Warping degree and bending degree detection system of wafer and detection method thereof

Abstract

The invention relates to the technical field of wafer warpage and curvature detection, in particular to a wafer warpage and curvature detection system and a detection method thereof, and the detection system comprises a laser, a beam expander, a diaphragm, a beam splitter prism, a collimating mirror, a reference mirror, an imaging lens, a CCD and a computer, the light beam is reflected by the sample to be measured and then returns along the same path to interfere with the reference light so as to generate three groups of interference fringes, and the three groups of interference fringes pass through the imaging lens, the CCD and the computer and then are calculated so as to obtain the warping degree and the bending degree of the sample to be measured. According to the invention, the multi-surface interference fringe pattern of the double-sided polished sample to be measured is acquired by using the wavelength-adjustable Hunfizeau interferometer, and the warping degree and the bending degree of the sample to be measured are obtained through calculation, so that the problem of mapping errors caused by measuring the surface shape by using two interferometers or overturning the measured surface shape is solved; therefore, the detection steps of the warping degree and the bending degree of the wafer can be simplified, and the precision of the detection result is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wafer warpage and curvature detection, and in particular to a wafer warpage and curvature detection system and a detection method thereof. Background Art

[0002] Wafer warpage refers to the quantification of the height difference at a specific position of the wafer, that is, the difference between the maximum (most positive) and minimum (most negative) deviations of the median surface in FQA and the least squares reference plane of the middle surface. This value reflects the unevenness of the wafer surface. Wafer curvature (usually described as Bow) refers to the deviation between the middle surface at the center of the wafer and the least squares reference plane of the middle surface. This deviation value reflects the degree of curvature of the wafer surface. The warpage and curvature of the wafer are very important parameters in semiconductor manufacturing. With the continuous development of semiconductor technology, the integration and performance requirements of chips are also constantly improving. As one of the basic materials for chip manufacturing, the warpage and deformation of the wafer directly affect the manufacturing quality and performance stability of the chip. For this reason, we need to provide a wafer warpage and curvature detection system and its detection method.

[0003] At present, the method for detecting the warpage and bow of wafers is interferometry measurement (such as Figure 1 As shown in the figure, the light of the laser is coupled into two beam splitters through optical fiber. The light beam is reflected by the beam splitters and then directed to the collimator. After the light beam collimated by the collimator reaches the reference mirror, part of the light beam returns to form the reference light, and the other part of the light beam passes through the reference mirror to reach the surface of the device under test. After the light beam is reflected by the device under test, it returns to the original path and interferes with the reference beam. The device under test is placed between the two reference mirrors. In this way, the front and back surfaces of the device under test are measured at the same time, and the warpage and curvature of the device under test are calculated based on the measured front and back surface shapes. However, when using two Fizeau interferometers to measure the front and back surface shapes of wafer samples, it is difficult to accurately align the two reference mirrors in space. Therefore, mapping errors will be introduced when solving the surface shape, affecting the accuracy of the measurement results of the warpage and curvature, and the measurement process is relatively cumbersome and the device is complicated. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in order to solve the technical problem that the existing wafer warpage and curvature detection process is cumbersome and affects the accuracy of the detection results, the present invention provides a wafer warpage and curvature detection system and a detection method thereof. By improving the wafer warpage and curvature detection method, the wafer warpage and curvature detection steps can be simplified and the accuracy of the detection results can be improved.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a wafer warpage and curvature detection system, comprising: a laser, a beam expander, an aperture, a beam splitter, a collimator, a reference mirror, an imaging lens, a CCD and a computer. The coherent light emitted by the laser enters the beam splitter after being expanded by the beam expander, and the light beam is reflected by the beam splitter and then emitted to the collimator. After the light beam collimated by the collimator reaches the reference mirror, a part of the light beam returns to form a reference light, and the other part of the light beam passes through the reference mirror to reach the sample to be tested. After being reflected by the sample to be tested, the light beam returns to the original path and interferes with the reference light to generate three groups of interference fringes, and is calculated after passing through the imaging lens, the CCD and the computer to obtain the warpage and curvature of the sample to be tested.

[0006] Therefore, a wavelength-tunable harmonic Fizeau interferometer is used to collect the multi-surface interference fringe pattern of the double-sided polished sample to be tested, and the warpage and curvature of the sample to be tested are obtained by calculation, thereby solving the mapping error problem caused by measuring the surface shape with two interferometers or flipping the measured surface shape, thereby simplifying the detection steps of the wafer warpage and curvature and improving the accuracy of the detection results.

[0007] Furthermore, the three groups of interference fringes include: interference fringes between the reference mirror and the front surface of the sample to be tested, interference fringes between the reference mirror and the rear surface of the sample to be tested, and interference fringes between the front surface of the sample to be tested and the rear surface of the sample to be tested.

[0008] A detection method of a wafer warpage and bow detection system comprises the following steps: S1. Fix the sample to be tested vertically in the sample holder; S2. Adjust the optical path of the detection system and collect three sets of interference fringes to obtain the light intensity of the three sets of interference fringes after K phase shifts. ; S3, using cavity length Calculate the phase shift value , and then use the least squares fitting iterative algorithm to make the first least squares error value Minimum, solve the phase of the front surface shape , the phase of the rear surface and the phase of the thickness surface shape , and continue to iterate until the shift value deviation , and then restore the multi-surface shape based on the relationship between the phase and the wavefront height; S4, calculating the warpage of the sample to be tested using the multi-surface shape restored in S3; S5. Calculate the curvature of the sample to be tested using the multi-surface shape restored in S3.

[0009] Therefore, the front and back surface shapes of the wafer are obtained through the least squares fitting iterative algorithm, and the reference plane and the median plane are constructed according to the front and back surface shapes to realize the measurement of the warpage and curvature of the sample to be tested.

[0010] Furthermore, in S2, the light intensity of the three sets of interference fringes after K phase shifts is The expression is: ; in: Indicates the background light intensity. represents the light emphasis system of the interference fringes between the reference mirror and the front surface of the sample to be measured, represents the light emphasis system of the interference fringes between the reference mirror and the rear surface of the sample to be measured, represents the light emphasis system of the interference fringes between the front surface of the sample to be tested and the back surface of the sample to be tested, represents the phase of the front surface of the sample to be tested, represents the phase of the front surface of the sample to be tested, represents the phase of the thickness surface of the sample to be measured, represents the phase shift value of the front surface after the Kth phase shift, represents the phase shift value of the rear surface after the Kth phase shift, Represents the phase shift value of the thickness surface after the Kth phase shift.

[0011] Furthermore, S3 comprises the following steps: S3-1. Using cavity length Calculate the phase shift value ; S3-2, using the least squares fitting iterative algorithm to make the first least squares error value Minimum, solve the phase of the front surface shape , the phase of the rear surface and the phase of the thickness surface shape ; S3-3, solve S3-2 , as well as As a known quantity, the phase shift value As the unknown quantity, the least squares fitting iterative algorithm is used again to make the first least squares error value Minimum, solve the phase shift value ; S3-4, repeat S3-2 and S3-3 until the phase shift value deviation , stop the iteration, at this time, the calculated phase value is the required phase value; S3-5, recovering the multi-surface shape according to the relationship between the phase and the wavefront height; in: is the phase shift value obtained in the Nth iteration, is the phase shift value obtained after the N-1th iteration.

[0012] Furthermore, in S3-1, the phase shift value The calculation formula is: ; in: represents the wavelength tuning amount, represents the wavelength of the laser.

[0013] Furthermore, in S3-2, , , , , , , As unknown quantities, 7 images were collected; Use the least squares fitting iterative algorithm to make the first least squares error value Minimum, solve the phase of the front and rear surface shapes , , ; The first least squares error The calculation formula is: ; in: represents the interference fringes actually collected, is the number of interference fringe patterns collected.

[0014] Furthermore, in S3-5, the relationship between phase and wavefront height is The expression is: ; in: Indicates the phase, represents the wavelength of the laser, Indicates the wave height.

[0015] Further, in S4, the median plane and the reference plane are constructed according to the restored front and rear surface shapes of the sample to be tested, and the reference plane is determined according to the least square method, so that the second least square error value Minimum, solve , as well as , thereby calculating the warpage of the sample to be tested, the calculation formula of the warpage of the sample to be tested is: ; Among them: the mid-plane refers to: the plane formed by points with the same distance from the front and back surfaces of the wafer. The expression of the mid-plane is: ; represents the shape of the front surface of the sample to be tested, represents the shape of the rear surface of the sample to be tested, represents the phase of the front surface of the sample to be tested, Indicates the phase of the rear surface of the sample to be tested; The reference surface refers to the plane fitted to the median plane using the least squares method. The expression of the reference surface is: ; in: , as well as are all constants; The second least squares error The calculation formula is: .

[0016] Further, in S5, the three-point method is used to construct the reference plane. For the three points constituting the reference plane, three points that divide the wafer into three equal parts are selected on the circumference of the circle excluding the 6 mm edge of the median plane, and a three-point reference plane is established. Three equations are solved simultaneously: ; Solve for the reference surface , is the height of three points on the circumference of the wafer; Finally, the curvature of the sample to be tested is solved , the curvature of the sample to be tested The calculation formula is: ; in: , as well as are constants, represents the position of the center point of the median plane, Indicates the location of the center point of the reference plane.

[0017] Compared with the prior art, the present invention has the following beneficial effects: A wavelength-tunable harmonic Fizeau interferometer is used to collect multi-surface interference fringe patterns of double-sided polished samples to be tested. The front and back surface shapes of the wafer are obtained through a least squares fitting iterative algorithm. A reference plane and a median plane are constructed based on the front and back surface shapes to achieve measurement of the warpage and curvature of the sample to be tested. This solves the mapping error problem caused by measuring the surface shape with two interferometers or flipping the measured surface shape, thereby simplifying the detection steps of wafer warpage and curvature and improving the accuracy of the detection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0019] Figure 1 A schematic diagram of the structure of a wafer warpage and bow detection system in the prior art; Figure 2 It is a structural schematic diagram of a wafer warpage and curvature detection system of the present invention; Figure 3 The present invention is a flow chart of a detection method of a wafer warpage and bow detection system.

[0020] In the figure: 1. Laser; 2. Beam expander; 3. Aperture; 4. Beam splitter; 5. Collimator; 6. Reference mirror; 7. Sample to be tested; 8. Imaging lens; 9. CCD; 10. Computer. DETAILED DESCRIPTION

[0021] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] like Figure 2 As shown, it is the optimal embodiment of the present invention. The wafer warpage and curvature detection system and detection method of the present embodiment include: a laser 1, a beam expander 2, an aperture 3, a beam splitter 4, a collimator 5, a reference mirror 6, an imaging lens 8, a CCD9 and a computer 10. The coherent light emitted by the laser 1 enters the beam splitter 4 after being expanded by the beam expander 2. The light beam is reflected by the beam splitter 4 and then emitted to the collimator 5. After the light beam is collimated by the collimator 5 and reaches the reference mirror 6, a part of the light beam returns to the original path to form the reference light, and the other part of the light beam passes through the reference mirror 6 to reach the sample 7 to be tested. After being reflected by the sample 7 to be tested, the light beam returns to the original path to interfere with the reference light to generate three groups of interference fringes, and is calculated after passing through the imaging lens 8, CCD9 and the computer 10 to obtain the warpage and curvature of the sample 7 to be tested. Therefore, a wavelength-adjustable harmonic Fizeau interferometer is used to collect the multi-surface interference fringe pattern of the double-sided polished sample 7 to be tested, and the warpage and curvature of the sample 7 to be tested are obtained by calculation, thereby solving the mapping error problem caused by measuring the surface shape with two interferometers or flipping the measured surface shape, thereby simplifying the detection steps of the wafer warpage and curvature and improving the accuracy of the detection results.

[0025] Specifically, this solution can simultaneously detect the warpage and curvature of the sample 7 to be tested.

[0026] In this embodiment, the three groups of interference fringes include: interference fringes between the reference mirror 6 and the front surface of the sample 7 to be tested, interference fringes between the reference mirror 6 and the rear surface of the sample 7 to be tested, and interference fringes between the front surface of the sample 7 to be tested and the rear surface of the sample 7 to be tested.

[0027] A detection method of a wafer warpage and bow detection system comprises the following steps: S1, fix the sample 7 to be tested vertically in the sample holder; S2. Adjust the optical path of the detection system and collect three sets of interference fringes to obtain the light intensity of the three sets of interference fringes after K phase shifts. ; S3, using cavity length Calculate the phase shift value , and then use the least squares fitting iterative algorithm to make the first least squares error value Minimum, solve the phase of the front surface shape , the phase of the rear surface and the phase of the thickness surface shape , and continue to iterate until the shift value deviation , and then restore the multi-surface shape based on the relationship between the phase and the wavefront height; S4, using the multi-surface shape restored in S3 to calculate the warpage of the sample 7 to be tested; S5. Calculate the curvature of the sample 7 to be tested using the multi-surface shape restored in S3. Thus, the front and rear surface shapes of the wafer are obtained through the least squares fitting iterative algorithm, and the reference plane and the median plane are constructed according to the front and rear surface shapes to achieve the measurement of the warpage and curvature of the sample 7 to be tested.

[0028] In this embodiment, in S2, the light intensity of the three groups of interference fringes after K phase shifts is The expression is: ; in: Indicates the background light intensity. represents the light emphasis system of the interference fringes between the reference mirror 6 and the front surface of the sample 7 to be measured, The light emphasis system representing the interference fringes between the reference mirror 6 and the rear surface of the sample 7 to be measured, The light emphasis system representing the interference fringes between the front surface of the sample 7 to be tested and the back surface of the sample 7 to be tested, represents the phase of the front surface of the sample 7 to be tested, represents the phase of the front surface of the sample 7 to be tested, represents the phase of the thickness surface of the sample 7 to be tested, represents the phase shift value of the front surface after the Kth phase shift, represents the phase shift value of the rear surface after the Kth phase shift, Represents the phase shift value of the thickness surface after the Kth phase shift.

[0029] In this embodiment, S3 includes the following steps: S3-1. Using cavity length Calculate the phase shift value ; S3-2, using the least squares fitting iterative algorithm to make the first least squares error value Minimum, solve the phase of the front surface shape , the phase of the rear surface and the phase of the thickness surface shape ; S3-3, solve S3-2 , as well as As a known quantity, the phase shift value As the unknown quantity, the least squares fitting iterative algorithm is used again to make the first least squares error value Minimum, solve the phase shift value ; S3-4, repeat S3-2 and S3-3 until the phase shift value deviation , stop the iteration, at this time, the calculated phase value is the required phase value; S3-5, recovering the multi-surface shape according to the relationship between the phase and the wavefront height; in: is the phase shift value obtained in the Nth iteration, is the phase shift value obtained after the N-1th iteration.

[0030] In this embodiment, in S3-1, the phase shift value The calculation formula is: ; in: represents the wavelength tuning amount, represents the wavelength of laser 1.

[0031] In this embodiment, in S3-2, , , , , , , As unknown quantities, 7 images were collected; Use the least squares fitting iterative algorithm to make the first least squares error value Minimum, solve the phase of the front and rear surface shapes , , ; The first least squares error The calculation formula is: ; in: represents the interference fringes actually collected, is the number of interference fringe patterns collected.

[0032] In this embodiment, in S3-5, the relationship between the phase and the wavefront height is The expression is: ; in: Indicates the phase, represents the wavelength of laser 1, Indicates the wave height.

[0033] Specifically, in the actual measurement process, there is a difference between the wavelength tuning error of laser 1 and the length of the interference cavity. Measurement error, so by repeating S3-2 and S3-3 to reduce the phase shift value error.

[0034] In this embodiment, in S4, the median plane and the reference plane are constructed according to the restored front and rear surface shapes of the sample 7 to be tested, and the reference plane is determined according to the least squares method so that the second least squares error value is Minimum, solve , as well as , thereby calculating the warpage of the sample 7 to be tested, the calculation formula for the warpage of the sample 7 to be tested is: ; Among them: the mid-plane refers to: the plane formed by points with the same distance from the front and back surfaces of the wafer. The expression of the mid-plane is: ; represents the front surface shape of the sample 7 to be tested, Indicates the surface shape of the rear surface of the sample 7 to be tested, represents the phase of the front surface of the sample 7 to be tested, represents the phase of the rear surface of the sample 7 to be tested; The reference surface refers to the plane fitted to the median plane using the least squares method. The expression of the reference surface is: ; in: , as well as are all constants; The second least squares error The calculation formula is: .

[0035] In this embodiment, in S5, a reference plane is constructed using a three-point method. For the three points constituting the reference plane, three points that divide the wafer into three equal parts are selected on the circumference of a circle excluding the 6 mm edge of the median plane, and a three-point reference plane is established. Three equations are solved simultaneously: ; Solve for the reference surface , is the height of three points on the circumference of the wafer; Finally, the curvature of the sample 7 to be tested is solved , bending degree of the sample to be tested 7 The calculation formula is: ; in: , as well as are constants, represents the position of the center point of the median plane, Indicates the location of the center point of the reference plane.

[0036] In summary, the present invention uses a wavelength-tunable harmonic Fizeau interferometer to collect multi-surface interference fringe patterns of a double-sided polished sample 7 to be tested, obtains the front and rear surface shapes of the wafer through a least squares fitting iterative algorithm, and constructs a reference plane and a mid-plane according to the front and rear surface shapes to achieve measurement of the warpage and curvature of the sample 7 to be tested, thereby solving the mapping error problem caused by measuring the surface shape with two interferometers or flipping the measured surface shape, thereby simplifying the detection steps of the wafer warpage and curvature and improving the accuracy of the detection results.

[0037] The above description is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A wafer warpage and curvature detection system, characterized in that: include: A laser (1), a beam expander (2), an aperture (3), a beam splitter (4), a collimator (5), a reference mirror (6), an imaging lens (8), a CCD (9) and a computer (10). Coherent light emitted by the laser (1) is expanded by the beam expander (2) and then enters the beam splitter (4). The light beam is reflected by the beam splitter (4) and then emitted to the collimator (5). After the light beam is collimated by the collimator (5) and reaches the reference mirror (6), a portion of the light beam returns along the original path to form reference light, and another portion of the light beam passes through the reference mirror (6) and reaches the sample to be tested (7). After the light beam is reflected by the sample to be tested (7), it returns along the original path to interfere with the reference light to generate three groups of interference fringes. After passing through the imaging lens (8), the CCD (9) and the computer (10), the light beam is calculated to obtain the warpage and curvature of the sample to be tested (7).

2. The wafer warpage and curvature detection system according to claim 1, characterized in that: The three sets of interference fringes include: Interference fringes between the reference mirror (6) and the front surface of the sample to be tested (7), interference fringes between the reference mirror (6) and the rear surface of the sample to be tested (7), and interference fringes between the front surface of the sample to be tested (7) and the rear surface of the sample to be tested (7).

3. A detection method for the wafer warpage and curvature detection system according to any one of claims 1-2, characterized in that: The following steps are involved: S1. Fix the sample to be tested (7) vertically in the sample holder; S2. Adjust the optical path of the detection system and collect three sets of interference fringes to obtain the light intensity of the three sets of interference fringes after K phase shifts. ; S3, using cavity length Calculate the phase shift value , and then use the least squares fitting iterative algorithm to make the first least squares error value Minimum, solve the phase of the front surface shape , the phase of the rear surface and the phase of the thickness surface shape , and continue to iterate until the shift value deviation , and then restore the multi-surface shape based on the relationship between the phase and the wavefront height; S4, using the multi-surface shape restored in S3 to calculate the warpage of the sample to be tested (7); S5. Calculate the curvature of the sample to be tested (7) using the multi-surface shape restored in S3.

4. The detection method of the wafer warpage and bow detection system according to claim 3, characterized in that: In S2, the light intensity of the three groups of interference fringes after K phase shifts The expression is: ； in: Indicates the background light intensity. a light emphasis system representing the interference fringes between the reference mirror (6) and the front surface of the sample to be measured (7), a light emphasis system representing the interference fringes between the reference mirror (6) and the rear surface of the sample (7) to be measured, a light emphasis system representing the interference fringes between the front surface of the sample to be tested (7) and the rear surface of the sample to be tested (7), represents the phase of the front surface of the sample (7) to be tested, represents the phase of the front surface of the sample (7) to be tested, represents the phase of the thickness surface of the sample (7) to be tested, represents the phase shift value of the front surface after the Kth phase shift, represents the phase shift value of the rear surface after the Kth phase shift, Represents the phase shift value of the thickness surface after the Kth phase shift.

5. The detection method of the wafer warpage and bow detection system according to claim 3, characterized in that: The S3 comprises the following steps: S3-1. Using cavity length Calculate the phase shift value ; S3-2, using the least squares fitting iterative algorithm to make the first least squares error value Minimum, solve the phase of the front surface shape , the phase of the rear surface and the phase of the thickness surface shape ; S3-3, solve S3-2 , as well as As a known quantity, the phase shift value As the unknown quantity, the least squares fitting iterative algorithm is used again to make the first least squares error value Minimum, solve the phase shift value ; S3-4, repeat S3-2 and S3-3 until the phase shift value deviation , stop the iteration, at this time, the calculated phase value is the required phase value; S3-5, recovering the multi-surface shape according to the relationship between the phase and the wavefront height; in: is the phase shift value obtained in the Nth iteration, is the phase shift value obtained after the N-1th iteration.

6. The detection method of the wafer warpage and bow detection system according to claim 5, characterized in that: In S3-1, the phase shift value The calculation formula is: ； in: represents the wavelength tuning amount, represents the wavelength of the laser (1).

7. The detection method of the wafer warpage and bow detection system according to claim 5, characterized in that: In S3-2, , , , , , , As unknown quantities, 7 images were collected; Use the least squares fitting iterative algorithm to make the first least squares error value Minimum, solve the phase of the front and rear surface shapes , , ; The first least squares error The calculation formula is: ； in: represents the interference fringes actually collected, is the number of interference fringe patterns collected.

8. The detection method of the wafer warpage and bow detection system according to claim 5, characterized in that: In S3-5, the relationship between phase and wavefront height The expression is: ； in: Indicates the phase, represents the wavelength of the laser (1), Indicates the wave height.

9. The detection method of the wafer warpage and bow detection system according to claim 1, characterized in that: In S4, the median plane and the reference plane are constructed according to the restored front and rear surface shapes of the sample to be tested (7), and the reference plane is determined according to the least square method so that the second least square error value is Minimum, solve , as well as , thereby calculating the warpage of the sample to be tested (7), the calculation formula of the warpage of the sample to be tested (7) is: ； Among them: the mid-plane refers to: the plane formed by points with the same distance from the front and back surfaces of the wafer. The expression of the mid-plane is: ； represents the shape of the front surface of the sample to be tested (7), represents the surface shape of the rear surface of the sample to be tested (7), represents the phase of the front surface of the sample (7) to be tested, Indicates the phase of the rear surface of the sample (7) to be tested; The reference surface refers to the plane fitted to the median plane using the least squares method. The expression of the reference surface is: ； in: , as well as are all constants; The second least squares error The calculation formula is: 。 10. The detection method of the wafer warpage and bow detection system according to claim 1, characterized in that: In S5, the three-point method is used to construct the reference plane. For the three points constituting the reference plane, three points that divide the wafer into three equal parts are selected on the circumference of the circle excluding the 6mm edge of the median plane to establish a three-point reference plane and solve the three equations: ； Solve for the reference surface , is the height of three points on the circumference of the wafer; Finally, the curvature of the sample to be tested (7) is solved , the curvature of the sample to be tested (7) The calculation formula is: ； in: , as well as are constants, represents the position of the center point of the median plane, Indicates the location of the center point of the reference plane.

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