Wafer warping morphology, crystal bar wire cutting morphology characterization method and evaluation method

Abstract

The application provides a wafer warping morphology and a crystal bar wire cutting morphology characterization method and evaluation method. The wafer warping morphology characterization method comprises the following steps: obtaining original data of wafer warping morphology after crystal bar wire cutting; based on the overall warping morphology of the wafer in the original data, selecting wafer warping data in the first to third radius ranges, and extracting the graphical features of the wafer warping data in the first to third radius ranges to obtain corresponding first information codes, wherein the second radius range is located between the first radius range and the third radius range in the radial direction and is located in the middle region of the wafer; the first information codes of the wafer in the first to third radius ranges in the same radial direction are sequentially combined to obtain the second information codes of the corresponding radial direction, and the second information codes of at least two radial directions of the wafer are sequentially combined to obtain the third information code of the wafer. In the application, the wafer warping morphology after the crystal bar wire cutting can be intuitively represented, and the wafer warping morphology can be easily identified and determined.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor, in particular to a wafer warping topography and a crystal bar wire cutting topography characterization method and evaluation method. BACKGROUND

[0002] In the field of semiconductor, with the increasingly high requirements of subsequent processes on wafer (silicon wafer), especially the flatness (warping) of wafer.

[0003] The main way of crystal bar cutting processing is wire cutting (multi-wire cutting). The basic principle of multi-wire cutting is to drive the cutting blade attached to the steel wire to rub against the crystal bar through a high-speed moving steel wire, so as to cut the crystal bar and other hard and brittle materials into multiple thin slices at one time. In this process, the size of the wafer warping (wafer warping topography) is often determined, and the wafer warping topography has an important influence on the quality of subsequent processes. Therefore, after wire cutting, the warping of the wafer is usually detected, the above-mentioned wire cutting process is monitored, and the warping of the corresponding wafer is obtained.

[0004] At present, after warping measurement, a numerical value is usually used to represent the warping of the wafer, but in practice, the warping topography of the wafer is relatively complex, and only one numerical value cannot be related to the warping topography of the wafer. Therefore, it is not only not conducive to accurately reflecting the fluctuation of the wire cutting process, but also not conducive to subsequent identification and judgment of the wafer according to the wafer warping topography, and it is also difficult to meet the needs of subsequent processes for different wafer warping topographies (selecting different processes according to different wafer warping topographies). SUMMARY

[0005] The purpose of the present application is to provide a wafer warping topography and a crystal bar wire cutting topography characterization method and evaluation method, which can intuitively represent the wafer warping topography after wire cutting and facilitate identification and judgment of the wafer warping topography.

[0006] To solve the above technical problems, the wafer warping topography characterization method provided by the present application comprises:

[0007] Obtaining the original data of the wafer warping topography after the crystal bar wire cutting, which includes the warping data of the wafer at different radial directions and different radii;

[0008] Based on the overall warping topography of the wafer in the original data, the warping data of the wafer at a plurality of radial directions in a first radius range, a second radius range and a third radius range are selected, and the graphical features of the warping data in the first radius range, the second radius range and the third radius range are extracted respectively to obtain corresponding first information codes, wherein the second radius range is located between the first radius range and the third radius range in the radial direction and is located in the middle region of the wafer;

[0009] combining the first information codes of the wafer in the first, second and third radius ranges in sequence to obtain a second information code of a corresponding radial direction, and combining the second information codes of at least two radial directions of the wafer in sequence to obtain a third information code of the wafer, which is used to represent the wafer warpage.

[0010] Optionally, the step of selecting the wafer warpage data in the first, second and third radius ranges of each of the radial directions of the wafer based on the overall wafer warpage in the original data comprises:

[0011] using the original data of the wafer warpage to statistically analyze the wafer warpage in the overall radius range of each of the radial directions of the wafer, and determining whether the wafer warpage is normal;

[0012] if yes, selecting the wafer warpage data in the first, second and third radius ranges of each of the radial directions of the wafer from the original data.

[0013] Optionally, a coordinate system is established with the center of the wafer as the origin and the radius of the corresponding radial direction as the horizontal coordinate, the first radius range is located on the negative half-axis of the coordinate system and includes one side edge of the wafer, the third radius range is located on the positive half-axis of the coordinate system and includes the other side edge of the wafer, the second radius range includes the origin and the partial radius on both sides thereof, the width of the second radius range is greater than the widths of the first radius range and the third radius range, and the graph feature of the wafer warpage data in the second radius range is used to represent the overall wafer warpage.

[0014] Optionally, the wafer diameter is 300 mm, the first radius range includes the radius range of -150 mm to -125 mm on the coordinate system, the third radius range includes the radius range of 125 mm to 150 mm on the coordinate system, and the second radius range includes the radius range of -75 mm to 75 mm on the coordinate system.

[0015] Optionally, the first information code includes a symbol part and a numerical part, the symbol part is used to represent the graph feature of the wafer warpage data with respect to the warpage direction, and the numerical part is used to represent the graph feature of the wafer warpage data with respect to the warpage degree.

[0016] Optionally, the step of extracting the graph feature of the wafer warpage data in the first, second and third radius ranges to obtain the corresponding first information code comprises:

[0017] a coordinate system is established with the center of the wafer as the origin, the radius of the corresponding radial direction as the horizontal coordinate and the height of the wafer surface as the vertical coordinate to form a wafer warpage curve of one radial direction of the wafer, wherein the vertical coordinate is centered on the ideal height of the wafer surface.

[0018] The wafer takes the absolute value of the maximum longitudinal coordinate in the corresponding radius range as the first information code of the corresponding radius range, the sign part of the first information code is the sign of the absolute value of the maximum longitudinal coordinate in the corresponding radius range, and the numerical part of the first information code is the absolute value of the maximum longitudinal coordinate in the corresponding radius range.

[0019] Based on another aspect of the present application, a wafer warping topography evaluation method is also provided, comprising:

[0020] The third information code of the wafer is obtained based on the above-mentioned characterization method, and the third information code is composed of the first information code in the first to third radius ranges.

[0021] Based on a preset acceptance threshold range, whether each first information code of the wafer is within the acceptance threshold range is compared to determine whether the wafer is acceptable.

[0022] If yes, the wafer is determined to be acceptable, and based on a preset concave-convex threshold range, the size of the first information code of each radial direction of the wafer in the second radius range relative to the concave-convex threshold range is compared to determine and compare the wafer warping topography.

[0023] Optionally, it comprises:

[0024] If the first information code of each radial direction of the wafer in the second radius range is within the concave-convex threshold range, it is determined that the wafer is flat, if the first information code of at least one radial direction of the wafer in the second radius range is greater than the concave-convex threshold range, it is determined that the wafer is convex, and if the first information code of at least one radial direction of the wafer in the second radius range is less than the concave-convex threshold range, it is determined that the wafer is concave.

[0025] Based on another aspect of the present application, a wafer warping topography evaluation method is also provided, comprising:

[0026] The first information code of each radial direction of a plurality of wafers in the second radius range after the wafer is cut is obtained, the second radius range is located in the middle region of the wafer, and the first information code is used to characterize the graph feature of the wafer warping data in the second radius range.

[0027] The first information code of each radial direction of a plurality of wafers in the second radius range is used to obtain a second topographic feature value, which is used to characterize the concave-convex topography of the wafer after the wafer is cut.

[0028] Optionally, at least one wafer located at the head, middle and tail of the wafer during the cutting of the wafer is obtained, which is used to characterize the wafer cutting topography.

[0029] Optionally, first information codes of each of the wafers in the first radius range and in the third radius range after the wire sawing of the ingot are also obtained, and first topographic feature values are obtained using the first information codes of each of the wafers in the first radius range and third topographic feature values are obtained using the first information codes of each of the wafers in the third radius range, and the first to third topographic feature values are used to represent the warping topography of the ingot after the wire sawing.

[0030] Optionally, when the corresponding topographic feature values are obtained using the first information codes of each of the wafers in the corresponding radius range, the first information code with the largest absolute value in the corresponding radius range is taken as the corresponding topographic feature value.

[0031] Based on another aspect of the present application, a method for evaluating the wire sawing topography of an ingot is also provided, comprising:

[0032] Obtaining the second topographic feature values of the ingot after the wire sawing based on the above-mentioned representing method.

[0033] Comparing the second topographic feature values of the ingot with the concave-convex threshold range to determine the concave-convex topography of the ingot after the wire sawing.

[0034] Optionally, comprising:

[0035] If the second topographic feature values of the ingot are within the concave-convex threshold range, it is determined that the overall topography of the ingot after the wire sawing is flat, if the second topographic feature values of the ingot are greater than the concave-convex threshold range, it is determined that the overall topography of the ingot after the wire sawing is convex, and if the second topographic feature values of the ingot are less than the concave-convex threshold range, it is determined that the overall topography of the ingot after the wire sawing is concave.

[0036] In summary, the wafer warping morphology characterization method of the present application comprises: obtaining original data of wafer warping morphology after wire sawing of a crystal bar, which includes wafer warping data at different radii in different radial directions; based on the overall wafer warping morphology in the original data, selecting wafer warping data at a first radius range, a second radius range and a third radius range in each radial direction, and extracting the graphical features of the wafer warping data in the first radius range, the second radius range and the third radius range to obtain corresponding first information codes, wherein the second radius range is located between the first radius range and the third radius range in the radial direction and is located in the middle region of the wafer; combining the first information codes of the wafer in the same radial direction in the first radius range, the second radius range and the third radius range in sequence to obtain the second information codes of the corresponding radial direction, and combining the second information codes of at least two radial directions of the wafer in sequence to obtain the third information code of the wafer, which is used to characterize the wafer warping morphology. When the above wafer warping morphology characterization method is applied to the characterization and evaluation of the wire sawing morphology of a crystal bar, it comprises: obtaining first information codes of each radial direction of a plurality of wafers after wire sawing of a crystal bar in a second radius range, wherein the second radius range is located in the middle region of the wafer and the first information code is used to characterize the graphical features of the wafer warping data in the second radius range; obtaining second morphology feature values by using the first information codes of each radial direction of a plurality of wafers in the second radius range, which are used to characterize the concave-convex morphology after wire sawing of the crystal bar; obtaining the second morphology feature values of the above crystal bar wire sawing morphology characterization method after wire sawing of the crystal bar; based on a pre-set concave-convex threshold range, comparing the size of the second morphology feature values of the crystal bar relative to the concave-convex threshold range to determine the concave-convex morphology after wire sawing of the crystal bar. The method of the present application only needs to extract and calculate the corresponding information codes and morphology feature values from the original data of the wafer warping morphology after wire sawing of the crystal bar, so as to automatically determine the wafer warping morphology and the overall morphology after wire sawing of the crystal bar. Compared with the wafer warping degree used in the related art to characterize the wafer and the morphology after wire sawing of the crystal bar, the characterization method and evaluation method of the present application can very intuitively represent the wafer warping morphology and the overall morphology after wire sawing of the crystal bar, which is beneficial to identifying the warping type of the wafer and the crystal bar after wire sawing, and determining the overall warping morphology of the two. BRIEF DESCRIPTION OF DRAWINGS

[0037] Those skilled in the art will understand that the provided drawings are for the purpose of better illustrating the present application and do not constitute any limitation on the scope of the present application. Among them:

[0038] Figure 1 is a flowchart of the wafer warping morphology characterization method provided in Example 1;

[0039] Figure 2 is a schematic diagram of the radial direction of the wafer provided in Example 1;

[0040] Figure 3aThis is a schematic diagram of the warped morphology of the wafer provided in Embodiment 1, which is a flat wafer and the corresponding second information code;

[0041] Figure 3b This is a schematic diagram of the warped morphology of the wafer provided in Embodiment 1, which is a concave wafer, and the corresponding second information code;

[0042] Figure 3c This is a schematic diagram of the warped morphology of the wafer provided in Embodiment 1, showing a raised surface and the corresponding second information code;

[0043] Figure 3d This is a schematic diagram of other warping morphologies of the wafer provided in Embodiment 1 and the corresponding second information codes;

[0044] Figure 3e This is a schematic diagram of the fourth information code provided in Embodiment 1;

[0045] Figure 4 This is a flowchart of the wafer warpage evaluation method provided in Example 2;

[0046] Figure 5 This is a flowchart of the characterization method for the line-cut morphology of the crystal rod provided in Example 3;

[0047] Figure 6 These are the feature codes and morphological feature values ​​of several wafers after wire cutting of a crystal rod, provided in Example 3;

[0048] Figure 7 This is a flowchart of the evaluation method for the wire-cut morphology of the crystal rod provided in Example 4;

[0049] Figure 8a These are the feature codes and morphological feature values ​​of each radial and radii range of several wafers after wire cutting of a crystal rod, as provided in Example 4.

[0050] Figure 8b It is provided in Example 4 Figure 8a Three-dimensional topographic images of crystal rods obtained by optical methods;

[0051] Figure 9a These are the feature codes and morphological feature values ​​for each radius range of several wafers after wire cutting of another crystal rod, as provided in Example 4.

[0052] Figure 9b It is provided in Example 4 Figure 9a Three-dimensional topographic images of the crystal rod obtained by optical methods. Detailed Implementation

[0053] In order to make the objects, advantages and features of the present application clearer, the following will further describe the present application in detail with reference to the accompanying drawings and specific embodiments. It should be noted that all the drawings are very simplified and not drawn according to the scale, and are only used to facilitate and clarify the purpose of assisting the description of the embodiments of the present application. In addition, the structures shown in the drawings are often a part of the actual structures. In particular, the emphasis shown in each drawing is different, and sometimes different scales are used.

[0054] It should be understood that when an element or layer is referred to as being "on", "connected to" or "coupled to" another element or layer, it can be directly on the other element or layer, or intervening elements or layers can be present. In contrast, when an element is referred to as being "directly on", "directly connected to" or "directly coupled to" another element or layer, then there are no intervening elements or layers present. Although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application. Spatially relative terms such as "beneath", "below", "lower", "above", "upper", and the like can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" or "over" the other elements or features. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. The terms of degree such as "substantially", "approximately", and the like, are used herein to account for manufacturing tolerances, imperfections, variations and / or

[0055] Embodiment One

[0056] Embodiment One provides a method for characterizing wafer warpage topography.

[0057] Figure 1is a flowchart of a wafer warpage profile characterization method provided in Embodiment One.

[0058] As shown in Figure 1 The wafer warpage profile characterization method provided in this embodiment includes:

[0059] S01: Obtain raw data of wafer warpage profile after wire sawing of a crystal bar, which includes warpage data of different radii in different radial directions of the wafer;

[0060] S02: Based on the overall warpage profile of the wafer in the raw data, select warpage data of the wafer in a first radius range, a second radius range and a third radius range in each radial direction, and extract the graphical features of the warpage data in the first radius range, the second radius range and the third radius range respectively to obtain corresponding first information codes, wherein the second radius range is located between the first radius range and the third radius range in the radial direction and is located in the middle region of the wafer;

[0061] S03: Combine the first information codes of the wafer in the first radius range, the second radius range and the third radius range in the same radial direction in sequence to obtain the second information codes of the corresponding radial direction, and combine the second information codes of at least two radial directions of the wafer in sequence to obtain the third information codes of the wafer, which are used to characterize the warpage profile of the wafer.

[0062] Firstly, step S01 is performed to provide raw data of wafer warpage profile after wire sawing of a crystal bar, which includes warpage data of different radii in different radial directions of the wafer.

[0063] The warpage test is performed on a plurality of wafers (e.g. silicon wafers) obtained from a crystal bar (e.g. a silicon bar) after wire sawing to obtain raw data of the plurality of wafers about warpage profile, which can substantially restore the warpage data (surface height data) of the wafer surface from three dimensions, i.e. the raw data can include warpage data of different radii in different radial directions (different radial angles) of the wafer.

[0064] Compared with the warpage data test on all wafers obtained from wire sawing of a crystal bar, the wafers obtained from wire sawing of a crystal bar can also be sampled and then the warpage data of the sampled wafers is measured. In an example, the wafers obtained from wire sawing of a crystal bar and packed into wafer boxes can be sampled and measured for warpage, for example, a longer crystal bar after wire sawing is packed into 16 wafer boxes, and a shorter crystal bar after wire sawing is packed into 7 wafer boxes, and one wafer is extracted from each of the wafer boxes for warpage measurement to obtain a corresponding number of raw files. Of course, in another example, the sampled wafers can be limited to the head, middle and tail of the crystal bar, for example, at least one wafer is taken from each of the head, middle and tail.

[0065] In addition, a budgeted program can be used to export and convert the raw data obtained from the warp measurement device into an easily identifiable and extractable data format, such as converting the raw data obtained from the warp measurement device into Excel format.

[0066] Next, step S02 is executed. Based on the overall warp morphology of the wafer in the original data, warp data of several radial directions of the wafer in the first radius range, the second radius range and the third radius range are selected, and the graphic features of the warp data in the first radius range, the second radius range and the third radius range are extracted to obtain the corresponding first information code. The second radius range is located in the radial direction between the first radius range and the third radius range and is located in the middle region of the wafer.

[0067] Taking the extraction and encoding of warp data for a selected wafer as an example, the wafer radial direction used for extracting warp data can be identified first. Then, the three radius ranges on the wafer radial direction used for extracting warp data can be identified. Finally, the warp data of the corresponding radius range on the wafer radial direction can be encoded as their respective first information codes.

[0068] like Figure 2 As shown, the selected wafer radial direction may include at least three radial directions with angles of 0° (which may be, for example, the direction of the orientation angle), 45°, 90°, and 135°. Of course, in a preferred example, the selected wafer radial direction may include four radial directions with angles of 0°, 45°, 90°, and 135°.

[0069] After confirming the wafer radial direction used to extract warp data, the selected warp data originating from the same ingot can be organized into different charts according to the wafer radial direction for statistical analysis of the overall (complete radius range) warp morphology of the wafer obtained from the ingot. Specifically, in the above charts, the horizontal axis represents the wafer radius, with the zero point of the horizontal axis being the wafer center (radius 0). The radius on one side of the wafer is located on the negative half-axis of the horizontal axis, and the radius on the other side of the wafer is located on the positive half-axis. The wafer surface height data (warp data) corresponding to the radius is the vertical axis of the chart, with the zero point of the vertical axis representing the ideal plane of the wafer surface (whose height is similar to the average height). In one example, the above warp data can be the actual height of the wafer surface (i.e., warp height), with units such as micrometers. In other examples, the above warp data can also be the ratio of the actual height of the wafer surface to the wafer diameter (i.e., warp degree).

[0070] Before selecting warpage data, the raw data of wafer warpage morphology can be used to preliminarily statistically analyze the warpage morphology within the overall radial radius of the wafer, and determine whether the wafer warpage morphology is normal, excluding cases with obviously abnormal warpage morphology (such as wavy shapes caused by wire shearing abnormalities). Therefore, when the wafer warpage morphology is preliminarily determined to be normal, an appropriate radius range should be selected to characterize the graphical features of the wafer warpage data. For example... Figures 3a to 3d As shown, the warpage of a wafer (typically all radial warpage shapes are considered conventional) can generally be described as a "convex," "concave," or "flat" shape. In this embodiment, three spaced-apart radius ranges (first to third radius ranges) can be used to characterize the wafer's warpage in that radial direction. The first and third radius ranges are located relative to each other at the edges of the wafer, while the second radius range is located at the center of the wafer. That is, the first radius range is located on the negative half-axis of the coordinate system and includes one edge of the wafer, the third radius range is located on the positive half-axis of the coordinate system and includes the other edge of the wafer, and the second radius range includes the origin and portions of the radii on both sides. The width of the second radius range is greater than the widths of the first and third radius ranges, and the graphical features of the warpage data in the second radius range are used to characterize the overall warpage of the wafer. Of course, the width of the second radius range is greater than the widths of the first and third radius ranges to improve its representativeness; in fact, the width of the second radius range can approach half of the entire radius range of the wafer. In one example, the wafer diameter is 300 mm, which means the horizontal axis in the graph ranges from -150 to 150 mm. The first radius range can be from -150 to -125 mm, the second radius range can be from -75 to 75 mm, and the third radius range can be from 125 to 150 mm.

[0071] When encoding the warped data within the aforementioned radius range to obtain the first information code, the first information code may include a sign part and a numerical part. The sign part is used to characterize the graphical features of the warped data with respect to the warping direction, and the numerical part is used to characterize the graphical features of the warped data with respect to the degree of warping. Both the sign part and the numerical part can be obtained from the radial data corresponding to the aforementioned chart. Specifically, the sign part of the first information code is the positive or negative sign of the ordinate with the largest absolute value within the corresponding radius range, and the numerical part of the first information code is the absolute value of the ordinate with the largest absolute value within the corresponding radius range. In one example, please refer to... Figures 3a to 3d Within the second radius, the absolute value of the ordinate is at most 2, and this point lies on the positive half-axis of the ordinate, meaning the numerical value is 2 and the sign is +. Therefore, the first information code within the second radius can be 2 (the + sign can be omitted). Please continue to refer to... Figures 3a to 3d The warped shape and corresponding first information code, within the first radius range, have a maximum absolute value of 3 for the ordinate, and this point is located on the negative half-axis of the ordinate, i.e., the numerical value is 3 and the sign is -. Therefore, the first information code within the first radius range can be -3, or it can be denoted as... For example, the symbol of the underlined part represents the negative semi-axis. As can be seen from the above, the smaller the numerical part (or average value) of the first information code of each first information code is, the smaller the warpage is. The smaller the numerical part (closer to 0) of the first information code of each radius range (the first to third radius ranges) is, the smaller the degree of warpage is (the better the warpage profile is). The warpage profile corresponding to the same (same sign) first information code of the first radius range and the third radius range is generally better than the warpage profile corresponding to the opposite sign of the first information code of the first radius range and the third radius range under the same conditions (the numerical part is approximately the same).

[0072] It should be noted that the above process of establishing a coordinate system through raw data and obtaining a corresponding information code through the coordinate system is only for illustration. In practice, establishing a coordinate system is not a necessary step. The corresponding data can be extracted from the raw data through a program to obtain the corresponding information code.

[0073] Next, step S03 is performed to combine the first information codes of the first radius range, the second radius range and the third radius range of the same radius of the wafer in sequence to obtain the second information code of the corresponding radius, and combine the second information codes of at least two radii of the wafer in sequence to obtain the third information code of the wafer, which is used to represent the warpage profile of the wafer.

[0074] Taking the first wafer (No. 1) selected and having a radial angle of 0° as an example, it is provided with the first to third radius ranges, the first information code of the first radius range is a1, the first information code of the second radius range is b1, and the first information code of the third radius range is c1. Therefore, the second information code of the wafer at 0° radial angle obtained by combining the above first information codes can be (a1, b1, c1). Similarly, the second information code of the wafer at 45° radial angle can be (d1, e1, f1), the second information code of the wafer at 90° radial angle can be (g1, h1, i1), and the second information code of the wafer at 135° radial angle can be (j1, k1, l1). Therefore, the third information code of the first wafer obtained by combining the above second information codes can be (a1, b1, c1), (d1, e1, f1), (g1, h1, i1), and (j1, k1, l1).

[0075] In the evaluation of the wafer warpage by using the third information code, if the first information code of each radial second radius range is within the range of ± the first preset value, i.e. the height fluctuation of the wafer larger central area is within ± the first preset value (i.e. the fluctuation is relatively small), the wafer can be classified as a "flat piece", and for the "flat piece", the first information code of each radial first radius range and third radius range generally needs to be within the range of ± the second preset value (the second preset value is equal to the first preset value) and the compliance of the two is the same as the best. On the other hand, if the first information code of part of the radial second radius range is outside the range of ± the first preset value and within the range of ± the third preset value, i.e. the height fluctuation of the wafer larger central area is relatively large, the wafer can be classified as a "concave piece" or a "convex piece", and generally the sign part of the first information code of the second radius range of the "concave piece" is negative, and the sign part of the first information code of the second radius range of the "convex piece" is positive. In an example, please continue to refer to the warpage profile and the corresponding second information code of Figures 3a to 3d , the first preset value can be 2, the second preset value can be 3, and the third preset value can be 6, that is, if the first information code of the second radius range is within the range of -2 to 2, and the first information code of the first radius range and the third radius range is within the range of -3 to 3, the wafer can be a "flat piece"; if the first information code of the second radius range is within the range of -6 to -2, the wafer can be a "concave piece"; if the first information code of the second radius range is within the range of 2 to 6, the wafer can be a "convex piece".

[0076] Therefore, after obtaining the third information code of the wafer provided by the encoding method of the present embodiment, the more detailed warpage data of the wafer can be obtained to better restore the warpage profile of the wafer, which is convenient for subsequent identification, classification and comparison (determination) of the wafer according to the warpage profile of the wafer. Specifically, taking the third information code of the wafer as (a1, b1, c1), (d1, e1, f1), (g1, h1, i1), (j1, k1, l1) as an example, from the number of the second information code in the third information code, it is known that it includes four radial warpage data, and from the number of the first information code in each second information code (the number of radius ranges), it is known that the warpage profile of the wafer belongs to the conventional shape, i.e. the wafer can be one of a flat piece, a concave piece or a convex piece, and the wafer belongs to which one of the flat piece, the concave piece or the convex piece is determined by the value and sign of the first information code of the second bit in each second information code, and the advantages and disadvantages of the warpage profile of the wafer are confirmed according to the value and sign of the first information code of the first bit and the third bit in each second information code.

[0077] In the case of cutting a wafer rod into multiple wafers by wire cutting, the warping degrees of the wafers have certain correlations, so the warping degrees of several representative wafers can be used to represent the warping degrees of the wafer rod after the wafers are cut by wire cutting. The third information codes of the wafers are combined to obtain the fourth information code of the wafer rod, which is used to represent the warping degrees of all the wafers obtained by cutting the wafer rod by wire cutting. In a preferred example, the fourth information code of the wafer rod can be obtained by combining the third information codes of one wafer from the head, the middle and the tail of the wafer rod (three wafers in total). Further, when one wafer is taken from each part, the wafer with the maximum warping data (numerical part) at a preset radial direction is selected from the multiple wafers of the part to represent the warping degrees of the wafer rod. When the fourth information codes of several wafer rods have the same number of bits (the same radial direction and radius range are selected), and the warping degrees of the wafer rods are evaluated by using the fourth information codes of different wafer rods, the fourth information codes of the wafer rods can be set in a matrix (determinant) format as shown in Figure 3e The fourth information codes of the wafer rods can be used for comparison and evaluation among different wafer rods, and can also be used for evaluation and statistical analysis of the warping degrees of different parts and different radial directions of the wafer rod.

[0078] Embodiment Two

[0079] Embodiment Two provides a wafer warping degree evaluation method.

[0080] Figure 4 is a flowchart of the wafer warping degree evaluation method provided by Embodiment Two.

[0081] As shown in Figure 4 , the wafer warping degree evaluation method provided by the embodiment includes the following steps:

[0082] S01: Obtain the third information code of the wafer based on the wafer warping degree evaluation method, and the third information code is composed of the first information codes in the first to third radius ranges of each radial direction;

[0083] S02: Compare whether each first information code of the wafer is within the preset acceptance threshold range based on the preset acceptance threshold range to determine whether the wafer is acceptable;

[0084] S03: If yes, determine that the wafer is acceptable, and compare the size of the first information code of each radial direction of the wafer in the second radius range relative to the concave-convex threshold range based on the preset concave-convex threshold range to judge and compare the warping degrees of the wafer.

[0085] In step S01, taking four radials including 0°, 45°, 90° and 135° as an example, the third information code of the wafer can include 12 first information codes, for example, (a1, b1, c1), (d1, e1, f1), (g1, h1, i1), (j1, k1, l1), each of which is in a radial range of three radials, by using the above-mentioned wafer warpage profile characterization method.

[0086] In step S02, the preset acceptance threshold range can be determined according to specific products and customers. Whether all the above-mentioned first information codes are within the acceptance threshold range is compared. If yes, it is determined that the wafer warpage profile is acceptable. If no, it is determined that the wafer warpage profile is unacceptable. In some examples, different acceptance threshold ranges can be set for different radial ranges. Whether the first information code of the corresponding radial range is acceptable is determined according to the corresponding acceptance threshold range. In other examples, the wafer that is not accepted can be further classified according to the number of first information codes that exceed the acceptance threshold range. For example, only one first information code exceeds the wafer, only two first information codes exceed the wafer, and the like. In addition, the severity of exceeding the acceptance threshold range can also be further classified. For example, the wafer that exceeds the acceptance threshold range by 0-10%, the wafer that exceeds the acceptance threshold range by 10-20%, and the like.

[0087] In step S03, the preset concave-convex threshold range can be determined according to specific products and customers. When the first information code of the second radial range of each radial of the wafer is compared with the size of the concave-convex threshold range to determine the wafer warpage profile, if the first information code of the second radial range of each radial is within the concave-convex threshold range, that is, the height fluctuation of the larger central region of the wafer is within the concave-convex threshold range, the wafer can be determined as “flat” (flat). If at least one (one radial) first information code of the second radial range is outside the concave-convex threshold range, that is, the height fluctuation of the larger central region of the wafer is relatively large, the wafer can be classified as “concave” or “convex”. Specifically, if the first information code of at least one (one radial) second radial range of the wafer is greater than the upper limit of the concave-convex threshold range, it is determined that the wafer is convex. If the first information code of at least one (one radial) second radial range of the wafer is less than the lower limit of the concave-convex threshold range, it is determined that the wafer is concave. When a wafer has both first information codes of some second radial ranges greater than the concave-convex threshold range and first information codes of other second radial ranges less than the concave-convex threshold range, the first information code with the largest absolute value in the second radial range can be used as a reference. In another aspect, the sign part of the first information code of the second radial range of the “concave wafer” is negative, and the sign part of the first information code of the second radial range of the “convex wafer” is positive. In an example, please continue to refer to Figures 3a to 3dthe first information code of the second radius range is in the range of -2 to 2, and the first information code of the first radius range and the third radius range is in the range of -3 to 3, and the wafer can be a "flat piece"; if the first information code of the second radius range is in the range of -6 to -2, the wafer can be a "concave piece"; if the first information code of the second radius range is in the range of 2 to 6, the wafer can be a "convex piece".

[0088] Of course, a plurality of threshold values can also be set for the first information code of the first radius range and the third radius range, in combination with the first information code of the second radius range, for further determining the degree of warping of the wafer in each type of piece (flat piece, concave piece, convex piece).

[0089] Thus, after obtaining the third information code of the wafer provided by the characterization method of the present embodiment, the more detailed warping data of the wafer can be obtained to better restore the warping topography of the wafer, which is convenient for subsequent identification, classification and comparison (determination) of the wafer according to the warping topography of the wafer. Specifically, taking the third information code of the wafer as (a1, b1, c1), (d1, e1, f1), (g1, h1, i1), (j1, k1, l1) as an example, the number of the second information code in the third information code indicates that it includes four radial warping data, and the number of the first information code in each second information code (the number of the radius range) indicates that the warping topography of the wafer belongs to a conventional shape, i.e. the wafer can be one of a flat piece, a concave piece or a convex piece, and the value and sign of the first information code of the second bit in each second information code specifically determine which one of the flat piece, the concave piece or the convex piece the wafer belongs to, and the value and sign of the first information code of the first bit and the third bit in each second information code confirm the pros and cons of the warping topography of the wafer.

[0090] Embodiment Three

[0091] Embodiment Three provides a characterization method of a wafer slice of a crystal bar.

[0092] Figure 5 is a flowchart of the characterization method of a wafer slice of a crystal bar provided by Embodiment Three.

[0093] As shown in Figure 5 , the characterization method of a wafer slice of a crystal bar provided by the present embodiment comprises:

[0094] S01: obtaining the first information code of each radial direction of a plurality of wafers in a second radius range after slicing a crystal bar, the second radius range being located in the middle region of the wafer, and the first information code being used to represent the graphical features of the warping data in the second radius range of the wafer;

[0095] S02: obtaining a second profile feature value from the first information code of each of the wafers in the second radius range, for representing the concave-convex profile of the wafer after the ingot is cut.

[0096] In step S01, a plurality of representative wafers can be selected (sampled) from the wafers after the ingot is cut, and the first information code of each of the wafers in the second radius range is obtained, or after the wafers are selected, the above-mentioned method for representing the profile of the wafer is performed to obtain the first information code of each of the wafers in the second radius range. In an example, at least one wafer from the head, middle and tail of the ingot after the ingot is cut is obtained, of course, in practice, at least 5 wafers from the head, middle and tail of the ingot can be obtained to improve accuracy. In another example, the wafers after the ingot is cut and packaged into wafer boxes can be sampled, for example, a long ingot after being cut is packaged into 16 wafer boxes, and a short ingot after being cut is packaged into 7 wafer boxes, and at least one wafer is sampled from each of the above-mentioned wafer boxes. Of course, the first information code of each of the wafers in the first radius range and the third radius range can also be obtained simultaneously, i.e., the third information code of the wafers is obtained.

[0097] In step S02, the first information code of each of the wafers in the second radius range can be first counted, and then the profile feature value of the ingot in the second radius range is obtained, i.e., the second profile feature value is obtained from the first information code of each of the wafers in the second radius range. Specifically, taking the profile feature value of the 0° radial direction in the second radius range as an example, the first information code of the selected wafers in the 0° radial direction in the second radius range is counted, and the first information code with the largest absolute value is selected as the characteristic code in the 0° radial direction in the second radius range. Then, the characteristic code of the selected wafers in other radial directions (such as 45°, 90° and 135°) in the second radius range is obtained, and then the second profile feature value is calculated using the corresponding characteristic codes (such as four) in the second radius range of the above-mentioned different radial directions (such as four), which is used as a representative of the concave-convex profile of the ingot after being cut. The calculation method can be, for example, to take the characteristic code with the largest absolute value in the above-mentioned characteristic codes as the second profile feature value. In addition, in a preferred example, the first profile feature value is obtained from the first information code of each of the wafers in the first radius range, and the third profile feature value is obtained from the first information code of each of the wafers in the third radius range, and the second profile feature value is combined, i.e., the first to third profile feature values are used to represent the profile of the wafer after the ingot is cut. In a specific example, Figure 6This describes the feature codes and morphological feature values ​​for each radial radius range of several selected wafers after wire cutting a crystal rod. The first radius range is -150~-125, the second radius range is -75~75, and the third radius range is 125~150. The feature codes and morphological feature values ​​(first to third feature values) for each radial radius range are as follows: Figure 6 As shown.

[0098] Example 4

[0099] Example 4 provides a method for evaluating the morphology of a crystal rod in a wire section.

[0100] Figure 7 This is a flowchart of the evaluation method for the wire-cut morphology of the crystal rod provided in Example 4.

[0101] like Figure 7 As shown, the method for evaluating the wire-section morphology of a crystal rod provided in this embodiment includes:

[0102] S01: Obtain the second morphological feature value of the above-mentioned crystal rod wire-cut morphology characterization method after wire cutting of the crystal rod;

[0103] S02: Based on a preset concavity / convexity threshold range, compare the size of the second morphological feature value of the crystal rod relative to the concavity / convexity threshold range to determine the concavity / convexity morphology of the crystal rod after line cutting.

[0104] In step S01, the second morphological feature value of the characterization method for the wire-cut morphology of the crystal rod can be obtained. Of course, in a preferred example, the first to third morphological feature values ​​can be obtained simultaneously by using the original data of the wafer warpage morphology after wire-cutting and performing the characterization method for the wire-cut morphology of the crystal rod. The acquisition process can generally include: firstly, selecting (defining) the radial and radii ranges for evaluating the wafer warpage morphology; then, calculating the morphological feature values ​​for characterizing the warpage morphology of each radii range based on the original data of each radial and radii range. The acquisition process can refer to the process described above of obtaining the first information code from the original data, then obtaining the feature code from the first information code, and then obtaining the morphological feature value from the feature code; or, the acquisition process can be simplified to directly obtaining the morphological feature value from the original data.

[0105] In step S02, the preset acceptance threshold range can be determined according to specific products and customer requirements. The threshold is the acceptance threshold of the wire sawing profile of the crystal bar, which is an internal standard and can be the same as or different from the acceptance threshold of the wafer. If the first to third profile characteristic values are all within the acceptance threshold range, it is determined that the wire sawing profile of the crystal bar is acceptable (the wire sawing process and the crystal bar are normal). If not, it is determined that the wire sawing profile of the crystal bar is not acceptable (the wire sawing process and / or the crystal bar is abnormal). In some examples, different acceptance threshold ranges can be set for different radius ranges, and whether the profile characteristic values of the corresponding radius range are acceptable is determined according to the corresponding acceptance threshold range. In addition, the severity of exceeding the acceptance threshold range can also be further classified.

[0106] In step S02, the preset concave-convex threshold range can be determined according to specific products and customers. The threshold is the acceptance threshold of the concave-convex profile of the crystal bar after wire sawing, which is an internal standard and can be the same as or different from the acceptance threshold of the wafer. If the second profile characteristic value of the crystal bar after wire sawing is within the concave-convex threshold range, it is determined that the overall profile of the crystal bar after wire sawing is flat. If the second profile characteristic value of the crystal bar is greater than the concave-convex threshold range, it is determined that the overall profile of the crystal bar after wire sawing is convex. If the second profile characteristic value of the crystal bar is less than the concave-convex threshold range, it is determined that the overall profile of the crystal bar after wire sawing is concave.

[0107] Of course, after obtaining the first profile characteristic value and the third profile characteristic value, i.e., obtaining the first to third profile characteristic values, the preset acceptance threshold range can be used to further judge the warping profile and warping degree of the crystal bar after wire sawing.

[0108] In an example, the concave-convex threshold range can be, for example, -2~2, Figure 8a The characteristic code and profile characteristic value of each radial range of a plurality of selected wafers of a crystal bar after wire sawing, the concave-convex profile of which can be concave (concave piece), Figure 8b The crystal bar of Figure 8a The three-dimensional profile graph (surface profile) of the crystal bar obtained by optical method, the overall warping profile of which basically corresponds to the profile characteristic value. In another example, the concave-convex threshold range can be, for example, -2~2, Figure 9a The characteristic code and profile characteristic value of each radial range of a plurality of selected wafers of another crystal bar after wire sawing, the concave-convex profile of which can be convex (convex piece), Figure 9b The crystal bar of Figure 9a The three-dimensional profile graph (surface profile) of the crystal bar obtained by optical method, the overall warping profile of which basically corresponds to the profile characteristic value.

[0109] In summary, the wafer warping morphology characterization method of the present application comprises: obtaining original data of wafer warping morphology after wire sawing of a crystal bar, which includes wafer warping data at different radii in different radial directions; based on the overall wafer warping morphology in the original data, selecting wafer warping data at a first radius range, a second radius range and a third radius range in each radial direction, and extracting the graphical features of the wafer warping data in the first radius range, the second radius range and the third radius range to obtain corresponding first information codes, wherein the second radius range is between the first radius range and the third radius range in the radial direction and is located in the middle region of the wafer; combining the first information codes in the first radius range, the second radius range and the third radius range in the same radial direction of the wafer to obtain the second information codes corresponding to the radial direction, and combining the second information codes of at least two radial directions of the wafer to obtain the third information codes of the wafer, which are used to characterize the wafer warping morphology. When the above wafer warping morphology characterization method is applied to the characterization and evaluation of the wire sawing morphology of a crystal bar, it comprises: obtaining first information codes of each radial direction of a plurality of wafers after wire sawing of a crystal bar in a second radius range, wherein the second radius range is located in the middle region of the wafer and the first information codes are used to characterize the graphical features of the wafer warping data in the second radius range; obtaining second morphology feature values by using the first information codes of each radial direction of a plurality of wafers in the second radius range, which are used to characterize the concave-convex morphology after wire sawing of the crystal bar; obtaining the second morphology feature values of the above crystal bar wire sawing morphology characterization method after wire sawing of the crystal bar; based on a pre-set concave-convex threshold range, comparing the size of the second morphology feature values of the crystal bar relative to the concave-convex threshold range to determine the concave-convex morphology after wire sawing of the crystal bar. The method of the present application only needs to extract and calculate the corresponding information codes and morphology feature values from the original data of the wafer warping morphology after wire sawing of the crystal bar, and can automatically determine the wafer warping morphology and the overall morphology after wire sawing of the crystal bar. Compared with the related art which uses warping degree to characterize the wafer and the morphology after wire sawing of the crystal bar, the characterization method and evaluation method of the present application can very intuitively represent the wafer warping morphology and the overall morphology after wire sawing of the crystal bar, which is beneficial to identifying the warping type of the wafer and the crystal bar after wire sawing, and determining the overall warping morphology of both.

[0110] The above description is only a description of the preferred embodiments of the present application, and is not any limitation on the scope of the present application. Any modification or modification of the present application by a person skilled in the art based on the above disclosure is within the scope of the claims.

Claims

1. A method of characterizing wafer bow topography, comprising: The method comprises the following steps: Obtaining original data of wafer warping topography after wire sawing of a crystal bar, which includes wafer warping data of different radii in different radial directions; Based on the overall wafer warping topography in the original data, wafer warping data of a plurality of radial directions in the first, second and third radius ranges are selected, and the graph features of the wafer warping data in the first, second and third radius ranges are extracted to obtain the corresponding first information code. The second radius range is located between the first radius range and the third radius range in the radial direction and in the middle region of the wafer. A coordinate system is established with the center of the wafer as the origin and the radius of the corresponding radial direction as the horizontal coordinate. The first information code of the wafer in the first, second and third radius ranges in the same radial direction is sequentially combined to obtain the second information code of the corresponding radial direction, and the second information codes of at least two radial directions of the wafer are sequentially combined to obtain the third information code of the wafer, which is used to represent the wafer warping topography. The step of extracting the graph features of the wafer warping data in the first, second and third radius ranges to obtain the corresponding first information code comprises:

2. The method of claim 1, wherein the wafer bow map is determined by: A coordinate system is established with the center of the wafer as the origin, the radius of the corresponding radial direction as the horizontal coordinate, and the height of the wafer surface as the vertical coordinate to form a wafer warping topography curve in one radial direction. The absolute value of the vertical coordinate of the wafer in the corresponding radius range is taken as the first information code of the corresponding radius range. The step of selecting wafer warping data of a plurality of radial directions in the first, second and third radius ranges based on the overall wafer warping topography in the original data comprises:

3. The method of claim 2, wherein the wafer bow map is determined by: Using the original data of wafer warping topography, the wafer warping topography in the overall radius range of each radial direction is counted, and it is determined whether the wafer warping topography is normal.

4. The method of claim 3, wherein the wafer bow map is determined by: If so, wafer warping data of a plurality of radial directions in the first, second and third radius ranges are selected from the original data.

5. The method of claim 1, wherein the wafer bow map is determined by: The width of the second radius range is greater than the width of the first radius range and the third radius range, and the graph features of the wafer warping data in the second radius range are used to represent the overall wafer warping topography. The diameter of the wafer is 300 mm, the first radius range includes the radius range of -150 mm to -125 mm on the coordinate system, the third radius range includes the radius range of 125 mm to 150 mm on the coordinate system, and the second radius range includes the radius range of -75 mm to 75 mm on the coordinate system. The first information code includes a symbol part and a numerical part. The symbol part is used to represent the graph features of the warping data with respect to the warping direction, and the numerical part is used to represent the graph features of the warping data with respect to the warping degree.

6. The method of claim 5, wherein the wafer bow map is determined by: The sign part of the first information code is the sign of the vertical coordinate with the largest absolute value in the corresponding radius range, and the numerical part of the first information code is the absolute value of the vertical coordinate with the largest absolute value in the corresponding radius range.

7. A method of evaluating wafer warpage topography, characterized by, The method comprises the following steps: Obtaining a third information code of a wafer based on the characterization method in any one of claims 1 to 6, wherein the third information code is composed of first information codes in first to third radius ranges; Comparing whether each first information code of the wafer is within a preset acceptance threshold range to determine whether the wafer is acceptable; If yes, determining that the wafer is acceptable, and comparing the size of each first information code of the wafer in the second radius range relative to the concave-convex threshold range to determine and compare the warping topography of the wafer based on a preset concave-convex threshold range.

8. The method of claim 7, wherein the wafer bow map is evaluated by: If the first information code of the wafer in the second radius range is within the concave-convex threshold range, it is determined that the wafer is flat, if the first information code of the wafer in the second radius range is greater than the concave-convex threshold range, it is determined that the wafer is convex, and if the first information code of the wafer in the second radius range is less than the concave-convex threshold range, it is determined that the wafer is concave. The method comprises the following steps:

9. A method for characterizing the morphology of a line section of a crystal rod, characterized in that, Obtaining original data of the wafer warping topography after wire cutting of a crystal bar, which includes wafer warping data in different radii in different radii; Based on the overall warping topography of the wafer in the original data, selecting wafer warping data in a second radius range, and extracting the graph features of the wafer warping data in the second radius range to obtain corresponding first information codes, wherein the second radius range is located in the middle region of the wafer; Obtaining first information codes of a plurality of wafers in the second radius range; establishing a coordinate system with the center of the wafer as the origin and the radius of the corresponding radius as the horizontal coordinate and the height of the wafer surface as the vertical coordinate to form a wafer warping topography curve in a corresponding radius range, wherein the vertical coordinate is centered on the ideal height of the wafer surface; taking the vertical coordinate with the largest absolute value in the corresponding radius range as the first information code in the corresponding radius range; Selecting the first information code with the largest absolute value as the feature code in the second radius range, and taking the feature code with the largest absolute value as the second topography feature value; Using the first information codes of a plurality of wafers in the second radius range to obtain the second topography feature value, which is used to represent the concave-convex topography after wire cutting of the crystal bar. Obtaining at least one wafer located at the head, middle and tail of the crystal bar during wire cutting, which is used to represent the wire cutting topography of the crystal bar.

10. The method of claim 9, wherein the method further comprises: Also obtaining first information codes of a plurality of wafers in the first radius range and in the third radius range after wire cutting of the crystal bar, and using the first information codes of a plurality of wafers in the first radius range to obtain the first topography feature value and using the first information codes in the third radius range to obtain the third topography feature value, and using the first to third topography feature values to represent the warping topography after wire cutting of the crystal bar.

11. The method of claim 9, wherein the method further comprises: ​ 12. The method of claim 9 to 11, wherein the method is characterized in that, In the case that the first information code of each radius in the corresponding radius range is used to obtain the corresponding topographic feature value, the first information code with the maximum absolute value in the corresponding radius range is taken as the corresponding topographic feature value.

13. A method for evaluating a wire sawing profile of a crystal bar, characterized by, The method comprises the following steps: Obtaining the second topographic feature value of the crystal bar after wire cutting based on the characterization method in any one of claims 9 to 12; Comparing the size of the second topographic feature value of the crystal bar with the concave-convex threshold range to determine the concave-convex topography of the crystal bar after wire cutting based on the preset concave-convex threshold range.

14. The method of claim 13, wherein the method is a method of evaluating a wire sawing profile of a crystal bar. The method comprises the following steps: If the second topographic feature value of the crystal bar is within the concave-convex threshold range, it is determined that the overall topography of the crystal bar after wire cutting is flat; if the second topographic feature value of the crystal bar is greater than the concave-convex threshold range, it is determined that the overall topography of the crystal bar after wire cutting is convex; and if the second topographic feature value of the crystal bar is less than the concave-convex threshold range, it is determined that the overall topography of the crystal bar after wire cutting is concave.

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