Characterization and evaluation methods for wafer warpage topography, and characterization and evaluation methods for ingot wire-cut topography

Abstract

The present invention provides characterization and evaluation methods for wafer warpage topography, and characterization and evaluation methods for ingot wire-cut topography. The characterization method for wafer warpage topography comprises: acquiring raw data of wafer warpage topography after ingot wire-cut; on the basis of the overall warpage topography of a wafer in the raw data, selecting warpage data of the wafer within first to third radius ranges in each of a plurality of radial directions, and respectively extracting graphic features of the warpage data within 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 located in the central area of the wafer; and sequentially combining the first information codes of the wafer within the first to third radius ranges in the same radial direction to obtain second information codes in corresponding radial directions, and sequentially combining the second information codes of the wafer in at least two radial directions to obtain third information codes of the wafer. The present invention can be used to visually represent warpage topography after ingot wire-cut and facilitate the identification and determination of the warpage topography of a wafer.

Description

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

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

[0002] In the field of semiconductor, with the increasing requirements of subsequent processes on wafer (silicon wafer), especially the flatness (warpage) 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 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 the same time. In this process, the size of wafer warpage (wafer warping morphology) is often determined, and the wafer warping morphology has an important influence on the quality of subsequent processes. Therefore, after wire cutting, the warpage of wafer is usually detected, the above wire cutting process is monitored, and the warpage of the corresponding wafer is obtained.

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

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

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

[0007] Obtaining the original data of wafer warping morphology after crystal bar wire cutting, which includes warping data of wafer in different radius ranges in different radial directions;

[0008] Based on the overall warping profile of the wafer in the original data, warping data in a first radius range, a second radius range and a third radius range of each of a plurality of radial directions of the wafer is selected, and a first information code corresponding to the first radius range, the second radius range and the third radius range of the same radial direction is obtained by extracting a graphical feature of the warping data in the first radius range, the second radius range and the third radius range, respectively, 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 a middle region of the wafer.

[0009] The first information codes of the first radius range, the second radius range and the third radius range of the same radial direction are sequentially combined to obtain a second information code corresponding to the radial direction, and the second information codes of at least two radial directions of the wafer are sequentially combined to obtain a third information code of the wafer, which is used to represent the warping profile of the wafer.

[0010] Optionally, the step of selecting warping data in a first radius range, a second radius range and a third radius range of each of a plurality of radial directions of the wafer based on the overall warping profile of the wafer in the original data comprises:

[0011] The overall warping profile of the wafer in each radial direction is counted by using the original data of the wafer warping profile, and it is determined whether the warping profile of the wafer is normal.

[0012] If yes, warping data in a first radius range, a second radius range and a third radius range of each of a plurality of radial directions of the wafer is selected from the original data.

[0013] Optionally, a coordinate system is established with the center of the wafer as the origin and with 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 a first side edge of the wafer, the third radius range is located on the positive half-axis of the coordinate system and includes a second side edge of the wafer, the second radius range includes the origin and a part of the 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 graphical feature of the warping data in the second radius range is used to represent the overall warping profile of the wafer.

[0014] Optionally, the diameter of the wafer is 300 mm, the first radius range includes a radius range of -150 mm to -125 mm on the coordinate system, the third radius range includes a radius range of 125 mm to 150 mm on the coordinate system, and the second radius range includes a 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 graphical feature of the warping data with respect to the warping direction, and the numerical part is used to represent the graphical feature of the warping data with respect to the warping degree.

[0016] Optionally, the step of extracting the graphical features of the warping data in the first, second and third radius ranges to obtain the corresponding first information code comprises:

[0017] establishing a coordinate system with the center of the wafer as the origin, with the radius of the corresponding radial direction as the horizontal coordinate, and with the height of the wafer surface as the vertical coordinate to form a radial warping topography curve of the wafer, wherein the vertical coordinate is centered on the ideal height of the wafer surface;

[0018] taking the vertical coordinate with the largest absolute value in the corresponding radius range as the first information code of the corresponding radius range, wherein 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.

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

[0020] obtaining the third information code of the wafer based on the above characterization method, wherein the third information code is composed of the first information code of each radial first to third radius range;

[0021] comparing whether each of the first information codes of the wafer is within the preset acceptance threshold range to determine whether the wafer is acceptable;

[0022] if yes, determining that the wafer is acceptable, and comparing the first information code of each radial second radius range of the wafer with the concave-convex threshold range to determine and compare the warping topography of the wafer based on the preset concave-convex threshold range.

[0023] Optionally, the method further comprises:

[0024] if each of the first information codes of the second radius range is within the concave-convex threshold range, determining that the wafer is flat, if at least one of the first information codes of the second radius range is greater than the concave-convex threshold range, determining that the wafer is convex, and if at least one of the first information codes of the second radius range is less than the concave-convex threshold range, determining that the wafer is concave.

[0025] Based on another aspect of the present application, a rod line cut topography characterization method is also provided, comprising:

[0026] obtaining the first information code of each radial second radius range of a plurality of wafers after a rod line cut, 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 warping data in the second radius range of the wafer;

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

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

[0029] Optionally, the first information code of each radial range of the first radius and the third radius of a plurality of wafers after slicing is obtained, and the first topographic feature value is obtained by using the first information code of each radial range of the first radius of the plurality of wafers, and the third topographic feature value is obtained by using the first information code of the third radius, and the first to third topographic feature values are used to represent the warping topography of the ingot after slicing.

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

[0031] Based on another aspect of the present application, a method for evaluating the slicing topography of an ingot is also provided, which comprises:

[0032] The second topographic feature value based on the above-mentioned evaluation method is obtained after slicing the ingot.

[0033] The second topographic feature value of the ingot is compared with the concave-convex threshold range to determine the concave-convex topography of the ingot after slicing, based on the preset concave-convex threshold range.

[0034] Optionally, the method further comprises:

[0035] If the second topographic feature value of the ingot is within the concave-convex threshold range, it is determined that the overall topography of the ingot after slicing is flat; if the second topographic feature value of the ingot is greater than the concave-convex threshold range, it is determined that the overall topography of the ingot after slicing is convex; and if the second topographic feature value of the ingot is less than the concave-convex threshold range, it is determined that the overall topography of the ingot after slicing 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 first radius range, the second radius range and the third radius range in the same radial direction in sequence to obtain the second information code corresponding to the 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, which 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. 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 flow chart of the wafer warping morphology characterization method provided by embodiment one;

[0039] Figure 2 is a schematic diagram of the radial direction of the wafer provided by embodiment one;

[0040] Figure 3a is a schematic diagram of the wafer warping morphology and the corresponding second information code provided by embodiment one;

[0041] Fig. 3b is a schematic view of a wafer with a concave wafer bow and a corresponding second information code according to an embodiment;

[0042] Fig. 3c is a schematic view of a wafer with a convex wafer bow and a corresponding second information code according to an embodiment;

[0043] Fig. 3d is a schematic view of a wafer with another wafer bow and a corresponding second information code according to an embodiment;

[0044] Fig. 3e is a schematic view of a fourth information code according to an embodiment;

[0045] Fig. 4 is a flow chart of a wafer bow evaluation method according to an embodiment;

[0046] Fig. 5 is a flow chart of a wafer line cut evaluation method according to an embodiment;

[0047] Fig. 6 is a schematic view of a wafer line cut evaluation method according to an embodiment;

[0048] Fig. 7 is a flow chart of a wafer line cut evaluation method according to an embodiment;

[0049] Fig. 8a is a schematic view of a wafer line cut evaluation method according to an embodiment;

[0050] Fig. 8b is a three-dimensional view of a wafer line cut according to an embodiment;

[0051] Fig. 9a is a schematic view of a wafer line cut evaluation method according to an embodiment;

[0052] Fig. 9b is a three-dimensional view of a wafer line cut according to an embodiment. DETAILED DESCRIPTION

[0053] To make the objects, advantages and features of the present application more clear, the following further describes the present application in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the accompanying drawings are very simplified and not drawn to 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 of 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, connected or coupled to 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, 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 terms are not intended to, and should not be interpreted to, restrict the scope, applicability and / or functionality of any of the present teachings. 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 describe applicable embodiments. When the term "substantially" is used in reference to a given property, characteristic, parameter or other metric, it is acting as a mere qualification that it is "a significant amount of" the property, characteristic, parameter or other metric, and that: (i) on a relatively general

[0055] Embodiment One

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

[0057] FIG. 1 is a flow chart of a method for characterizing wafer bowing topography according to Embodiment One.

[0058] As shown in FIG. 1, the method for characterizing wafer bowing topography according to the present embodiment includes:

[0059] S01: obtaining original data of wafer bowing topography after wire sawing of a crystal bar, which includes wafer bowing data in different radius ranges at different radial directions;

[0060] S02: Based on the overall warping profile of the wafer in the original data, select the warping data in the first radius range, the second radius range and the third radius range of each of the several radial directions of the wafer, and respectively extract the graphical features of the warping data in the first radius range, the second radius range and the third radius range to obtain the corresponding first information code, 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: The first information codes of the first radius range, the second radius range and the third radius range of the same radial direction of the wafer are 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 warping profile of the wafer.

[0062] Firstly, step S01 is performed to provide the original data of the wafer warping profile after the wire cutting of the crystal bar, which includes the warping data of the wafer in different radius ranges in different radial directions.

[0063] The warping degree test is performed on the multiple wafers (such as silicon wafers) obtained from the wire cutting of the crystal bar (such as silicon bar) to obtain the original data of the wafer about the warping profile, which can basically restore the warping data (surface height data) of the wafer surface from three dimensions, that is, the original data can include the warping data of the wafer in different radius ranges in different radial directions (different radial angles).

[0064] Compared with the warping degree data test on all wafers obtained by wire cutting of the crystal bar, the warping degree data of the wafers obtained by wire cutting of the crystal bar can also be measured after sampling. In an example, the wafers obtained by wire cutting of the crystal bar and packaged into wafer boxes can be sampled to measure the warping degree, for example, one longer wafer obtained by wire cutting of the crystal bar is packaged into 16 wafer boxes, and one shorter wafer obtained by wire cutting of the crystal bar is packaged into 7 wafer boxes. One wafer is extracted from each of the above wafer boxes for warping degree measurement to obtain a corresponding number of original 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 budget program can also be used to export and convert the original data obtained from the warping degree measurement device into a data format that is easy to identify and extract, for example, the original data obtained from the warping degree measurement device is converted into an excel format.

[0066] Then, step S02 is performed to select, based on the overall warpage profile of the wafer in the raw data, warpage data of the wafer in each of a plurality of radial directions within a first radius range, a second radius range and a third radius range, and to extract a pattern feature of the warpage data within the first radius range, the second radius range and the third radius range, respectively, to obtain a corresponding first information code, 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.

[0067] Taking the wafer selected as an example, the wafer radial direction for extracting the warpage data can be determined first, then the three radius ranges for extracting the warpage data in the wafer radial direction are determined, and the warpage data corresponding to the radius range of the wafer radial direction extracted is encoded as the first information code of the corresponding radius range.

[0068] As shown in FIG. 2, the selected wafer radial direction can include at least three radial directions with angles of 0° (which can be, for example, the direction of the direction angle), 45°, 90° and 135°. Of course, in alternative examples, the selected wafer radial direction can include four radial directions with angles of 0°, 45°, 90° and 135°.

[0069] After determining the wafer radial direction for extracting the warpage data, the above-mentioned selected warpage data from the same ingot can be arranged in different charts according to the wafer radial direction for statistical analysis of the overall (complete radius range) warpage profile of the wafer obtained from the ingot. Specifically, in the above-mentioned chart, the abscissa is the radius of the wafer, the zero point of the abscissa is the center of the wafer (the radius is 0), the radius on one side of the wafer is located on the negative half-axis of the abscissa, the radius on the other side of the wafer is located on the positive half-axis of the abscissa, the wafer surface height data (warpage data) corresponding to the radius is the ordinate of the chart, and the zero point of the ordinate is the ideal plane of the wafer surface (the height is similar to the average height). In an example, the above-mentioned warpage data can be the actual height of the wafer surface (i.e., the warpage height), which has a unit of microns, for example. In other examples, the above-mentioned warpage data can also be the proportion of the actual height of the wafer surface to the diameter of the wafer (i.e., the warpage degree).

[0070] Before selecting the warping data, the original data of wafer warping topography can be used to preliminarily count the wafer warping topography in the overall radius range of each radial direction, and to determine whether the wafer warping topography is normal or not, and to exclude the case that the wafer warping topography is obviously abnormal (for example, wave shape caused by line cutting abnormality). Therefore, when the wafer warping topography is preliminarily determined to be normal, a suitable width of radius range is selected to represent the graph features of the wafer warping data. As shown in FIGS. 3a to 3d, generally (all the wafer warping topography in the radial direction is normal), the wafer warping topography can be overall "convex", "concave" or "flat". In the embodiment, three interval arranged radius ranges (first to third radius ranges) are used to represent the wafer warping topography in the radial direction, wherein the first radius range and the third radius range are respectively arranged at the edge position of the wafer, and the second radius range is arranged at the center position of the wafer, that is, the first radius range is located at the negative half axis of the coordinate system and includes one side edge of the wafer, the third radius range is located at the positive half axis of the coordinate system and includes the other side edge of the wafer, and the second radius range includes the origin and the partial radius on both sides of the origin. 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 warping data in the second radius range are used to represent the overall wafer warping topography. Of course, the width of the second radius range is greater than the width of the first radius range and the third radius range to improve its representativeness, and even the width of the second radius range can be close to half of the overall radius range of the wafer. In an example, the wafer diameter is 300 mm, that is, the range of the horizontal coordinate in the graph is -150 to 150 mm, the first radius range can be -150 to -125 mm, the second radius range can be -75 to 75 mm, and the third radius range can be 125 to 150 mm.

[0071] When the first information code is encoded from the warping data in the radius range, the first information code can include a sign part and a value part, the sign part is used to represent the pattern feature of the warping data about the warping direction, and the value part is used to represent the pattern feature of the warping data about the warping degree. The sign part and the value part can be obtained from the data of the corresponding radial direction of the above-mentioned graph. Specifically, the sign part of the first information code is the sign of the maximum absolute value of the ordinate in the corresponding radius range, and the value part of the first information code is the absolute value of the maximum absolute value of the ordinate in the corresponding radius range. In an example, please refer to FIGS. 3a-3d, the maximum absolute value of the ordinate in the second radius range is 2, and the point is located on the positive half axis of the ordinate, that is, the value part is 2 and the sign is +, so the first information code of the second radius range can be 2 (the + sign can be omitted). Please continue to refer to the warping topography and the corresponding first information code of FIGS. 3a-3d, the maximum absolute value of the ordinate in the first radius range is 3, and the point is located on the negative half axis of the ordinate, that is, the value part is 3 and the sign is -, so the first information code of the first radius range can be -3, or 3 (for example, the symbol of the negative half axis is represented by an overline). As can be seen from the above, the smaller the value part (or average value) of each first information code indicates the smaller the warping degree, the smaller the value part (closer to 0) of the first information code of each radius range (the first to third radius ranges) indicates the smaller the warping degree (the better the warping topography); the warping topography corresponding to the same signs (same signs) of the first information codes of the first radius range and the third radius range is generally better than the warping topography corresponding to the opposite signs of the first information codes of the first radius range and the third radius range under the same conditions (the value parts are approximately the same).

[0072] It should be noted that the above process of establishing a coordinate system through original 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 original data through a program to obtain the corresponding information code.

[0073] Next, in step S03, the first information codes of the first radius range, the second radius range and the third radius range of the same radial direction of the wafer are combined in sequence 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 combined in sequence to obtain the third information code of the wafer, which is used to represent the warping topography of the wafer.

[0074] For example, the first wafer (No. 1) with a radial angle of 0° is selected, which is provided with 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 a radial angle of 0° obtained by combining the above first information codes can be (a1, b1, c1). Similarly, the second information code of the wafer at a radial angle of 45° can be (d1, e1, f1), the second information code of the wafer at a radial angle of 90° can be (g1, h1, i1), and the second information code of the wafer at a radial angle of 135° 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] When the wafer is evaluated for warpage by using the third information code, if the first information code of the second radius range at each radial angle is within the range of ± the first preset value, that is, the height fluctuation of the wafer in the larger central region is within ± the first preset value (that is, the fluctuation is relatively small), the wafer can be classified as a “flat piece”. For the “flat piece”, the first information code of the first radius range and the third radius range at each radial angle generally needs to be within the range of ± the second preset value (the second preset value is equal to the first preset value) and both of them are optimal. On the other hand, if the first information code of the second radius range at part of the radial angles is outside the range of ± the first preset value and within the range of ± the third preset value, that is, the height fluctuation of the wafer in the larger central region is relatively large, the wafer can be classified as a “concave piece” or a “convex piece”. 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 topography and the corresponding second information code of FIGS. 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”; and 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] Thus, after learning the third information code provided by the wafer adopting the encoding method of the embodiment, the more detailed warping data of the wafer can be obtained to better restore the wafer warping pattern, so as to facilitate subsequent identification, classification and comparison (determination) of the wafer according to the wafer warping pattern. 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 wafer warping pattern belongs to the conventional shape, that is, the wafer can be one of a flat sheet, a concave sheet or a convex sheet, 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 sheet, the concave sheet or the convex sheet 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 advantages and disadvantages of the wafer warping pattern.

[0077] When a wafer rod is simultaneously divided into multiple wafers by wire cutting, the warping degrees of the above-mentioned wafers have certain correlation, so the warping patterns of all wafers after wire cutting of the wafer rod can also be represented by the warping degrees of several representative wafers, such as the fourth information code of the wafer rod obtained by combining the third information codes of the above-mentioned wafers. In an optional 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 (a total of three wafers). Further, when one wafer from each part is taken, the wafer with the maximum warping data (value part) in a certain preset radial direction is also selected from multiple wafers in the part to represent the warping pattern 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 patterns of the wafer rods are evaluated by using the fourth information codes of different wafer rods, the fourth information codes of the above-mentioned wafer rods can all be set in a format similar to a matrix (determinant) as shown in FIG. 3e, so as to facilitate the comparison of the parts and the radial directions of the wafer rod one by one. In addition, the fourth information codes of the above-mentioned wafer rods can be used not only for comparison and evaluation between different wafer rods, but also for evaluation and statistical analysis of the warping patterns of different parts and different radial directions of the wafer rod.

[0078] Embodiment Two

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

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

[0081] As shown in FIG. 4, the wafer warping pattern evaluation method provided by the embodiment includes:

[0082] S01: Obtain third information code of the wafer based on the third information code of the wafer warping topography characterization method, the third information code is composed of the first information code of each radial first to third radius range;

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

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

[0085] In step S01, taking four radial directions including 0°, 45°, 90° and 135° as an example, the third information code of the wafer obtained by the wafer warping topography characterization method can include 12 first information codes of three radius ranges in each of the four radial directions, which can be, for example, (a1, b1, c1), (d1, e1, f1), (g1, h1, i1), (j1, k1, l1).

[0086] In step S02, the preset acceptance threshold range can be determined according to specific products and customers. If all the first information codes are within the acceptance threshold range, it is determined that the wafer warping topography is acceptable, otherwise it is determined that the wafer warping topography is unacceptable. In some examples, different acceptance threshold ranges can be set for different radius ranges, and it is determined whether the first information code of the corresponding radius range is acceptable according to the corresponding acceptance threshold range. In other examples, the wafer that is not acceptable can also be classified more finely according to the number of first information codes that exceed the acceptance threshold range, for example, a wafer with only one first information code exceeding the acceptance threshold range, a wafer with only two first information codes exceeding the acceptance threshold range, etc. In addition, the severity of exceeding the acceptance threshold range can also be classified more finely, for example, a wafer with 0-10% exceeding the acceptance threshold range, a wafer with 10-20% exceeding the acceptance threshold range, etc.

[0087] In step S03, the pre-set concave-convex threshold range can be determined according to specific products and customers. When comparing the size of the first information code of each radial second radius range of the wafer with the concave-convex threshold range to determine the warping profile of the wafer, if the first information code of each radial second radius range is within the concave-convex threshold range, i.e. 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 the first information code of at least one (a radial) second radius range is outside the concave-convex threshold range, i.e. 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 (a radial) second radius range of the wafer is greater than the upper limit of the concave-convex threshold range, the wafer is determined to be convex, and if the first information code of at least one (a radial) second radius range of the wafer is less than the lower limit of the concave-convex threshold range, the wafer is determined to be concave. When a wafer has both a part of the first information code of the second radius range greater than the concave-convex threshold range and another part of the first information code of the second radius range less than the concave-convex threshold range, the first information code with the largest absolute value in the second radius range can be used as the reference. In another aspect, generally the sign part of the first information code of the second radius range of the "concave" wafer is negative, and the sign part of the first information code of the second radius range of the "convex" wafer is positive. In an example, please continue to refer to the warping profiles and corresponding second information codes of FIGS. 3a-3d, the first pre-set value can be 2, the second pre-set value can be 3, and the third pre-set value can be 6, i.e. 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 "flat"; if the first information code of the second radius range is within the range of -6 to -2, the wafer can be "concave"; if the first information code of the second radius range is within the range of 2 to 6, the wafer can be "convex".

[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, to further determine the warping degree of the wafer in each type of wafer (flat, concave, convex).

[0089] Therefore, after learning the third information code of the wafer provided by the characterization method of the embodiment, the more detailed warping data of the wafer can be obtained to better restore the warping pattern of the wafer, which facilitates subsequent identification, classification and comparison (determination) of the wafer according to the warping pattern 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 pattern of the wafer belongs to the conventional shape, that is, the wafer can be one of a flat sheet, a concave sheet or a convex sheet, 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 sheet, the concave sheet or the convex sheet 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 advantages and disadvantages of the warping pattern of the wafer.

[0090] Embodiment three

[0091] Embodiment three provides a characterization method of a wafer line cut pattern.

[0092] Figure 5 is a flow chart of the characterization method of the wafer line cut pattern provided by embodiment three.

[0093] As shown in Figure 5, the characterization method of the wafer line cut pattern provided by the embodiment includes:

[0094] S01: obtaining the first information code of each radial second radius range of a plurality of wafers after line cutting of a wafer rod, 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 warping data in the second radius range of the wafer;

[0095] S02: obtaining a second pattern feature value using the first information code of each radial second radius range of a plurality of wafers, for characterizing the concave-convex pattern after line cutting of the wafer rod.

[0096] In step S01, several representative wafers can be selected (sampled) from the wafers cut from the ingot, and the first information code of the second radius range of each radial direction of the wafers is obtained, or after the wafers are selected, the wafer warping topography characterization method described above is performed to obtain the first information code of the second radius range of each radial direction. In an example, at least one wafer located at the head, middle and tail of the ingot is obtained after the ingot is cut, and of course, in practice, at least 5 wafers can be taken from the head, middle and tail of the ingot to improve accuracy. In another example, the wafers cut from the ingot and packaged into wafer boxes can be sampled, for example, one long ingot cut wafer is packaged into 16 wafer boxes, and one short ingot cut wafer is packaged into 7 wafer boxes. At least one wafer is sampled from each of the above wafer boxes. Of course, the first information code of the first radius range and the third radius range of each radial direction of the wafers can also be obtained synchronously, that is, the third information code of the wafers is obtained.

[0097] In step S02, the first information code of the second radius range of each radial direction of the wafers selected after the ingot is cut can be first counted, and then the topography characteristic value of the second radius range of the ingot cut is obtained, that is, the first information code of the second radius range is obtained. The second topography characteristic value. Specifically, taking the topography characteristic value of the second radius range of the 0° radial direction as an example, the first information code of the second radius range of the 0° radial direction of the selected wafers is counted, and the first information code with the largest absolute value is selected as the characteristic code of the second radius range of the 0° radial direction. Then, the characteristic code of the second radius range of the other radial directions (such as 45°, 90° and 135°) of the selected wafers is obtained in the same way, and then the second topography characteristic value is calculated by using the corresponding several (for example, four) characteristic codes of the second radius range of the different (for example, four) radial directions. As a representative of the convex-concave topography characteristic of the ingot cut in the second radius range, the calculation method can be, for example, to take the characteristic code with the largest absolute value in the above several characteristic codes as the second topography characteristic value. In addition, in an optional example, the first topography characteristic value can also be obtained by using the first information code of the first radius range of each radial direction of several wafers synchronously, and the third topography characteristic value can also be obtained by using the first information code of the third radius range, and the second topography characteristic value is combined, that is, the first to third topography characteristic values are used to characterize the warping topography of the ingot cut. In a specific example, FIG. 6 shows the characteristic code of the radius range of each radial direction of several selected wafers after the ingot is cut, the first radius range is -150~ -125, the second radius range is -75~75, and the third radius range is 125~150. The characteristic code of the radius range of each radial direction and the topography characteristic value (first to third characteristic values) of each radius range are shown in FIG. 6.

[0098] Embodiment four

[0099] Embodiment four provides a method for evaluating the wire sawing profile of a crystal bar.

[0100] FIG. 7 is a flow chart of the method for evaluating the wire sawing profile of a crystal bar according to embodiment four.

[0101] As shown in FIG. 7, the method for evaluating the wire sawing profile of a crystal bar according to the present embodiment comprises:

[0102] S01: obtaining the second profile characteristic value of the wire sawing profile of a crystal bar according to the method for evaluating the wire sawing profile of a crystal bar;

[0103] S02: comparing the second profile characteristic value of the crystal bar with the preset concave-convex threshold range to determine the concave-convex profile of the wire sawed crystal bar.

[0104] In step S01, the second profile characteristic value of the wire sawing profile of a crystal bar can be obtained according to the method for evaluating the wire sawing profile of a crystal bar. Of course, in an optional example, the first to third profile characteristic values can be obtained simultaneously by performing the method for evaluating the wire sawing profile of a crystal bar on the raw data of the wafer warping profile after wire sawing. The obtaining process can generally comprise: first, selecting (defining) the radial direction and the radius range for evaluating the wafer warping profile, and then calculating the profile characteristic values for characterizing the warping profile of each radius range according to the raw data of each radial direction and each radius range. The obtaining process can refer to the process of obtaining the first information code from the raw data, obtaining the feature code from the first information code, and obtaining the profile characteristic value from the feature code, or the obtaining process can be simplified to directly obtaining the profile characteristic value from the raw data.

[0105] In step S02, the preset acceptance threshold range can be determined according to the specific product and customer requirements. The threshold is the acceptance threshold of the wire sawing profile of a 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 warping 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 warping 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 it is determined whether the profile characteristic values of the corresponding radius ranges are acceptable according to the corresponding acceptance threshold ranges. In addition, the severity of the profile characteristic values exceeding the acceptance threshold range can also be classified in more detail.

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

[0107] Of course, after obtaining the first morphology characteristic value and the third morphology characteristic value, i.e., obtaining the first to third morphology characteristic values, the pre-set acceptance threshold range can be combined to further determine the warping morphology and warping degree of the crystal bar after line cutting.

[0108] In an example, the concave-convex threshold range can be, for example, -2-2. FIG. 8a is a characteristic code and a morphology characteristic value of each radial range of a plurality of selected wafers of a crystal bar after line cutting, and the concave-convex morphology thereof can be concave (concave pieces). FIG. 8b is a three-dimensional morphology (surface morphology) map of the crystal bar of FIG. 8a obtained by an optical method, and the overall warping morphology thereof basically corresponds to the morphology characteristic value. In another example, the concave-convex threshold range can be, for example, -2-2. FIG. 9a is a characteristic code and a morphology characteristic value of each radial range of each radius of a plurality of selected wafers of another crystal bar after line cutting, and the concave-convex morphology thereof can be convex (convex pieces). FIG. 9b is a three-dimensional morphology (surface morphology) map of the crystal bar of FIG. 9a obtained by an optical method, and the overall warping morphology thereof basically corresponds to the morphology 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 for characterizing wafer warpage morphology, characterized in that, include: The raw data of wafer warpage morphology after wire cutting of crystal rods are obtained, wherein the raw data includes warpage data of the wafer in different radial ranges; Based on the overall warp morphology of the wafer in the original data, warp data of the wafer in the first, second, and third radius ranges of each of several radial directions are selected, and the graphic features of the warp data in the first, second, and third radius ranges are extracted to obtain the corresponding first information code. The second radius range is located radially between the first and third radius ranges and in the middle region of the wafer. The first information codes of the first, second, and third radius ranges of the same radial direction of the wafer 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, which is used to characterize the warping morphology of the wafer.

2. The method for characterizing wafer warpage morphology according to claim 1, characterized in that, Based on the overall warpage morphology of the wafer in the original data, the step of selecting warpage data of the wafer within the first, second, and third radii of each of several radial directions includes: Using the raw data of wafer warpage morphology, the warpage morphology of the wafer within the overall radius range of each radial direction is statistically analyzed, and it is determined whether the warpage morphology of the wafer is normal. If so, select warpage data of the wafer within the first, second, and third radii of each of several radial directions from the original data.

3. The method for characterizing wafer warpage morphology according to claim 2, characterized in that, A coordinate system is established with the center of the wafer as the origin and the corresponding radial radius as the abscissa. The first radius range is located on the negative half-axis of the coordinate system and includes the first side edge of the wafer. The third radius range is located on the positive half-axis of the coordinate system and includes the second side edge of the wafer. The second radius range includes the origin and a portion of the radius on both sides. The width of the second radius range is greater than the width of the first radius range and the third radius range. The graphical features of the warp data of the second radius range are used to characterize the overall warp morphology of the wafer.

4. The method for characterizing wafer warpage morphology according to claim 3, characterized in that, The wafer diameter is 300mm, the first radius range includes a radius range of -150mm to -125mm in the coordinate system, the third radius range includes a radius range of 125mm to 150mm in the coordinate system, and the second radius range includes a radius range of -75mm to 75mm in the coordinate system.

5. The method for characterizing wafer warpage morphology according to claim 1, characterized in that, The first information code includes a symbol part and a numerical part. The symbol part is used to characterize the graphic features of the warped data with respect to the warped direction, and the numerical part is used to characterize the graphic features of the warped data with respect to the degree of warping.

6. The method for characterizing wafer warpage morphology according to claim 5, characterized in that, The steps of extracting the graphic features of the warped data within the first, second, and third radius ranges to obtain the corresponding first information code include: A coordinate system is established with the center of the wafer as the origin, the corresponding radial radius as the abscissa, and the height of the wafer surface as the ordinate, forming a radial warping profile curve of the wafer, wherein the ordinate is centered at the ideal height of the wafer surface. The ordinate with the largest absolute value within the corresponding radius of the wafer is taken as the first information code for the corresponding radius. 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, and the value part of the first information code is the absolute value of the ordinate with the largest absolute value within the corresponding radius.

7. A method for evaluating wafer warpage morphology, characterized in that, include: Obtain a third information code of the wafer based on any one of the characterization methods of claims 1 to 6, wherein the third information code is composed of a first information code for each radial range of first to third radii; Based on a preset acceptance threshold range, compare whether each of the first information codes of the wafer is within the acceptance threshold range to determine whether the wafer is acceptable. If so, the wafer is determined to be acceptable, and based on a preset concavity / convexity threshold range, the size of the first information code of the wafer in the second radius range of each radial direction is compared with the size of the concavity / convexity threshold range to determine and compare the warpage of the wafer.

8. The method for evaluating wafer warpage morphology according to claim 7, characterized in that, include: If the first information code of the second radius range in each radial direction is within the concave-convex threshold range, the wafer is determined to be flat. If the first information code of the second radius range in at least one radial direction is greater than the concave-convex threshold range, the wafer is determined to be convex. If the first information code of the second radius range in at least one radial direction is less than the concave-convex threshold range, the wafer is determined to be concave.

9. A method for characterizing the morphology of a line section of a crystal rod, characterized in that, include: Obtain a first information code for several wafers after wire cutting a crystal rod within a second radius range in each radial direction. The second radius range is located in the middle region of the wafer, and the first information code is used to characterize the graphic features of warpage data within the second radius range of the wafer. A second morphological feature value is obtained using a first information code within the second radius range of each of the wafers in each radial direction, which is used to characterize the concave-convex morphology of the crystal rod after wire cutting.

10. The method for characterizing the line-cut morphology of a crystal rod according to claim 9, characterized in that, At least one wafer each from the head, middle and tail of a crystal rod is obtained during wire cutting to characterize the wire-cut morphology of the crystal rod.

11. The method for characterizing the line-cut morphology of a crystal rod according to claim 9, characterized in that, The first information code of several wafers after wire cutting of the crystal rod is obtained in the first radius range and the third radius range in each radial direction. Similarly, the first information code of several wafers in the first radius range in each radial direction is used to obtain the first morphological feature value and the first information code of the third radius range is used to obtain the third morphological feature value. The first to third morphological feature values ​​are used to characterize the warping morphology of the wire-cut crystal rod.

12. The method for characterizing the wire-section morphology of a crystal rod according to any one of claims 9 to 11, characterized in that, When obtaining the corresponding morphological feature value using the first information code of the corresponding radius range of each of the several wafers in each radial direction, the first information code with the largest absolute value in the corresponding radius range of each radial direction is taken as the corresponding morphological feature value.

13. A method for evaluating the morphology of a wire section of a crystal rod, characterized in that, include: Obtain the second morphological feature value of the wire-cut crystal rod based on the characterization method of any one of claims 9 to 12; Based on a preset concavity / convexity threshold range, the second morphological feature value of the crystal rod is compared with the size of the concavity / convexity threshold range to determine the concavity / convexity morphology of the crystal rod after line cutting.

14. The method for evaluating the wire-section morphology of a crystal rod according to claim 13, characterized in that, include: If the second morphological feature value of the crystal rod is within the concavity / convexity threshold range, the overall morphology of the crystal rod after wire cutting is determined to be flat; if the second morphological feature value of the crystal rod is greater than the concavity / convexity threshold range, the overall morphology of the crystal rod after wire cutting is determined to be convex; if the second morphological feature value of the crystal rod is less than the concavity / convexity threshold range, the overall morphology of the crystal rod after wire cutting is determined to be concave.

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