A data fusion method, an eddy current measurement system, a polishing unit, and an apparatus

Abstract

The application discloses a data fusion method, an eddy current measurement system, a polishing unit and equipment. The data fusion method comprises the following steps: acquiring wafer surface metal film thickness data through a plurality of eddy current probes to obtain a plurality of profile curves; segmenting each profile curve into a plurality of segmented profile curves according to air film partitioning of a polishing head; extracting curve features of each segmented profile curve; constructing an evaluation function to convert the curve features into a similarity index; and fusing the segmented profile curves according to the similarity index to obtain a fused profile curve. The application can improve the accuracy and robustness of wafer surface metal film thickness measurement.

Description

Technical Field

[0001] This invention belongs to the field of chemical mechanical polishing technology and is used for processing semiconductor chips. Specifically, it relates to a data fusion method, an eddy current measurement system, a polishing unit, and equipment. Background Technology

[0002] In semiconductor chip manufacturing, chemical mechanical polishing (CMP) is a key technology for achieving global planarization of the wafer surface. As technology nodes continue to shrink, the requirements for wafer surface planarity are becoming increasingly stringent. Therefore, accurately and in real-time acquiring the true morphology signal of the metal film layer on the wafer surface during polishing is crucial for controlling polishing uniformity and improving chip yield.

[0003] Currently, eddy current probes are widely used in online film thickness measurement in CMP processes due to their advantages such as non-contact operation, fast response, and sensitivity to metal films. However, limited by the basic measurement principle of eddy current probes, when measuring the metal thickness on the wafer surface, they are inevitably affected by external factors such as polishing head oscillation, wafer symmetry deviation, and vibration, resulting in single-probe measurement results that cannot truly and completely reflect the global morphology of the wafer.

[0004] To improve sampling frequency and topography perception capabilities, existing technologies employ multiple eddy current probes spaced apart to collect thickness data from the wafer surface. While multi-probe solutions increase data acquisition density, traditional simple averaging or weighted fusion methods often treat the data from each probe equally. When a probe experiences local topography anomalies due to external interference, this abnormal data directly contaminates the overall fusion result, leading to the loss of local detail features in the final reconstructed topography curve. This, in turn, affects the feedback control accuracy of the polishing process.

[0005] Therefore, there is an urgent need for a data fusion method that can make full use of multi-probe data while effectively isolating local anomaly interference, so as to improve the accuracy of morphology reconstruction while ensuring the robustness of the fusion results. Summary of the Invention

[0006] In view of this, the present invention provides a data fusion method, an eddy current measurement system, a polishing unit, and an apparatus, thereby solving or at least alleviating one or more of the above-mentioned problems and other problems existing in the prior art.

[0007] A first aspect of the present invention provides a data fusion method for measuring the thickness of a metal film on a wafer surface, comprising:

[0008] Acquisition steps: Using multiple eddy current probes arranged at intervals, the thickness data of the metal film at different locations on the wafer surface is collected to obtain multiple morphology curves;

[0009] Segmentation steps: According to the air film partition of the polishing head, each morphology curve is divided into multiple segmented morphology curves that correspond one-to-one with the partition;

[0010] Characterization steps: For each partition, extract the curve features of each segment of the topography curve in that partition;

[0011] Evaluation steps: Construct an evaluation function to convert curve features into similarity indices, which are used to characterize the degree of similarity of the morphology of each segment;

[0012] Fusion steps: Based on the similarity index, the morphology curves of each segment are fused to obtain the fused morphology curve of each partition, and then spliced ​​together to obtain the fused morphology curve of the wafer surface.

[0013] Optionally, the curve feature has rotational invariance or translational invariance.

[0014] Optionally, the characterization step includes:

[0015] The topographic curves of each segment of a partition are mapped onto a two-dimensional coordinate system XOY, where the X-axis represents the distance along the wafer radial direction and the Y-axis represents the metal film thickness data, resulting in a function. , and These are the coordinates of the X-axis and Y-axis, respectively;

[0016] The curve features are represented as the cumulative energy functions of the segmented topography curves deviating from the reference point in the X and Y directions.

[0017] Optionally, representing the curve features as cumulative energy functions of the piecewise topography curve deviating from the reference point in the X and Y directions includes:

[0018] Define the work function in the X direction as follows: Let a be the order of x.

[0019] Define the work function in the Y direction Let b be the order of y.

[0020] The points corresponding to the average work done in the X direction and the average work done in the Y direction are used as the reference points.

[0021] The curve features are represented as a joint work function based on a reference point.

[0022] Optionally, the reference point is represented as ( , ),in, , , To make the function middle , To make the function middle , To make the function middle , To make the function middle .

[0023] Optionally, the joint work function based on the reference point is expressed as: .

[0024] Optionally, the fusion step includes:

[0025] The similarity index is normalized to make it resistant to scaling and distortion.

[0026] By fusing the morphology curves of each segment according to the normalized similarity index, the fused morphology curve of each partition is obtained, and the fused morphology curve of the wafer surface is obtained by splicing them together.

[0027] Optionally, the similarity index is The normalized similarity index is ,in, To make the function middle and , To make the function middle and .

[0028] Optionally, the step of fusing the morphological curves of each segment based on the normalized similarity index to obtain the fused morphological curve of each partition includes:

[0029] Establish a set of normalized similarity indices Sim= for the morphological curves of each segment of the partition. ,in, Let be the normalized similarity index of the i-th segmented topography curve, and n be the number of segmented topography curves;

[0030] Establish the minimum value set D= ,in, for The minimum absolute value of the difference between the similarity index and other normalized similarity indices in the Sim set;

[0031] The fusion coefficient of the i-th segmented topography curve is ,in, It is the minimum value in set D;

[0032] The fusion coefficient of the i-th segmented topography curve is used as the weight of the i-th segmented topography curve. The n segmented topography curves are weighted and fused to obtain a fused topography curve of a partition.

[0033] Repeat the above steps to obtain the fusion topography curve for each partition.

[0034] A second aspect of the present invention provides an eddy current measurement system for measuring the thickness of a metal film on a wafer surface during a chemical mechanical polishing process, comprising:

[0035] Multiple eddy current probes are arranged at intervals on the polishing disk to collect eddy current data on the wafer surface;

[0036] A fusion module is used to perform the data fusion method as described in the first aspect to obtain the fusion topography curve of the wafer surface;

[0037] The output module is used to output the fused topography curve or the corresponding metal film thickness data.

[0038] A third aspect of the present invention provides a polishing unit, comprising: a polishing head, a polishing disk, and an eddy current measurement system as described in the second aspect, wherein the polishing unit is used to polish a wafer according to the fusion morphology curve or the corresponding metal film thickness data output by the eddy current measurement system.

[0039] A fourth aspect of the present invention provides a polishing apparatus, comprising a polishing unit as described in the third aspect.

[0040] The present invention has the following technical effects:

[0041] It has good resistance to local anomaly interference. When a probe produces local morphological anomalies due to polishing head oscillation or wafer symmetry deviation, the similarity index of the morphology of the abnormal segment will deviate significantly from other normal segments, thus being automatically assigned a lower weight during the fusion process, effectively avoiding local anomalies from contaminating the overall fusion result.

[0042] Curve features based on reference points possess rotation or translation invariance, ensuring the uniformity of the fusion reference. This means that data errors caused by different probes, different acquisition conditions, delay errors, etc., will not affect the overall fusion result. In other words, comparable feature quantities can be extracted from each data point without precise registration, fundamentally solving the impact of spatial alignment deviation on the fusion result in multi-point measurements.

[0043] The normalized similarity index has anti-scaling and anti-distortion properties, which enhances the robustness of fusion. Even if the response sensitivity of individual probes changes due to wear or signal attenuation, the normalized similarity can still accurately reflect the geometric similarity of the curve shape, ensuring the stability and consistency of similarity evaluation.

[0044] This application can accurately reproduce the topography curve, ensuring global topography consistency while preserving local details to the greatest extent, thereby improving the feedback control accuracy of the polishing process and ensuring the processing quality of the wafer. Attached Figure Description

[0045] 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 recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0046] Figure 1 This is a schematic diagram of the structure of a polishing unit provided in an embodiment of the present invention.

[0047] Figure 2 A flowchart of a data fusion method provided in an embodiment of the present invention.

[0048] Figure 3 This is a schematic diagram of the trajectory curve of an eddy current probe sweeping across the surface of a wafer, provided in an embodiment of the present invention.

[0049] Figure 4 This is a schematic diagram of a topographic curve mapped to a two-dimensional coordinate system according to an embodiment of the present invention.

[0050] Figure 5 This is a schematic diagram illustrating the fusion effect provided in an embodiment of the present invention.

[0051] Reference numerals: Polishing unit 100; Polishing head 10; Polishing disc 20; Polishing pad 21; Dresser 30; Liquid supply unit 40; Eddy current measurement system 50; Eddy current probe 51; Fusion module 52; Output module 53. Detailed Implementation

[0052] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions in 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 should fall within the protection scope of the present invention.

[0053] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0054] In addition, in the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0055] This invention provides a data fusion method, an eddy current measurement system, a polishing unit, and an apparatus. The polishing apparatus of this invention includes a polishing unit 100, which includes an eddy current measurement system 50. The eddy current measurement system and the data fusion method are used to measure the thickness of a metal film on the surface of a wafer. The polishing unit 100 is used to polish the wafer according to the metal film thickness output by the eddy current measurement system.

[0056] The metal film layer on the wafer surface after thin film deposition; wafer polishing methods include data fusion methods.

[0057] like Figure 1 As shown, the polishing unit 100 of the present invention includes a polishing head 10 for holding the wafer and rotating the wafer, a polishing disk 20 covered with a polishing pad 21, a dresser 30 for dressing the polishing pad 21, and a liquid supply section 40 for providing polishing liquid.

[0058] During chemical mechanical polishing (CMP), the polishing disk 20 rotates, the liquid supply unit 40 sprays polishing fluid onto the surface of the polishing pad 21, the polishing head 10 picks up the wafer and presses it onto the polishing pad 21 covering the surface of the polishing disk 20, and then the polishing head 10 rotates and reciprocates radially along the polishing disk 20. Under the chemical action of the polishing fluid, the relative movement between the polishing head 10 and the polishing disk 20 causes the wafer to rub against the polishing pad 21, gradually polishing away the surface of the wafer in contact with the polishing pad 21 to achieve surface smoothing. During polishing, a dresser 30 is used to trim and activate the surface morphology of the polishing pad 21. The dresser 30 can remove impurity particles remaining on the surface of the polishing pad 21, such as abrasive particles in the polishing fluid and waste material falling off the wafer surface, and can also smooth out the surface deformation of the polishing pad 21 caused by abrasion. The polishing unit 100 also includes multiple eddy current probes 51 disposed on the surface of the polishing disk 20. As the polishing disc 20 rotates, driving the polishing pad 21, the eddy current probe 51 also rotates with the polishing disc 20. Simultaneously, the polishing head 10 drives the wafer in a combined motion. When each of the multiple eddy current probes 51 coincides with the wafer, the metal film on the wafer surface generates an eddy current effect, causing a change in the magnetic field generated by the eddy current probe. This results in a changing signal output by the eddy current probe 51, the amplitude of which can be a function of the thickness of the conductive layer being polished. Online measurement of the thickness of the metal film on the wafer surface is achieved through signal analysis.

[0059] The data fusion method of the present invention will now be described in detail through at least one embodiment based on the polishing unit 100. Figure 2 As shown, an embodiment of the present invention provides a data fusion method including the following steps.

[0060] S1: Acquisition Steps: Using multiple eddy current probes arranged at intervals, collect metal film thickness data at different locations on the wafer surface to obtain multiple morphology curves.

[0061] Taking the acquisition of metal film thickness data by three eddy current probes 51 as an example, the trajectory curves of the three eddy current probes 51 spaced apart on the polishing disk 20 as they sweep across the wafer surface from below during the relative movement between the polishing disk 20 and the wafer are as follows: Figure 3 As shown. Each eddy current probe 51 can continuously measure according to a preset sampling frequency. During each sweep, it synchronously collects eddy current data on its respective sweep trajectory. The time series data of each eddy current probe 51 is converted into the relationship between position and thickness along the wafer radial direction, thus obtaining 3 morphology curves.

[0062] S2: Segmentation step: According to the air film partition of the polishing head, each morphology curve is divided into multiple segmented morphology curves that correspond one-to-one with the partition.

[0063] The polishing head 10 adsorbs the wafer via a film gas and applies polishing pressure to it. Film gas systems with multiple gas film zones are widely used in wafer polishing. Except for the central gas film zone, which is circular, the other gas film zones are multiple concentric annular gas film zones along the radial direction. Each gas film zone has an independent gas film chamber, and the pressure of each chamber can be adjusted independently. This allows for independent control of the pressure applied to different areas of the wafer surface, thereby adjusting the material removal rate of the corresponding area.

[0064] The wafer surface morphology corresponding to the same gas film partition should be consistent. Before fusing the thickness data of the eddy current probe, each morphology curve is divided into several identical segments according to the radial boundary position of each gas film partition of the polishing head 10.

[0065] S3: Characterization steps: Extract the curve features of each segment of the topography curve in a partition.

[0066] For any given air film region, there are three segmented topography curves corresponding to the data from the three eddy current probes. The curve features of each segmented topography curve are extracted. The curve features can be low-order or high-order mathematical features of the curve, such as the geometric features of the curve; they can also be physical features or mixed features.

[0067] Optionally, the curve features may have rotational invariance or translational invariance.

[0068] Optionally, for any air-supported film zone, hereinafter referred to as the target zone, the morphological curves of each segment of the target zone are mapped to the two-dimensional coordinate system XOY. In practice, such as... Figures 3 to 4 As shown, the three complete topographic curves can be mapped onto the two-dimensional coordinate system XOY, and then segmented. Figure 4 The image uses four vertical dashed lines as dividing lines to show three partitions. Then, in the characterization step, curve features are extracted from the three segmented topographic curves in each partition. It is understandable that... Figure 4 For illustrative purposes only, the numerical values ​​do not represent any actual meaning.

[0069] like Figure 4 As shown, the radial direction of the wafer is taken as the X-axis, and the thickness of the metal film is taken as the Y-axis. and These are the coordinates of the X and Y axes, respectively. To facilitate calculations, the discrete measurement points are first fitted to a smooth, continuous function. .

[0070] Optionally, the curve feature is represented as the cumulative energy function of the segmented topography curve deviating from the reference point in the X and Y directions, where the reference point is a spatial characterization point that makes the characterization translationally invariant or rotationally invariant.

[0071] Optionally, the work function in the X direction can be defined as the a-th order moment: Let a be the order of x. Define the work function in the y-direction as the b-th moment: Let b be the order of y. This is understandable. This represents the total area of ​​the topographic curve.

[0072] Optionally, the reference point can be the origin of the XY coordinate axes or the geometric center of the curve (i.e., directly taking the midpoint of the X-axis and Y-axis ranges). This simplifies calculation but weakens translation invariance. Preferably, the point corresponding to the average work done in the X-direction and the average work done in the Y-direction is used as the reference point. The reference point is represented as ( , This allows the curve characteristics to be represented as a joint work function based on a reference point. .

[0073] Optional, , That is, the first moment in the X direction divided by the total area. , That is, the first moment in the Y direction divided by the total area. Where, Let function middle , Let function middle , Let function middle , Let function middle .

[0074] In other words, the benchmark point ( , The centroid (or center of mass) of the entire curve is the center of mass. This joint work function describes the energy distribution of the curve as it deviates from the centroid in the X and Y directions. Since the centroid is used as a reference, if the entire curve moves parallel to the XY coordinate system, the centroid (…) , The same movement will also occur, and the relative offset of any point on the curve from the centroid remains unchanged. Therefore, the joint work function has translation invariance.

[0075] Optionally, Fourier descriptors can be used as curve features for each segmented topography curve. Specifically, the segmented topography curves are subjected to Fourier transform, and the magnitude of the transform coefficients is taken as the curve features.

[0076] Optionally, a curvature scale space descriptor can be used as the curve feature for each segmented topography curve. Specifically, the curvature zero-crossing point information of the curve at different smoothing scales is extracted, and the curvature zero-crossing point information of all smoothing scales of each segmented topography curve is used as the curve feature.

[0077] The curve features of each segmented topography curve extracted above all have certain rotational invariance or translational invariance. In practical use, appropriate features can be selected according to the actual shape of each segmented topography curve to achieve the elimination of the influence of real abnormal data through data fusion, rather than erroneously eliminating local measurement errors.

[0078] S4: Evaluation steps: Construct an evaluation function to convert curve features into similarity indices, which are used to characterize the degree of similarity of the morphology of each segment.

[0079] After obtaining the curve features of each segmented shape curve in step S3, the curve features can be converted into similarity indices by constructing an evaluation function. Those skilled in the art will understand that the evaluation function can be defined according to the form of the curve features; for example, it can be directly calculated by subtraction, quotient, or cosine similarity of the curve features represented as vectors.

[0080] Optionally, for reference points ( , The joint work function of ) We can directly use the orders of a and b as the evaluation function, that is, select a joint work function of different orders (such as...). , , (e.g., etc.) or combinations thereof can be used as similarity indicators, as long as their order can distinguish between normal and abnormal morphologies. Preferably, a joint work function with a≥2 and b≥2 is selected as the similarity indicator to improve the anti-scaling and anti-distortion properties of the similarity indicator through higher-order features.

[0081] Optionally, different values ​​can be assigned to 'a' and 'b' for partitions at different radial locations on the wafer to adapt to the geometric characteristics of different partitions. In typical chemical mechanical polishing scenarios, the central region of the wafer is prone to over-polishing, while the edge region is prone to under-polishing. Therefore, for partitions located at the wafer edge, the radial span of their segmented topography curves is larger, and the value of the X-direction order 'a' in the joint work function can be appropriately increased to enhance the resolution of radial variations. For partitions in the central region, more reliance can be placed on higher-order moments in the Y-direction.

[0082] S5: Fusion Step: Based on the similarity index, fuse the topography curves of each segment to obtain the fused topography curve of each partition, and stitch them together to obtain the fused topography curve of the wafer surface. Figure 5 It shows the result of Figure 3 A schematic diagram of the fusion of three topographic curves into one fused topographic curve.

[0083] The similarity index is used to characterize the degree of similarity between the morphologies of each segment within a partition. Since the three eddy current probes acquire the wafer surface morphology within one revolution of the polishing disk, when a certain probe has a local morphology abnormality due to external interference, the segment morphology at the abnormal position will deviate from the segment morphology acquired by the other two probes, and thus its similarity index will also decrease significantly.

[0084] like Figure 4 As shown, the two curves with the highest similarity are circled in the three partitions of the three topography curves. The figure also reveals that even the two curves with the highest similarity exhibit differences in shape due to rotation or translation. These differences are not data anomalies but rather measurement errors. Without segmentation and characterization, such errors could be mistakenly identified as data anomalies, leading to the loss of local detail features during fusion.

[0085] Optionally, step S5 further includes a step of normalizing the similarity index. After normalization, the similarity index becomes more comparable between shape curves of different amplitudes and dimensions, thus exhibiting further resistance to scaling and distortion, thereby further ensuring the accuracy of abnormal data identification. Preferably, the normalized similarity index is in a dimensionless form, specifically... , To make the function middle and , To make the function middle and .

[0086] Optionally, the morphology curves of each segment can be fused according to the normalized similarity index to obtain the fused morphology curve of each partition, and then spliced ​​together to obtain the fused morphology curve of the wafer surface.

[0087] Specifically, it is preferable to fuse the segmented topography curves according to the following steps and then stitch them together to obtain the fused topography curve of the wafer surface.

[0088] S51. Calculate the similarity index of the topographic curves of each segment in the current partition sequentially, and obtain the set of normalized similarity indices Sim= ,in, Let be the normalized similarity index of the i-th segmented topography curve, and n be the number of segmented topography curves. The step of creating the set can also be performed in step S5.

[0089] S52. Sim=, a set of similarity indices derived from the evaluation steps. For the i-th segment of the topography curve, calculate its similarity index. The minimum of the absolute differences between the similarity indices and those in the Sim set is taken. Establish the minimum value set D= In other words, ,in, and .

[0090] S53. Define the fusion coefficient of the i-th segmented topography curve. The minimum value in set D The minimum value corresponding to this curve The ratio, that is Using this fusion coefficient as the weight of the segmented topography curve, the n segmented topography curves within the current partition are weighted and fused to generate the fused topography curve of the current partition.

[0091] S54. Repeat the above characterization, evaluation, and fusion steps, calculate the feature and similarity index of the morphology curve of each segment for each partition, determine the fusion coefficient, and generate the fused morphology curve of each partition by weighting.

[0092] S55. The fusion topography curves of all partitions are spliced ​​end to end according to their radial positions to obtain a continuous fusion topography curve covering the entire wafer surface. This fusion curve represents the stable and reliable radial distribution of the wafer surface metal film thickness after the fusion of data from multiple eddy current probes, and can be directly used for polishing endpoint determination or gas film partition pressure feedback control.

[0093] Optionally, in step S53, when the fusion coefficient of a certain segmented topography curve is lower than a preset threshold, it can be directly removed as an outlier, and only the remaining curves can be fused by equal weighting.

[0094] Optionally, a fusion framework based on Kalman filtering or Bayesian inference can be adopted, treating each segmented topography curve as multiple noisy observations of the true topography, and iteratively estimating the optimal fusion result.

[0095] Steps S1 to S5 of this embodiment partition the wafer and extract features representing the fused topography curve of a partition. Specific steps ensure that these features are rotationally or translationally invariant and resistant to scaling and distortion, allowing the similarity index to be sensitive only to genuine outlier data and unaffected by measurement errors. Furthermore, by fusing the topography curves of each segment based on the similarity index within the current partition, the impact of outlier data on the fused data can be reduced, ensuring that the restored segmented topography curves do not lose local detail features. By stitching together the fused segmented topography curves of each partition, the fused topography curve of the wafer surface is obtained. This fused topography curve also ensures the authenticity of detail features, thus accurately reflecting the actual film thickness on the wafer surface and improving the feedback control accuracy of the polishing process. An embodiment of the present invention also provides an eddy current measurement system 50. Figure 1 As shown, the eddy current measurement system 50 includes: multiple eddy current probes 51, a fusion module 52, and an output module 53.

[0096] Optionally, step S2 can be skipped from step S1 and step S3 can be executed directly, especially when the wafer surface is not subjected to zoned voltage adjustment or the zoned voltage adjustment is relatively consistent, or when polishing smaller wafers such as 6-inch or 8-inch wafers. Skipping step S2 can speed up the fusion calculation, but it will also increase the error that occurs during the overall comparison of the accompanying curves.

[0097] Optionally, when segmenting the morphology curve in step S2, each segmented morphology curve shall span at least one gas film partition of the polishing head to avoid the influence of abnormal data caused by nonlinear pressure changes at the gas film partition on steps S3 to S5.

[0098] Optionally, before segmenting the morphology curves in step S2, the method further includes evaluating multiple morphology curves based on predetermined evaluation rules, selecting a morphology curve as a reference curve based on the evaluation results, determining the segmentation rules based on the reference curve, and then segmenting each morphology curve into multiple corresponding segmented morphology curves according to the segmentation rules.

[0099] The evaluation rule preferably involves performing steps S3 to S5 on each morphology curve to obtain its respective fusion coefficient, and using the morphology curve with the largest fusion coefficient as the baseline curve. The segmentation rule preferably ensures that each segmented morphology curve includes at least two curve extrema.

[0100] Multiple eddy current probes 51 are arranged at equal intervals with respect to the center of the polishing disk 20 on the polishing disk 20 to collect eddy current signals on the wafer surface. The multiple eddy current probes 51 are communicatively connected to the fusion module 52, transmitting the collected eddy current data to the fusion module 52 in real time. The fusion module 52 executes a data fusion method according to an embodiment of this application to obtain a fusion morphology curve of the wafer surface. An output module 53 is communicatively connected to the fusion module 52 and outputs the fusion morphology curve or corresponding metal film thickness data generated by the fusion module after executing the data fusion method according to an embodiment of this application, for use by a host computer or polishing process control system. Optionally, the fusion module 52 includes:

[0101] Acquisition unit: used to acquire eddy current signals collected by multiple eddy current probes 51 on the wafer surface, generate metal film thickness data based on the eddy current signals, and finally obtain multiple morphology curves.

[0102] Segmentation unit: According to the radial boundary position of each air film partition of the polishing head 10, each morphology curve is divided into several segments.

[0103] Characterization unit: Used to extract the curve features of each segment of the topography curve of a partition.

[0104] Evaluation Unit: Used to construct the indicator evaluation function and convert curve feature values ​​into similarity indicators.

[0105] Normalization and fusion unit: The similarity index is normalized to obtain the normalized similarity index of each segment morphology. The morphology curves of each segment are fused according to the normalized similarity index to obtain the fused morphology curve of each partition. The fused morphology curve of the wafer surface is obtained by splicing them together.

[0106] An embodiment of the present invention also provides a wafer polishing method, comprising:

[0107] The wafer is polished according to the predetermined polishing formula;

[0108] The data fusion method according to the present invention obtains the fusion morphology curve of the wafer surface;

[0109] The polishing formula is updated based on the obtained fusion morphology curve of the wafer surface.

[0110] Updating the polishing formula includes, but is not limited to, at least one of the following operations: changing the polishing temperature, polishing fluid flow rate, polishing head or polishing disc rotation speed, polishing pressure of at least one zone and continuing polishing; or, stopping polishing.

[0111] An embodiment of the present invention also provides a polishing apparatus, including a controller and a polishing unit 100, wherein the controller is used to control the polishing unit 100 to perform a wafer polishing method provided in an embodiment of the present invention.

[0112] The above embodiments are only used to illustrate the embodiments of the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the embodiments of the present invention, and the patent protection scope of the embodiments of the present invention should be defined by the claims.

Claims

1. A data fusion method for measuring the thickness of a metal film on a wafer surface, characterized in that, include: Acquisition steps: Using multiple eddy current probes arranged at intervals, the thickness data of the metal film at different locations on the wafer surface is collected to obtain multiple morphology curves; Segmentation steps: According to the air film partition of the polishing head, each morphology curve is divided into multiple segmented morphology curves that correspond one-to-one with the partition; Characterization steps: For each partition, extract the curve features of each segment of the topography curve in that partition; Evaluation steps: Construct an evaluation function to convert curve features into similarity indices, which are used to characterize the degree of similarity of the morphology of each segment; Fusion steps: Based on the similarity index, the morphology curves of each segment are fused to obtain the fused morphology curve of each partition, and then spliced ​​together to obtain the fused morphology curve of the wafer surface.

2. The data fusion method as described in claim 1, characterized in that, The curve features are rotationally invariant or translationally invariant.

3. The data fusion method as described in claim 2, characterized in that, The characterization steps include: The topographic curves of each segment of a partition are mapped onto a two-dimensional coordinate system XOY, where the X-axis represents the distance along the wafer radial direction and the Y-axis represents the metal film thickness data, resulting in a function. , and These are the coordinates of the X-axis and Y-axis, respectively; The curve features are represented as the cumulative energy functions of the segmented topography curves deviating from the reference point in the X and Y directions.

4. The data fusion method as described in claim 3, characterized in that, The description of representing the curve features as the cumulative energy function of the segmented topography curve deviating from the reference point in the X and Y directions includes: Define the work function in the X direction as follows: Let a be the order of x. Define the work function in the Y direction Let b be the order of y. The points corresponding to the average work done in the X direction and the average work done in the Y direction are used as the reference points. The curve features are represented as a joint work function based on a reference point.

5. The data fusion method as described in claim 4, characterized in that, The reference point is represented as ( , ),in, , , To make the function middle , To make the function middle , To make the function middle , To make the function middle .

6. The data fusion method as described in claim 5, characterized in that, The joint work function based on the reference point is expressed as follows: .

7. The data fusion method as described in claim 6, characterized in that, The fusion step includes: The similarity index is normalized to make it resistant to scaling and distortion. By fusing the morphology curves of each segment according to the normalized similarity index, the fused morphology curve of each partition is obtained, and the fused morphology curve of the wafer surface is obtained by splicing them together.

8. The data fusion method as described in claim 7, characterized in that, The similarity index is The normalized similarity index is ,in, To make the function middle and , To make the function middle and .

9. The data fusion method as described in claim 8, characterized in that, The process of fusing the morphological curves of each segment based on the normalized similarity index to obtain the fused morphological curve of each partition includes: Establish a set of normalized similarity indices Sim= for the morphological curves of each segment of the partition. ,in, Let be the normalized similarity index of the i-th segmented topography curve, and n be the number of segmented topography curves; Establish the minimum value set D= ,in, for The minimum absolute value of the difference between the similarity index and other normalized similarity indices in the Sim set; The fusion coefficient of the i-th segmented topography curve is ,in, The minimum value in set D; The fusion coefficient of the i-th segmented topography curve is used as the weight of the i-th segmented topography curve. The n segmented topography curves are weighted and fused to obtain a fused topography curve of a partition. Repeat the above steps to obtain the fusion topography curve for each partition.

10. An eddy current measurement system for measuring the thickness of a metal film on a wafer surface during chemical mechanical polishing (CMP) processes, characterized in that... include: Multiple eddy current probes are arranged at intervals on the polishing disk to collect metal film thickness data on the wafer surface and obtain multiple morphology curves; A fusion module is configured to perform the data fusion method as described in any one of claims 1-9 to obtain the fusion topography curve of the wafer surface; The output module is used to output the fused topography curve or the corresponding metal film thickness data.

11. A polishing unit, characterized in that, include: The polishing head, polishing disc, and eddy current measurement system as described in claim 10, wherein the polishing unit is used to polish the wafer according to the fusion morphology curve or the corresponding metal film thickness data output by the eddy current measurement system.

12. A polishing device, characterized in that, Includes the polishing unit as described in claim 11.

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