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Abstract

The present invention relates to a method for obtaining surface characteristic parameters of a longitudinal orientation mark of a single crystal ingot, a method for producing a single crystal ingot with an orientation mark, and an ingot scanner system for performing the method. The method comprises rotating the single crystal ingot around a rotation axis, recording the distance from a measuring point to the surface of the single crystal ingot at an angular position, comparing the distance with a background shape to identify the distance deviating from the background shape, and recording the angular position and the corresponding distance of the distance deviating from the background shape. The surface characteristic parameters are defined according to the continuous angular positions and the corresponding distances with the distance deviating from the background shape. The method allows the determination of the surface characteristic parameters with low uncertainty.

Description

Technical Field

[0001] The present invention relates to a method for obtaining surface property parameters from longitudinal markings of a single crystal ingot and to a method for producing a single crystal ingot with orientation markings. These methods provide single crystal ingots with improved tolerances. The invention also relates to an ingot scanner system for performing the method. Prior art

[0002] Single crystal materials have many applications, and typically because the material is a single crystal material, the single crystal material also has a crystal orientation, and furthermore, the crystal orientation may be important to the use of the single crystal material. For example, silicon wafers cut from silicon single crystal ingots are used to produce microelectronic devices, and silicon single crystal ingots are typically arranged in a {100} or {111} orientation, however other orientations may also be relevant. As an example of how orientation marking is relevant in the semiconductor field, EP 0610563 discloses an apparatus and process for combined determination of the crystal orientation of a semiconductor ingot and marking the ingot with an orientation flat or notch.

[0003] Single crystals, such as single crystals of Si, GaAs, InAs, InP or sapphire, can be made using different methods, such as the Czochralski (CZ) process or the floating zone (FZ) method, both of which will provide single crystals in the form of single crystal ingots. Many single crystal materials are used in thin slices or the like. For example, silicon single crystal ingots are typically cut into wafers, such as up to about 1 mm thick.

[0004] In order to correctly orient the wafers, ie with respect to the crystal orientation, for subsequent processing, silicon single crystal ingots are usually provided with orientation marks at positions based on knowledge of the actual orientation of the silicon single crystal ingot. Thus, all wafers cut from the silicon single crystal ingot can have orientation marks and be correctly oriented.

[0005] Silicon single crystal ingots and other single crystal ingots are usually prepared into a cylindrical shape with a generally circular cross-section, such as in a CZ or FZ process, and then the silicon single crystal ingot is ground to provide a smooth surface of the circular silicon single crystal ingot. Then, an orientation mark is engraved on the smooth surface, usually along the entire length of the silicon single crystal ingot.

[0006] The orientation mark of silicon single crystal ingots is traditionally a "flat edge", a "notch", or a combination of a flat edge and a notch. The flat edge has a secant shape in a circular cross-section, and the notch can be shaped like the letter "V" or "U" in the surface of the single ingot. The "U"-shaped notch can also be called a circular notch and has a circular shape. For large single crystal ingots, such as single crystal ingots with a diameter of 150 mm or more, a notch is usually preferred because the flat edge may remove too much material from the single crystal ingot.

[0007] The actual shape of the orientation mark does not usually contain any specific information about the single crystal ingot. However, a single crystal ingot can have more than one orientation mark, where additional information about the single crystal can be indicated by multiple orientation marks. Typically, the primary flat edge is used to identify the crystal orientation of the wafer. The secondary flat edge (also known as the secondary flat edge) is typically used to identify the type of dopant by placing it at a given angle to the primary flat edge. According to the SEMI standard, a secondary flat edge positioned at 45 degrees to the primary flat edge indicates a {111} n-type crystal. However, this is only a guide, and flat edges different from those defined by the SEMI standard are possible. The secondary flat edge can also be used to identify the front and back sides of the wafer.

[0008] For the end customer, crystal orientation is important during the processing steps.

[0009] It is possible to measure the crystal orientation of a wafer directly, however, this is cumbersome and requires additional steps and equipment. It is easier to measure the crystal orientation on an ingot, for example using an X-ray goniometer, than on a single wafer. Therefore, it is an advantage for the end customer to have a mark identifying the crystal orientation. The master flat edge can be used to align the wafer orientation during the processing step by placing the flat edge in a holder designed for the wafer, or using an alignment flat edge.

[0010] The notches can be used to mark the crystal orientation in the same way as the flat edges. That is, instead of a flat edge, a notch can be made. Using a notch is beneficial because a notch cuts away less material than a flat edge. The benefit is greater for larger crystals because the material to be cut away increases when making a flat edge, while the material to be cut away by a notch remains the same. However, it is easier to align the wafer based on a flat edge than on a notch. Typically, flat edges are used on ingots up to 6 inches, but making these flat edges in even larger crystals is also an option. Notches are typically used for 6-inch crystals or larger. It is possible to place a flat edge and a notch on the same ingot.

[0011] In the prior art, the measurement of the notch depth is usually performed using a tactile device. The tactile measuring device includes a ball-tipped stylus that contacts the test surface at the bottom of the notch, a beam placed on the top of the hole, and a graduated scale for reading the measurement results. The estimated measurement uncertainty of such a device is about 0.01 mm. However, there are many defects in the tactile measuring device. For example, due to the size of the ball-tipped probe, there is a risk of erroneous measurement that does not detect the bottom of the notch. When the radius of curvature of the notch is smaller than the radius of curvature of the ball-tipped probe, the bottom of the notch may not be measured. In addition, the contact probe measurement may scratch the surface and cause product degradation. Moreover, measuring several notches requires several measurements. Therefore, especially for ingots with multiple characteristics, it is very time-consuming to perform measurements.

[0012] According to the prior art, the width of the notch is usually recorded using a graduated ruler (such as a ruler combined with a magnifying glass). The graduated ruler is placed on the surface of the notch and readings are taken at the start and end of the notch. The difference between the two readings is the width of the notch. The estimated measurement uncertainty of such a device is about 0.1 mm.

[0013] In the prior art method, a graduated ruler (such as a sliding caliper or a ruler) can be used to measure the width of a flat edge on a single crystal ingot. The graduated ruler is placed on the surface of the flat edge and readings are taken at the start and end of the flat edge. The difference between the two readings is the width of the flat edge. This method is very sensitive to the operator performing the measurement because the edge between the curvature of the cylinder and the flat edge is estimated by eye. The estimated measurement uncertainty of this device is about 0.1 mm.

[0014] In order to record the angle between the orientation marks in the prior art method, a digital protractor can be used. However, the positioning of the protractor depends on the skill of the operator, who should be very careful to find the center of the surface mark.

[0015] For alignment of wafers without flat edges, notches can also be used for mechanical alignment of wafers. For example, a wafer with two notches positioned 180 degrees from each other is aligned by positioning a pin in each notch. The precision of the alignment depends on the precision and accuracy of the notch position and geometry. The shape of the pin should match the shape of the notch. Therefore, an improved measurement method for notches is beneficial to the end customer in achieving improved alignment of wafers.

[0016] For example, the calibration of an ingot scanner can be obtained by measuring certified gauge blocks. Both are used for angle and depth measurement. Through the calibration of the instrument, traceability can be established, which is important for the end customer to ensure that the given specifications are as described.

[0017] US 2017 / 052024 discloses an optical analyzer for profiling an object of interest and a method for generating a profile image of an object of interest. The analyzer and the corresponding method provide for measuring complex test objects, such as camshafts, sliding cams and their spiral cam grooves, or even more complex shapes, such as aircraft propellers. US 2017 / 052024 does not involve associating the profiled contour with specific invisible details of the object.

[0018] CN 106323193 discloses a sapphire ingot profile measurement device and a corresponding method. In the device, a laser emitter emits a laser beam, which is detected by a laser sensor. When a sapphire crystal is placed between the laser emitter and the laser sensor, the laser beam is blocked by the sapphire crystal, and the width of the laser beam can be used to calculate the profile of the sapphire crystal. The device of CN 106323193 is limited to recording the profile of a convex crystal having a periphery described by a continuous curve.

[0019] Given the importance of knowing the orientation of a single crystal material when using the material, there is a need for an improved method of correlating an orientation signature on a single crystal material with the actual orientation of the single crystal material. The present invention is directed to addressing this need. Summary of the invention

[0020] The present invention relates to a method for obtaining surface characteristic parameters of a longitudinal orientation mark of a single crystal ingot, the method comprising the following steps: providing a single crystal ingot having a cylindrical shape, the single crystal ingot having a longitudinal center axis and a radius from the longitudinal center axis, the radius defining the surface of the single crystal ingot, the single crystal ingot having a longitudinal orientation mark in the surface of the single crystal ingot, the longitudinal orientation mark having a width; rotating the single crystal ingot around a rotation axis, the rotation axis being substantially parallel to the longitudinal center axis and being located within an offset value relative to the longitudinal center axis; recording the angular position of the single crystal ingot; recording the distances at these angular positions from measurement points located at a measurement distance from the rotation axis to the surface of the single crystal ingot; providing a data array containing these angular positions and the distances at corresponding angular positions; calculating the background shape of the single crystal ingot based on the data array; comparing the distance with the background shape to identify the distance deviating from the background shape; recording the angular position and the corresponding distance of the distance deviating from the background shape; and defining the surface characteristic parameters and the width based on continuous angular positions having the distance deviating from the background shape and the corresponding distance.

[0021] In another aspect, the present invention relates to a method for producing an orientation-marked single crystal ingot, the method comprising the following steps: providing a single crystal ingot having a cylindrical shape, the single crystal ingot having a longitudinal center axis and a radius from the longitudinal center axis, the radius defining a surface of the single crystal ingot; determining a crystal orientation of the single crystal ingot; applying a longitudinal orientation mark based on the crystal orientation to the surface of the single crystal ingot to provide an orientation-marked single crystal, the longitudinal mark having a width; obtaining surface characteristic parameters of the orientation-marked single crystal ingot in the following steps: rotating the orientation-marked single crystal ingot around a rotation axis, the rotation axis being substantially parallel to the longitudinal center axis and being located within an offset value relative to the longitudinal center axis; recording Recording the angular positions of the orientation-marked single crystal ingot; recording the distances at these angular positions from the measurement points located at the measurement distances from the rotation axis to the surface of the orientation-marked single crystal ingot; providing a data array containing these angular positions and the distances at the corresponding angular positions; calculating the background shape of the orientation-marked single crystal ingot based on the data array; comparing the distances with the background shape to identify the distances that deviate from the background shape; recording the angular positions and corresponding distances of the distances that deviate from the background shape; and defining the surface characteristic parameters and the width based on the continuous angular positions with the distances that deviate from the background shape and the corresponding distances; and annotating the orientation-marked single crystal ingot using the surface characteristic parameters. The method may optionally include the step of grinding the surface of the single crystal ingot so that the single crystal ingot has a substantially circular cross-section in the radial dimension.

[0022] On the other hand, the present invention relates to an ingot scanner system, which includes: a rotating device for rotating a single crystal ingot, the rotating device having a rotation axis; a light source for emitting light toward the rotation axis, the light source being located at a measuring point at a measuring distance from the rotation axis; a light detector for recording light reflected and / or scattered from the surface of the single crystal ingot on the rotating device; a data storage unit for storing a data array containing the angular position of the single crystal ingot and the light recorded by the light detector at these angular positions; and a data processing unit, the data processing unit being configured to calculate the distance from the measuring point to the surface of the single crystal ingot based on the data array, the data processing unit being further configured to calculate a background shape of the single crystal ingot based on the calculated distance, and to identify a distance that deviates from the background shape.

[0023] In a specific embodiment, the ingot scanner system is configured to obtain a surface characteristic parameter of the longitudinal mark in a surface of a single crystal ingot having the longitudinal mark in the following steps:

[0024] Rotate the single crystal ingot around the rotation axis, which is substantially parallel to the longitudinal center axis of the single crystal ingot and is located within an offset value relative to the longitudinal center axis of the single crystal ingot; record the angular positions of the single crystal ingot; record the distances at these angular positions from measurement points located at measurement distances from the rotation axis to the surface of the single crystal ingot; provide a data array containing these angular positions and the distances at corresponding angular positions; calculate the background shape of the single crystal ingot based on the data array; compare the distance with the background shape to identify the distance that deviates from the background shape; record the angular position and corresponding distance of the distance that deviates from the background shape; and define the surface characteristic parameter based on continuous angular positions and corresponding distances having the distance that deviates from the background shape.

[0025] In general, all embodiments of the method of the first aspect may be used in the method of the second aspect, and any advantages of features obtained in the first method that are also applicable to the method of the second aspect are equally relevant in the second aspect. Likewise, the ingot scanner system of the present invention may be used in any embodiment of the method aspect. The steps in these methods may employ various apparatuses, devices, etc., and any such apparatus or device is relevant to the ingot scanner system of the present invention, and any advantages described in the context of an apparatus or device are also relevant to the ingot scanner system of the present invention.

[0026] In a first aspect, the method of the present invention obtains surface characteristic parameters of the longitudinal orientation mark of a single crystal ingot. The longitudinal orientation mark can be used to indicate information about the single crystal ingot, so based on the crystal orientation of the single crystal ingot, the relevant longitudinal orientation mark will be applied to the surface of the single crystal ingot. "Surface characteristic parameters" can be any parameters related to any longitudinal mark. The longitudinal orientation mark has at least a width, which is obtained together with the surface characteristic parameters in this method. In the context of the present invention, the width can also be considered as a surface characteristic parameter. In the context of the present invention, "width" is defined in a plane orthogonal to the longitudinal center axis. Certain longitudinal marks will also have depth, and parameters related to the shape of the longitudinal mark. For example, the longitudinal mark can be a notch, and for the notch, for example, for a U-shaped notch ("U-shaped notch"), the surface characteristic parameters can be width, depth and radius of curvature and / or roundness, or, for example, for a V-shaped notch ("V-shaped notch"), the surface characteristic parameters can be width, depth and sidewall angle. The longitudinal mark can also be a flat edge. The flat edge has a secant shape in a plane orthogonal to the longitudinal center axis, such as a circular cross-section of a silicon single crystal ingot, so that the flat edge has a width defined in a plane orthogonal to the longitudinal center axis. The surface characteristic parameters of the flat edge can be a flat edge, for example, it has no depth and / or it is not a notch. For example, the surface characteristic parameters can distinguish between a notch and a flat edge. The single crystal ingot can have more than one longitudinal mark, and in this case, the surface characteristic parameters can also include the angle between two longitudinal marks or the distance between the longitudinal marks, such as the distance from the bottom of one notch to the bottom of another notch.

[0027] Generally speaking, a single crystal ingot will have a longitudinal mark indicating the crystal orientation of the single crystal ingot. The longitudinal mark indicating the crystal orientation of the single crystal ingot may also be referred to as the first longitudinal mark or the "longitudinal orientation mark". The surface characteristic parameters of the longitudinal mark do not depend on whether the longitudinal mark is a longitudinal orientation mark, and when the present application refers to a "longitudinal mark", the term may be replaced by a "longitudinal orientation mark", and vice versa.

[0028] The method of the present invention advantageously allows for the simultaneous measurement of multiple surface characteristic parameters, such as width and another surface characteristic parameter. In particular, since the longitudinal mark is an orientation mark, better information about the orientation mark, for example on a single crystal ingot produced according to the present invention, related to its actual orientation is obtained compared to the methods of the prior art. As a result, when the crystal orientation is important, the method provides improved tolerances and the end user obtains a lower single crystal ingot scrap rate. For example, the depth and width of the notch are measured simultaneously by the present invention. Using instruments of the prior art, this may require two measurements, one for the depth and one for the width. Similarly, the width of the flat edge can be analyzed, and at the same time it can be determined whether the flat edge is a primary flat edge or a secondary flat edge, and other relevant details will be revealed during the simultaneous analysis.

[0029] As a single crystal, a single crystal ingot has an orientation, i.e. a crystal orientation, which is important for the subsequent use of the single crystal material. Any single crystal with an orientation is relevant to the present invention. For example, the single crystal ingot may be a silicon single crystal. The length of the single crystal ingot may be freely selected, and for example for a silicon single crystal, the length will typically be up to 200 cm. Before analysis in the method of the present invention, the silicon ingot may be cut into shorter lengths, and a 4" ingot will typically have a length of up to 40 cm, and an 8" ingot will typically have a length of up to 30 cm. In the context of the present invention, the dimensions of a single crystal ingot, in particular a silicon single crystal ingot, may be indicated in inches (") or mm; typically, 4" corresponds to 100 mm, 6" corresponds to 150 mm, 8" corresponds to 200 mm, and so on, and these two values ​​may be used interchangeably. Silicon single crystals are cut into wafers, for example with a thickness of 1 mm or less, and the knowledge of the crystal orientation is relevant for all wafers, so the silicon single crystal ingot will typically have orientation marks along its entire length.

[0030] A single crystal ingot, in particular a silicon single crystal ingot, may have more than one longitudinal mark. When the single crystal ingot has two or more longitudinal marks, the method for obtaining surface characteristic parameters according to the present invention is particularly advantageous, because the obtained information, such as the surface characteristic parameters of the two or more longitudinal marks, is associated. For example, the surface characteristic parameters of the first longitudinal mark are associated with the surface characteristic parameters of the second longitudinal mark, and the two surface characteristic parameters are associated with the background shape. Thus, a single crystal ingot with two or more longitudinal marks can be better described than analyzing the longitudinal marks using other techniques.

[0031] The single crystal ingot has longitudinal markings in the surface of the single crystal ingot. In the context of the present invention, the term "in the surface" means that longitudinal markings may be engraved on the surface or longitudinal markings may be applied on the surface of the single crystal ingot.

[0032] The distance from the measuring point to the surface of the single crystal ingot is recorded in the method of the present invention. In the context of the present invention, "distance" can be expressed as a single point, or the distance can be expressed as a matrix of several points. For example, the distance of an angular position, such as an angle indicated as a single value, can be indicated as a two-dimensional matrix, a one-dimensional matrix (ie, a "line"), or as a single point. The data of the line or matrix will generally correspond to a single angular position, but the data in the line or matrix will represent a segment of the surface, such as several mm or cm, so that when a line or matrix is ​​used, the same point in the surface of the single crystal ingot may be better described than when a single point is used. For example, a method or system may use a laser scanner that emits light at an angle from an emission point, and the laser scanner detects light in a line or matrix. When the distance is indicated as a line, the line will generally be in the lateral plane of the single crystal ingot. The distance from the measuring point to the surface of the single crystal ingot at the angular position is recorded in the method of the present invention. The distance between the measuring point and the surface of the single crystal ingot can be obtained using any method as needed. It is also possible to use more than one measuring point, and the distance to the surface of the single crystal ingot can be recorded for each measuring point. Likewise, the acquired data may be recorded using any method and appropriate apparatus as desired. In the context of the present invention, the distance of acquiring and recording the angular position may also be referred to as "scanning", and in the method, the surface of the single crystal ingot is thus "scanned". Accordingly, the device for acquiring the distance may be referred to as a "scanner". The data will typically be digital. In general, the scanner may store the data, or the data may be transmitted to a computer or the like. Data transmission may be via any protocol, such as via a cable or wireless connection.

[0033] In a preferred embodiment, the ingot scanner system is also used to characterize the roughness of the single crystal ingot, and similarly, the method can characterize the roughness of the single crystal ingot. Roughness is a surface parameter that describes the degree of deviation of a surface from a perfect surface. The roughness can be measured using a line scan for the roughness in the lateral direction, or by using a vertical stage movement scanner for the roughness in the axial direction.

[0034] In a preferred embodiment, light is applied toward the axis of rotation, and the reflected and / or scattered light from the surface of a single crystal ingot (e.g., a rotating single crystal ingot) is recorded and used to calculate the distance. The light source may be located at an emission point, which may be the same as or different from the measurement point. When the emission point is different from the measurement point, the distance from the emission point to the axis of rotation may be referred to as the emission distance. The emission distance may be the same as or different from the measurement distance. The distance from the measurement point and / or the emission point to the surface of the single crystal ingot will typically be in the range of 10 mm to 100 mm. The distance from the measurement point and / or the emission point to the surface of the single crystal ingot may depend on the scanner technology used. When light is used to measure the distance, the scanner may be referred to as an "optical scanner". Any light source may be used, but preferably the light has a narrow wavelength distribution, such as monochromatic light. The light source may also be referred to as a light emitter. In a specific embodiment, the light is a laser, such as a laser diode. Accordingly, any method and device may be used to record reflected light and / or scattered light as desired. For example, any detector may be used to record reflection and / or scattering. Laser light sources and detectors of laser light (i.e., reflected laser light) may be collectively referred to as "laser scanners." When these methods employ light to record distances, any additional optical elements may be used. Suitable optical elements include lenses, gratings, and mirrors. In another embodiment, the distance from the measurement point to the surface of the single crystal ingot comprises a tactile measurement of the distance. Regardless of the method of measuring the distance, the distance included in the data array should be the distance in the direction from the measurement point toward the axis of rotation.

[0035] The single crystal ingot has a cylindrical shape with a longitudinal center axis and a radius from the longitudinal center axis. It should be understood that the single crystal ingot is not limited to having a circular cross-section, but may also have a cross-section that deviates from a circular cross-section. The calculations used in the method provide the actual shape of the cross-section, i.e., the cross-sectional shape of the single crystal ingot without the orientation mark, which is determined as the background shape, and these calculations are valid for any cross-section whose perimeter can be described by a continuous curve. In the context of the present invention, the term "continuous" means that the curve can be described by a single mathematical function. The continuous perimeter can also be described as "smooth", and the two terms can be used interchangeably. The cross-sectional shape of the single crystal ingot is generally convex. In the context of the present invention, the term "convex" means that a straight line between any two points within the background shape does not intersect the surface of the background shape. A longitudinal orientation mark (e.g., a notch) can represent a shape of a convex shape that deviates from the background shape, but the longitudinal orientation mark will deviate from the continuous curve of the perimeter of the convex background shape. Therefore, for any perimeter that can be described as a continuous curve, deviations from the background shape can be identified. For example, a single crystal ingot may have an oval cross section, or a cross section that can be described as an ellipse, and a single crystal ingot having an oval or elliptical cross section may also be processed in the method of the present invention to obtain surface property parameters.

[0036] Background shape, in particular the diameter of a circular single crystal ingot is determined in the method of the present invention. In the methods of the prior art, the diameter of a circular single crystal ingot is usually recorded using a screw micrometer. However, the measurement is very sensitive to the skill of the operator operating the equipment. If it is not placed on the widest point of the circumference, the measured diameter is too small. The measurement is sensitive to the force used to tighten the screws. In contrast, for the method of the present invention, the measurement uncertainty is as low as 0.01 mm and there is no risk of measurement errors. Therefore, when the single crystal ingot has a substantially circular cross-section in the radial dimension, the uncertainty in determining the diameter of the single crystal ingot is reduced compared to recording the diameter using the method of the prior art. Moreover, the method of the present invention will also provide information about deviations from a circular cross-section.

[0037] The longitudinal center axis is located at the centroid of a plane orthogonal to the longitudinal center axis. For a single crystal ingot with a circular cross-section, the centroid is a point equidistant from the surface of the single crystal ingot in a plane orthogonal to the longitudinal center axis.

[0038] The single crystal ingot rotates around an axis of rotation which is substantially parallel to the longitudinal center axis and is located within an offset value relative to the longitudinal center axis. The closer the axis of rotation is to the longitudinal center axis, the simpler the calculation for determining the background shape is and, furthermore, the lower the uncertainty in determining the distance from the measuring point to the surface of the single crystal ingot is. In particular, the lower the offset value, the lower the uncertainty in the distance determined as a deviation from the background shape. Therefore, the lower the offset value, the better the description of the single crystal ingot and its orientation marks and corresponding surface characteristic parameters. Preferably, the offset value is 5 mm or less, for example 2 mm or less, for example 0.5 mm or less.

[0039] The method for obtaining surface characteristic parameters includes recording the angular position of a single crystal ingot, and recording the distance of a measuring point at the measuring distance from the axis of rotation to the surface of the single crystal ingot at these angular positions. Compared with the rotating single crystal ingot, the measuring point is at a constant position so that the recorded distance will describe the surface of the rotating single crystal ingot. Thus, a data array containing angular positions and distances at corresponding angular positions is obtained for the single crystal ingot. Therefore, when the single crystal ingot rotates 360°, the entire surface of the single crystal ingot plane will be included in the data array. The data in the data array is used to calculate the background shape of the single crystal ingot. Therefore, the data array will provide knowledge about the cross section of the single crystal ingot. The background shape can be included in the data array. For example, the data array may contain information about the cross-sectional shape (e.g., circular, elliptical, etc.), and parameters defining the corresponding cross-sectional shape (e.g., diameter, minor axis, major axis, etc.).

[0040] The data array obtained from a 360° rotation of the single crystal ingot will contain information allowing the background shape to be determined and therefore also data points that deviate from the background shape to be identified. The background shape corresponds to the cross-sectional shape of the single crystal ingot without orientation marks, and therefore the cross-sectional shape will be determined based on the group of continuous distances corresponding to a specific background shape (i.e. the distances of continuous angular positions). Similarly, the group of continuous distances that deviate from a specific background shape will represent an orientation mark. If the distances that deviate from the background shape cannot be grouped with other deviation distances in a series of continuous angular positions, these distances can generally be discarded as outliers. Once a data point has been classified as "background" or "marker", the data point in the data array at the corresponding angular position will be labeled accordingly.

[0041] Once the background shape has been determined, for example when the single crystal ingot has been rotated 360° in the method of the present invention, the offset value can be determined. Therefore, the calculation of the background shape will also determine the offset value. By determining the offset value, the method of the present invention will provide information about the uncertainty of the surface property parameters obtained in the method. For single crystal ingots, the offset value will usually be included in the data array.

[0042] The calculation of the background shape and the accompanying offset value provides the operator with information on how to reposition the single crystal ingot so as to minimize the offset value. In a particular embodiment, the method includes the step of repositioning the single crystal ingot so as to minimize the offset value. Once the offset value has been minimized, the method should be repeated with the single crystal ingot being located at a position with a lower offset value. After repositioning the single crystal ingot, the method can therefore be restarted to provide an improved data array at a lower offset value and a correspondingly lower uncertainty in the surface characteristic parameters. By repositioning the single crystal ingot to minimize the offset value and repeating or continuing the method, the uncertainty in the surface characteristic parameters will be improved so that the values ​​of the single crystal ingot, and thereby also the values ​​of portions (e.g., wafers) from the silicon single crystal ingot, will be improved for the end user of the single crystal ingot segment.

[0043] The background shape can be determined based on knowledge of the general shape of the single crystal ingot. For example, prior to executing the method, an operator will recognize that the single crystal ingot for analysis has a cross-section such as a circular or elliptical shape, and this information can be used to help determine the background shape. With a prior indication of the general shape of the single crystal ingot, the background shape can be determined more quickly than without this information. In particular, when the data array is obtained with prior knowledge of the general background shape, the actual background shape can be determined by analyzing a smaller section of the single crystal ingot, such as 180° of the single crystal ingot.

[0044] The method can record the distances of any number of angular positions, in particular any number of angular positions distributed within a 360° rotation. In an embodiment, the single crystal ingot is rotated 360° and the distances of the angular positions at angular intervals in the range of 0.06° to 36° are recorded. The angles between the angular positions can be the same or different within the 360° rotation. In the context of the present invention, the angular positions at angular intervals in the range of 0.06° to 36° are referred to as "low-resolution scans". For example, the data array of a low-resolution scan can contain data for up to 6000 angular positions. For example, a low-resolution scan within a 360° rotation is sufficient to determine the background shape. In a specific embodiment, the background shape is determined in an initial low-resolution scan, which may be followed by a higher resolution scan.

[0045] The single crystal ingot can be rotated using any method as needed. In the context of the present invention, it should be understood that the single crystal ingot and the equipment for recording the distance (e.g., a scanner) move relative to each other around the axis of rotation. Therefore, the single crystal ingot can be rotated or the scanner can be rotated, but in both cases the rotation will be around the axis of rotation. The rotation rate of the single crystal ingot can be freely selected. For example, the single crystal ingot can be rotated at a rate in the range of 0.06° / s to 72° / s (e.g., 1° / s, 2° / s, 4° / s, 10° / s or 20° / s, 50° / s), for example, for a silicon single crystal ingot with a diameter of 150mm, it is rotated at a rate of about 6° / s. Generally, for larger single crystal ingots, such as single crystal ingots with a diameter of 150mm or 200mm, a lower rotation speed is preferred, while for smaller ingots, such as single crystal ingots with a diameter of 100mm or less, a higher rotation speed is preferred. The direction of rotation can be clockwise or counterclockwise. It is also possible that these methods use a combination of clockwise or counterclockwise rotation. For example, the single crystal ingot can be rotated clockwise by a certain angle, and then the direction of rotation can be reversed to counterclockwise. Data points can be recorded in either or both rotation directions. Any rotating device, such as a rotating table, can be used in the method. The rotating device can be rotated using any method as needed. In a preferred embodiment, the rotating device is a rotating table with a stepper motor. Compared with other drives, the stepper motor will reduce the uncertainty of the angular position, thereby correspondingly improving the determination of the surface characteristic parameters of the single crystal ingot analyzed in the method. In a preferred embodiment, the rotating table is equipped with an encoder to obtain a higher precision angle value compared to a motor without an encoder.

[0046] In an embodiment, the method further comprises the step of moving the measuring point in the longitudinal direction relative to the single crystal ingot. Thus, the scanner and / or the single crystal ingot may be moved. For example, the ingot scanner system may comprise a device for lifting the single crystal ingot, or a lifting device may lift and / or lower the scanner. By moving the measuring point relative to the single crystal ingot, it is possible to extend the surface characteristic parameters so as to also include information in the longitudinal direction of the single crystal ingot. For example, the surface characteristic parameters may therefore include information about longitudinal marks at several positions along the length of the single crystal ingot, which information may be included in the same data array, thereby providing further knowledge to the end user and providing improved tolerances compared to analyzing the longitudinal marks at a single position. For example, by moving the scanner and / or the single crystal ingot longitudinally relative to each other, it is possible to determine whether the longitudinal mark deviates from the longitudinal center axis of the single crystal ingot, or whether the longitudinal mark deviates over the length of the longitudinal mark.

[0047] In certain embodiments, the lifting device can also move the scanner in a lateral plane relative to the single crystal ingot. Thus, the measurement distance can be changed so that the same surface characteristic parameter can be analyzed at different settings of the scanner to further improve the data. The device for lifting the single crystal ingot can also move the single crystal ingot in a lateral plane, for example to re-center the single crystal ingot to reduce the offset value.

[0048] In general, as the data array is recorded, the recorded distances are added to the data array so that the method can indicate when enough data has been obtained to determine the background shape. For example, when the method is performed with a priori knowledge of the general background shape, the background shape can be obtained after rotating the single crystal ingot 180°. By continuing to rotate more than 360° while obtaining data, the determination of the background shape can be improved by recording several data points at the same angular position.

[0049] Once the background shape has been determined, the continuous distance group that deviates from the specific background shape will indicate the angular position of the longitudinal mark. In general, the method of the present invention determines the background shape in the initial scan, for example, by using a low-resolution scan within 360° or a section of the single crystal ingot. The angular position of the longitudinal mark will be found in the initial scan. At any time, the direction of rotation can be reversed, and the single crystal ingot is rotated to allow the scanner to (re) analyze the surface of the single crystal ingot at the angular position identified as the longitudinal mark. Therefore, the method of the present invention may further include a step of reanalyzing the continuous angular positions of the surface characteristic parameters at a higher resolution after identifying the continuous angular positions. The reanalysis can be performed using the same scanner as in the first analysis or using a different scanner. Once the continuous angular positions of the surface characteristic parameters have been identified, the reanalysis will generally record the distances of at least 5 angular positions of the identified longitudinal marks, such as at least 10 angular positions, at least 50 angular positions, or at least 100 angular positions. By initially calculating the background shape of the single crystal ingot and finding the position of the longitudinal mark from the initial scan, and then reanalyzing the longitudinal mark to obtain the surface characteristic parameters, a much faster process than performing a full high-resolution scan is provided. Furthermore, the initial scan will provide additional information, such as information about the relative position of one or more longitudinal marks, which would not be provided by analyzing only the position of the longitudinal marks, such as by manually positioning the scanner and analyzing the longitudinal marks. Thus, in particular the initial scan will be over 360° of the single crystal ingot.

[0050] In an embodiment, the surface of the single crystal ingot is analyzed at a low resolution in an initial scan, and the angular position corresponding to the longitudinal mark is subsequently rescanned, for example, at a higher resolution. Specifically, the longitudinal mark can be identified in the low-resolution scan, and the scanner can be repositioned to the identified angular position corresponding to the longitudinal mark. The longitudinal mark can then be scanned at a higher resolution. For example, the rotation of the single crystal ingot can be stopped at an angular position having a distance from the background shape, and the distance from the measuring point to the surface of the single crystal ingot is recorded at the angular position without rotating the single crystal ingot. Low-resolution and high-resolution scans can be performed using the same scanner, or a high-resolution scan can use a different scanner from the low-resolution scan. When the method includes a high-resolution scan, it is preferred to obtain a high-resolution scan without rotating the single crystal ingot. By stopping the rotation and recording the high-resolution scan, the data quality (e.g., the resolution of the high-resolution scan) will generally be improved compared to the scan performed when the single crystal ingot is rotating. In particular, when the single crystal ingot is not rotating, the uncertainty of the angular position will be lower. In a preferred embodiment, the acquisition time is fast relative to the rotation of the ingot, so that interference from the moving sample is negligible. Thus, it is possible to obtain high-resolution scans without actually stopping the motion.

[0051] A preferred scanner, in particular a scanner for performing high-resolution scanning, is a laser scanner having a laser source and a suitable detector. The laser scanner will typically provide a laser with a wavelength in the range of 400nm to 700nm, emitted toward the surface of the single crystal ingot at an aperture angle in the range of 5° to 30°, such as a 405nm laser (blue laser) or a 658nm laser (red laser). The distance from the emitter of the laser (i.e., the emission point) to the surface of the single crystal ingot may depend on the specific laser scanner, for example, defined by the wavelength and aperture angle of the laser, but the distance is typically in the range of 20mm to 100mm. Similarly, the distance from the surface of the single crystal ingot to the measuring point may also depend on the specific laser scanner. The laser scanner will, for example, have a detector at the measuring point for detecting laser light reflected and / or scattered from the surface of the single crystal ingot. The detector can record, for example, simultaneously, multiple points. The number of points can, for example, be in the range of 500 to 5000, for example, 1000 to 2000, but other numbers outside these ranges are also possible. Thus, the laser scanner may have a nominal lateral resolution in the range of 1 μm to 10 μm. In general, the shorter the wavelength, the better the resolution of the detector, and thus the higher the resolution of the laser scanner. Micro-Epsilon Messtechnik GmbH & Co. KG of Oldenburg, Germany sells exemplary laser scanners, such as the laser scanner sold under the name of the LLT2900 series ( https: / / www.micro-epsilon.co.uk / 2D_ 3D / laser-scanner / model-overview / ? select=A_LLT_2600-25 ). Laser scanners are well known to the skilled person. A high resolution laser scanner may record a matrix of points simultaneously, such as a line array, or a high resolution laser scanner may record a single point at a time. A single point may be obtained by retrieving a single value, taking the average of a plurality of values ​​(e.g., from 2 to 100 values, such as 10 values), or taking the median of a plurality of values ​​(e.g., from 2 to 100 values, such as 10 values). Single point recording may be used for low resolution scanning in order to quickly identify background shapes, and then the same laser scanner may be used as a high resolution scanner to record a matrix at the locations indicated to represent longitudinal marks.

[0052] High resolution scans, particularly those obtained when the ingot is not rotating, are particularly effective for analyzing notches. Notches are typically more complex than flat edges and therefore contain more information than flat edges. For example, a flat edge will be primarily described by its position in the ingot and its width. In the method of the present invention, the flat edge will be detected based on a "starting point" relative to the rotation, so that the angular position will correspond to the starting point, and similarly, the flat edge will have an "end point" which will also be detected when the ingot is rotated and will have a corresponding angular position. For a 150 mm ingot, the width of the main flat edge will typically be up to 70 mm, but for smaller ingots, the width of the main flat edge will typically be smaller, for example in the range of 50 mm to 60 mm or less, for example about 25 mm to 35 mm for a 4" ingot. The method of the present invention allows the use of smaller flat edges, which is due to the improved description of the surface characteristic parameters compared to the methods of the prior art, thereby requiring the method of the present invention to remove less material from the ingot.

[0053] In contrast, in addition to the start and end points and the corresponding width, a notch will also have a shape and a depth. Due to the smaller size of a notch compared to a flat edge, it is more difficult to accurately determine the position of a notch using the prior art methods than it is to determine the position of a flat edge, and in particular the shape and also the depth of a notch cannot be determined according to the prior art methods with the same accuracy as can be obtained with the present method.

[0054] In an embodiment of the present invention, the surface characteristic parameters include details about the longitudinal markings. For flat edges, these details generally include the starting point and the end point, thereby also including the width of the flat edge, and the position of the flat edge relative to the crystal orientation of the single crystal ingot. For notches, these details generally include the starting point and the end point, thereby also including the width of the notch, and the position of the notch relative to the crystal orientation of the single crystal ingot, and for notches, the surface characteristic parameters may further include the shape, for example, if the notch has a V shape or a U shape, then including its depth and width. Specifically, for a U-shaped notch, the radius and roundness can be determined, and for a V-shaped notch, the sidewall angle can be determined. Notches and flat edges are particularly relevant for silicon single crystal ingots. The width of the notch is generally in the range of 1mm to 8mm, for example, 2mm to 4mm. The depth of the notch is generally in the range of 0.5mm to 3mm. For a typical silicon single crystal ingot, such as a silicon single crystal ingot with a diameter of 150mm, 200mm or 300mm, the width of the notch can also be expressed as an angle compared to the circumference of the silicon single crystal ingot. The "angle" of the notch will indicate the optimal resolution for obtaining the surface characteristic parameters of the notch. In a specific embodiment, the longitudinal mark is a notch, and the background shape of the single crystal ingot is determined in a low-resolution scan, wherein the position of the notch is determined. After identifying the angular position corresponding to the distance from the background shape and therefore representing the notch, the angular position of the notch is re-analyzed by recording the distance of at least 5 angular positions in the notch "angle". The same method can also be used for other longitudinal marks besides notches, in particular longitudinal marks that only occupy a small "angle" in the surface of the single crystal ingot, and again this method is not limited to silicon single crystal ingots.

[0055] When the method of the present invention uses a scanner to measure the reflection / scattering from the surface of the single crystal ingot, such as a laser scanner, the measurement uncertainty for measuring the depth of the notch can be as low as 0.005 mm, compared to the measurement uncertainty of the order of 0.01 mm measured by the ball stylus of the prior art. Similarly, the method of the present invention provides a greatly improved uncertainty for obtaining the width of the notch, so that when the width is obtained, for example, using a laser scanner, the measurement uncertainty is as low as 0.01 mm, compared to the uncertainty of 0.1 mm when using a scale combined with a magnifying glass in the prior art. In addition, the prior art requires visual judgment to determine that the record is actually a diameter, but this is not necessary in the method of the present invention. When a notch is applied in a single crystal ingot produced by the method of the present invention, as an example of a longitudinal mark, the width of the notch will generally have a predetermined value, such as 2.80 mm, which can be prepared in the method of the present invention with a tolerance of ±0.20 mm. The predetermined value of the width can be indicated as a surface characteristic parameter in the label of the single crystal ingot, and the actual width of the notch obtained in the method of the present invention will also be included in the label.

[0056] Moreover, when measuring light reflection / scattering, there is no risk of damaging the sample and thus recording an erroneous measurement. When a notch is applied in a single crystal ingot produced according to the method of the invention, as an example of a longitudinal marking, the depth of the notch will generally have a predetermined value, such as 1.25 mm, which can be prepared according to the invention with a tolerance of ±0.15 mm. The predetermined value of the depth can be indicated as a surface characteristic parameter in the label of the single crystal ingot, and the actual depth of the notch obtained in the method of the invention will also be included in the label.

[0057] The method of the present invention can also obtain the side wall angle of the V-shaped notch and the curvature radius of the U-shaped notch. In the method of the prior art, these surface characteristic parameters can usually only be recorded at the end of the single crystal ingot, where the notch and the cross section of the notch are exposed. In contrast, the method of the present invention allows these surface characteristic parameters to be obtained at several positions along the single crystal ingot. The angle between the side walls is usually recorded with an uncertainty of the order of 1° in the method of the prior art. The radius of curvature is usually recorded with an uncertainty of the order of 0.1mm in the method of the prior art. Using the laser scanner in the method of the present invention, the angle between the side walls can be measured with an uncertainty as low as 0.1°. Similarly, when a laser scanner is used in the method of the present invention, the measurement uncertainty of the radius of curvature is as low as 0.005mm. For the angle between the side walls and the radius of curvature, measurements can be performed at all positions of the ingot. When the single crystal ingot produced according to the present invention is marked with a V-shaped notch, the angle between the side walls will generally have a predetermined value. For example, the predetermined value of the side wall angle may be 90°, which may be prepared according to the present invention with a tolerance between +5° and -1°. When a single crystal ingot produced according to the present invention is marked with a U-shaped notch, the radius of curvature will have a predetermined value. For example, the predetermined value of the radius of curvature may be 1.50 mm, which may have a tolerance of 0.05 mm.

[0058] The method of the present invention also provides improved measurement of flat edges as longitudinal marks on a single crystal ingot. When light reflection / scattering is used in the method, such as a laser scanner, the measurement uncertainty is typically as low as 0.01 mm compared to 0.1 mm for a sliding caliper or ruler used in the prior art. In addition, in the method of the present invention, the uncertainty caused by determining the correct measurement position of the flat edge width by eye, which is required in the methods of the prior art, is avoided because determination by eye is not necessary. The flat edges of the single crystal ingot prepared in the method of the present invention will have predetermined values. For example, the main flat edge can have a width of 52.5 mm with a tolerance of 2.5 mm.

[0059] According to the methods of the prior art, the use of a digital protractor to record the angle between longitudinal marks generally does not provide a measurement uncertainty of less than 0.5°. By calculating the angle between the longitudinal marks from the data array in the method of the present invention, the uncertainty can be as low as 0.05°. When a single crystal ingot with two or more longitudinal marks is produced in the method of the present invention, the angle between the longitudinal marks will have a predetermined value. Typical values ​​of the angle are 45° and 90°, but regardless of the actual angle, the method of the present invention allows the positioning of the longitudinal marks within a tolerance of ±2.5°.

[0060] The method of obtaining surface property parameters of a longitudinal mark of a single crystal ingot can therefore provide surface property parameters, the obtained surface property parameters having an uncertainty improved by a factor of 10 compared to surface property parameters obtained using methods of the prior art.

[0061] The label included in the single crystal ingot prepared in the method of the present invention may include predetermined values ​​of longitudinal marks and obtained surface characteristic parameters, such as the width, depth and other surface characteristic parameters of the notch, the width of the flat edge, and the obtained values ​​and corresponding tolerances.

[0062] Silicon single crystal ingots can be manufactured using different methods (such as the Czochralski process or the floating zone method). The length of the single crystal ingot is typically 50 cm to 200 cm, and the weight ranges from a few kg to hundreds of kg (such as 100 kg, 200 kg, 300 kg), depending on the crystal diameter and the manufacturing method. Typical crystal diameters are 2 inches, 3 inches, 4 inches, 5 inches, 6 inches (150 mm), 8 inches (200 mm), 12 inches (300 mm) or 18 inches (450 mm). The grown crystal is usually several mm larger than the target diameter because the crystal is ground in a later processing step. Single crystal ingots of materials other than silicon (such as GaAs, InAs, InP) can be manufactured using similar processing methods. The method for preparing a silicon single crystal ingot of the present invention may also include the step of cutting wafers from the silicon single crystal ingot. Wafers cut from the silicon single crystal ingot prepared according to the present invention are within the range.

[0063] The large single crystal ingot is sliced ​​into smaller single crystal ingots, with typical lengths ranging from 1 cm to 80 cm, such as 10 cm to 60 cm.

[0064] The single crystal ingot is now ground to have a smooth and uniform surface. After grinding, longitudinal orientation marks can be engraved in the single crystal ingot to mark the crystal orientation. The orientation of the mark is important for further processing steps. The mark is usually a flat edge or a notch. One or more marks can be engraved in the crystal. In the case of two flat edges, one flat edge is usually larger than the other flat edge, and they are called "primary flat edge" and "secondary flat edge". The mark can also consist of a flat edge and a notch. These marks can also be used for improved alignment at subsequent processing steps.

[0065] The width of the flat edge depends on the crystal diameter. For a 6 inch single crystal ingot, the typical width of the flat edge is in the range of 10 mm to 70 mm. In the case where more than one flat edge is defined in the ingot, one flat edge is usually in the higher range, such as between 50 mm and 60 mm, and the other flat edge is in another lower range, such as between 20 mm and 30 mm. For larger and smaller ingot diameters, the size of the orientation flat edge is scaled accordingly.

[0066] In the case of two or more longitudinal markings, the subsequent longitudinal marking is usually positioned relative to the first longitudinal marking. As an example, the secondary flat edge can be positioned at, for example, 45°, 90° or 180° relative to the primary flat edge. As an example, two notches can be positioned at 45°, 90° or 180° relative to each other. For example, one or more notches can be positioned at 45°, 90° or 180° relative to the flat edge.

[0067] The marked ingot can now be sliced ​​into multiple wafers, thin single crystal disks, typically in the range of 300μm to 1000μm thick. The longitudinal marks engraved on the ingot will also be present at the individual wafers. Therefore, the geometry of the marks on the ingot is critical to the geometry of the marks on the wafers. However, the longitudinal marks are not necessarily the same because the wafers are ground and polished after being cut from the single crystal ingot.

[0068] The position of the longitudinal mark relative to the crystal orientation of the single crystal ingot will generally be expressed as an angle. In a particular embodiment, the single crystal ingot, in particular a silicon single crystal ingot, will have two longitudinal marks, wherein a first orientation mark indicates the crystal orientation of the single crystal ingot, and a second longitudinal mark indicates a specific type of the single crystal ingot, such as the doping type of the silicon single crystal ingot. When the single crystal ingot thus includes two longitudinal marks, both of the longitudinal marks may be flat edges, both may be notches, or both of the longitudinal marks may be flat edges and notches. The first orientation mark will indicate the crystal orientation, such as {100}, {110} or {111}, and will be placed relative to the crystal orientation, and the second longitudinal mark will be placed relative to the first orientation mark.

[0069] The method of obtaining surface property parameters may include the step of determining the crystal orientation of the single crystal ingot, and the method of producing a single crystal ingot with an orientation marked includes the step of determining the crystal orientation of the single crystal ingot. Any method may be used to determine the crystal orientation. The crystal orientation is preferably determined using X-ray crystallography, for example using an X-ray goniometer. X-ray crystallography is well known to the skilled person.

[0070] Determining the crystal orientation is particularly relevant for silicon single crystal ingots. When surface property parameters are obtained for a single crystal ingot (the single crystal ingot has a longitudinal orientation mark in the surface of the single crystal ingot), the information provided by the determination is included in the data array. Thus, in addition to the information about the longitudinal orientation mark, the data array will also contain information about the determined crystal orientation, thereby providing higher value surface property parameters to the end user of the single crystal ingot, because the single crystal has an improved tolerance compared to the single crystal ingot that has not been analyzed accordingly. The same observation is true for other longitudinal marks in the surface of the single crystal ingot with the longitudinal orientation mark. Due to the improved tolerance, the end user's final product, that is, the final product produced by the single crystal ingot, will have a lower scrap rate. Since the price of silicon single crystal ingots increases with the increase of diameter, the lower scrap rate is particularly relevant for large diameter silicon single crystal ingots. For example, in the case of FZ silicon single crystal ingots with a diameter of 150mm or more, or 200mm or more, and CZ silicon single crystal ingots with a diameter of 300mm or more, it is particularly valuable to use X-ray crystallography in the method of the present invention. In an embodiment of the present invention, the single crystal ingot is a FZ silicon single crystal ingot having a diameter of 150 mm or more, for example, 200 mm. In another embodiment of the present invention, the single crystal ingot is a CZ silicon single crystal ingot having a diameter of 300 mm or more.

[0071] The determination of the crystal orientation is used in the method of producing the single crystal ingot with orientation marking of the present invention. The crystal orientation is determined before applying the longitudinal orientation mark based on the crystal orientation, but the subsequent analysis of the crystal orientation can also be included in the method. The combination of determining the crystal orientation, applying the orientation mark and obtaining the surface characteristic parameters provides the best single crystal ingot for the end user of the single crystal ingot, because the single crystal ingot can be equipped with orientation marks according to the specific needs of the end user, such as specific details about the relevant notch (such as depth and width), and for U-shaped notches, there are also radii and roundness, and for V-shaped notches, it is the angle between the side walls, and when two or more longitudinal marks are desired, there are also notches and notches. Angle, parallelism of the notch to the main flat edge, the angle of the main flat edge to the notch, the angle of the flat edge to the flat edge, etc. For example, if the longitudinal mark is described using the method of the prior art, it is impossible to obtain a single crystal ingot of the same quality by determining the crystal orientation and applying the longitudinal mark according to the present invention without obtaining the surface characteristic parameters. The method of the present invention advantageously allows measuring more than one longitudinal mark of the same single crystal ingot. Since two or more longitudinal marks may be measured simultaneously, information about the longitudinal marks will be in the same data array and improved data relating to the relative positioning of the two or more longitudinal marks, such as the angle between these longitudinal marks, will be obtained.

[0072] FZ silicon single crystal ingots with a diameter of 150 mm or more, for example 200 mm or more, and CZ silicon single crystal ingots with a diameter of 300 mm or more are particularly relevant for the production method of the present invention, due to the higher value of such single crystal ingots compared to silicon single crystal ingots of smaller diameters, and due to the fact that the tolerances are even further improved compared to silicon single crystal ingots not produced according to the method. Therefore, in an embodiment, the method produces FZ silicon single crystal ingots with a diameter of 150 mm or more, for example 200 mm. In another embodiment, the method produces CZ silicon single crystal ingots with a diameter of 300 mm or more.

[0073] Single crystal ingots with marked orientations produced according to the present invention are marked with surface characteristic parameters. Single crystal ingots analyzed but not produced according to the present invention may also be marked with surface characteristic parameter markings obtained in the method of the present invention. The marking ensures that information about the crystal orientation of a particular single crystal ingot is associated with the orientation mark, so that authentication is improved. The marking can be performed as required, and the marking can take the form of a physical label, for example, on the single crystal itself, on the packaging containing the single crystal ingot, attached to the single crystal itself or to a sticker on the packaging containing the single crystal ingot. Each wafer cut from a silicon single crystal ingot can also be marked, or a group of wafers cut from the same single crystal ingot can be marked. The label can contain actual information about the surface characteristic parameters, or the information about the surface characteristic parameters can be digitally or electronically stored in the label. Thus, for example, a single crystal ingot can have a label with a unique identification number. The unique identification number can be further linked, for example, hyperlinked to a database storing information. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] In the following the invention will be explained in more detail with the aid of examples and with reference to schematic drawings, in which:

[0075] Figure 1 shows a schematic diagram of a single crystal ingot with longitudinal markings;

[0076] Figure 2 Examples of shapes of longitudinal markings are shown;

[0077] Figure 3 An example of the location of notches and flat edges in a single crystal ingot is shown;

[0078] Figure 4 An ingot scanner system of the present invention is shown;

[0079] Figure 5 A single crystal ingot is shown installed in the ingot scanner system of the present invention;

[0080] Figure 6 The differences between scans at different offset values ​​are shown;

[0081] Figure 7 shows experimental data of circular notches obtained in the method of the present invention;

[0082] Figure 8 shows experimental data obtained in the method of the present invention from an ingot having two notches and two flat edges plotted in a polar coordinate system;

[0083] Fig. 9 Experimental data obtained in the method of the invention from an ingot with two notches and two flat edges plotted in a Cartesian coordinate system are shown.

[0084] It should be understood that the combination of features in various embodiments and aspects is also contemplated, and various features, details and embodiments can be combined into other embodiments. In particular, it is contemplated that all definitions, features, details and embodiments of the above-described method and ingot scanner system are equally applicable to each other.

[0085] Reference to the drawings is for the purpose of illustrating the invention and should not be construed as limiting the features to the specific embodiments depicted. DETAILED DESCRIPTION

[0086] The present invention relates to a method for obtaining surface characteristic parameters of a longitudinal mark 11 of a single crystal ingot 10, a method for producing a single crystal ingot 10 with an orientation mark, and an ingot scanner system 20 for performing the method. These methods include: rotating the single crystal ingot 10 around a rotation axis 23, recording the distance from a measuring point 24 to the surface 14 of the single crystal ingot 10 at an angular position, comparing the distance with a background shape to identify the distance deviating from the background shape, and recording the angular position and the corresponding distance of the distance deviating from the background shape. The surface characteristic parameters are defined based on the continuous angular positions with the distance deviating from the background shape and the corresponding distance. The method allows the determination of the surface characteristic parameters with low uncertainty.

[0087] In the method of the first aspect, a single crystal ingot 10 having a longitudinal mark 11 is analyzed to obtain surface characteristic parameters of the longitudinal mark 11. Figure 1 . The single crystal ingot 10 is preferably a silicon single crystal ingot 10, and the single crystal ingot can be produced in a floating zone (FZ) method or a Czochralski (CZ) process. For example, a circular FZ silicon single crystal ingot 10 can have a diameter of 150 mm or 200 mm, and a circular CZ silicon single crystal ingot 10 can have a diameter of 300 mm. The FZ method and the CZ method are well known to technicians who can easily obtain the silicon single crystal ingot 10. The circular silicon single crystal ingot 10 has a cylindrical shape with a longitudinal center axis 12 and a radius 13 from the longitudinal center axis 12. The radius 13 defines a surface 14 of the single crystal ingot 10.

[0088] The longitudinal mark 11 is in the surface 14 of the single crystal ingot 10, for example the longitudinal mark 11 follows the entire length of the single crystal ingot 10. The longitudinal mark 11 is usually engraved on the surface 14 of the single crystal ingot 10. The longitudinal mark 11 can be a notch 3 or a flat edge 4. Figure 2 and Figure 3 An exemplary notch 3 and flat edge 4 are shown in FIG. Figure 2 A U-shaped notch is shown in picture A and a V-shaped notch in picture B, and a flat edge is shown in picture C. The notch will have a width 31 and a depth 32, and the flat edge 4 will have a width 41. Figure 2The X-axis and the Z-axis are shown. Thus, in this example, the X-axis corresponds to the width 31 of the notch 3 and the width 41 of the flat edge 4, and the Z-axis corresponds to the depth 32 of the notch 3. The Y-axis (not shown) is the longitudinal axis of the single crystal ingot 10. Figure 3 A single crystal ingot 10 with a single notch 3 is shown in picture A, a single crystal ingot 10 with two notches 3 is shown in picture B, a single crystal ingot 10 with a single flat edge 4 is shown in picture C, a single crystal ingot 10 with two flat edges 4 is shown in picture D, and a single crystal ingot 10 with two notches 3 and two flat edges 4 is shown in picture E. When the single crystal ingot 10 has two or more longitudinal marks 11, the angle between the longitudinal marks 11 will be determined by the end user of the single crystal ingot 10, but will generally follow a standard, such as the SEMI standard for silicon single crystal ingots 10.

[0089] A single crystal ingot 10 is analyzed in the ingot scanner system 2 of the present invention. Figure 4 The ingot scanner system 2 is shown in Figure 5 A single crystal ingot 10 is shown mounted on a rotating device 22 (e.g., a rotating table) of an ingot scanner system 2. Figure 4 and Figure 5 In FIG. 2 , the rotation of the rotating table 22 is indicated by the arrow below the rotating table 22. Figure 4 and Figure 5 2 is shown with a lifting device 28. The lifting device 28 can raise and / or lower the optical line scanner 24, 25 and / or move the optical line scanner 24, 25 in the lateral direction; possible movements are indicated by arrows.

[0090] The ingot scanner system 2 has a rotating device 22 having a rotation axis 23, and the single crystal ingot 10 is rotated about the rotation axis 23. The lateral distance between the rotation axis 23 and the longitudinal center axis 12 of the single crystal ingot 10 corresponds to the offset value. The offset value should be as low as possible, and optimally the offset value is 0, i.e. the longitudinal center axis 12 of the single crystal ingot 10 is aligned with the rotation axis 23 during the analysis of the single crystal ingot 10.

[0091] Surface characteristic parameters are obtained by analyzing the longitudinal mark 11. Specifically, the distance from the measuring point 21 located at the measuring distance from the rotation axis 23 to the surface 14 of the single crystal ingot 10 is recorded. The ingot scanner system 2 has a light source 24 at an emission point 241, which can emit light toward the rotation axis 23. The ingot scanner system 20 has a light detector 25 at the measuring point 21, which is located at the measuring distance from the rotation axis 23. The light detector 25 records the light reflected and / or scattered from the surface 14 of the single crystal ingot 10 on the rotating device. The light source 24 and the light detector 25 can be combined in one unit, which is called a "scanner". The scanner can be a laser scanner in particular, for example using a wavelength of 405nm or 658nm. The light source 24 and the light detector 25 can be collectively referred to as "optical line analyzers" 24, 25.

[0092] The light recorded by the light detector 25 can be stored in the data storage unit 26 as a data array, which contains the angular positions of the single crystal ingot 10 whose surface 14 has been analyzed and the light recorded by the light detector 25 at the corresponding angular positions. The ingot scanner system 2 also has a data processing unit 27 for processing the data in the data array. Figure 4 and Figure 5 , possible data flows of the ingot scanner system 2 are shown as dashed lines. Thus, the data processing unit 27 can control either or both of the light source 24 and the light detector 25, and the light source 24 and / or the light detector 25 can send data to either or both of the data processing unit 27 and the data storage unit 26. The data processing unit 27 and the data storage unit 26 can also transmit and receive data to each other. The data storage unit 26 and the data processing unit 27 can be collectively referred to as "measurement calculation means" 26, 27.

[0093] The ingot scanner system 20 is preferably configured to carry out the method of the first aspect of the invention, and it may also be used for the method of the second aspect of the invention.

[0094] Therefore, the present invention provides an ingot scanner system 20, such as a light detection system, for obtaining information of a notch 3 and / or a flat edge 4 on a single crystal ingot 10. In an embodiment, the ingot scanner system 20 includes an optical line analyzer 24, 25, a rotating stage 22, and a measurement calculation device 26, 27. The optical line analyzer 24, 25 includes a light emitter 24, a focusing lens and a light detector 25, and is capable of measuring one or more points, such as 1280 data points, simultaneously.

[0095] In the method for obtaining data, a single crystal ingot 10 is positioned on a rotating table 22 within the measuring range of an optical line analyzer 24, 25. The single crystal ingot 10 is rotated while the optical line analyzer 24, 25 records the profile. The rotation of the single crystal ingot 10 can also be stopped for high-resolution analysis of a specific section, such as an angle corresponding to the position of a longitudinal mark 11. The data storage unit 26 stores the angular position and the corresponding distance obtained at that point; the distance can be a matrix, a line or a single point. In the context of the present invention, the matrix, the line or the single point can be collectively referred to as a "profile". The single crystal ingot 10 is rotated by a certain angle, such as 360°, to perform a full scan. For each angle, a value is retrieved from the profile obtained using the optical line analyzer 24, 25. The value can be the absolute distance from the measuring point 21 of the optical line analyzer 24, 25 to the single crystal ingot 10. These values ​​can be graphically visualized using, for example, a Cartesian coordinate system or a polar coordinate system, depending on the angle retrieved from the rotating device 22. The measurement calculation device 26, 72 is now used to fit the background shape and find the offset value of the rotation center 23 compared to the longitudinal center axis 12 (e.g., the geometric center) of the single crystal ingot 10. If the offset value is less than a given threshold, such as 5 mm or less, such as less than 1 mm or less than 0.5 mm, the analysis continues. The operator can be guided to improve the centering of the single crystal ingot 10 to reduce the offset value and repeat the measurement. For further analysis, the background is subtracted from the original data to provide a data set with most values ​​around zero, for example in the range of -0.1 mm to 0.1 mm. Individual points that do not meet this criterion can be regarded as outliers and removed or ignored from the data set. Groups of points below zero are interpreted as notches 3 and / or flat edges 4 depending on the size of the point group. The angular position of the center of the notch 3 and / or the center of the flat edge 4 is found from the data with the background removed.

[0096] In a subsequent step, the notches 3 and / or flat edges 4 in the surface 14 of the single crystal ingot 10 are analyzed at a higher resolution. The preferred method for analyzing the notch 3 is to rotate the single crystal ingot 10 to the position of the notch 3 found in the previous step. A line scan is now obtained using an optical line analyzer 24, 25 to obtain a high-resolution profile (for example, a profile consisting of 1280 data points spanning a 10 mm line segment). These data are analyzed using measurement calculation devices 26, 27 to retrieve characteristics of the shape of the notch 3, such as depth 32, width 31, radius of curvature and roundness. One, two or more notches 3 can be analyzed in sequence using the method of the present invention. The width of the oriented flat edge 4 can be found from the angular scan with the background subtracted, for example by thresholding the data, fitting a second-order polynomial and finding the intersection at z=0.

[0097] The ingot scanner system includes optical line analyzers 24, 25 (including light emitters 24 and light detectors 25) and a rotating stage 22. The optical line analyzers 24, 25 can be placed on one or more translation stages (not shown). The movement direction of these stages can be a direction parallel to the longitudinal center axis 12 of the single crystal ingot 10, or a direction perpendicular to the surface of the single crystal ingot 10. In a preferred embodiment, one or more of these stages are motorized to achieve automatic movement of the optical line analyzers 24, 25. Measurement and calculation devices 26, 27 are connected to the optical line analyzers 24, 25 and the rotating stage 22 for simultaneous acquisition of data.

[0098] The characteristics of the notch 3 and flat edge 4 on the single crystal ingot 10 are an important part of quality control. The single crystal ingot 10 is generally geometrically rotationally invariant, but the crystal structure has a specific orientation, which may affect the manufacture and performance of the device made from it. In order to identify the specific crystal orientation, an X-ray goniometer can be used. Equipment is available on the market that can measure the crystal orientation and make the flat edge 4 and / or notch 3 at the found position without manual manipulation.

[0099] The single crystal ingot 10 is positioned on a turntable 22. The longitudinal center axis 12 of the cylindrical single crystal ingot 10 should overlap the rotation axis 23 of the turntable 22. The distance between these two axes is called the "offset value". Ideally, the offset value should be exactly zero. However, under practical conditions, small offsets such as less than 2 mm, less than 1 mm, less than 0.5 mm, less than 0.3 mm, less than 0.2 mm, and less than 0.1 mm are acceptable. For example, the offset value can be estimated by fitting a sine fit to the data using a least squares regression algorithm. For a sinusoidal form

[0100]

[0101] The fitting parameter A (amplitude of the sine) is equal to the offset between the two axes. The measurement and calculation means 26, 27 can automatically check whether A is less than a predefined threshold value, which is defined as the maximum allowed offset value. If A is greater than the threshold value, the measurement and calculation means 26, 27 can stop the execution of the program and tell the operator to improve the centering of the single crystal ingot 10. In a preferred embodiment, the centering is automatically performed using a motorized stage (not shown).

[0102] In addition to background fitting, several data processing steps may be included. These steps include, but are not limited to, outlier removal, denoising, smoothing, filtering, thresholding, and calibration adjustments.

[0103] The optical line scanner 24, 25 comprises a light source 24, an optical element and a detector 25. For monochromatic light sources, these are also called laser scanners. The light source 24 can be a monochromatic light source, such as a laser with a wavelength of 405nm or 658nm. The recorded data can consist of a single point, an average value of a point or a line scan. A line scan is a plurality of individual points obtained near each other, such as having a distance of 1μm, 5μm, 10μm, 20μm, 50μm, 100μm, 200μm, 500μm or 1000μm. A plurality of individual points refers to at least 3 points, at least 5 points, at least 10 points, at least 50 points. In a preferred embodiment, 1280 data points are obtained in the line scan. The optical element can include a lens, a grating and a mirror. The detector device 25 can be a highly sensitive sensor matrix. For example, an optical line scanner 24, 25 based on laser line triangulation is used, which is suitable for two-dimensional profile detection on many different surfaces (including the surface of the silicon single crystal ingot 10). Optical line scanners based on the laser triangulation principle are commercially available, such as the ScanControl series from MicroEpsilon, Germany. If the sample (e.g. single crystal ingot 10) and the optical line scanners 24, 25 are moved relative to each other, for example if the single crystal ingot 10 is rotated, it is possible to obtain 3D measurements.

[0104] Data from the optical line scanners 24, 25 are transmitted to the measurement computing devices 26, 27 using a cable or wireless interface. The cable interface may include Ethernet or RS422 protocols. The wireless interface may utilize the Wi-Fi protocol.

[0105] The single crystal ingot 10 is positioned on the rotating device 22. An encoder (not shown) is used to record the actual position of the rotating device 22, thereby recording the actual position of the single crystal ingot 10. The single crystal ingot 10 is rotated incrementally by a predefined angle. As an example, the predefined angle is 360°. The encoder is used to measure the position of the rotating stage 22. In a preferred embodiment, the rotating stage 22 is rotated to a certain angle based on a priori knowledge of the position of the longitudinal mark. In a preferred embodiment, the rotation is stopped when a predefined number of surface marks is reached. In a preferred embodiment, the rotating stage 22 is set to rotate continuously while the optical line scanners 24 and 25 acquire data. This requires that the data acquisition from the optical line scanners 24 and 25 is fast relative to the angular rotation. For example, for a 6-inch crystal, a rotation speed of 6° / s and a profile acquisition frequency greater than 10Hz are acceptable. For a 6-inch crystal, other rotation speeds, such as 1° / s, 2° / s, 4° / s, 10° / s or 20° / s, 50° / s, are found to be acceptable. For larger single crystal ingots 10, lower rotation speeds are preferred, while for smaller single crystal ingots 10, faster rotation speeds are preferred. Higher profile acquisition frequencies, such as 20 Hz, 50 Hz, 100 Hz, 300 Hz, 1 kHz, 2 kHz or 5 kHz, are preferred. The control and reading of the position of the rotating stage 22 are controlled by the measurement and calculation devices 26, 27. In a preferred embodiment, a high-resolution stage with a resolution of less than 1 arc second, less than 2 arc seconds, less than 5 arc seconds, less than 10 arc seconds, less than 20 arc seconds, less than 50 arc seconds is used. However, the rotating device 22 should be able to handle the load of the single crystal ingot 10, typically weighing up to 20 kg, up to 30 kg, up to 40 kg, or up to 50 kg. High-resolution rotating stages with high load capacity are already commercially available, such as Thorlabs, Inc.'s 360° continuous rotating stage with a stepper motor actuator model NR360S.

[0106] At a given angle, the optical line scanners 24, 25 are used to acquire one or more data points. The data are saved using measurement calculation devices 26, 27. The angular position of the rotating stage 22 is also saved. For visualization, the data acquired with the optical line scanners 24, 25 can be displayed as a function of the angular position in a Cartesian coordinate system or a polar coordinate system.

[0107] The measurement process includes a first step of centering the single crystal ingot 10 on the rotating table 22. Mechanical equipment is used to assist the operator in locating the center of the single crystal ingot 10 on the center of the rotating table 22. In a preferred embodiment, the positioning of the single crystal ingot 10 is assisted by using a plate with a hole matching the diameter of the single crystal ingot 10. For example, for a single crystal ingot 10 with a diameter of 150 mm, a plate with a 150.5 mm hole can be used. In a preferred embodiment, a mechanical centering device (not shown), such as a spring centering piece, is used to assist the alignment of the single crystal ingot 10 on the rotating table 22.

[0108] The optical line scanners 24 and 25 are positioned at the point of interest relative to the single crystal ingot 10. For example, the single crystal ingot 10 can be measured in the middle of the single crystal ingot 10. For example, the single crystal ingot 10 can be measured near both ends, such as 5 mm, for example 20 mm from each end. For example, the single crystal ingot 10 can be measured at 5 positions or 10 positions distributed along its length. The vertical placement of the optical line scanners 24 and 25 can be performed by an operator, or automatically using a lifting device 28 (such as a motorized stage). In a preferred embodiment, the encoder is attached to a vertical stage (not shown). Positioning can be performed using a positioning arm, a robotic arm, a fixed setting, or a manual translation stage. The position of the positioning device can be measured using an encoder. In a preferred embodiment, a vertical motorized linear translation stage equipped with an encoder is used. The control and reading of the position of the lifting device 28 are controlled by measurement and calculation devices 26 and 27.

[0109] The optical line scanners 24, 25 are now placed within the measurement range of the single crystal ingot 10. The horizontal linear translation stage is used to position the optical line scanners 24, 25 in a direction orthogonal to the surface of the single crystal ingot 10. The optical line scanners 24, 25 typically have a limited measurement range from the light detector 25 to the single crystal ingot 10 (i.e., the single crystal ingot 10), such as a range between 50 mm and 300 mm, for example, between 50 mm and 60 mm, or 70 mm to 120 mm, or 190 mm to 290 mm. For example, the optical line scanners 24, 25 have a measurement range of 48 mm to 58 mm, and the distance in the middle of the measurement range (53 mm in this case) should be the target of placement. However, in some cases, it is beneficial to aim at a target near one of the ends of the range to allow for a more dynamic depth in a particular direction. The horizontal placement of the optical line scanners 24, 25 can be performed by an operator, or automatically using a lifting device 28. The horizontal linear translation stage of the lifting device 28 is used to place the optical line scanners 24, 25 at a distance from the single crystal ingot 10 that is within its measurement range. The operator can perform the positioning by hand based on predefined indicators. In a preferred embodiment, the horizontal linear translation stage is motorized. In a preferred embodiment, an encoder is used to record the position of the translation stage. The control of the stage and the reading of the actual position are controlled by a measurement calculation device.

[0110] The center of the measurement line of the optical line scanner 24, 25 should be positioned at the rotation center 23. For measurements on the single crystal ingot 10, when the single crystal ingot 10 is completely located in the center of the rotating device, when the line scan is obtained, the measurement with the optical line scanner 24, 25 will show a symmetrical curve. If the optical line scanner 24, 25 is off-center, an asymmetrical curve will be seen. Figure 6 An exemplary asymmetric curve is shown in Figure A of FIG. Figure 6 A symmetric curve for the same single crystal ingot 10 is shown in Figure B. The asymmetry does not prevent the measurement result from being obtained, but the measurement uncertainty is higher when the optical line scanners 24, 25 are offset. Therefore, an offset of the optical line scanners 24, 25 that is as small as possible is beneficial. Likewise, the asymmetry does not prevent the identification of the longitudinal mark 11. This positioning is independent of the size of the single crystal ingot 10, so no adjustments are required between measurements. Ideally, no further adjustments are required when first installed and set up. In a preferred embodiment, the translation stage is mounted below the rotation stage 22 and / or the optical line scanners 24, 25 to facilitate alignment.

[0111] In a preferred embodiment, two or more detectors 25 are used in the ingot scanner system 20 to improve measurement speed and / or measurement capability. The detectors 25 may be placed on the same translation stage or on multiple separate stages.

[0112] The described fitting algorithms can all be executed on a common desktop computer, a Raspberry Pi or similar device. The typical calculation time for running the algorithm is less than 1 second. For multi-processing such as threads, data acquisition and analysis can be performed simultaneously. For example, the measurement and calculation devices 26, 27 can be a personal desktop computer, a microcomputer (such as a Raspberry Pi 3 model B+ from the Raspberry Pi Foundation), an FPGA or a similar device. In a preferred embodiment, more than one measurement and calculation device 26, 27 is used for the acquisition and / or analysis of data.

[0113] In a preferred embodiment, vertical placement of optical line scanners 24, 25 is used to measure the length of the single crystal ingot 10 by finding the edges of the single crystal ingot 10 at the top and bottom. The length of the single crystal ingot 10 can be found from the difference in readings of the top and bottom edges.

[0114] In the next step, the data set of line scans, either single data points or averages of data points, and corresponding angular positions are analyzed using a digital processor 27. In a preferred embodiment, the diameter of the single crystal ingot 10 is measured from the data set by finding the average distance from the single crystal ingot 10 to the optical line scanners 24, 25. This step requires knowledge of the distance from the optical line scanners 24, 25 to the center of rotation of the rotating stage 22.

[0115] The background fit is now subtracted from the experimental data. In a preferred embodiment, the background fit and removal algorithm is performed more than once to improve the fit parameters. In a preferred embodiment, the data is corrected for geometric distortion due to the off-centering of the single crystal ingot 10.

[0116] This new data set is used to find the location of the surface markers in the single crystal ingot 10. For example, a peak finding algorithm is used to detect the location. One or more calculations can be applied to improve the found location of the markers. The location of the surface features is saved.

[0117] The flats 4 and / or notches 3 of the single crystal ingot 10 are now identified. For example, the depth of the peak found in the previous step is used for identification. The largest longitudinal mark is marked as the main flat 4. Based on a priori knowledge, other longitudinal marks can be identified relative to the main flat 4. In a preferred embodiment, the longitudinal marks are identified without a priori knowledge of the position by using other characteristics (such as width) to distinguish between the main flat, secondary flat and notches.

[0118] The width of the oriented flat edge 4 is calculated from the data set. For example, the flat edge 4 is selected by thresholding the data, and a second order polynomial is fitted to the selected data. When the background is subtracted, the width of the flat edge 4 is not found as an intersection of the polynomial with z=0. The measurement of the width can be further improved by applying additional processing steps. These steps can include linear regression fitting near the end of the flat edge and / or shape analysis of the curve. In the case of more than one flat edge, each flat edge follows the process individually.

[0119] In the next step, the crystal is rotated to a specific position based on the position found in the previous step. For example, if the angular position of notch 3 is measured to θ 凹口 , the rotating stage 22 is moved to an angle θ 凹口 A line scan is now acquired at this location for detailed analysis of the specific mark. For large marks (such as the main flat edge 4), multiple points can be acquired. This can be, for example, the two ends of the flat edge 4.

[0120] In a preferred embodiment, the line scan obtained from the first rotation is used for the second analysis. Instead of rotating the single crystal ingot 10 to a given position, the data processing unit 27 is used to extract previously obtained data for the position closest to the specific position. This is beneficial to reduce the total time for data acquisition. However, the accuracy of the data obtained by moving to a specific position instead of using pre-acquired data will be better or equal.

[0121] In a preferred embodiment, the longitudinal marks 11 in the surface 14 are measured at multiple points by moving the vertical stage. Using multiple points, it is possible to detect changes in the length of the single crystal ingot 10. For example, the single crystal ingot 10 is measured near both ends.

[0122] In a preferred embodiment, the ingot scanner system 20 is used to characterize surface scratches, breaks or other defects in the single crystal ingot 10. The vertical line scanner is moved a short distance, such as 10μm, 20μm, 30μm, 50μm, 100μm, 200μm, 500μm, 1000μm, and a line scan is acquired. This sequence is repeated over a section of the single crystal ingot 10, extending up to the length of the single crystal ingot 10. In a preferred embodiment, the vertical stage is moving while the optical line scanners 24, 25 acquire data. For example, starting from the bottom of the single crystal ingot 10 to the upper end of the single crystal ingot 10, the notch 3 is scanned at a speed of 1mm / s in the length direction of the single crystal ingot 10. A line scan is acquired every 50μm that the vertical stage moves. Each line scan is now analyzed for defects relative to a reference profile. The flat edge 4 or a portion of the flat edge 4 (such as the edge of the flat edge) can be characterized and analyzed using a similar method.

[0123] Analysis of the notch 3 is performed by comparing the perimeter of the single crystal ingot 10 to data points that are not considered to be part of the notch (i.e., background shapes). For example, the data points including the notch 3 are filtered using thresholding and / or prior knowledge, and a circle (i.e., for a circular single crystal ingot 10) is fit to the remaining data using a least mean square algorithm. The data points representing the notch 3 are now selected for geometric analysis of the notch shape. For example, the notch data points are found by subtracting the perimeter of the single crystal ingot 10 (as described above) and thresholding the data.

[0124] The geometry of the notch 3 is found by analyzing the selected data points. For example, a circular notch 3 is fitted by circle fitting using the least mean square algorithm. Then the radius of curvature is equal to the radius of the fitted circle. The width of the notch 3 is found by finding the intersection with the perimeter fit, and the height is found according to the distance from the bottom of the notch 3 to the edge of the crystal. Other notch 3 types (such as V-shaped notches 3) can be fitted by using another fitting type (such as a second-order or higher-order polynomial). In a preferred embodiment, two or more fittings are used to extract parameters. For example, a first-order polynomial is used to find the intersection with the perimeter fit, and a second-order polynomial is used to find the bottom of the notch 3.

[0125] The "roundness" parameter is defined to describe the uniformity of the notch 3. The roundness is defined as the difference between the right and left sides of the notch 3. For a symmetrical notch 3 without any difference between the right and left sides, the roundness is zero.

[0126] Other parameters describing the geometry of the notch 3 can be defined and measured from the data. This includes but is not limited to the side wall angle of the V-shaped notch 3, wear detection of the grinding ratchet, and roughness.

[0127] In a preferred embodiment, the perimeter of the single crystal ingot 10 (ie, the background shape) and the shape of the notch 3 are found simultaneously by a fitting algorithm.

[0128] In a preferred embodiment, the ingot scanner system 20 measures the diameter of the single crystal ingot 10 based on a single line scan. For example, in the absence of surface markings, a circle is fitted to the data set, and the fitted radius of curvature corresponds to the radius of the single crystal ingot 10. Accuracy can be improved by repeating this measurement at multiple points on the single crystal ingot 10. This method is beneficial compared to diameter measurement using absolute distances to the optical line scanners 24, 25 because reference points for the optical line scanners 24, 25 are not necessary.

[0129] The parameters of the geometry of the single crystal ingot 10 found, as well as the surface characteristic parameters are saved to a data array, such as a database, a text file or the like. The experimental data and the processed data are also saved for later reference. The data can be stored on a local storage device, a network storage device or a cloud storage. In order to organize the data more easily, these data are stored in a database structure. The database refers to other measurements performed on the same single crystal ingot 10. Graphical representations of experimental data, processed data and analysis results are also saved.

[0130] In a preferred embodiment, an operator only has to position the single crystal ingot 10 and start the measurement sequence. Data acquisition and analysis are then automatically handled by the measurement computing device.

[0131] Example

[0132] Example 1

[0133] In the method according to the invention, a silicon single crystal ingot 10 having a notch 3 is analyzed. Figure 7 The acquired data are presented in , which show a high-resolution scan of a section of the surface 14 with the notches, as a Cartesian coordinate curve plot. The data were acquired by using the line scan function of the optical measurement device and therefore consist of 1280 data points. Individual outliers have been removed from the data set. Figure 7 The graph in indicates a curved surface of silicon single crystal ingot 10 and shows notch 3. Width 31 and depth 32 of notch 3 obtained for notch 3 are: width 31: 3.24 mm, depth 32: 1.44 mm, radius: 1.63 mm, and roundness: 60 μm.

[0134] Example 2

[0135] A 150 mm diameter silicon single crystal ingot 10 having two notches 3 and two flat edges 4 was prepared and analyzed in the method of the present invention using a low resolution scan with 750 data points. Figure 8 A cross section of a silicon single crystal ingot 10 being analyzed is shown in FIG, where it is overlaid on a polar coordinate graph. The graph shows the angles between orientation marks 11 calculated from the analysis. As part of the analysis, surface marks are identified as major flat edge, minor flat edge, notch 1, and notch 2.

[0136] Analysis in Fig. 91 is shown as a Cartesian coordinate graph. Picture A shows a graph obtained before removing the background of the silicon single crystal ingot 10. The data in Picture A shows that the offset value is 1.1 mm. After removing the background of the silicon single crystal ingot 10, Picture B shows that the offset value is not significant (the curve is "flat") after the repositioning of the silicon single crystal ingot 10. The angular position of the flat edge 4 and the notch 3 is found from the data. The angle between the secondary flat edge and the main flat edge 4 can be calculated based on the angular position. Analysis shows that the width of the main flat edge 4 is 56.12 mm, and the width of the secondary flat edge 4 is 27.89 mm. The resolution of this scan is not enough to determine the surface description parameters of the notch 3, for which a higher resolution scan can be used, such as a scan of more than 750 points within 360° of the single crystal ingot 10. Specifically, the notch 3 is shown at about 150° and 330°, so that the angle between the longitudinal marks can still be calculated, and this position can be used to rotate the single crystal ingot 10 for the scanner to re-analyze the notch 3 with a higher resolution.

Claims

1. A method for obtaining surface characteristic parameters of a longitudinal orientation mark (11) of a single crystal ingot (10), the method comprising the following steps: - providing a single crystal ingot (10) having a cylindrical shape, the single crystal ingot having a longitudinal central axis (12) and a radius (13) from the longitudinal central axis (12), the radius (13) defining a surface (14) of the single crystal ingot (10), the single crystal ingot (10) having a longitudinal orientation mark (11), the longitudinal orientation mark (11) being engraved on the surface (14) of the single crystal ingot (10), the longitudinal orientation mark (11) having a width (31, 41), - rotating the single crystal ingot (10) about a rotation axis (23) which is substantially parallel to the longitudinal center axis (12) and is located within an offset value relative to the longitudinal center axis (12), - recording the angular position of the single crystal ingot (10), - recording the distances at these angular positions from the measuring points (21) located at the measuring distance from the axis of rotation (23) to the surface (14) of the single-crystal ingot (10), - providing a data array containing these angular positions and the distances at the corresponding angular positions, - calculating the background shape of the single crystal ingot (10) based on the data array, - comparing these distances to the background shape to identify distances that deviate from the background shape, - record the angular position and corresponding distance of the deviation from this background shape, and - simultaneously defining the surface characteristic parameter and the width (31, 41) based on successive angular positions having a distance from the background shape and said corresponding distances.

2. The method for obtaining surface characteristic parameters according to claim 1, wherein: The single crystal ingot (10) has a substantially circular cross-section in a radial dimension.

3. A method for producing an orientation-marked single crystal ingot (10), the method comprising the following steps: - providing a single crystal ingot (10) having a cylindrical shape, the single crystal ingot having a longitudinal center axis (12) and a radius (13) from the longitudinal center axis (12), the radius (13) defining a surface (14) of the single crystal ingot (10), - determining the crystal orientation of the single crystal ingot (10), - engraving a longitudinal orientation mark (11) on the surface (14) of the single crystal ingot (10) based on the crystal orientation to provide an orientation-marked single crystal, the longitudinal orientation mark (11) having a width (31, 41), - Obtaining the surface characteristic parameters of the single crystal ingot (10) with the orientation marked in the following steps: - rotating the orientation-marked single-crystal ingot (10) about a rotation axis (23) which is substantially parallel to the longitudinal center axis (12) and is located within an offset value relative to the longitudinal center axis (12), - recording the angular position of the single crystal ingot (10) whose orientation is marked, - recording the distances at these angular positions from the measuring points (21) located at the measuring distance from the axis of rotation (23) to the surface (14) of the orientation-marked single-crystal ingot (10), - providing a data array containing these angular positions and the distances at the corresponding angular positions, - calculating the background shape of the orientation-marked single crystal ingot (10) based on the data array, - comparing these distances to the background shape to identify distances that deviate from the background shape, - record the angular position and corresponding distance of the deviation from this background shape, and - simultaneously defining the surface characteristic parameter and the width (31, 41) based on successive angular positions having a distance from the background shape and said corresponding distances, - labeling the orientation-marked single crystal ingot (10) using the surface characteristic parameter.

4. The method for producing an orientation-marked single crystal ingot (10) according to claim 3, further comprising the step of grinding the surface (14) of the single crystal ingot (10) so that the single crystal ingot (10) has a substantially circular cross-section in a radial dimension.

5. The method for obtaining surface characteristic parameters according to claim 1, or the method for producing an orientation-marked single crystal ingot (10) according to claim 3, wherein: The method further comprises the step of moving the measuring point (21) in a longitudinal direction relative to the single crystal ingot (10).

6. The method for obtaining surface characteristic parameters according to claim 1, or the method for producing an orientation-marked single crystal ingot (10) according to claim 3, wherein: The offset value is 5 mm or less.

7. The method for obtaining surface property parameters according to claim 1, or the method for producing an orientation-marked single crystal ingot (10) according to claim 3, further comprising determining the offset value.

8. The method for obtaining surface property parameters according to claim 1, or the method for producing an orientation-marked single crystal ingot (10) according to claim 3, further comprising the step of repositioning the single crystal ingot (10) to minimize the offset value.

9. The method for obtaining surface characteristic parameters according to claim 1, or the method for producing an orientation-marked single crystal ingot (10) according to claim 3, wherein: The longitudinal orientation mark is a notch (30).

10. The method for obtaining surface characteristic parameters according to claim 1, or the method for producing an orientation-marked single crystal ingot (10) according to claim 3, wherein: The single crystal ingot (10) includes two or more orientation marks (11).

11. The method for obtaining surface characteristic parameters according to claim 1, or the method for producing an orientation-marked single crystal ingot (10) according to claim 3, wherein: Light is emitted toward the axis of rotation (23), and the distance is measured based on light reflected and / or scattered from a surface (14) of the single crystal ingot (10).

12. The method for obtaining surface characteristic parameters according to claim 1, or the method for producing an orientation-marked single crystal ingot (10) according to claim 3, wherein: The background shape is calculated from distances recorded for angular positions at angular intervals in the range of 0.06° to 36° within a 360° rotation of the single crystal ingot (10).

13. The method for obtaining surface characteristic parameters according to claim 1, or the method for producing a single crystal ingot (10) with an orientation marked according to claim 3, further comprises the step of re-analyzing the continuous angular positions of the surface characteristic parameters with a higher resolution after identifying these continuous angular positions.

14. The method for obtaining surface characteristic parameters according to claim 1, or the method for producing an orientation-marked single crystal ingot (10) according to claim 3, wherein: The single crystal ingot (10) is a silicon single crystal ingot (10).

15. The method for producing an orientation-marked single crystal ingot (10) according to claim 3, further comprising the step of cutting wafers from the single crystal ingot (10).

16. An ingot scanner system (20), comprising: - a rotating device (22) for rotating the single-crystal ingot (10), the rotating device (22) having a rotation axis (23), a light source (24) for emitting light towards the axis of rotation (23), the light source (24) being located at a measuring distance from the axis of rotation (23), - a light detector (25) for recording light reflected and / or scattered from the surface (14) of the single crystal ingot (10) on the rotating device, a data storage unit (26) for storing a data array containing the angular positions of the single crystal ingot (10) and the light recorded by the light detector (25) at these angular positions, and - a data processing unit (27) configured to calculate the distance from the measurement point (21) to the surface (14) of the single crystal ingot (10) based on the data array, the data processing unit (27) further configured to calculate the background shape of the single crystal ingot (10) based on the calculated distance, and to identify the distance that deviates from the background shape, Wherein, the ingot scanner system (20) is configured to obtain surface feature parameters according to the method according to any one of claims 1 or 3.

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