Wafer warpage measurement method and detection equipment

Abstract

The present invention provides a method for measuring the warpage of a wafer and a detection device thereof. The method comprises setting n groups of marking patterns on the wafer; measuring the projection distance L of each group of marking patterns; 1m ; Wafer process; Measure the projection distance L of each set of marking patterns after the process 2m ; Make the length of the mth arc L 1m Chord length L 2m , calculate the quasi-warping degree B of the mth arc m Wafer warp is calculated based on n quasi-warp degrees. This method measures the projected distances before and after the process for n sets of distance marks, establishes a geometric model, and obtains the warp degree. This method is time-efficient, easy to operate, and improves warp measurement accuracy. Simultaneously measuring multiple pairs of distance marks yields warp degrees at multiple locations, further improving warp measurement accuracy. Furthermore, the optical imaging device automatically adjusts the focus to detect the center length and reference height to confirm the direction of wafer warp. Finally, the angles connecting the marking patterns are uniform to avoid accidentally detecting only locations without warp, further improving warp measurement accuracy.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor integrated circuit manufacturing, and in particular relates to a wafer warpage measurement method and detection equipment. Background Art

[0002] During the semiconductor manufacturing process, various processes are performed on the surface of the wafer to stack various material layers and various semiconductor devices layer by layer. However, a series of high-temperature processes such as diffusion and oxidation will generate various stresses on the wafer surface, causing the wafer to warp after the process. Warping can lead to many problems such as the nitride-oxygen stacking layer falling off, wafer cracking, unstable pattern alignment, and deterioration of lithography accuracy. In addition, in some process steps, adsorption tools are required to adsorb and fix the wafer. If the wafer warpage is too large, it will be difficult to adsorb and fix, resulting in the inability to proceed with the process. These problems will lead to unstable product performance and reduce product output and yield. Therefore, it is necessary to detect the warpage of the wafer after the process in order to adjust the process conditions and meet the warpage requirements of subsequent processes.

[0003] The current method for measuring wafer warpage involves directly sampling multiple points on the surface of a processed wafer, all located in the same plane. The heights of these points are then connected to form a line that fits an arc, and the warpage is calculated using the radius of curvature. However, this method is time-consuming and requires limited sampling. Furthermore, fitting an arc to areas with surface patterns is difficult, resulting in significant warpage errors.

[0004] Furthermore, conventional wafer warpage measurement requires transferring the wafer to a corresponding measuring instrument for measurement, which is time-consuming and complex to operate.

[0005] Therefore, there is an urgent need for a method for measuring wafer warpage that can quickly and conveniently obtain high precision.

[0006] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of this application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are explained in the background technology part of this application. Summary of the Invention

[0007] In view of the above shortcomings of the prior art, the purpose of the present invention is to provide a wafer warpage measurement method and detection equipment to solve the problem of long time consumption and large error in wafer warpage measurement in the prior art.

[0008] To achieve the above object, the present invention provides a method for measuring wafer warpage, the method comprising:

[0009] A wafer is provided, wherein n groups of distance markings are provided on an upper surface of the wafer, where n is an integer greater than or equal to 1, each group of distance markings includes two marking patterns, a plane on which the upper surface lies is a first plane, and a line connecting projections of two marking patterns in each group of distance markings on the first plane passes through a projection of a center point of the wafer on the first plane;

[0010] The straight-line distance between the projections of the two marking patterns in each group of the distance markings on the first plane is measured as the first distance, and the first distance of the mth group of the distance markings is L 1m , m is an integer greater than or equal to 1 and less than or equal to n;

[0011] performing a preset process on the wafer;

[0012] The straight-line distance between the projections of the two marking patterns in each group of the distance markings on the wafer after the preset process on the first plane is measured as the second distance, and the second distance of the distance markings of the mth group is L 2m ;

[0013] Establish a geometric model, the geometric model includes n arcs, and the arc length of the mth arc is L 1m , the chord length of the mth arc is L 2m , the quasi-warping degree B corresponding to the mth arc is calculated according to the geometric model m ;

[0014] The warpage of the wafer after undergoing a preset process is determined according to the n quasi-warpages.

[0015] Optionally, the quasi-warping degree B corresponding to the mth arc is calculated m The method is: solve the equation sin(θ m / 2) / (θ m / 2)=L 2m / L 1m , get the center angle θ of the mth arc m ; Calculate the curvature radius R of the mth arc m =L 1m / θ m ; Calculate the quasi-warping degree B corresponding to the mth arc m =R m -R m *cos(θ m / 2).

[0016] Optionally, the method for measuring the first distance is: the wafer is placed on a movable stage, an optical imaging device is provided above the wafer, the movable stage moves the wafer so that the optical imaging device respectively recognizes two of the marking patterns in a set of the distance markings, and a straight-line distance moved by the movable stage during the process of the optical imaging device recognizing the two marking patterns is recorded as the first distance;

[0017] And / or the method for measuring the second distance is: the wafer is placed on a movable table, an optical imaging device is arranged above the wafer, the movable table moves the wafer that has undergone a preset process so that the optical imaging device can respectively identify two of the mark graphics in a group of the distance marks, and the straight-line distance moved by the movable table in the process of the optical imaging device identifying the two mark graphics is recorded as the second distance.

[0018] Optionally, the measurement method further includes:

[0019] The wafer is positioned on a moving stage. Before the wafer undergoes a preset process, the moving stage moves the wafer until one of the mark patterns of the mth group of distance marks is located directly below an optical imaging device. The optical imaging device detects the distance from the mark pattern to the optical imaging device as a reference height D1.

[0020] After the wafer has undergone a preset process, a center mark is set at a position between two mark patterns of the mth group of distance marks on the upper surface of the wafer;

[0021] The moving stage moves the wafer until the center mark is directly below the optical imaging device, and the optical imaging device detects the distance from the center mark to the optical imaging device as the center height D2;

[0022] Compare the sizes of D1 and D2. When D1 is greater than D2, it is determined that the wafer is warped downward after the preset process. When D1 is less than D2, it is determined that the wafer is warped upward after the preset process. When D1 is equal to D2 and the first distance L 1m Equal to the second distance L 2m When the wafer is subjected to the preset process, it is determined that no warping occurs at the position where the distance mark is located.

[0023] Optionally, the measurement method further includes:

[0024] After the wafer undergoes a preset process, a center mark is provided between two mark patterns of the mth group of distance marks on the upper surface of the wafer;

[0025] The wafer is located on a moving stage, and the moving stage moves the wafer until the center mark is directly below the optical imaging device, and the optical imaging device detects the distance from the center mark to the optical imaging device as the center height D2;

[0026] The moving stage moves the wafer to a position directly below one of the mark patterns of the mth group of distance marks, and the optical imaging device detects the distance from the mark pattern to the optical imaging device as a reference height D1;

[0027] Compare the sizes of D1 and D2. When D1 is greater than D2, it is determined that the wafer is warped downward after the preset process. When D1 is less than D2, it is determined that the wafer is warped upward after the preset process. When D1 is equal to D2 and the first distance L 1m Equal to the second distance L 2m When the wafer is subjected to the preset process, it is determined that no warping occurs at the position where the distance mark is located.

[0028] Optionally, the method for the optical imaging device to detect the center height is as follows: the optical imaging device includes an automatically focusing optical lens and a rangefinder, the optical lens automatically adjusts the focal length to make the center mark image clear, the rangefinder measures the focal length of the optical lens at this time, and the center height D2 is calculated based on the focal length;

[0029] And / or the method for the optical imaging device to detect the reference height is: the optical imaging device includes an automatically focusing optical lens and a rangefinder, the optical lens automatically adjusts the focal length to make the image of the mark graphic clear, the rangefinder measures the focal length of the optical lens at this time, and calculates the reference height D1 through the focal length.

[0030] Optionally, when n is greater than 1, before the wafer is subjected to a preset process, the line connecting the projections of two of the mark graphics in each group of the distance marks on the first plane is a first line, and the angle between the first lines of two adjacent groups of the distance marks is (180° / n).

[0031] Optionally, the marking pattern is a device pattern of the wafer; or the marking pattern is a cutting path of the wafer;

[0032] And / or the minimum distance between each of the marking patterns and the edge of the wafer is greater than or equal to 3 mm.

[0033] The present invention also provides a wafer warpage detection device, which is used by any one of the above-mentioned wafer warpage measurement methods, and includes: an optical imaging device, a moving stage, and a computing device;

[0034] The movable platform is used to place and move the wafer; the optical imaging device is located above the movable platform and is used to identify the mark on the upper surface of the wafer;

[0035] The calculation device is used to calculate L 1m and L 2m 、Solve the equation sin(θ m / 2) / (θ m / 2)=L 2m / L 1m Get θ m According to R m =L 1m / θ m Calculate R m According to B m =R m -R m *cos(θ m / 2) Calculate the quasi-warpage B m , calculating the warpage of the wafer after a preset process based on n quasi-warpages.

[0036] Optionally, the optical imaging device further comprises: an automatically focusing optical lens and a rangefinder; the optical lens automatically adjusts its focal length so that a mark directly below the optical lens is clearly imaged, the rangefinder measures the focal length of the optical lens at this time, and calculates the distance between the mark directly below the optical lens and the optical lens based on the focal length;

[0037] And / or the calculation device is also used to obtain the warping direction of the wafer after the preset process by comparing the distance from one of the mark graphics of the mth group of distance marks directly below the optical imaging device before the wafer undergoes the preset process to the optical imaging device, that is, the reference height D1, and the distance from the center mark directly below the optical imaging device to the optical imaging device after the wafer undergoes the preset process, that is, the center height D2, wherein the center mark is located between the two mark graphics of the mth group of distance marks; when D1 is greater than D2, it is judged that the wafer is warped downward after the preset process; when D1 is less than D2, it is judged that the wafer is warped upward after the preset process; D1 is equal to D2, and the first distance L 1m Equal to the second distance L 2m When the wafer is subjected to the preset process, it is determined that no warping occurs at the position where the distance mark is located;

[0038] Or the calculation device is further used to obtain the warping direction of the wafer after the preset process by comparing the distance from one of the mark graphics of the mth group of distance marks directly below the optical imaging device after the wafer undergoes the preset process to the optical imaging device, that is, the reference height D1, and the distance from the center mark directly below the optical imaging device after the wafer undergoes the preset process to the optical imaging device, that is, the center height D2, wherein the center mark is located between the two mark graphics of the mth group of distance marks; when D1 is greater than D2, it is judged that the wafer is warped downward after the preset process; when D1 is less than D2, it is judged that the wafer is warped upward after the preset process; D1 is equal to D2, and the first distance L 1m Equal to the second distance L 2m When the wafer is subjected to the preset process, it is determined that no warping occurs at the position where the distance mark is located.

[0039] As described above, the wafer warpage measurement method and detection device of the present invention have the following beneficial effects:

[0040] The present invention measures the projection distance between two marking patterns before and after the process as the arc length and chord length after warping, thereby directly calculating the parameters of the radius and central angle of the arc after warping without the need to perform actual multi-point sampling of the shape formed by the warped wafer. The operation is convenient and quick, and an accurate representation of the arc formed after warping can be obtained, thereby obtaining a more accurate wafer warping degree.

[0041] The present invention sets the angles between the connecting lines of the marking pattern to be uniform, so that the subsequently obtained quasi-warpage can more accurately reflect the overall warpage of the wafer, thereby obtaining a warpage with higher accuracy.

[0042] The present invention uses the device pattern or cutting path of the wafer itself as the marking pattern, thereby eliminating the need to set additional marks on the wafer. The warpage can be measured using the existing pattern of the wafer, which is convenient to operate and has high measurement efficiency. There is no additional operation or modification on the wafer, which reduces the impact on the wafer.

[0043] The present invention sets a distance between the marking pattern and the edge so that the marking pattern is not located in the edge area of ​​the wafer, which can better reflect the warpage of the area of ​​the wafer used for device making after the process;

[0044] The present invention places the marking patterns at both ends of the wafer to reflect the maximum warpage of the wafer and improve the measurement accuracy of the wafer warpage;

[0045] The present invention obtains multiple quasi-warpages in different directions and selects the maximum value, mean value or other appropriate statistical value as the warpage of the wafer, thereby avoiding the warpage obtained due to the randomness of sampling and failing to accurately reflect the actual warpage of the wafer, thereby further improving the accuracy of the characterization of the wafer warpage;

[0046] The present invention obtains the height of the mark pattern before the process and the height of the center mark after the process. Since the heights of the mark pattern and the center mark of a wafer that has not warped are consistent, the height change of the center mark after the process can reflect the warping direction of the wafer more accurately.

[0047] The present invention obtains the warping direction by directly measuring the height of the mark pattern and the center mark after the process and comparing them. The whole process can be measured after the process, which has higher measurement efficiency.

[0048] The present invention measures the base height and center height through the automatic focus adjustment function of the optical imaging device itself, eliminating the need for additional height measurement tools, improving measurement efficiency and saving costs. Furthermore, because imaging devices are common in production lines, the present invention can detect wafer warpage online without requiring dedicated measurement equipment for warpage detection, thus improving detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic structural diagram showing the measurement of the first distance in step 2 of the wafer warpage measurement method according to the first embodiment of the present invention.

[0050] Figure 2 It is a schematic structural diagram showing the measurement of the second distance in step 4 of the wafer warpage measurement method according to the first embodiment of the present invention.

[0051] Figure 3 Shown is a structural schematic diagram of a wafer warpage detection device according to a second embodiment of the present invention.

[0052] Component number description

[0053] 1. Wafer; 2. Optical imaging equipment; 3. Mobile stage. DETAILED DESCRIPTION

[0054] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0055] For example, when describing the embodiments of the present invention, schematic diagrams illustrating device structures may be partially enlarged for ease of explanation. These schematic diagrams are merely illustrative and should not limit the scope of the present invention. Furthermore, in actual production, three-dimensional dimensions, including length, width, and depth, should be included.

[0056] For convenience of description, spatially relative terms such as "under," "below," "below," "below," "above," and "upper" may be used herein to describe the relationship of one element or feature to other elements or features shown in the drawings. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the drawings.

[0057] In the context of the present application, a structure described as a first feature being "above" a second feature may include embodiments where the first and second features are in direct contact, and may also include embodiments where additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0058] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated. Example 1

[0059] The present invention provides a method for measuring the warpage of a wafer 1, the method comprising:

[0060] Step 1: Providing a wafer 1, wherein n groups of distance markings are provided on the upper surface of the wafer 1, where n is an integer greater than or equal to 1, each group of distance markings includes two marking patterns, wherein the plane on which the upper surface lies is a first plane, and a line connecting the projections of the two marking patterns in each group of distance markings on the first plane passes through the projection of the center point of the wafer 1 on the first plane;

[0061] Step 2: Measure the straight-line distance between the projections of the two marking patterns in each group of the distance markings on the first plane as the first distance. The first distance of the mth group of distance markings is L 1m , m is an integer greater than or equal to 1 and less than or equal to n;

[0062] Step 3: performing a preset process on the wafer 1;

[0063] Step 4: Measure the straight-line distance between the projections of the two marking patterns in each group of the distance markings on the wafer 1 after the preset process on the first plane as the second distance, and the second distance of the distance markings of the mth group is L 2m ;

[0064] Step 5: Establish a geometric model, which includes n arcs, and make the length of the mth arc L 1m , the chord length of the mth arc is L 2m , the quasi-warping degree B corresponding to the mth arc is calculated according to the geometric model m ;

[0065] Step 6: Determine the warpage of the wafer after the preset process based on the n quasi-warpages.

[0066] The following will describe in detail the method for measuring the warpage of wafer 1 of the present invention in conjunction with the accompanying drawings. It should be noted that the above sequence does not strictly represent the sequence of the method for measuring the warpage of wafer 1 protected by the present invention, and those skilled in the art may change it according to the actual preparation steps.

[0067] First, step 1 is performed to provide a wafer 1. The upper surface of the wafer 1 is provided with n groups of distance marks, where n is an integer greater than or equal to 1, and each group of the distance marks includes two marking graphics. At this time, the plane where the upper surface is located is the first plane, and the line connecting the projections of the two marking graphics in each group of the distance marks on the first plane passes through the projection of the center point of the wafer 1 on the first plane.

[0068] In one embodiment, when n is greater than 1, before the preset process is performed on the wafer 1, the line connecting the projections of two of the mark graphics in each group of the distance marks on the first plane is a first line, and the angle between the first lines of two adjacent groups of the distance marks is (180° / n).

[0069] The present invention sets the angles between the connecting lines of the marking pattern to be uniform, so that the subsequently obtained quasi-warpage can more accurately reflect the overall warpage of the wafer 1, thereby obtaining a warpage with higher accuracy.

[0070] In one embodiment, the marking pattern is a device pattern of the wafer 1 .

[0071] In one embodiment, the marking pattern is a dicing line of the wafer 1 .

[0072] The present invention uses the device pattern or cutting path of the wafer 1 itself as the marking pattern, so that there is no need to set additional marks on the wafer 1. The warpage can be measured using the existing pattern of the wafer 1. The operation is convenient and the measurement efficiency is high. There is no additional operation change to the wafer 1, which reduces the impact on the wafer 1.

[0073] In one embodiment, the minimum distance between each of the marking patterns and the edge of the wafer 1 is greater than or equal to 3 mm.

[0074] The present invention sets a distance between the marking pattern and the edge so that the marking pattern is not located in the edge area of ​​the wafer 1, which can better reflect the warpage of the area of ​​the wafer 1 used for device manufacturing after processing.

[0075] Specifically, it is preferred that the minimum distance between each of the marking patterns and the edge of the wafer 1 is equal to 3 mm, so that the marking patterns are located at both ends of the wafer 1 to reflect the maximum warpage of the wafer 1 and improve the measurement accuracy of the warpage of the wafer 1.

[0076] Then, if Figure 1 As shown, step 2 is performed, measuring the straight-line distance between the projections of the two marking patterns in each group of the distance markings on the first plane as the first distance, and the first distance of the distance markings in the mth group is L 1m , m is an integer greater than or equal to 1 and less than or equal to n. Specifically, Figure 1 A and B shown are two marking graphics in a set of distance markings.

[0077] In one embodiment, the method for measuring the first distance is: the wafer 1 is placed on a movable table 3, an optical imaging device 2 is arranged above the wafer 1, the movable table 3 moves the wafer 1 so that the optical imaging device 2 respectively recognizes two of the mark graphics in a group of the distance marks, and the straight-line distance moved by the movable table 3 in the process of the optical imaging device 2 recognizing the two mark graphics is recorded as the first distance.

[0078] Next, proceed to step 3 to perform a preset process on the wafer 1 .

[0079] In one embodiment, the preset process is a process that requires high temperature, such as diffusion and oxidation, or other processes that may affect the warpage of the wafer 1 .

[0080] Then, if Figure 2 As shown, step 4 is performed to measure the straight-line distance between the projections of the two marking patterns in each group of the distance markings on the wafer 1 after the preset process on the first plane as the second distance, and the second distance of the distance markings of the mth group is L 2m . Specifically, Figure 2A and B are the two marking patterns for measuring the first distance in step 2. It can be seen that the length of the arc formed after the wafer 1 is warped is the projection L of the two marking patterns on the first plane before the process. 1m The chord length of the arc formed after the wafer 1 is warped is the projection L of the two marking patterns on the first plane before the process. 2m .

[0081] In one embodiment, the method for measuring the second distance is: the wafer 1 is placed on a movable table 3, an optical imaging device 2 is arranged above the wafer 1, the movable table 3 moves the wafer 1 that has undergone a preset process so that the optical imaging device 2 respectively recognizes two of the mark graphics in a group of the distance marks, and the straight-line distance moved by the movable table 3 in the process of the optical imaging device 2 recognizing the two mark graphics is recorded as the second distance.

[0082] Next, proceed to step 5 to establish a geometric model, wherein the geometric model includes n arcs, and the length of the mth arc is L 1m , the chord length of the mth arc is L 2m , the quasi-warping degree B corresponding to the mth arc is calculated according to the geometric model m .

[0083] In one embodiment, the quasi-warping degree B corresponding to the mth arc is calculated as follows: m The method is:

[0084] Solve the equation sin(θ m / 2) / (θ m / 2)=L 2m / L 1m , get the center angle θ of the mth arc m ; Calculate the curvature radius R of the mth arc m =L 1m / θ m ; Calculate the quasi-warping degree B corresponding to the mth arc m =R m -R m *cos(θ m / 2).

[0085] In the prior art, multi-point sampling is generally performed on the warped wafer 1 to obtain the heights of multiple points on the surface of the wafer 1, and then an arc is fitted at a certain position after the warping to calculate the warping degree at that position. This method requires measuring multiple sampling points and is also difficult to fit an accurate arc. The present invention measures the projected distance between two marked figures before and after the process as the arc length and chord length after the warping, thereby directly calculating the parameters of the radius and central angle of the arc after the warping, without the need to perform actual multi-point sampling on the shape formed by the warped wafer 1. The operation is convenient and quick, and an accurate representation of the arc formed after the warping can be obtained, thereby obtaining a more accurate warping degree of the wafer 1.

[0086] Finally, step 6 is performed to determine the warpage of the wafer 1 after the preset process according to the n quasi-warpages.

[0087] The present invention obtains quasi-warpages in multiple directions and selects the maximum value as the warpage of the wafer 1, thereby avoiding the warpage obtained due to the randomness of sampling and failing to accurately reflect the actual warpage of the wafer 1, thereby further improving the accuracy of the characterization of the warpage of the wafer 1.

[0088] In one embodiment, the warpage of the wafer 1 after undergoing a preset process may be obtained by calculating the maximum value, average value, or other suitable statistical value of n quasi-warpages.

[0089] In one embodiment, the measuring method further comprises:

[0090] The wafer 1 is placed on a moving stage 3. Before the wafer 1 undergoes a preset process, the moving stage 3 moves the wafer 1 until one of the mark patterns of the mth group of distance marks is located directly below the optical imaging device 2. The optical imaging device 2 detects the distance from the mark pattern to the optical imaging device 2 as a reference height D1.

[0091] After the wafer 1 undergoes a preset process, a center mark is set at a position between two mark patterns of the mth group of distance marks on the upper surface of the wafer 1;

[0092] The moving stage 3 moves the wafer 1 until the center mark is located directly below the optical imaging device 2, and the optical imaging device 2 detects the distance from the center mark to the optical imaging device 2 as the center height D2;

[0093] Compare the sizes of D1 and D2. When D1 is greater than D2, it is determined that the wafer 1 is warped downward after the preset process; when D1 is less than D2, it is determined that the wafer 1 is warped upward after the preset process; when D1 is equal to D2, and the first distance L 1m Equal to the second distance L 2mWhen the distance mark is located, it is determined that the wafer 1 has not been warped at the location of the distance mark after undergoing the preset process.

[0094] The present invention obtains the height of the mark pattern before the process and the height of the center mark after the process. Since the heights of the mark pattern and the center mark of the wafer 1 that has not warped are consistent, the change in the height of the center mark after the process can reflect the warping direction of the wafer 1 more accurately.

[0095] In one embodiment, the measuring method further comprises:

[0096] After the wafer 1 undergoes a preset process, a center mark is set between two mark patterns of the mth group of distance marks on the upper surface of the wafer 1;

[0097] The wafer 1 is placed on a moving stage 3, and the moving stage 3 moves the wafer 1 until the center mark is directly below the optical imaging device 2. The optical imaging device 2 detects the distance from the center mark to the optical imaging device 2 as the center height D2;

[0098] The moving stage 3 moves the wafer 1 to a position directly below one of the mark patterns of the mth group of distance marks, and the optical imaging device 2 detects the distance from the mark pattern to the optical imaging device 2 as a reference height D1;

[0099] Compare the sizes of D1 and D2. When D1 is greater than D2, it is determined that the wafer 1 is warped downward after the preset process; when D1 is less than D2, it is determined that the wafer 1 is warped upward after the preset process; when D1 is equal to D2, and the first distance L 1m Equal to the second distance L 2m When the distance mark is located, it is determined that the wafer 1 has not been warped at the location of the distance mark after undergoing the preset process.

[0100] The present invention obtains the warping direction by directly measuring the height of the mark pattern and the center mark after the process and comparing them. The entire process can be measured after the process, and the measurement efficiency is higher.

[0101] In one embodiment, the method for the optical imaging device 2 to detect the center height is: the optical imaging device 2 includes an automatically focusing optical lens and a rangefinder, the optical lens automatically adjusts the focal length to make the center mark image clear, the rangefinder measures the focal length of the optical lens at this time, and calculates the center height D2 through the focal length.

[0102] In one embodiment, the method for the optical imaging device 2 to detect the reference height is: the optical imaging device 2 includes an automatically focusing optical lens and a rangefinder, the optical lens automatically adjusts the focal length to make the image of the marking graphic clear, the rangefinder measures the focal length of the optical lens at this time, and calculates the reference height D1 through the focal length.

[0103] The present invention measures the base height and center height through the automatic focus adjustment function of the optical imaging device 2, eliminating the need for additional height measurement tools. This improves measurement efficiency and contributes to cost savings. Furthermore, because imaging devices are common in production lines, the present invention can detect wafer warpage online without requiring dedicated measurement equipment for warpage detection, thus improving detection efficiency. Example 2

[0104] The present invention provides a wafer 1 warpage detection device, wherein the wafer 1 warpage detection device is used by any one of the wafer 1 warpage measurement methods in the first embodiment, such as Figure 3 As shown, the detection device includes: an optical imaging device 2, a mobile station 3 and a computing device (not shown);

[0105] The movable platform 3 is used to place and move the wafer 1; the optical imaging device 2 is located above the movable platform 3 and is used to identify the mark on the upper surface of the wafer 1;

[0106] The calculation device is used to calculate L 1m and L 2m 、Solve the equation sin(θ m / 2) / (θ m / 2)=L 2m / L 1m Get θ m According to R m =L 1m / θ m Calculate R m According to B m =R m -R m *cos(θ m / 2) Calculate the quasi-warpage B m , calculating the warpage of the wafer 1 after undergoing a preset process based on the n quasi-warpages.

[0107] In one embodiment, the optical imaging device 2 further includes: an automatically focusing optical lens and a rangefinder; the optical lens automatically adjusts the focal length so that the image of the mark directly below the optical lens is clear, and the rangefinder measures the focal length of the optical lens at this time, and calculates the distance between the mark directly below the optical lens and the optical lens through the focal length.

[0108] In one embodiment, the calculation device obtains the warpage of the wafer 1 after undergoing a preset process by calculating the maximum value, average value or other suitable statistical values ​​of n quasi-warpages.

[0109] In one embodiment, the calculation device is further used to obtain the warping direction of the wafer 1 after the preset process by comparing the distance from one of the mark graphics of the mth group of distance marks directly below the optical imaging device 2 to the optical imaging device 2 before the wafer 1 undergoes the preset process, that is, the reference height D1, and the distance from the center mark directly below the optical imaging device 2 to the optical imaging device 2 after the wafer 1 undergoes the preset process, that is, the center height D2, wherein the center mark is located between the two mark graphics of the mth group of distance marks; when D1 is greater than D2, it is determined that the wafer 1 is warped downward after the preset process; when D1 is less than D2, it is determined that the wafer 1 is warped upward after the preset process; D1 is equal to D2, and the first distance L 1m Equal to the second distance L 2m When the distance mark is located, it is determined that the wafer 1 has not been warped at the location of the distance mark after undergoing the preset process.

[0110] In one embodiment, the calculation device is further used to obtain the warping direction of the wafer 1 after the preset process by comparing the distance from one of the mark graphics of the mth group of distance marks directly below the optical imaging device 2 to the optical imaging device 2 after the wafer 1 undergoes the preset process, that is, the reference height D1, and the distance from the center mark directly below the optical imaging device 2 to the optical imaging device 2 after the wafer 1 undergoes the preset process, that is, the center height D2, wherein the center mark is located between the two mark graphics of the mth group of distance marks; when D1 is greater than D2, it is judged that the wafer 1 is warped downward after the preset process; when D1 is less than D2, it is judged that the wafer 1 is warped upward after the preset process; D1 is equal to D2, and the first distance L 1m Equal to the second distance L 2m When the distance mark is located, it is determined that the wafer 1 has not been warped at the location of the distance mark after undergoing the preset process.

[0111] In summary, the wafer warpage measurement method and detection equipment of the present invention can obtain the warpage by measuring the projection distance of n groups of distance marks before and after the process, establishing a geometric model, which is time-saving, easy to operate, and improves the measurement accuracy of the warpage; at the same time, by measuring multiple pairs of distance marks, the warpage of multiple positions can be obtained, further improving the measurement accuracy of the warpage; in addition, the center length and reference height are automatically focused and detected by the optical imaging equipment, so that the warpage direction of the wafer can be confirmed; finally, by setting the connecting line angle of the mark graphics to be uniform, it is avoided that only the position without warpage is accidentally detected, thereby further improving the measurement accuracy of the warpage.

[0112] Therefore, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0113] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for measuring wafer warpage, characterized in that: The measuring method comprises: A wafer is provided, wherein n groups of distance markings are provided on an upper surface of the wafer, where n is an integer greater than or equal to 1, each group of distance markings includes two marking patterns, a plane on which the upper surface lies is a first plane, and a line connecting projections of two marking patterns in each group of distance markings on the first plane passes through a projection of a center point of the wafer on the first plane; The straight-line distance between the projections of the two marking patterns in each group of the distance markings on the first plane is measured as the first distance, and the first distance of the mth group of the distance markings is L 1m , m is an integer greater than or equal to 1 and less than or equal to n; performing a preset process on the wafer; The straight-line distance between the projections of the two marking patterns in each group of the distance markings on the wafer after the preset process on the first plane is measured as the second distance, and the second distance of the distance markings of the mth group is L 2m ; Establish a geometric model, the geometric model includes n arcs, and the arc length of the mth arc is L 1m , the chord length of the mth arc is L 2m , the quasi-warping degree B corresponding to the mth arc is calculated according to the geometric model m ; Calculate the quasi-warping degree B corresponding to the mth arc m The method is: solve the equation sin(θ m / 2) / (θ m / 2)=L 2m / L 1m , get the center angle θ of the mth arc m ; Calculate the curvature radius R of the mth arc m =L 1m / θ m ; Calculate the quasi-warping degree B corresponding to the mth arc m =R m -R m *cos(θ m / 2); The warpage of the wafer after undergoing a preset process is determined according to the n quasi-warpages.

2. The wafer warpage measurement method according to claim 1, wherein: The method for measuring the first distance is as follows: the wafer is placed on a movable stage, an optical imaging device is provided above the wafer, the movable stage moves the wafer so that the optical imaging device respectively recognizes two marking patterns in a set of the distance markings, and a straight-line distance moved by the movable stage during the process of the optical imaging device recognizing the two marking patterns is recorded as the first distance; And / or the method for measuring the second distance is: the wafer is placed on a movable table, an optical imaging device is arranged above the wafer, the movable table moves the wafer that has undergone a preset process so that the optical imaging device can respectively identify two of the mark graphics in a group of the distance marks, and the straight-line distance moved by the movable table in the process of the optical imaging device identifying the two mark graphics is recorded as the second distance.

3. The wafer warpage measurement method according to claim 1, wherein: The measuring method further comprises: The wafer is positioned on a moving stage. Before the wafer undergoes a preset process, the moving stage moves the wafer until one of the mark patterns of the mth group of distance marks is located directly below an optical imaging device. The optical imaging device detects the distance from the mark pattern to the optical imaging device as a reference height D1. After the wafer has undergone a preset process, a center mark is set at a position between two mark patterns of the mth group of distance marks on the upper surface of the wafer; The moving stage moves the wafer until the center mark is directly below the optical imaging device, and the optical imaging device detects the distance from the center mark to the optical imaging device as the center height D2; Compare the sizes of D1 and D2. When D1 is greater than D2, it is determined that the wafer is warped downward after the preset process. When D1 is less than D2, it is determined that the wafer is warped upward after the preset process. When D1 is equal to D2 and the first distance L 1m Equal to the second distance L 2m When the wafer is subjected to the preset process, it is determined that no warping occurs at the position where the distance mark is located.

4. The wafer warpage measurement method according to claim 1, wherein: The measuring method further comprises: After the wafer undergoes a preset process, a center mark is provided between two mark patterns of the mth group of distance marks on the upper surface of the wafer; The wafer is located on a moving stage, and the moving stage moves the wafer until the center mark is directly below the optical imaging device, and the optical imaging device detects the distance from the center mark to the optical imaging device as the center height D2; The moving stage moves the wafer to a position directly below one of the mark patterns of the mth group of distance marks, and the optical imaging device detects the distance from the mark pattern to the optical imaging device as a reference height D1; Compare the sizes of D1 and D2. When D1 is greater than D2, it is determined that the wafer is warped downward after the preset process. When D1 is less than D2, it is determined that the wafer is warped upward after the preset process. When D1 is equal to D2 and the first distance L 1m Equal to the second distance L 2m When the wafer is subjected to the preset process, it is determined that no warping occurs at the position where the distance mark is located.

5. The wafer warpage measurement method according to claim 3 or 4, characterized in that: The method for detecting the center height by the optical imaging device is as follows: the optical imaging device includes an automatically focusing optical lens and a rangefinder, the optical lens automatically adjusts the focal length to make the center mark image clear, the rangefinder measures the focal length of the optical lens at this time, and the center height D2 is calculated based on the focal length; And / or the method for the optical imaging device to detect the reference height is: the optical imaging device includes an automatically focusing optical lens and a rangefinder, the optical lens automatically adjusts the focal length to make the image of the mark graphic clear, the rangefinder measures the focal length of the optical lens at this time, and calculates the reference height D1 through the focal length.

6. The wafer warpage measurement method according to claim 1, wherein: When n is greater than 1, before the preset process is performed on the wafer, the line connecting the projections of the two mark graphics in each group of the distance marks on the first plane is the first line, and the angle between the first lines of two adjacent groups of the distance marks is 180° / n.

7. The wafer warpage measurement method according to claim 1, wherein: The marking pattern is a device pattern of the wafer; or the marking pattern is a dicing street of the wafer; And / or the minimum distance between each of the marking patterns and the edge of the wafer is greater than or equal to 3 mm.

8. A wafer warpage detection device, characterized in that: The detection device is used by the wafer warpage measurement method according to any one of claims 1 to 7, and the detection device comprises: an optical imaging device, a mobile stage, and a computing device; The movable platform is used to place and move the wafer; the optical imaging device is located above the movable platform and is used to identify the mark on the upper surface of the wafer; The calculation device is used to calculate L 1m and L 2m 、Solve the equation sin(θ m / 2) / (θ m / 2)=L 2m / L 1m Get θ m According to R m =L 1m / θ m Calculate R m According to B m =R m -R m *cos(θ m / 2) Calculate the quasi-warpage B m , calculating the warpage of the wafer after a preset process based on n quasi-warpages.

9. The wafer warpage detection device according to claim 8, characterized in that: The optical imaging device further includes: an automatically focusing optical lens and a rangefinder; the optical lens automatically adjusts its focal length so that a mark directly below the optical lens is clearly imaged; the rangefinder measures the focal length of the optical lens at that time, and calculates the distance between the mark directly below the optical lens and the optical lens based on the focal length; And / or the calculation device is also used to obtain the warping direction of the wafer after the preset process by comparing the distance from one of the mark graphics of the mth group of distance marks directly below the optical imaging device before the wafer undergoes the preset process to the optical imaging device, that is, the reference height D1, and the distance from the center mark directly below the optical imaging device to the optical imaging device after the wafer undergoes the preset process, that is, the center height D2, wherein the center mark is located between the two mark graphics of the mth group of distance marks; when D1 is greater than D2, it is judged that the wafer is warped downward after the preset process; when D1 is less than D2, it is judged that the wafer is warped upward after the preset process; D1 is equal to D2, and the first distance L 1m Equal to the second distance L 2m When the wafer is subjected to the preset process, it is determined that no warping occurs at the position where the distance mark is located; Or the calculation device is further used to obtain the warping direction of the wafer after the preset process by comparing the distance from one of the mark graphics of the mth group of distance marks directly below the optical imaging device after the wafer undergoes the preset process to the optical imaging device, that is, the reference height D1, and the distance from the center mark directly below the optical imaging device after the wafer undergoes the preset process to the optical imaging device, that is, the center height D2, wherein the center mark is located between the two mark graphics of the mth group of distance marks; when D1 is greater than D2, it is judged that the wafer is warped downward after the preset process; when D1 is less than D2, it is judged that the wafer is warped upward after the preset process; D1 is equal to D2, and the first distance L 1m Equal to the second distance L 2m When the wafer is subjected to the preset process, it is determined that no warping occurs at the position where the distance mark is located.

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