Method and device for correcting alignment deviation of wafer bonding pad and probe array

Abstract

The invention discloses a method and a device for correcting alignment deviation of a wafer bonding pad and a probe array, and relates to the field of wafer testing and optical detection. The method and the device are used for solving the problems of test accuracy reduction, pad damage and subsequent packaging bonding failure caused by wafer rotation deviation in a wafer probe card test. The method comprises the following steps: constructing a second reflectivity distribution function when rotation deviation exists based on Manhattan geometric characteristics of a wafer, performing two-dimensional Fourier transform on the second reflectivity distribution function to obtain a mapping relation between spatial domain rotation deviation and frequency domain spectrum characteristics, obtaining a spectrum image according to imaging data of a to-be-detected area of the to-be-detected wafer, and obtaining an image of the to-be-detected area of the to-be-detected wafer. Determining a frequency domain straight line angle based on Hough transform and the frequency spectrum image; according to the mapping relation and the frequency domain straight line angle, obtaining a to-be-measured rotation deviation angle, and if the to-be-measured rotation deviation angle is larger than an angle threshold value, controlling the high-precision rotation displacement table to drive the to-be-measured wafer to rotate reversely.

Description

Technical Field

[0001] This invention relates to the fields of wafer testing and optical inspection, and more specifically to a method and apparatus for correcting alignment deviations between wafer pads and probe arrays. Background Technology

[0002] As the semiconductor industry rapidly develops towards high integration, high performance, and miniaturization, wafer manufacturing and advanced packaging place extremely high demands on precision and quality control. As a core component of wafer testing, probe card electrical testing uses hundreds to thousands of micron-sized probes on the probe card to contact the pads on the wafer surface. This enables full-function electrical screening of chips before wafer dicing, eliminating defective chips and reducing subsequent packaging costs. It is a key means to improve overall yield.

[0003] However, with the advancement of advanced manufacturing processes, the number of pads on wafers has increased dramatically while their area has continued to shrink. Coupled with changes in testing conditions, issues such as probe offset are prone to occur during wafer testing, becoming a major bottleneck affecting testing stability and accuracy. Probe offset manifests as the probe's actual contact point deviating from the geometric center of the pad, or even exceeding the edge of the aluminum layer opening. This can cause damage to the pad window passivation layer or exposure of the sidewalls, and in severe cases, lead to subsequent bonding failures or reliability issues. The core cause of probe offset is wafer rotational deviation, which results in alignment misalignment between the probe and the wafer. This prevents the probe from accurately landing in the effective contact area of ​​the pad, ultimately causing the probe mark to deviate from the pad center or even exceed the pad window range. Therefore, achieving high-precision, rapid detection and correction of rotational alignment deviations between the wafer pads and the probe array, eliminating the risk of probe offset at its source, is crucial for improving wafer testing yield, stability, and overall production efficiency. Summary of the Invention

[0004] This invention provides a method and apparatus for correcting alignment deviations between wafer pads and probe arrays. It addresses the technical problem that in wafer probe card testing, rotational deviations of the wafer cause alignment deviations between probes and pads, probe marks deviating from the center of the pads or even exceeding the pad opening range, leading to decreased testing accuracy, pad damage, subsequent packaging bonding failures, and reliability risks.

[0005] This invention provides a method for correcting alignment deviations between wafer pads and probe arrays, comprising:

[0006] Based on the Manhattan geometry of the wafer, a wafer surface reflectance distribution model is constructed. The reflectance distribution model includes a first reflectance distribution function without rotational deviation and a second reflectance distribution function with rotational deviation. The second reflectance distribution function is determined based on the first reflectance distribution function combined with the rotational deviation angle.

[0007] A two-dimensional Fourier transform is performed on the second reflectivity distribution function to obtain the mapping relationship between the spatial rotation deviation and the frequency domain spectral characteristics. The mapping relationship indicates that the rotation deviation angle of the wafer is mapped to a cross-shaped frequency domain spectrum.

[0008] A preprocessed spectral image is obtained from the imaging data of the test area of ​​the wafer under test. The frequency domain straight line angle is determined based on the Hough transform and the spectral image. The rotational deviation angle to be tested is obtained based on the mapping relationship and the frequency domain straight line angle, and the rotational deviation angle to be tested is equal to the frequency domain straight line angle.

[0009] The measured rotational deviation angle is compared with a set angle threshold. If the measured rotational deviation angle is greater than the angle threshold, the high-precision rotary displacement stage is controlled to drive the wafer under test to rotate in the opposite direction. The angle of the reverse rotation is equal to the measured rotational deviation angle.

[0010] This invention provides an apparatus for correcting alignment deviations between wafer pads and probe arrays, comprising:

[0011] A construction unit is used to construct a wafer surface reflectance distribution model based on the Manhattan geometry features of the wafer. The reflectance distribution model includes a first reflectance distribution function without rotational deviation and a second reflectance distribution function with rotational deviation. The second reflectance distribution function is determined based on the first reflectance distribution function combined with the rotational deviation angle.

[0012] The mapping unit is used to perform a two-dimensional Fourier transform on the second reflectivity distribution function to obtain the mapping relationship between the spatial rotation deviation and the frequency domain spectral characteristics. The mapping relationship indicates that the rotation deviation angle of the wafer is mapped to a cross-shaped frequency domain spectrum.

[0013] The unit is used to obtain a preprocessed spectral image based on the imaging data of the area to be tested of the wafer under test, determine the frequency domain straight line angle based on the Hough transform and the spectral image, and obtain the rotational deviation angle to be tested based on the mapping relationship and the frequency domain straight line angle, wherein the rotational deviation angle to be tested is equal to the frequency domain straight line angle.

[0014] The calibration unit is used to compare the measured rotational deviation angle with a set angle threshold. If the measured rotational deviation angle is greater than the angle threshold, the high-precision rotary displacement stage is controlled to drive the wafer under test to rotate in the opposite direction. The angle of the reverse rotation is equal to the measured rotational deviation angle.

[0015] This invention provides a computer device, which includes a memory and a processor. The memory stores a computer program, and when the computer program is executed by the processor, the processor performs any of the above-described methods for correcting alignment deviations between wafer pads and probe arrays.

[0016] This invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform any of the above-described methods for correcting alignment deviations between wafer pads and probe arrays.

[0017] This invention provides a method and apparatus for correcting alignment deviations between wafer pads and probe arrays. The method includes: constructing a wafer surface reflectivity distribution model based on the Manhattan geometry of the wafer; the reflectivity distribution model includes a first reflectivity distribution function without rotational deviation and a second reflectivity distribution function with rotational deviation, the second reflectivity distribution function being determined based on the first reflectivity distribution function combined with the rotational deviation angle; performing a two-dimensional Fourier transform on the second reflectivity distribution function to obtain a mapping relationship between spatial rotational deviation and frequency domain spectral features, the mapping relationship indicating that the wafer rotational deviation angle is mapped to a frequency domain cross-shaped spectrum; obtaining a preprocessed spectral image based on imaging data of the test area of ​​the wafer under test, and determining a frequency domain straight-line angle based on the Hough transform and the spectral image; obtaining the test rotational deviation angle based on the mapping relationship and the frequency domain straight-line angle, and the test rotational deviation angle being equal to the frequency domain straight-line angle; comparing the test rotational deviation angle with a set angle threshold; if the test rotational deviation angle is greater than the angle threshold, controlling a high-precision rotary displacement stage to rotate the wafer under test in the opposite direction, the angle of the reverse rotation being equal to the test rotational deviation angle. This method constructs a reflectivity distribution model based on the Manhattan geometry of the wafer. Through spatial-frequency domain mapping, it transforms minute spatial rotational deviations into quantifiable rotational features of a cross-shaped spectrum in the frequency domain. Combined with Hough transform, it performs high-precision straight-line detection of the spectral arms, achieving high-precision detection of the wafer's rotational deviation angle. Simultaneously, it employs a reflective off-axis digital holographic optical system for in-situ non-contact imaging, avoiding physical damage to the wafer pads caused by contact detection and eliminating secondary alignment deviations caused by wafer relocation, ensuring correction accuracy from the source of detection. Furthermore, through two-dimensional Fourier transform, a one-to-one correspondence between the spatial rotational deviation angle and the frequency domain cross-shaped spectrum rotation angle is derived, and the two orthogonal spectral arms of the frequency domain cross-shaped spectrum correspond to the wafer's rotational deviation angle. The rotational deviation angle is associated with a fixed angle, transforming the spatial rotational deviation, which was originally difficult to detect directly, into a frequency domain spectral feature that can be intuitively identified and accurately quantified. This provides clear mathematical theoretical support for deviation detection, resulting in more accurate detection results and no subjective errors compared to traditional visual comparison methods. Furthermore, the frequency domain linear angle obtained by Hough transform detection can be directly used as the rotational deviation angle of the wafer under test, eliminating the need to back-project the detection parameters back to the original image and removing intermediate conversion steps. In this method, the high-precision rotary displacement stage can directly drive the wafer under test to rotate in the opposite direction based on the detected deviation angle, achieving a direct mapping between the measured rotational deviation angle and the correction angle. This significantly simplifies the detection and correction process and improves the efficiency of alignment and correction. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic flowchart of a method for correcting alignment deviations between wafer pads and probe arrays, provided by an embodiment of the present invention.

[0020] Figure 2A This is a schematic diagram of the wafer array layout when there is no wafer rotation deviation, provided in an embodiment of the present invention;

[0021] Figure 2B This is a schematic diagram illustrating the alignment relationship between the probe card and the pad of the die to be tested when there is no rotational deviation in the wafer, as provided in an embodiment of the present invention.

[0022] Figure 3 A schematic diagram of the spectral distribution of a hologram of a wafer without rotational deviation, provided in an embodiment of the present invention;

[0023] Figure 4A This is a schematic diagram of the wafer array layout when the wafer has rotational deviation, provided in an embodiment of the present invention;

[0024] Figure 4B This is a schematic diagram illustrating the alignment relationship between the probe card and the pad of the die to be tested when the wafer has a rotational deviation, provided in an embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the spectral distribution of a hologram when a wafer has rotational deviation, provided in an embodiment of the present invention.

[0026] Figure 6 This is a schematic diagram of a device for correcting alignment deviations between wafer pads and probe arrays, provided as an embodiment of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Figure 1 This is a schematic flowchart of a method for correcting alignment deviations between wafer pads and probe arrays according to an embodiment of the present invention. The following is in conjunction with... Figure 1This invention provides a method for correcting alignment deviations between wafer pads and probe arrays, as detailed in the embodiments of the present invention. Figure 1 As shown, the method specifically includes the following steps:

[0029] Step 101: Based on the Manhattan geometry of the wafer, construct a wafer surface reflectance distribution model. The reflectance distribution model includes a first reflectance distribution function without rotational deviation and a second reflectance distribution function with rotational deviation. The second reflectance distribution function is determined based on the first reflectance distribution function combined with the rotational deviation angle.

[0030] Step 102: Perform a two-dimensional Fourier transform on the second reflectivity distribution function to obtain the mapping relationship between the spatial rotation deviation and the frequency domain spectral characteristics. The mapping relationship indicates that the rotation deviation angle of the wafer is mapped to a cross-shaped frequency domain spectrum.

[0031] Step 103: Obtain a preprocessed spectral image based on the imaging data of the area to be tested of the wafer to be tested; determine the frequency domain straight line angle based on the Hough transform and the spectral image; obtain the rotational deviation angle to be tested based on the mapping relationship and the frequency domain straight line angle, and the rotational deviation angle to be tested is equal to the frequency domain straight line angle.

[0032] Step 104: Compare the measured rotational deviation angle with a set angle threshold. If the measured rotational deviation angle is greater than the angle threshold, control the high-precision rotary displacement stage to drive the wafer under test to rotate in the opposite direction. The angle of the reverse rotation is equal to the measured rotational deviation angle.

[0033] In this embodiment of the invention, alignment deviation specifically refers to the rotational alignment deviation between the wafer pads and the probe array caused by the relative rotation of the wafer. Rotational deviation is the sole core factor causing alignment deviation, and the two are causally related. Specifically, the alignment deviation between the wafer pads and the probe array is mainly caused by the wafer's rotational deviation, which is the direct cause of the alignment deviation. The rotational deviation angle is a key quantitative indicator of the alignment deviation. This embodiment of the invention achieves the correction of the alignment deviation between the wafer pads and the probe array by detecting and correcting the rotational deviation.

[0034] In step 101, the rotational deviation in the wafer spatial domain is correlated with the spectral characteristics in the frequency domain through mathematical modeling.

[0035] Specifically, in this embodiment of the invention, the functional patterns of the wafer (pads, metal interconnects, gates, etc.) strictly follow Manhattan geometry, and the pattern edges and periodic structures are distributed only in horizontal and vertical orthogonal directions. Therefore, when there is a rotational deviation of the wafer relative to the optical system, the first reflectivity distribution function of the wafer surface is as follows:

[0036] (1)

[0037] in, This represents the first reflectivity distribution function of the wafer surface when there is no rotational deviation. Represents the horizontal coordinate in a two-dimensional spatial coordinate system. Represents the vertical coordinates in a two-dimensional spatial coordinate system. This represents the one-dimensional intensity distribution function along the horizontal direction after the vertical projection integral of all horizontally oriented fine structures on the wafer. This represents the one-dimensional intensity distribution function along the vertical direction after the horizontal projection integral of all vertical fine structures on the wafer.

[0038] The aforementioned horizontal fine structures on the wafer can refer to Manhattan geometric features such as horizontally arranged pads and circuits. Similarly, the aforementioned vertical fine structures on the wafer can refer to Manhattan geometric features such as vertically arranged pads and circuits.

[0039] The Manhattan geometry mentioned in this embodiment of the invention refers to the geometric layout feature where the edges and periodic structures of functional graphics such as wafer surface pads, metal interconnects, and gates are distributed only along horizontal and vertical orthogonal directions, without any oblique structures.

[0040] Furthermore, when the wafer rotates relative to the optical system coordinate system, assuming the rotation deviation angle is... Then, the second reflectivity distribution function of the wafer surface is as follows:

[0041] (2)

[0042] in, This represents the second reflectivity distribution function of the wafer surface when there is rotational deviation. This indicates the rotational deviation angle of the wafer relative to the optical inspection system or probe array. The cosine value representing the rotational deviation angle. The sine value represents the rotational deviation angle. The wafer rotation deviation angle is indicated as When the spatial two-dimensional coordinates of the horizontally oriented fine structure are rotated, the corresponding one-dimensional intensity distribution function reflects the reflectivity characteristics of the horizontal structure after rotation. The wafer rotation deviation angle is indicated as When the spatial two-dimensional coordinates of the vertically oriented fine structure are rotated, the corresponding one-dimensional intensity distribution function reflects the reflectivity characteristics of the vertical structure after rotation.

[0043] It should be noted that, in this embodiment of the invention, the first reflectivity distribution function and the second reflectivity distribution function constitute a wafer surface reflectivity distribution model; wherein, the first reflectivity distribution function represents the horizontal and vertical fine structure of the wafer and is the baseline model; the second reflectivity distribution function is determined based on the first reflectivity distribution function combined with the rotational deviation angle, and represents the horizontal and vertical fine structure of the wafer and the rotational deviation angle of the wafer, and is the deviation model.

[0044] In this embodiment of the invention, formula (2) directly reflects the rotational deviation of the physical space of the wafer, which will change the spatial distribution law of its surface reflectivity and is a prerequisite for subsequent frequency domain mapping.

[0045] In step 102, a two-dimensional Fourier transform is performed on the second reflectivity distribution function of the wafer to map the spatial rotation deviation to the frequency domain. The transformation formula is as follows:

[0046] (3)

[0047] Furthermore, the second reflectivity distribution function Substituting into formula (3) and simplifying using the Jacobian determinant, we obtain the core formula for the frequency domain spectrum distribution:

[0048] (4)

[0049] in, This represents the frequency domain spectral characteristics corresponding to wafer rotation deviation. This represents the second reflectivity distribution function of the wafer surface when there is rotational deviation. This indicates the rotational deviation angle of the wafer relative to the optical inspection system or probe array. The cosine value representing the rotational deviation angle. The sine value represents the rotational deviation angle. This represents the one-dimensional intensity distribution function corresponding to the spatial two-dimensional coordinates of the horizontally oriented fine structure after a rotational transformation when the wafer rotation deviation angle is θ. This represents the one-dimensional intensity distribution function corresponding to the spatial two-dimensional coordinates of the vertically oriented fine structure after a rotational transformation when the wafer rotation deviation angle is θ. The kernel function represents the two-dimensional Fourier transform. Represents the imaginary unit. Represents pi (π). Indicates the spatial frequency in the horizontal direction. Indicates the spatial frequency in the vertical direction; Describes the intensity distribution function of the horizontal fine structure in the spatial domain. The frequency domain corresponding function after one-dimensional Fourier transform, Represents the vertical fine structure intensity distribution function in the spatial domain The frequency domain corresponding function after one-dimensional Fourier transform, Dirac function, This indicates that the frequency domain energy of the defined horizontal structure is concentrated only in a straight line. Above, corresponding to the first spectral arm of the cross-shaped spectrum, its frequency vector direction is... , The frequency domain energy of a fixed vertical structure is concentrated only along a straight line. Above, corresponding to the second spectral arm of the cross-shaped spectrum, its frequency vector direction is... .

[0050] Furthermore, when there is a rotational deviation angle θ in the wafer spatial domain, the second reflectivity distribution function with rotational deviation on its surface will change synchronously with the rotational deviation. After performing a two-dimensional Fourier transform on this second reflectivity distribution function, a cross-shaped spectrum will be formed in the frequency domain (composed of two mutually orthogonal first and second spectral arms, corresponding to the frequency domain energy distribution of the wafer's horizontal and vertical fine structures, respectively). This cross-shaped spectrum will rotate synchronously with the wafer spatial domain rotational deviation angle θ by the same angle; that is, the frequency vector direction corresponding to the first spectral arm is consistent with the spatial domain rotational deviation angle θ, and the frequency vector direction corresponding to the second spectral arm is θ+90°, perfectly reflecting the wafer spatial domain rotational deviation. This causes the frequency domain cross-shaped spectrum to rotate synchronously by the same angle. The mapping law. According to formula (4), the wafer spatial rotation deviation angle can be determined. This will cause the cross-shaped features of its two-dimensional Fourier spectrum in the frequency domain to rotate synchronously by the same angle. Furthermore, the high-frequency energy is still strictly limited to two orthogonal straight lines passing through the origin.

[0051] like Figure 2A The diagram shown is a schematic of the wafer array layout when there is no rotational deviation. It is a partially enlarged schematic of a semiconductor wafer, showing the regular arrangement of the grain array on the wafer surface. The diagram divides the wafer into multiple independent grain units in a grid pattern. Each grain is the basic unit for subsequent probe testing. The area highlighted by the dashed line is... Figure 2B The magnified area shown is as follows: Figure 2B The alignment relationship between the probe card and the pads of the die to be tested is shown. When there is no rotational deviation in wafer 1, there is no alignment deviation between the pad 4 and the probes 3 included in the probe card, and the tips of the probes 3 all fall on the center of the pad 4. The figure clearly shows the precise alignment relationship between the probe tips and the pads: each probe tip falls vertically on the center of the corresponding pad, without offset or exceeding the pad range. This is the ideal alignment state that the correction method provided in this embodiment of the invention ultimately aims to achieve, providing a benchmark reference for subsequent comparison scenarios with rotational deviations. Figure 3 To and Figure 2BThe frequency domain distribution characteristics of the original off-axis hologram image when the wafer has no rotational deviation are shown in the figure. The figure shows the standard shape of the cross-shaped spectrum in the frequency domain when the wafer has no rotational deviation. The two orthogonal spectral arms of the cross-shaped spectrum are strictly horizontal and vertically distributed, and the spectral energy is highly concentrated on the orthogonal axis without any rotational offset. This intuitively reflects the basic spatial-frequency mapping relationship from no rotational deviation in the wafer spatial domain to no rotation in the frequency domain cross-shaped spectrum, and serves as the alignment reference at the frequency domain level.

[0052] like Figure 4A The diagram shown illustrates the wafer array layout under rotational deviation. It is a magnified view of a portion of a semiconductor wafer, demonstrating the orderly arrangement of the grain array on the wafer surface when rotational deviation exists. The diagram divides the wafer into multiple independent grain units in a grid pattern, with each grain serving as the basic unit for subsequent probe testing. The area highlighted by the dashed line represents... Figure 4B The magnified area shown is as follows: Figure 4B The diagram shows the precise alignment between the probe tip and the pad, and the hardware configuration of the probe card body, probe array, and the pad of the die under test, in line with the ideal alignment. Figure 1 However, due to the rotational deviation angle θ of the wafer, the alignment relationship between the probe tip and the pad is significantly offset. For example, taking pad number 1 as a reference, as the pad number increases, the deviation of the probe tip from the geometric center of the pad gradually increases, and some probe tips have approached or are about to exceed the edge of the pad opening. Figure 5 for Figure 4B Frequency domain distribution characteristics of the original off-axis hologram image with rotational deviation. Figure 5 This demonstrates the rotational shape of the cross-shaped frequency spectrum when the wafer has a rotational deviation angle θ. In this case, the cross-shaped frequency spectrum rotates synchronously with the wafer's spatial deviation by the same angle θ, and both orthogonal spectral arms deviate from their normal positions. Figure 2B In the horizontal and vertical reference directions, the spectral energy is still concentrated on the rotated orthogonal straight line.

[0053] In this embodiment of the invention, the frequency domain straight line angle is determined as the wafer rotation deviation angle. This can transform the tiny rotation deviation angle, which is difficult to detect directly in the wafer spatial domain, into an observable and quantifiable rotation feature of the cross-shaped spectrum in the frequency domain, thereby achieving a quantitative correspondence between spatial domain rotation deviation and frequency domain spectrum rotation.

[0054] In step 103, a reflective off-axis digital holographic optical system is used to perform in-situ, non-contact, and non-destructive imaging of a certain area to be tested in the wafer under test, and to directly obtain an off-axis hologram of the area to be tested.

[0055] It should be noted that when acquiring an off-axis hologram of a certain region of the wafer under test, it is not necessary to remove the wafer from the test platform, which can avoid secondary alignment deviation and ensure the accuracy of subsequent correction. Furthermore, the spectrum of the wafer under test has the characteristic of complete separation of the original image, conjugate image, and zero-order term, which lays the foundation for accurate extraction of the effective spectrum in the future.

[0056] Furthermore, a two-dimensional Fourier transform is performed on the acquired off-axis hologram to transform the off-axis hologram from the spatial domain (spatial coordinates). Convert to the frequency domain (frequency coordinates) This yields the complete spectral distribution containing the original image, conjugate image, and zero-order term.

[0057] By utilizing the spectral separation characteristics of off-axis holograms, the original image spectrum can be accurately extracted from the complete spectral distribution through window filtering. This method can completely eliminate conjugate images and zero-order term interference, retaining only the effective frequency domain information.

[0058] In this embodiment of the invention, the original image spectrum consists of a series of scattered points representing spatial frequencies. Due to the complex structure of the wafer, a diffuse low-frequency background is generated in the frequency domain, causing the edges of the spectral arms to be blurred and accompanied by noise. To solve the above problems, the extracted original image spectrum is preprocessed by normalization and binarization to obtain a spectral image. This can eliminate spectral intensity differences, highlight the linear features of the spectral arms, eliminate interference for subsequent Hough transform line detection, and improve detection accuracy. It should be noted that in practical applications, normalization can map the intensity values ​​of the spectrum to a uniform range, avoiding the influence of excessively high / low local intensity on the effective detection of scattered points; binarization can convert the spectrum into a black and white binary image, setting the effective scattered points of the spectral arms as the foreground and the low-frequency background and noise as the background, greatly improving the robustness of subsequent line detection.

[0059] Furthermore, the classic global voting line detection algorithm (Hough transform) is selected to perform line detection on the preprocessed spectral image. Specifically:

[0060] The preprocessed spectrum image is mapped from the image space to the Hough line detection space. The Hough line detection space represents each line with two parameters: the normal distance from the line to the origin and the angle between the line normal and the horizontal direction. Further, within a preset angle range, the non-zero frequency points included in the spectrum image are traversed with a set step size. Each valid spectrum point corresponds to a set of line parameters in the Hough line detection space. These parameters are counted and accumulated to form a voting accumulation array. The peak point with the highest number of votes is found in the voting accumulation array and determined as the global maximum peak point. The global maximum peak point corresponds to the most obvious and dominant line direction in the spectrum image, which is the true direction of the spectrum arm. The angle between the direction of the spectrum arm and the vertical direction is the frequency domain line angle.

[0061] Furthermore, based on the frequency domain straight line angle and the mapping relationship determined in step 102, the frequency domain straight line angle detected by the Hough transform can be directly determined as the rotational deviation angle of the wafer under test. This method does not require back-projecting the result back to the spectrum image, which simplifies the calculation process and ensures detection accuracy.

[0062] It should be noted that the rotational deviation angle mentioned in step 101 refers to the theoretical rotational angle of the wafer relative to the optical detection system or probe array, used for model building, spatial-frequency domain mapping, and mathematical derivation. The rotational deviation angle to be measured obtained in this step refers to the rotational angle actually detected from the spectral image through Hough transform, used for comparison with a threshold and to drive the correction mechanism to perform its actions.

[0063] In this embodiment, because the rotational deviation angle of the wafer under test is small in actual testing, when the normal of the straight line in the defined frequency domain is... When the angle between the axes is reduced, the detection range can be narrowed, which can improve detection efficiency and accuracy. Furthermore, setting the step size to a high-precision small step size can ensure that all effective spectral points in the spectral image are traversed, resulting in high angle detection accuracy and matching the stringent accuracy requirements of the wafer test.

[0064] For example, the Hough line detection space is presented in polar coordinate parameterization. ,in This represents the normal distance from the origin to the straight line in the frequency domain. The normal to a straight line in the frequency domain is represented by the line and the line. The included angle of the axis.

[0065] Furthermore, with a step size of 0.01°, within the angular range Within a relatively small range, parameter space voting is performed on all non-zero frequency points in the spectrum to construct... Voting accumulator array; each non-zero frequency point corresponds to a series of [various parameters] in the Hough line detection space. The voting process involves counting and accumulating these parameters. In the voting accumulation array, search for the global maximum peak point and find the global maximum peak point with the highest number of votes. The peak point with the highest number of votes is determined as the global maximum peak point, and the global maximum peak point corresponds to the most prominent straight line direction of the spectral arm in the spectral image.

[0066] Through geometric derivation, the angle between the direction of the spectral arm and the vertical direction (i.e., the measured rotational deviation angle of the wafer under test) is derived. ) and the global maximum peak point Equal, that is:

[0067] (5)

[0068] in, This represents the normal to the line in the frequency domain within the Hough line detection space. The included angle of the axis, The angle parameter corresponding to the global maximum peak point obtained from the Böhf transform detection. This indicates the rotational deviation angle to be measured.

[0069] In the example, there is no need to backproject the detection parameters onto the spectral image; they can be directly obtained from... Obtain the rotational deviation angle This simplifies the operation process; the Hough transform itself supports detection of arbitrary angle ranges, so this method can be adapted to the detection of rotational deviations in all possible ranges of wafers.

[0070] Based on the mapping relationship between the spatial rotation deviation and the frequency spectrum characteristics of the wafer determined in step 102, a spectrum angle constraint mechanism is introduced. The rotation deviation angle to be measured determined in step 103 is compared with the ideal value (0°) to determine whether correction is needed. The rotation position alignment before needle insertion is completed by a high-precision rotary displacement stage, which is the final execution step to achieve deviation correction.

[0071] In step 104, the measured rotational deviation angle is compared with a set angle threshold. If the measured rotational deviation angle is greater than the angle threshold, it is determined that the wafer under test has a rotational deviation, and an angle correction command needs to be sent to the high-precision rotary displacement stage. In this embodiment of the invention, the rotation angle in the angle correction command is equal to the measured rotational deviation angle, but in the opposite direction. After receiving the angle correction command, the high-precision rotary displacement stage drives the wafer under test to rotate in the opposite direction. The angle of the reverse rotation is equal to the measured rotational deviation angle, thereby accurately canceling the measured rotational deviation angle and restoring the wafer under test to a perfectly aligned state with the optical system and probe array.

[0072] Furthermore, if the rotational deviation angle to be tested is less than the angle threshold, it can be determined that the wafer under test has no rotational deviation, and the system directly releases the probe permission and enters the probe card electrical testing stage.

[0073] It should be noted that, in the implementation of this invention, after calibration by a high-precision rotary displacement stage, the frequency domain cross-shaped spectrum of the wafer under test will be restored to a standard horizontal / vertical distribution, and the probe tip can accurately fall on the geometric center of the pad, fundamentally eliminating the problems of probe misalignment and pad damage caused by tiny rotational deviations of the wafer.

[0074] For example, if the angle threshold is set to 0.1°, the rotational deviation angle to be measured will be... Hard constraint comparison with the ideal value of 0 degrees:

[0075] like Once the system determines that the wafer under test has no rotational deviation, it directly releases the probe insertion permission and enters the probe card electrical testing phase.

[0076] like If a rotational deviation is detected in the wafer under test, an angle correction command is immediately sent to the high-precision rotary displacement stage. The required rotation angle is equal to the rotational deviation angle under test, but in the opposite direction, i.e., in the opposite direction. After receiving the angle correction command, the high-precision rotary displacement stage drives the wafer under test to rotate in the opposite direction. Angle, precisely offsetting the original rotational deviation angle to be measured. This restores the wafer under test to a properly aligned position with the optical system and probe array.

[0077] In summary, this invention provides a method and apparatus for correcting alignment deviations between wafer pads and probe arrays. The method constructs a reflectivity distribution model using the Manhattan geometry of the wafer, transforms minute spatial rotational deviations into quantifiable rotational features of a cross-shaped spectrum in the frequency domain through spatial-frequency domain mapping, and combines this with Hough transform for high-precision straight-line detection of the spectral arms, achieving sub-micron-level high-precision angle detection of the wafer's rotational deviation angle. Simultaneously, a reflective off-axis digital holographic optical system is used for in-situ non-contact imaging, avoiding physical damage to the wafer pads caused by contact detection and eliminating secondary alignment deviations caused by wafer relocation, ensuring correction accuracy from the source of detection. Furthermore, a one-to-one correspondence between the spatial rotational deviation angle and the frequency domain cross-shaped spectrum rotation angle is derived through two-dimensional Fourier transform. Furthermore, the two orthogonal spectral arms of the cross-shaped frequency domain spectrum are fixedly correlated with the wafer rotation deviation angle. This transforms the spatial rotation deviation, which was originally difficult to detect directly, into a frequency domain spectral feature that can be intuitively identified and accurately quantified. This provides clear mathematical theoretical support for deviation detection, resulting in more accurate detection results and no subjective errors compared to traditional visual comparison methods. Moreover, the frequency domain straight-line angle obtained by Hough transform detection can be directly used as the rotation deviation angle of the wafer under test, eliminating the need to back-project the detection parameters back to the original image and removing intermediate conversion steps. In this method, the high-precision rotating displacement stage can directly drive the wafer under test to rotate in the opposite direction according to the detected deviation angle, achieving a direct mapping between the measured rotation deviation angle and the correction angle. This significantly simplifies the detection and correction process and improves the efficiency of alignment and correction.

[0078] Based on the same inventive concept, this invention provides an apparatus for correcting alignment deviations between wafer pads and probe arrays. Since the principle by which this apparatus solves the technical problem is similar to that of a method for correcting alignment deviations between wafer pads and probe arrays, the implementation of this apparatus can refer to the implementation of the method, and repeated details will not be described again.

[0079] like Figure 6As shown, the device includes a construction unit 601, a mapping unit 602, a obtaining unit 603, and a correction unit 604.

[0080] Construction unit 601 is used to construct a wafer surface reflectance distribution model based on the Manhattan geometry features of the wafer. The reflectance distribution model includes a first reflectance distribution function without rotational deviation and a second reflectance distribution function with rotational deviation. The second reflectance distribution function is determined based on the first reflectance distribution function combined with the rotational deviation angle.

[0081] The mapping unit 602 is used to perform a two-dimensional Fourier transform on the second reflectivity distribution function to obtain the mapping relationship between the spatial rotation deviation and the frequency domain spectral characteristics. The mapping relationship indicates that the rotation deviation angle of the wafer is mapped to a cross-shaped frequency domain spectrum.

[0082] Unit 603 is used to obtain a preprocessed spectral image based on the imaging data of the area to be tested of the wafer under test, determine the frequency domain straight line angle based on the Hough transform and the spectral image, and obtain the rotational deviation angle to be tested based on the mapping relationship and the frequency domain straight line angle, wherein the rotational deviation angle to be tested is equal to the frequency domain straight line angle.

[0083] The correction unit 604 is used to compare the rotational deviation angle to be measured with a set angle threshold. If the rotational deviation angle to be measured is greater than the angle threshold, the high-precision rotary displacement stage is controlled to drive the wafer to be measured to rotate in the opposite direction. The angle of the reverse rotation is equal to the rotational deviation angle to be measured.

[0084] It should be understood that the units included in the above-described device for correcting alignment deviations between wafer pads and probe arrays are merely a logical division based on the functions implemented by the device. In practical applications, the units can be superimposed or separated. Furthermore, the functions implemented by the device for correcting alignment deviations between wafer pads and probe arrays provided in this embodiment correspond one-to-one with the method for correcting alignment deviations between wafer pads and probe arrays provided in the above-described embodiment. The more detailed processing flow implemented by this device has been described in detail in the first embodiment of the method described above, and will not be described in detail here.

[0085] Another embodiment of the present invention provides a computer device, the computer device including: a processor and a scene database; the scene database is used to store computer program code, the computer program code including computer instructions; when the processor executes the computer instructions, the electronic device performs each step of the method for correcting alignment deviation between wafer pads and probe arrays as shown in the above method embodiment.

[0086] Another embodiment of the present invention provides a computer-readable storage medium storing computer instructions that, when executed on a computer device, cause the computer device to perform the steps of the method for correcting alignment deviations between wafer pads and probe arrays as described in the above-described method embodiment.

[0087] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for correcting alignment deviations between wafer pads and probe arrays, characterized in that, include: Based on the Manhattan geometry of the wafer, a wafer surface reflectance distribution model is constructed. The reflectance distribution model includes a first reflectance distribution function without rotational deviation and a second reflectance distribution function with rotational deviation. The second reflectance distribution function is determined based on the first reflectance distribution function combined with the rotational deviation angle. A two-dimensional Fourier transform is performed on the second reflectivity distribution function to obtain the mapping relationship between the spatial rotation deviation and the frequency domain spectral characteristics. The mapping relationship indicates that the rotation deviation angle of the wafer is mapped to a cross-shaped frequency domain spectrum. The preprocessed spectral image is obtained from the imaging data of the test area of ​​the wafer under test, and the frequency domain straight line angle is determined based on the Hough transform and the spectral image. Based on the mapping relationship and the frequency domain straight line angle, the rotational deviation angle to be measured is obtained, and the rotational deviation angle to be measured is equal to the frequency domain straight line angle. The measured rotational deviation angle is compared with a set angle threshold. If the measured rotational deviation angle is greater than the angle threshold, the high-precision rotary displacement stage is controlled to drive the wafer under test to rotate in the opposite direction. The angle of the reverse rotation is equal to the measured rotational deviation angle.

2. The method as described in claim 1, characterized in that, The first reflectance distribution function is shown below: The second reflectance distribution function is shown below: in, This represents the first reflectivity distribution function of the wafer surface when there is no rotational deviation. Represents the horizontal coordinate in a two-dimensional spatial coordinate system. Represents the vertical coordinates in a two-dimensional spatial coordinate system. This represents the one-dimensional intensity distribution function along the horizontal direction after the vertical projection integral of all horizontal fine structures on the wafer. This represents the one-dimensional intensity distribution function along the vertical direction after projecting and integrating all vertically oriented fine structures on the wafer in the horizontal direction. This represents the second reflectivity distribution function of the wafer surface when there is rotational deviation. This indicates the rotational deviation angle of the wafer relative to the optical inspection system or probe array. The cosine value representing the rotational deviation angle. The sine value represents the rotational deviation angle. This represents the one-dimensional intensity distribution function corresponding to the spatial two-dimensional coordinates of the horizontally oriented fine structure after a rotational transformation when the wafer rotational deviation angle is θ. This represents the one-dimensional intensity distribution function corresponding to the spatial two-dimensional coordinates of the vertically oriented fine structure after a rotational transformation when the wafer rotation deviation angle is θ.

3. The method as described in claim 1, characterized in that, The two-dimensional Fourier transform is shown below: The formula for frequency domain spectrum distribution is shown below: in, This represents the frequency domain spectral characteristics corresponding to wafer rotation deviation. This represents the second reflectivity distribution function of the wafer surface when there is rotational deviation. This indicates the rotational deviation angle of the wafer relative to the optical inspection system or probe array. The cosine value representing the rotational deviation angle. The sine value represents the rotational deviation angle. This represents the one-dimensional intensity distribution function corresponding to the spatial two-dimensional coordinates of the horizontally oriented fine structure after a rotational transformation when the wafer rotational deviation angle is θ. This represents the one-dimensional intensity distribution function corresponding to the spatial two-dimensional coordinates of the vertically oriented fine structure after a rotational transformation when the wafer rotation deviation angle is θ. The kernel function represents the two-dimensional Fourier transform. Represents the imaginary unit. Represents pi (π). Indicates the spatial frequency in the horizontal direction. Indicates the spatial frequency in the vertical direction; Describes the intensity distribution function of the horizontal fine structure in the spatial domain. The frequency domain corresponding function after one-dimensional Fourier transform, Represents the vertical fine structure intensity distribution function in the spatial domain The frequency domain corresponding function after one-dimensional Fourier transform, Dirac function, This indicates that the frequency domain energy of the defined horizontal structure is concentrated only along a straight line. Above, corresponding to the first spectral arm of the cross-shaped spectrum, its frequency vector direction is... , The frequency domain energy of a fixed vertical structure is concentrated only along a straight line. Above, corresponding to the second spectral arm of the cross-shaped spectrum, its frequency vector direction is... .

4. The method as described in claim 1, characterized in that, The frequency domain cross-shaped spectrum consists of two mutually orthogonal spectral arms, and the frequency vector directions corresponding to the two spectral arms are respectively... and The rotation angle of the frequency domain cross-shaped spectrum is the same as the rotation deviation angle of the wafer.

5. The method as described in claim 1, characterized in that, The process of obtaining the preprocessed spectral image based on the imaging data of the area under test of the wafer specifically includes: An off-axis digital holographic optical system is used to acquire an off-axis hologram of the test area of ​​the wafer under test. A two-dimensional Fourier transform is performed on the off-axis hologram to convert it from the spatial domain to the frequency domain, resulting in a complete spectral distribution containing the original image, conjugate image, and zero-order term. The complete spectral distribution is obtained by window filtering to obtain the original image spectrum. The original image spectrum is then normalized and binarized to obtain a preprocessed spectral image. The spectral image shows the distribution shape of the cross-shaped spectrum to be measured and the rotation deviation angle to be measured.

6. The method as described in claim 1, characterized in that, The determination of the frequency domain line angle based on the Hough transform and the spectral image specifically includes: The spectral image is mapped from the image space to the Hough line detection space. The Hough line detection space represents each line with two parameters: the normal distance from the line to the origin and the angle between the line normal and the horizontal direction. Within a preset angle range, parameter space voting is performed on the non-zero frequency points included in the spectrum image with a set step size to obtain a voting accumulation array; The peak point with the highest number of votes determined from the voting accumulation array is identified as the global maximum peak point. The global maximum peak point is used to represent the direction of the spectral arm of the spectrum image. The frequency domain straight line angle is obtained based on the angle between the direction of the spectral arm and the vertical direction.

7. A device for correcting alignment deviations between wafer pads and probe arrays, characterized in that, include: A construction unit is used to construct a wafer surface reflectance distribution model based on the Manhattan geometry features of the wafer. The reflectance distribution model includes a first reflectance distribution function without rotational deviation and a second reflectance distribution function with rotational deviation. The second reflectance distribution function is determined based on the first reflectance distribution function combined with the rotational deviation angle. The mapping unit is used to perform a two-dimensional Fourier transform on the second reflectivity distribution function to obtain the mapping relationship between the spatial rotation deviation and the frequency domain spectral characteristics. The mapping relationship indicates that the rotation deviation angle of the wafer is mapped to a cross-shaped frequency domain spectrum. The unit is used to obtain a preprocessed spectral image based on the imaging data of the area to be tested of the wafer under test, and to determine the frequency domain straight line angle based on the Hough transform and the spectral image. Based on the mapping relationship and the frequency domain straight line angle, the rotational deviation angle to be measured is obtained, and the rotational deviation angle to be measured is equal to the frequency domain straight line angle. The calibration unit is used to compare the measured rotational deviation angle with a set angle threshold. If the measured rotational deviation angle is greater than the angle threshold, the high-precision rotary displacement stage is controlled to drive the wafer under test to rotate in the opposite direction. The angle of the reverse rotation is equal to the measured rotational deviation angle.

8. A computer device, characterized in that, The computer device includes a memory and a processor. The memory stores a computer program, which, when executed by the processor, causes the processor to perform a method for correcting alignment deviations between wafer pads and probe arrays as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The device contains a computer program that, when executed by a processor, causes the processor to perform a method for correcting alignment deviations between wafer pads and probe arrays as described in any one of claims 1-6.

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