Wafer warping degree measurement method and detection equipment

Abstract

The invention provides a wafer warping degree measurement method and detection equipment. The method comprises the following steps: setting n groups of mark patterns on a wafer; measuring the projection distance L1m of each group of marked patterns; performing a process on the wafer; measuring the projection distance L2m of each group of marked patterns after the process; enabling the arc length of the mth arc to be L1m and the chord length to be L2m, and calculating the quasi-warping degree Bm of the mth arc; and calculating the wafer warping degree according to the n quasi warping degrees. By measuring n groups of projection distances before and after the distance marking process, the geometric model is established to obtain the warping degree, the consumed time is short, the operation is convenient, and the warping degree measurement accuracy is improved; multiple pairs of distance marks are measured at the same time, the multi-position warping degree is obtained, and the warping degree measurement accuracy is further improved; in addition, the optical imaging equipment automatically focuses to detect the center length and the warping length, and confirms the warping direction of the wafer; and finally, the included angles of the connecting lines of the marked patterns are set to be uniform, so that the situation that only positions without warping are detected accidentally is avoided, and the warping degree measurement accuracy is further improved.

Description

Technical Field

[0001] The 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] In 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 produce various stresses on the surface of the wafer, causing the wafer to warp after the process. Warping can cause many problems such as the nitride-oxygen stacking layer falling off, wafer cracking, unstable pattern alignment, and poor lithography accuracy. In addition, in some process steps, an adsorption tool is 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 is to directly take multiple points on the surface of the wafer after processing, and the selected points are located in the same plane; by measuring the height values ​​of multiple points, the multiple points are connected into a line to fit an arc, and the warpage is obtained by the curvature radius of the arc. However, this method samples the wafer surface and takes a long time, and it is difficult to fit the arc at the position where there are patterns on the surface, and the error of the warpage obtained is large.

[0004] In addition, the existing wafer warpage measurement requires transferring the wafer to a corresponding measuring instrument for measurement, which is time-consuming and complicated 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 the present 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 described in the background technology part of the present application. Summary of the invention

[0007] In view of the above shortcomings of the prior art, an object of the present invention is to provide a wafer warpage measurement method and detection equipment, which are used to solve the problem that the measurement of wafer warpage in the prior art is time-consuming and has large errors.

[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 marks are arranged on the upper surface of the wafer, where n is an integer greater than or equal to 1, each group of the distance marks includes two mark patterns, and the plane where the upper surface is located is a first plane, and a line connecting the projections of the two mark patterns in each group of the distance marks on the first plane passes through the projection of the center point of the wafer on the first plane;

[0010] The straight-line distance between the projections of 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 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 two of the 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 as 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 moving stage, an optical imaging device is arranged above the wafer, the moving stage moves the wafer so that the optical imaging device respectively recognizes two of the marking patterns in a group of the distance markings, and the straight-line distance moved by the moving stage in 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 moving table, an optical imaging device is arranged above the wafer, the moving table moves the wafer that has undergone a preset process so that the optical imaging device can respectively identify two of the mark patterns in a group of the distance marks, and the straight-line distance moved by the moving table in the process of the optical imaging device identifying the two mark patterns is recorded as the second distance.

[0018] Optionally, the measuring method further includes:

[0019] The wafer is located on a moving stage. Before the wafer is subjected to 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 been through 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 located directly below the optical imaging device, and the optical imaging device detects that the distance from the center mark to the optical imaging device is a 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 measuring method further includes:

[0024] After the wafer has been through a preset process, a center mark is set between two graphic marks 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 a center height D2;

[0026] The moving stage moves the wafer to a position directly below a mark pattern 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: 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 by the focal length;

[0029] And / or the method for the optical imaging device to detect the warping length 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 marking pattern clear, the rangefinder measures the focal length of the optical lens at this time, and the reference height D1 is calculated through the focal length.

[0030] Optionally, when n is greater than 1, before the wafer is subjected to a preset process, a line connecting the projections of two of the mark graphics in each group of distance marks on the first plane is a first line, and an angle between the first lines of two adjacent groups of 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 comprises: an optical imaging device, a mobile station 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 computing 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 according to the n quasi-warpages.

[0036] Optionally, the optical imaging device further comprises: 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, 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;

[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 patterns 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 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 patterns 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 a preset process, it is determined that no warping occurs at the position where the distance mark is located;

[0038] 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 patterns 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 patterns 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 of two marking patterns before and after the process as the arc length and chord length after warping, so that the radius and center angle parameters of the arc after warping can be directly calculated without the need to perform actual multi-point sampling on 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 road of the wafer itself as the marking pattern, so that there is no need to set additional marks on the wafer. The warpage can be measured by 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 making devices 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 suitable statistical values ​​as the warpage of the wafer, thereby avoiding the warpage obtained due to the randomness of sampling failing to accurately reflect the actual warpage of the wafer, and further improving the accuracy of characterizing the warpage of the wafer;

[0046] The present invention obtains the height of the mark pattern before the process and obtains the height of the center mark after the process. Since the height of the mark pattern and the center mark of a wafer that has not been warped are consistent, the change in the height 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 measurement can be performed as a whole after the process, and the measurement efficiency is higher.

[0048] The present invention measures the reference height and center height through the automatic focal length adjustment function of the optical imaging device itself, and does not need to add other height measurement tools, thereby improving the measurement efficiency and saving costs. In addition, since the imaging device is more common in the production line, the present invention can detect the warpage of the wafer online without transferring it to a specific measuring machine for warpage detection, thereby improving the 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 schematic structural 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, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways 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 in detail, for the sake of convenience, the schematic diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0056] For convenience of description, spatially relative terms such as "under", "below", "below", "below", "above", "on", etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. 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 in which a first feature is described as being "above" a second feature may include embodiments in which the first and second features are in direct contact, and may also include embodiments in which 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 illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0059] Embodiment 1:

[0060] The present invention provides a method for measuring the warpage of a wafer 1, the method comprising:

[0061] Step 1: providing a wafer 1, wherein n groups of distance marks are arranged on the upper surface of the wafer 1, where n is an integer greater than or equal to 1, and each group of the distance marks includes two marking patterns, and the plane where the upper surface is located is a first plane, and a line connecting the projections of the two marking patterns 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;

[0062] Step 2: Measure the straight-line distance between the projections of two marking patterns in each group of distance markings on the first plane as the first distance, and 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;

[0063] Step 3: performing a preset process on the wafer 1;

[0064] Step 4: Measure the straight-line distance between the projections of 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 ;

[0065] Step 5: 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 ;

[0066] Step 6: Determine the warpage of the wafer after a preset process according to the n quasi-warpages.

[0067] 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.

[0068] First, perform step 1 and 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 figures. 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 figures 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.

[0069] In one embodiment, when n is greater than 1, before the preset process is performed on the wafer 1, the line between the projections of two of the 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).

[0070] 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.

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

[0072] In one embodiment, the marking pattern is a cutting path of the wafer 1 .

[0073] The present invention uses the device pattern or cutting path of the wafer 1 itself as the marking pattern, thereby eliminating the need to set additional marks on the wafer 1. The warpage can be measured using the existing pattern of the wafer 1, which is easy to operate and has high measurement efficiency. There is no additional operation or modification to the wafer 1, thereby reducing the impact on the wafer 1.

[0074] 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.

[0075] 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 making devices after the process.

[0076] 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.

[0077] Then, if Figure 1 As shown, step 2 is performed to measure the straight-line distance between the projections of two marking patterns in each group of 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.

[0078] In one embodiment, the method for measuring the first distance is: the wafer 1 is placed on a moving table 3, an optical imaging device 2 is arranged above the wafer 1, the moving table 3 moves the wafer 1 so that the optical imaging device 2 respectively recognizes two of the mark patterns in a group of the distance marks, and the straight-line distance moved by the moving table 3 in the process of the optical imaging device 2 recognizing the two mark patterns is recorded as the first distance.

[0079] Next, proceed to step 3, performing a preset process on the wafer 1.

[0080] 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 .

[0081] 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 in the figure are two marking patterns for measuring the first distance in step 2. It can be seen that the arc length formed after the wafer 1 is warped is the projection L of the two marking patterns on the first plane before the process is performed. 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 .

[0082] In one embodiment, the method for measuring the second distance is as follows: the wafer 1 is placed on a moving table 3, an optical imaging device 2 is arranged above the wafer 1, the moving table 3 moves the wafer 1 that has undergone a preset process so that the optical imaging device 2 can respectively identify two of the mark graphics in a group of the distance marks, and the straight-line distance moved by the moving table 3 in the process of the optical imaging device 2 identifying the two mark graphics is recorded as the second distance.

[0083] Next, proceed to step 5 to establish a geometric model, wherein 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 .

[0084] In one embodiment, the quasi-warping degree B corresponding to the mth arc is calculated. m The method is:

[0085] 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).

[0086] In the prior art, the height of multiple points on the surface of the wafer 1 is obtained by multi-point sampling of the warped wafer 1, and the arc at a certain position after the warping is fitted to calculate the warping degree of the position. This method requires measuring multiple sampling points, and it is also difficult to fit an accurate arc. The present invention measures the projection distance of two marking figures before and after the process as the arc length and chord length after the warping, so that the parameters of the radius and the center angle of the arc after the warping can be directly calculated 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.

[0087] Finally, step 6 is performed to determine the warpage of the wafer 1 after the preset process according to the n quasi-warpages.

[0088] The present invention obtains quasi-warpages in multiple different directions and selects the maximum value as the warpage of the wafer 1, thereby avoiding the warpage that cannot accurately reflect the actual warpage of the wafer 1 due to the randomness of sampling, and further improves the accuracy of characterizing the warpage of the wafer 1.

[0089] 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.

[0090] In one embodiment, the measuring method further comprises:

[0091] The wafer 1 is located on the 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.

[0092] After the wafer 1 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 1;

[0093] 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;

[0094] 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 where the distance mark is located after undergoing the preset process.

[0095] 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 been 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.

[0096] In one embodiment, the measuring method further comprises:

[0097] After the wafer 1 undergoes a preset process, a center mark is set between two graphic marks of the mth group of distance marks on the upper surface of the wafer 1;

[0098] The wafer 1 is located on a moving stage 3, and 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 that the distance from the center mark to the optical imaging device 2 is a center height D2;

[0099] The moving stage 3 moves the wafer 1 to a position directly below one of the marking patterns of the mth group of distance marks, and the optical imaging device 2 detects the distance from the marking pattern to the optical imaging device 2 as a reference height D1;

[0100] 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 where the distance mark is located after undergoing the preset process.

[0101] 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, and the measurement efficiency is higher.

[0102] 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 the center height D2 is calculated through the focal length.

[0103] In one embodiment, the method for the optical imaging device 2 to detect the warping length 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 pattern clear, the rangefinder measures the focal length of the optical lens at this time, and the reference height D1 is calculated through the focal length.

[0104] The present invention measures the reference height and the center height through the automatic focus adjustment function of the optical imaging device 2 itself, and does not need to add other height measurement tools, thereby improving the measurement efficiency and saving costs. In addition, since the imaging device is more common in the production line, the present invention can detect the warpage of the wafer online without transferring it to a specific measuring machine for warpage detection, thereby improving the detection efficiency.

[0105] Embodiment 2:

[0106] 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);

[0107] The moving platform 3 is used to place and move the wafer 1; the optical imaging device 2 is located above the moving platform 3 and is used to identify the mark on the upper surface of the wafer 1;

[0108] The computing 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 a preset process according to the n quasi-warpages.

[0109] 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, 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.

[0110] 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 value of n quasi-warpages.

[0111] In one embodiment, the calculation device is also used to obtain the warping direction of the wafer 1 after the preset process by comparing the distance from one of the mark patterns 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 patterns 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 where the distance mark is located after undergoing the preset process.

[0112] In one embodiment, the calculation device is also used to obtain the warping direction of the wafer 1 after the preset process by comparing the distance from one of the mark patterns 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 patterns 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 where the distance mark is located after undergoing the preset process.

[0113] In summary, the wafer warpage measurement method and detection equipment of the present invention can obtain the warpage by measuring the projection distances of n groups of distance marks before and after the process and establishing a geometric model. It 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 at multiple positions can be obtained, which further improves the measurement accuracy of the warpage. In addition, the center length and the warpage length can be detected by automatic focusing of the optical imaging device to confirm the warpage direction of the wafer. Finally, by setting the connecting line angles of the mark graphics to be uniform, it is avoided that only the positions without warpage are accidentally detected, which further improves the measurement accuracy of the warpage.

[0114] Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0115] 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 familiar with 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still 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 marks are arranged on the upper surface of the wafer, where n is an integer greater than or equal to 1, each group of the distance marks includes two mark patterns, and the plane where the upper surface is located is a first plane, and a line connecting the projections of the two mark patterns in each group of the distance marks on the first plane passes through the projection of the center point of the wafer on the first plane; The straight-line distance between the projections of 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 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 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, so that 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 ; Determine the warpage of the wafer after a preset process based on n quasi-warpages.

2. The wafer warpage measurement method according to claim 1, characterized in that: 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).

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

4. The wafer warpage measurement method according to claim 1, characterized in that: The measurement method further includes: the wafer is located on a moving stage, and before the wafer is subjected to 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, and 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 been through 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.

5. The wafer warpage measurement method according to claim 1, characterized in that: The measuring method further comprises: after the wafer has been subjected to a preset process, setting a center mark between two graphic marks 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 a center height D2; The moving stage moves the wafer to a position directly below a mark pattern 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.

6. The wafer warpage measurement method according to claim 4 or 5, characterized in that: 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 by the focal length; And / or the method for the optical imaging device to detect the warping length 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 marking pattern clear, the rangefinder measures the focal length of the optical lens at this time, and the reference height D1 is calculated through the focal length.

7. The wafer warpage measurement method according to claim 1, characterized in that: When n is greater than 1, before the preset process is performed on the wafer, the line between the projections of two of the 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).

8. The wafer warpage measurement method according to claim 1, characterized in that: The marking pattern is a device pattern of the wafer; or the marking pattern is a cutting path 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.

9. 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 8, and the detection device comprises: an optical imaging device, a mobile station 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 computing 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 according to the n quasi-warpages.

10. The wafer warpage detection device according to claim 9, characterized in that: The optical imaging device further comprises: 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, 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; 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 patterns 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 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 patterns 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 a preset process, it is determined that no warping occurs at the position where the distance mark is located; 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 patterns 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 patterns 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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