As an implementation manner, regarding how to determine the length information and width information of the bubble defect, the above-mentioned fourth determination sub-module is specifically used for:

[0163] According to the surface shape gradient of the target position area, take the difference in the number of horizontal pixels between the two points with the largest change in horizontal gradient values as the horizontal width range of the bubble defect;

[0164] Based on the pixel resolution and the horizontal width range, determine the length information of the bubble defect;

[0165] According to the surface shape gradient of the target position area, take the difference in the number of vertical pixels between the two points with the largest change in vertical gradient values as the vertical width range of the bubble defect;

[0166] Based on the pixel resolution and the vertical width range, determine the width information of the bubble defect.

[0167] In summary, the present application first obtains the interference fringe pattern of the bonding wafer to be measured, and determines the three-dimensional topography map corresponding to the bonding wafer to be measured based on the interference fringe pattern. Then, it determines whether there are bubble defects in the bonding wafer to be measured based on the interference fringe pattern. If so, it determines the target position area corresponding to the bubble defects. Finally, it determines the size information of the bubble defects by combining the three-dimensional topography map and the target position area. The size information includes thickness information, length information, and width information. In this way, by using the principle of optical interference, the interference fringe pattern of the entire bonding wafer is collected, and then the three-dimensional topography map of the bonding wafer is calculated. Then, the possible bubble defects and the quantitative measurement results of the bubbles, that is, the size information of the bubble defects, are visually detected through the interference fringe pattern and the three-dimensional topography map. In this way, the method provided by the present application can accurately measure the bubble size while ensuring the detection efficiency of bubble defect detection.

[0168] In addition, the present application also provides a bubble defect detection device in a wafer bonding process, including: a memory for storing a computer program; a processor for implementing the steps of the bubble defect detection method in the wafer bonding process as described above when executing the computer program.

[0169] In addition, the present application also provides a readable storage medium, on which a computer program is stored, and the computer program implements the steps of the bubble defect detection method in the wafer bonding process as described above when executed by a processor.

[0170] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A detection method, characterized in that: The method is a bubble defect method in a wafer bonding process, and the method comprises: Obtaining the interference fringe pattern of the bonded wafer to be tested; Determine a three-dimensional topography image corresponding to the bonded wafer to be tested based on the interference fringe image; Determine whether there is a bubble defect in the bonded wafer to be tested based on the interference fringe pattern; if so, determine the target position area corresponding to the bubble defect; The size information of the bubble defect is determined in combination with the three-dimensional morphology image and the target position area; the size information includes thickness information, length information and width information.

2. The method according to claim 1, characterized in that Before obtaining the interference fringe pattern of the bonded wafer to be tested, the method further includes: Fixing the bonded wafer to be tested in the interference cavity, and determining the initial optical path difference between the reference light and the test light corresponding to the bonded wafer to be tested; A target phase shift parameter is determined based on the initial optical path difference.

3. The method according to claim 2, characterized in that The step of obtaining the interference fringe pattern of the bonded wafer to be tested comprises: Adjusting the initial optical path difference between the reference light and the test light based on the target phase shift parameter, collecting the interference fringe pattern corresponding to the bonded wafer to be tested during the phase shift process, and forming an interference fringe pattern set; The interference fringe pattern set includes at least two interference fringe patterns corresponding to the bonded wafer to be tested.

4. The method according to claim 1, characterized in that: The method of determining a three-dimensional topography image corresponding to the bonded wafer to be tested based on the interference fringe image includes: determining a wrapping phase according to the interference fringe pattern; A three-dimensional topography image corresponding to the bonded wafer to be tested is determined according to the wrapping phase.

5. The method according to claim 4, characterized in that The step of determining a three-dimensional topography image corresponding to the bonded wafer to be tested according to the wrapping phase comprises: Unpacking the wrapped phase and obtaining the unpacked phase value; In combination with the phase value, a three-dimensional topography image corresponding to the bonded wafer to be tested is determined according to a surface height solution formula; The surface height solution formula is: Where H is the height of the surface, is the phase value after unpacking, and λ is the wavelength of the test light.

6. The method according to claim 1, characterized in that The determining whether there is a bubble defect in the bonded wafer to be tested based on the interference fringe pattern includes: Determining gradient information of the interference fringe pattern; If there is a gradient change in the gradient information, it is determined that there is a bubble defect in the bonded wafer to be tested; If there is no gradient change in the gradient information, it is determined that the bubble defect does not exist in the bonded wafer to be tested.

7. The method according to claim 6, characterized in that The determining of the target location area corresponding to the bubble defect includes: The area where the gradient change exists is used as the target position area corresponding to the bubble defect, and the area coordinate information of the target position area is determined.

8. The method according to claim 7, characterized in that The method further comprises: Annotating the three-dimensional topography image according to the regional coordinate information to distinguish the target location area from other areas; The three-dimensional topography image corresponding to the target position area is retained from the three-dimensional topography image, and the three-dimensional topography images corresponding to the other areas are deleted.

9. The method according to claim 1, characterized in that: The determining the size information of the bubble defect by combining the three-dimensional topography image and the target position area includes: In combination with the three-dimensional topography image, the thickness information, length information and width information of the bubble defect are determined according to the surface gradient of the target position area.

10. The method according to claim 9, characterized in that The step of determining the thickness information of the bubble defect according to the surface gradient of the target position area includes: According to the surface gradient of the target position area, the height value of the point where the gradient value on the left and right sides changes the most is used as the thickness information of the bubble defect.

11. The method according to claim 9, characterized in that The determining of the length information and width information of the bubble defect according to the surface gradient of the target position area includes: According to the surface gradient of the target position area, the difference in the number of lateral pixels between two points with the largest lateral gradient value change is used as the lateral width range of the bubble defect; Determining length information of the bubble defect based on pixel resolution and the lateral width range; According to the surface gradient of the target position area, the difference in the number of longitudinal pixels between two points with the largest change in longitudinal gradient value is used as the longitudinal width range of the bubble defect; Width information of the bubble defect is determined based on the pixel resolution and the longitudinal width range.

12. A detection device, characterized in that: The detection device is used for bubble defect detection in a wafer bonding process, and comprises: An acquisition module, used for acquiring an interference fringe pattern of a bonded wafer to be tested; A first determination module, configured to determine a three-dimensional topography image corresponding to the bonded wafer to be tested based on the interference fringe image; A second determination module is used to determine whether there is a bubble defect in the bonded wafer to be tested based on the interference fringe pattern; if there is, determine a target position area corresponding to the bubble defect; The third determination module is used to determine the size information of the bubble defect in combination with the three-dimensional morphology image and the target position area; the size information includes thickness information, length information and width information.

13. A detection device, characterized in that: The detection device is used for bubble defect detection in a wafer bonding process, and includes: Memory for storing computer programs; A processor, configured to implement the steps of the detection method according to any one of claims 1 to 11 when executing the computer program.

14. A readable storage medium, characterized in that: The readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the detection method according to any one of claims 1 to 11 are implemented.

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