Chemical mechanical polishing method and apparatus

Abstract

This disclosure provides a chemical mechanical polishing (CMP) method and apparatus. The CMP method includes: performing a polishing operation on a wafer surface, wherein the polishing slurry used in the polishing operation contains an inhibitor; obtaining an endpoint detection result of a metal film layer on the wafer surface, the endpoint detection result being used to characterize the thickness of the metal film layer; performing a cleaning operation on a polishing pad and the wafer surface based on the endpoint detection result being outside a preset range, at least removing residual inhibitors from the wafer surface; and alternately performing the polishing operation and the cleaning operation until the endpoint detection result is within the preset range or the number of polishing operations reaches a preset number.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor technology, and more particularly to a chemical mechanical polishing method and apparatus. Background Technology

[0002] Chemical mechanical polishing (CMP) is a method for achieving global planarization in integrated circuit manufacturing. When polishing the metal film layer on the wafer surface, inhibitors are added to the polishing slurry to adjust the chemical reaction rate and mechanical action rate of the slurry, thereby controlling the removal rate and polishing uniformity of the metal film layer. However, residual inhibitors can lead to undesirable metal residues, affecting subsequent processes and causing wafer surface inhomogeneity, quality problems, or contamination. Summary of the Invention

[0003] According to some aspects of embodiments of the present disclosure, embodiments of the present disclosure provide a chemical mechanical polishing method, the method comprising:

[0004] A polishing operation is performed on the surface of a wafer, wherein the polishing slurry used in the polishing operation contains an inhibitor;

[0005] Obtain the endpoint detection result of the metal film layer on the surface of the wafer, and the endpoint detection result is used to characterize the thickness of the metal film layer;

[0006] If the endpoint detection result is outside the preset range, a cleaning operation is performed on the polishing pad and the wafer surface to at least remove the inhibitors remaining on the wafer surface;

[0007] The polishing and cleaning operations are performed alternately until the endpoint detection result is within the preset range or the number of polishing operations reaches the preset number.

[0008] In some embodiments, performing a cleaning operation on the polishing pad and the wafer surface based on the endpoint detection result being outside a preset range includes:

[0009] A first cleaning operation is performed on the wafer surface and the polishing pad using a first cleaning solution;

[0010] A second cleaning operation is performed on the wafer surface and the polishing pad using a second cleaning solution; wherein the second cleaning solution is water and the pressure of the second cleaning solution is greater than or equal to 200 kPa.

[0011] In some embodiments, the solubility of the inhibitor in the first cleaning solution is greater than a first preset threshold, and the solubility of the first cleaning solution in the second cleaning solution is greater than a second preset threshold; the pH value of the first cleaning solution and the pH value of the polishing solution are both less than 7, and the difference between the pH value of the first cleaning solution and the pH value of the polishing solution is less than or equal to a third preset threshold.

[0012] In some embodiments, the inhibitor of the polishing fluid includes benzotriazole; the first cleaning fluid includes an alcoholic organic solvent and an organic acid, wherein the pH value of the organic acid is greater than 4 and less than 7.

[0013] In some embodiments, the alcoholic organic solvent includes at least one of methanol, ethanol, or ethylene glycol; the organic acid includes at least one of citric acid, formic acid, or acetic acid.

[0014] In some embodiments, the volume fraction of the alcohol-based organic solvent is 30%-50%.

[0015] In some embodiments, performing the polishing operation on the wafer surface includes:

[0016] Based on the endpoint detection result of the metal film layer on the wafer surface obtained after the Nth polishing operation, and combined with the preset function model, the polishing parameters for the N+1th polishing operation are set; the preset function model is used to characterize the relationship between the endpoint detection result and the polishing parameters, where N is a positive integer greater than or equal to 1.

[0017] In some embodiments, the endpoint detection result of the metal film layer on the wafer surface obtained after the Nth polishing operation includes at least one or more sub-parameters corresponding to multiple regions on the wafer surface; based on the endpoint detection result obtained after the Nth polishing operation and in conjunction with a preset function model, the polishing parameters for the N+1th polishing operation are set, including:

[0018] Based on the sub-parameters and combined with the preset function model, corresponding polishing parameters are set for each of the multiple regions.

[0019] In some embodiments, the alternating execution of the polishing operation and the cleaning operation until the endpoint detection result is within the preset range or the number of polishing operations reaches the preset number includes:

[0020] If the endpoint detection result is within the preset range, the polishing operation on the wafer surface is terminated.

[0021] or,

[0022] Once the preset number of polishing operations is reached, the polishing operation on the wafer surface ends and an alarm message is issued.

[0023] According to some aspects of embodiments of this disclosure, embodiments of this disclosure provide a chemical mechanical polishing apparatus, comprising:

[0024] A polishing pad covered with a polishing pad for polishing a wafer surface, wherein the polishing fluid used in the polishing operation contains an inhibitor;

[0025] A support head for holding the wafer and pressing the wafer onto the polishing pad;

[0026] The detection module is used to detect the metal film layer on the surface of the wafer to obtain an endpoint detection result, which is used to characterize the thickness of the metal film layer.

[0027] A cleaning module is used to perform a cleaning operation on the polishing pad and the wafer surface, at least removing residual inhibitors on the wafer surface;

[0028] The control module is configured to: control the polishing pad to perform a polishing operation on the wafer surface; acquire the endpoint detection result output by the endpoint detector; and, if the endpoint detection result is outside a preset range, control the cleaning module to perform a cleaning operation on the polishing pad and the wafer surface; and control the polishing pad and the cleaning module to alternately perform the polishing operation and the cleaning operation until the endpoint detection result is within the preset range or the number of polishing operations reaches a preset number.

[0029] In various embodiments of this disclosure, if the endpoint detection result after the polishing operation is outside a preset range, a cleaning operation for the polishing pad and wafer surface is inserted before the subsequent polishing operation. This removes at least the inhibitors remaining on the wafer surface from the previous polishing operation, thereby providing good polishing conditions for the subsequent polishing operation and improving the overall polishing quality and the uniformity of the wafer surface. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is one of the flowcharts illustrating a specific implementation process of a chemical mechanical polishing method provided in this embodiment of the present disclosure;

[0032] Figure 2This is a schematic diagram of a chemical mechanical polishing apparatus provided in an embodiment of the present disclosure;

[0033] Figure 3 A second schematic flowchart illustrating the specific implementation process of a chemical mechanical polishing method provided in this embodiment of the present disclosure;

[0034] Figure 4 A schematic diagram of the chemical mechanical polishing method provided in the embodiments of this disclosure;

[0035] Figure 5 One of the schematic diagrams of the endpoint detection results provided in the embodiments of this disclosure;

[0036] Figure 6 A second schematic diagram illustrating the endpoint detection results provided in an embodiment of this disclosure;

[0037] Figure 7 This is a schematic diagram of the partitioning of a wafer surface provided in an embodiment of this disclosure. Detailed Implementation

[0038] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0039] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of this disclosure. However, it will be apparent to those skilled in the art that this disclosure may be practiced without one or more of these details. In other instances, to avoid confusion with this disclosure, certain technical features well-known in the art have not been described; that is, not all features of actual embodiments are described herein, nor are well-known functions and structures described in detail.

[0040] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this disclosure, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And the discussion of a second element, component, area, layer, or portion does not imply that the first element, component, area, layer, or portion necessarily exists in this disclosure.

[0041] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below,” “under,” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0042] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprise” and / or “comprising,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0043] In the CMP process for metal films, poor uniformity of metal film thickness is prone to occur during polishing due to inhomogeneities in electroplating, inhomogeneities in metal film deposition during Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD), or instability in the CMP process. Since the polishing solution contains inhibitors with positively charged surfaces, these inhibitors accumulate on the metal film surface, protecting the residual metal film after polishing and preventing further removal. This can lead to defects on the wafer surface, causing short circuits or leakage, and reducing product yield. Removing the wafer when the residual signal exceeds a preset threshold and manually repeating the process by engineers significantly increases workload and process time.

[0044] In view of this, the present disclosure provides a chemical mechanical polishing method and a chemical mechanical polishing apparatus.

[0045] Figure 1 This is one of the flowcharts illustrating a specific implementation process of a chemical mechanical polishing method provided in this embodiment of the disclosure. (Reference) Figure 1 The chemical mechanical polishing method includes the following steps:

[0046] Step S101: Perform a polishing operation on the wafer surface, wherein the polishing slurry used in the polishing operation contains an inhibitor;

[0047] Step S102: Obtain the endpoint detection result of the metal film layer on the wafer surface, wherein the endpoint detection result is used to characterize the thickness of the metal film layer;

[0048] Step S103: If the endpoint detection result is outside the preset range, perform a cleaning operation on the polishing pad and the wafer surface to at least remove the inhibitors remaining on the wafer surface;

[0049] Step S104: Alternately perform the polishing operation and the cleaning operation until the endpoint detection result is within the preset range or the number of polishing operations reaches the preset number.

[0050] In some embodiments, the material of the metal film layer includes, but is not limited to, copper (Cu), aluminum (Al), or tungsten (W).

[0051] In some embodiments, endpoint detection (EPD) is used to monitor the metal film layer on the wafer surface online to obtain endpoint detection results. For example, optical endpoint detection, acoustic endpoint detection, electrical endpoint detection, and other methods can be used to monitor the metal film layer on the wafer surface online to obtain endpoint detection results.

[0052] In some specific implementations, an eddy current endpoint detector is used to detect the magnitude of the eddy currents in the metal film layer on the wafer surface, thereby obtaining the thickness of the metal film layer on the wafer surface.

[0053] In some specific implementations, an optical endpoint detector is used to detect the intensity of the reflected signal of the metal film layer on the wafer surface, thereby obtaining the thickness of the metal film layer on the wafer surface.

[0054] In some embodiments, the alternating execution of the polishing operation and the cleaning operation until the endpoint detection result is within the preset range or the number of polishing operations reaches the preset number includes: ending the polishing operation on the wafer surface based on the endpoint detection result being within the preset range; or ending the polishing operation on the wafer surface and issuing an alarm message based on the number of polishing operations reaching the preset number.

[0055] In this embodiment of the disclosure, the preset range is a parameter range defined according to process requirements and quality standards, used to measure whether the thickness of the metal film layer on the wafer surface after polishing has reached the target state.

[0056] In some embodiments, when the endpoint detection result is within a preset range, it indicates that the polishing operation on the wafer surface has reached the polishing endpoint and the thickness of the metal film layer on the wafer surface has reached the target state. The polishing operation on the wafer surface can then be terminated, and subsequent process steps can be initiated.

[0057] When the endpoint detection result is outside the preset range, it means that the polishing operation has not reached the polishing endpoint and the polishing operation needs to continue. Therefore, before the next polishing operation, a cleaning operation for the polishing pad and wafer surface is inserted to at least remove the inhibitors remaining in the previous polishing operation, so as to provide good polishing conditions for the next polishing operation, thereby improving the overall polishing quality and the uniformity of the wafer surface.

[0058] Here, the target state of the thickness of the metal film layer on the wafer surface includes, but is not limited to, the thickness difference of the metal film layer in different regions of the wafer surface being less than or equal to a preset value. For example, the difference in the reflected signal intensity of the metal film layer in different regions of the wafer surface, obtained by an optical endpoint detector, corresponds to the thickness difference of the metal film layer in different regions of the wafer surface. When the difference in the reflected signal intensity of the metal film layer in different regions of the wafer surface is less than or equal to 10%, it indicates that the thickness difference of the metal film layer in different regions of the wafer surface is less than or equal to the preset value.

[0059] It should be noted that the cleaning of the wafer and polishing pad in the subsequent process steps after the polishing operation differs from the cleaning operation interspersed between two polishing operations. Specifically, in the subsequent process steps after the polishing operation, cleaning equipment can be used to perform a combination of physical cleaning methods such as brush washing or ultrasonic rinsing to clean the wafer and polishing pad. The wafer and polishing pad are then dried using spin drying or nitrogen blowing to prepare them for subsequent processes (such as deposition processes, etching processes, etc.). In some embodiments, the preset number of polishing operations is the maximum safe number of polishing operations determined based on process experience, equipment performance, and the material characteristics of the metal film layer. This is used to prevent over-polishing, protect equipment lifespan, improve production efficiency, and ensure process stability. Specifically, to avoid damage or quality degradation of the wafer surface material due to excessive polishing operations, as well as wear or malfunctions caused by excessive equipment use, recording the preset number of polishing operations and issuing timely alarm information when the polishing operation does not reach the polishing endpoint within the preset number of operations can reduce ineffective operations and resource waste. Furthermore, setting the preset number of operations serves as an upper limit condition for process control, ensuring that the entire polishing process is conducted within a controllable range.

[0060] After the preset number of polishing operations is reached, it indicates that the maximum number of polishing operations has been reached, but the metal film layer on the wafer surface has not yet reached the polishing endpoint. At this time, the machine issues an alarm message to prompt the engineer to intervene manually.

[0061] In some embodiments, the preset number of times can be 3, 4, or 5.

[0062] In other embodiments, if the total polishing time exceeds the preset time but the metal film layer on the wafer surface has not yet reached the polishing endpoint, the machine alarm can be used to prompt the engineer to intervene manually, saving time and costs.

[0063] This disclosure also provides a chemical mechanical polishing (CMP) apparatus, comprising: a polishing disc covered with a polishing pad for polishing a wafer surface, wherein the polishing fluid used in the polishing operation contains an inhibitor; a support head for holding the wafer and pressing it onto the polishing pad; a detection module for detecting a metal film layer on the wafer surface to obtain an endpoint detection result, the endpoint detection result being used to characterize the thickness of the metal film layer; a cleaning module for performing a cleaning operation on the polishing pad and the wafer surface to at least remove residual inhibitors from the wafer surface; and a control module configured to: control the polishing disc to perform a polishing operation on the wafer surface; acquire the endpoint detection result output by the endpoint detector; and, if the endpoint detection result is outside a preset range, control the cleaning module to perform a cleaning operation on the polishing pad and the wafer surface; and control the polishing disc and the cleaning module to alternately perform the polishing operation and the cleaning operation until the endpoint detection result is within the preset range or the number of polishing operations reaches a preset number.

[0064] For example, such as Figure 2 As shown, the chemical mechanical polishing apparatus 200 includes a support head 20, a polishing disc 24 covered with a polishing pad 22, a liquid supply device 26, a detection module (not shown in the figure), a cleaning module 28, and a control module 30.

[0065] In some embodiments, the liquid supply device 26 is used to supply polishing liquid.

[0066] In some embodiments, the cleaning module can be integrated into the liquid supply device, which integrates cleaning fluid piping to directly supply cleaning fluid to the polishing pad and wafer surface through the polishing head. This results in a simpler overall structure for the chemical mechanical polishing (CMP) apparatus, avoiding the need for additional space.

[0067] In some embodiments, the cleaning module and the liquid supply device are set separately, which is beneficial for accurately adjusting the flow rate and cleaning time of the cleaning liquid, thereby achieving a high-efficiency cleaning effect and helping to maintain the long-term stable operation of the device.

[0068] It should be noted that the connection between the control module 30 and the polishing disc 24, the liquid supply device 26, the detection module, and the cleaning module can be an electrical connection.

[0069] During the polishing operation on the wafer surface, the carrier head 20 can press the wafer to be polished onto the polishing pad 22 and drive the wafer to be polished to rotate (refer to indicator arrow F1) and move horizontally (refer to indicator arrow F2) relative to the polishing disk 24. The polishing disk 24 also rotates at the same time (refer to indicator arrow F3). Under the chemical action of the polishing liquid provided by the liquid supply device 26, the polishing pad 22 rubs the surface of the wafer through the relative movement of the carrier head 20 and the polishing disk 24, thus polishing the wafer surface.

[0070] For ease of understanding, the following will be based on Figure 2 The chemical mechanical apparatus shown provides a detailed description of the chemical mechanical polishing method in the embodiments of this disclosure.

[0071] In some embodiments, the step of performing a cleaning operation on the polishing pad and the wafer surface based on the endpoint detection result being outside a preset range includes: performing a first cleaning operation on the wafer surface and the polishing pad using a first cleaning solution; and performing a second cleaning operation on the wafer surface and the polishing pad using a second cleaning solution; wherein the second cleaning solution is water and the pressure of the second cleaning solution is greater than or equal to 200 kPa.

[0072] In some embodiments, the second cleaning solution is ultrapure water or deionized water.

[0073] In some embodiments, the pressure of the second cleaning fluid ranges from 200 kPa to 250 kPa. For example, the pressure of the second cleaning fluid can be 200 kPa, 225 kPa, or 250 kPa.

[0074] In some embodiments, the flow rate of the second cleaning fluid is in the range of 10L / min to 15L / min. For example, the flow rate of the second cleaning fluid can be 10L / min, 12.5L / min, or 15L / min.

[0075] In some embodiments, the duration of the second cleaning operation performed on the wafer surface and the polishing pad with the second cleaning solution is 10s-20s. For example, the duration of the second cleaning operation is 10s, 15s or 20s.

[0076] In some embodiments, the solubility of the inhibitor in the first cleaning solution is greater than a first preset threshold, and the solubility of the first cleaning solution in the second cleaning solution is greater than a second preset threshold; the pH value of the first cleaning solution and the pH value of the polishing solution are both less than 7, and the difference between the pH value of the first cleaning solution and the pH value of the polishing solution is less than or equal to a third preset threshold.

[0077] In some embodiments, the third preset threshold is 0.5, the pH value of the first cleaning solution is greater than the pH value of the polishing solution, and the difference between the pH value of the first cleaning solution and the pH value of the polishing solution is less than or equal to 0.5.

[0078] In some embodiments, the pH value of the first cleaning solution is in the range of 4-6, and more specifically, the pH value of the first cleaning solution can be 4.5, 5, 5.5 or 6.

[0079] For example, the first cleaning solution has a pH of 5, and the polishing solution has a pH of 4.5.

[0080] For example, the first cleaning solution has a pH of 5.5, and the polishing solution has a pH of 5.

[0081] For example, the first cleaning solution has a pH of 5, and the polishing solution has a pH of 5.5.

[0082] In some embodiments, the pH value of the first cleaning solution is equal to the pH value of the polishing solution. For example, the pH value of both the first cleaning solution and the polishing solution is 4.5, 5, 5.5, or 6.

[0083] In some embodiments, the solubility of the inhibitor in the first cleaning solution is greater than a first preset threshold. For example, the first preset threshold can be in the range of 50 g / L to 60 g / L. In some specific embodiments, the first preset threshold can be 50 g / L, 55 g / L, or 60 g / L; it is understood that the solubility of the inhibitor in the first cleaning solution is greater than 50 g / L, 55 g / L, or 60 g / L.

[0084] In some embodiments, the solubility of the first cleaning solution in the second cleaning solution is greater than a second preset threshold. For example, the second preset threshold can range from 100 g / L to 150 g / L. In some specific embodiments, the second preset threshold can be 100 g / L, 125 g / L, or 150 g / L. It is understood that the solubility of the first cleaning solution in the second cleaning solution is greater than 100 g / L, 125 g / L, or 150 g / L.

[0085] It should be noted that the components of the first cleaning solution do not react with the polishing pad and will not cause the polishing pad to vitrify or become brittle, thus ensuring the cleaning effect of the cleaning operation, providing a good polishing environment for the subsequent polishing operation to remove residual metal film, and also extending the service life of the polishing pad.

[0086] In some embodiments, the polishing slurry inhibitor includes benzotriazole (BTA); the cleaning slurry includes an alcoholic organic solvent and an organic acid, wherein the organic acid has a pH value greater than 4 and less than 7. In some embodiments, the alcoholic organic solvent includes at least one of methanol, ethanol, or ethylene glycol; the weak organic acid includes at least one of citric acid, formic acid, or acetic acid.

[0087] In some embodiments, the volume fraction of the alcoholic organic solvent is 30%-50%. More specifically, the volume fraction of the alcoholic organic solvent is 30%, 40%, or 50%.

[0088] In some embodiments, performing a polishing operation on the wafer surface includes: setting polishing parameters for the (N+1)th polishing operation based on the endpoint detection result of the metal film layer on the wafer surface obtained after the Nth polishing operation and in conjunction with a preset function model; the preset function model is used to characterize the relationship between the endpoint detection result and the polishing parameters, where N is a positive integer greater than or equal to 1.

[0089] For example, such as Figure 3 As shown, in step S201, the Nth polishing operation is performed on the wafer surface, wherein the polishing slurry used in the polishing operation contains an inhibitor. Here, N is a positive integer.

[0090] In step S202, it is mainly determined whether the endpoint detection result of the metal film layer on the wafer surface is outside the preset range.

[0091] If the result of step S202 is negative, it means that the polishing endpoint has been reached and the thickness of the metal film layer on the wafer surface has reached the target state. At this time, step S208 is executed to end the operation and proceed to the subsequent process steps.

[0092] If the judgment result of step S202 is yes, proceed to step S203 to perform a cleaning operation on the polishing pad and the wafer surface.

[0093] Next, step S204 is executed, where the polishing parameters for the N+1th polishing operation are set based on the endpoint detection result obtained after the Nth polishing operation and in conjunction with the preset function model.

[0094] Execute step S205 to determine the relationship between N+1 and the preset number of times.

[0095] If N+1 is less than or equal to the preset number of times, then proceed to step S206.

[0096] If N+1 is greater than the preset number of times, then step S207 is executed to trigger the machine alarm and notify the engineer to intervene manually.

[0097] In some embodiments, the polishing parameters include at least one of polishing pressure, polishing time, polishing pad temperature, and polishing fluid flow rate.

[0098] In some embodiments, polishing parameters may also include the polishing fluid droplet, the oscillation frequency of the polishing head, or the pressure and frequency of the dresser.

[0099] In this embodiment of the disclosure, a preset function model can be established based on experimental data obtained from a large number of experiments, or a preset function model can be obtained based on machine learning modeling of historical data.

[0100] For example, during the process development phase, experimental combinations of different polishing parameters (such as polishing head pressure, polishing time, and polishing fluid flow rate) are designed using the controlled variable method, and the variation patterns of the metal film thickness in different regions of the wafer are recorded. Through statistical analysis, a functional relationship between the endpoint detection results and the polishing parameters is established.

[0101] For example, a large amount of historical data from actual production processes is input into machine learning algorithms (such as linear regression, support vector machines, or neural networks) to train the model to predict the correlation between endpoint detection results and polishing parameters.

[0102] In some embodiments, the preset function model can be a linear function model, a quadratic function model, an exponential function model, or a logarithmic function model.

[0103] Thus, by analyzing the endpoint detection results of the metal film layer on the wafer surface during the polishing process and combining them with a preset function model, the polishing parameters for subsequent polishing operations can be dynamically adjusted, thereby reducing the number of debugging attempts, significantly shortening the process cycle, and improving the overall polishing uniformity to reduce defects generated in subsequent processes.

[0104] In some embodiments, such as Figure 4 As shown in (a), a metal film 302 is coated on the surface of wafer 300, and an inhibitor 304 in the polishing slurry acts on the surface of the wafer during the polishing operation.

[0105] After the first polishing operation, as Figure 4 As shown in (b), the endpoint detection result is outside the preset range, and a large amount of residual inhibitor 304 covers the surface of the metal film 302, affecting the further removal of the metal film 302.

[0106] At this point, a cleaning operation is performed on the polishing pad and wafer 300. Specifically, a first cleaning solution is used to perform a first cleaning operation on the surface of wafer 300 and the polishing pad; a second cleaning solution is used to perform a second cleaning operation on the surface of wafer 300 and the polishing pad. After performing the above first and second cleaning operations, as follows... Figure 4As shown in (c), the inhibitor 304 covering the surface of the metal film 302 and the inhibitor 304 remaining on the surface of the wafer 300 are significantly reduced.

[0107] At this point, a second polishing operation is performed, such as... Figure 4 As shown in (d), the metal film layer on the surface of wafer 300 has been completely removed. At this point, the endpoint detection result is within the preset range, the operation ends, and the process proceeds to the next step.

[0108] In some embodiments, the endpoint detection result of the metal film layer on the wafer surface obtained after the Nth polishing operation includes at least one or more sub-parameters corresponding to multiple regions on the wafer surface; based on the endpoint detection result obtained after the Nth polishing operation and in conjunction with a preset function model, the polishing parameters for the N+1th polishing operation are set, including: based on the sub-parameters and in conjunction with the preset function model, setting corresponding polishing parameters for each of the multiple regions.

[0109] In some embodiments, such as Figure 5 As shown, the endpoint detection results of the metal film layer on the wafer surface are obtained in real time through an optical endpoint detector. For example, Figure 5 The diagram shows the intensity changes of the first, second, third, and fourth signals over time. The first signal corresponds to the main signal (Signal(main)) of the metal film layer on the wafer surface, which characterizes the overall thickness of the metal film layer on the wafer surface. The fourth signal corresponds to the signal of the metal film layer in the edge region of the wafer surface (Signal(E)). The third signal corresponds to the signal of the metal film layer in the middle region of the wafer surface (Signal(M)). The second signal corresponds to the signal of the metal film layer in the center region of the wafer surface (Signal(C)).

[0110] Understandably, the endpoint detection results include a fourth signal, a third signal, and a second signal corresponding to the three regions (edge ​​region, middle region, and center region) on the wafer surface, respectively. The endpoint detection results also include a first signal characterizing the overall thickness of the metal film layer on the wafer surface.

[0111] For example, in Figure 5 At the first moment T1, after the first polishing operation, the obtained endpoint detection result was outside the preset range. Specifically, the intensity difference between the fourth signal and the first signal exceeded 30%.

[0112] exist Figure 5 The endpoint detection results obtained at the second time point T2, which is after the cleaning operation, show no significant change. This is because the process mainly involves removing residual inhibitors and byproducts generated during the first polishing operation to expose the surface of the metal film. Therefore, the thickness of the metal film in each region of the wafer surface does not change significantly.

[0113] In some implementations, polishing parameters are set for multiple regions on the wafer surface based on sub-parameters and a preset function model. Specifically, if the difference between the fourth signal and the first signal is significantly greater than the difference between the second signal or the third signal and the first signal, it is determined that the metal film thickness in the edge region of the wafer surface is too large. When the polishing parameter is the polishing head pressure, by setting the polishing head pressure in the edge region to be greater than that in other regions, the residual metal film can be removed in a targeted manner while avoiding over-polishing of other regions.

[0114] For example, the polishing parameters for the second polishing operation are set as shown in Table 1.

[0115] Table 1

[0116] partition Zone 1 Zone2 Zone 3 Zone4 Zone5 Zone6 Zone 7 Stress (Psi) 2.3 2.1 1.7 0.5 0.5 0.5 0.5

[0117] refer to Figure 7 Zone1, Zone2, and Zone3 are three sub-regions at the edge of the wafer surface; Zone4 and Zone5 are two sub-regions in the middle of the wafer surface; and Zone6 and Zone7 are two sub-regions in the center of the wafer surface.

[0118] It should be noted that, Figure 7 This is a schematic diagram of the partitioning of a wafer surface provided in an embodiment of this disclosure. The first direction can be the direction of the wafer thickness, and the second and third directions are both parallel to the wafer surface and perpendicular to the first direction. In some specific embodiments, the second direction is perpendicular to the third direction. For example, the first direction can be the extension direction of the z-axis shown in the figure, the second direction can be the extension direction of the x-axis shown in the figure, and the third direction can be the extension direction of the y-axis shown in the figure.

[0119] Because the metal film thickness in the edge region of the wafer surface is too large, when the polishing parameter is the polishing head pressure, the polishing head pressure of the three sub-regions Zone1, Zone2 and Zone3 of the edge region is set to be greater than that of other regions, and the second polishing operation is performed using the above polishing head pressure.

[0120] exist Figure 5 At the third time point T3, which is after the second polishing operation, the intensity difference between the fourth signal and the first signal is less than or equal to 10%. At this point, the endpoint detection result is within the preset range, indicating that the polishing endpoint has been reached, and the operation can be terminated to proceed to subsequent process steps. Here, the preset range can be less than or equal to 10%.

[0121] It should be noted that the specific numerical range of the preset range given in the embodiments of this disclosure is only an example. In actual applications, the specific setting of the preset range depends on the specific requirements of the material and process of the metal film layer. The scope of protection of this disclosure should not be excessively limited here.

[0122] like Figure 6 As shown, Figure 6 The dashed line in the middle is Figure 5 The curves showing the signal intensity changes at different locations on the wafer surface at the third time point T3 are shown. Figure 6 The solid line in the middle is Figure 5 The curves showing the signal intensity variation at different locations on the wafer surface at the first moment T1 are shown.

[0123] Depend on Figure 6 It can be seen that at the first time T1, the signal intensity at the edge region (130mm) of the wafer surface decreases significantly at the third time T3 after the cleaning operation, indicating that the cleaning operation in the embodiment of this disclosure effectively improves the uniformity and efficiency of the overall polishing operation.

[0124] In some embodiments, the wafer surface can be further divided into more refined regions, such as 10, 15, or 20 regions, to achieve more precise control of polishing parameters.

[0125] In practical applications, the wafer surface can be rationally divided according to the size of the wafer.

[0126] In some embodiments, when establishing a preset function model, the relationship between the endpoint detection result and the polishing parameters can be further refined. For example, based on the endpoint detection result being outside a preset range, the relationship between the endpoint detection result and the polishing parameters can be further established according to the degree to which the endpoint detection result exceeds the preset range. It is understood that the preset function model can further characterize the specific numerical value of the difference between the endpoint detection result and the preset range and the relationship between the polishing parameters, so as to more accurately set appropriate polishing parameters based on the endpoint detection result and improve polishing quality.

[0127] Here, the preset function model can be a linear function model, a quadratic function model, an exponential function model, or a logarithmic function model.

[0128] In some implementations, when setting polishing parameters based on endpoint detection results in conjunction with a preset function model, the larger the difference between the endpoint detection result and the preset range, the larger the value of the polishing parameters should be.

[0129] In some implementations, such as Figure 5As shown, the endpoint detection result includes a fourth signal, a third signal, and a second signal corresponding to the thickness of the metal film layer in three regions (edge ​​region, middle region, and center region) of the wafer surface, respectively. The endpoint detection result also includes a first signal characterizing the overall thickness of the metal film layer on the wafer surface. The difference between the fourth signal and the first signal is recorded as the first sub-parameter, the difference between the third signal and the first signal is recorded as the second sub-parameter, and the difference between the second signal and the first signal is recorded as the third sub-parameter. A preset function model is established based on the differences between the first sub-parameter, the second sub-parameter, and the third sub-parameter and a preset range. For example, if the first sub-parameter is 40%, the second sub-parameter is 20%, the third sub-parameter is 8%, and the preset range is 10%, then the first sub-parameter and the second sub-parameter are both outside the preset range. The polishing parameters are set according to the difference between the first sub-parameter and the preset range being 30% and the difference between the second sub-parameter and the preset range being 10%. For example, the polishing pressure of the edge region corresponding to the first sub-parameter is set to 2.5 Psi, and the polishing pressure of the middle region corresponding to the second sub-parameter is set to 0.8 Psi.

[0130] In some embodiments, when the polishing parameter is polishing time, the polishing time can be controlled by dividing the area to achieve selective removal of metal film layers of different thicknesses in different areas.

[0131] In some embodiments, when the polishing parameter is the polishing pad temperature, the polishing pad temperature can be controlled in different regions to achieve selective removal of metal film layers of different thicknesses in different regions.

[0132] In some embodiments, when the polishing parameter is the polishing slurry landing point, Figure 5 In the scenario shown, the polishing slurry landing point in the second polishing operation can be set to the edge region of the wafer surface to increase the concentration of polishing slurry in the edge region of the wafer surface and improve the removal rate of the metal film layer in the edge region of the wafer surface.

[0133] In some embodiments, when the polishing parameters are the pressure and frequency of the dresser, Figure 5 In the scenario shown, the pressure and frequency of the dressing device for the polishing pad corresponding to the wafer edge region in the second polishing operation can be set to be larger to improve the removal capability of the polishing pad corresponding to the wafer edge region and increase the removal rate of the metal film layer in the edge region.

[0134] It should be understood that the phrases "some embodiments," "one embodiment," or "an embodiment" throughout the specification mean that a specific feature, structure, or characteristic related to an embodiment is included in at least one embodiment of this disclosure. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of this disclosure, the sequence numbers of the above-described processes do not imply a sequential order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this disclosure. The sequence numbers of the above-described embodiments are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0135] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0136] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A chemical mechanical polishing method, characterized in that, The method includes: A polishing operation is performed on the surface of a wafer, wherein the polishing slurry used in the polishing operation contains an inhibitor; Obtain the endpoint detection result of the metal film layer on the surface of the wafer, and the endpoint detection result is used to characterize the thickness of the metal film layer; If the endpoint detection result is outside the preset range, a cleaning operation is performed on the polishing pad and the wafer surface to at least remove the inhibitors remaining on the wafer surface; The polishing and cleaning operations are performed alternately until the endpoint detection result is within the preset range or the number of polishing operations reaches the preset number.

2. The chemical mechanical polishing method according to claim 1, characterized in that, The step of performing a cleaning operation on the polishing pad and the wafer surface based on the endpoint detection result being outside the preset range includes: A first cleaning operation is performed on the wafer surface and the polishing pad using a first cleaning solution; A second cleaning operation is performed on the wafer surface and the polishing pad using a second cleaning solution; wherein the second cleaning solution is water and the pressure of the second cleaning solution is greater than or equal to 200 kPa.

3. The chemical mechanical polishing method according to claim 2, characterized in that, The solubility of the inhibitor in the first cleaning solution is greater than a first preset threshold, and the solubility of the first cleaning solution in the second cleaning solution is greater than a second preset threshold; the pH value of the first cleaning solution and the pH value of the polishing solution are both less than 7, and the difference between the pH value of the first cleaning solution and the pH value of the polishing solution is less than or equal to a third preset threshold.

4. The chemical mechanical polishing method according to claim 3, characterized in that, The polishing slurry contains an inhibitor of benzotriazole; the first cleaning slurry contains an alcoholic organic solvent and an organic acid, wherein the organic acid has a pH value greater than 4 and less than 7.

5. The chemical mechanical polishing method according to claim 4, characterized in that, The alcoholic organic solvent includes at least one of methanol, ethanol, or ethylene glycol; the organic acid includes at least one of citric acid, formic acid, or acetic acid.

6. The chemical mechanical polishing method according to claim 4, characterized in that, The volume fraction of the alcohol-based organic solvent is 30%-50%.

7. The chemical mechanical polishing method according to claim 1, characterized in that, The polishing operation on the wafer surface includes: Based on the endpoint detection result of the metal film layer on the wafer surface obtained after the Nth polishing operation, and combined with the preset function model, the polishing parameters for the N+1th polishing operation are set; the preset function model is used to characterize the relationship between the endpoint detection result and the polishing parameters, where N is a positive integer greater than or equal to 1.

8. The chemical mechanical polishing method according to claim 7, characterized in that, The endpoint detection result of the metal film layer on the wafer surface obtained after the Nth polishing operation includes at least one or more sub-parameters corresponding to multiple regions of the wafer surface. Based on the endpoint detection result obtained after the Nth polishing operation, and in conjunction with a preset function model, the polishing parameters for the (N+1)th polishing operation are set, including: Based on the sub-parameters and combined with the preset function model, corresponding polishing parameters are set for each of the multiple regions.

9. The chemical mechanical polishing method according to any one of claims 1 to 8, characterized in that, The alternating execution of the polishing and cleaning operations until the endpoint detection result is within the preset range or the number of polishing operations reaches the preset number includes: If the endpoint detection result is within the preset range, the polishing operation on the wafer surface is terminated. or, Once the preset number of polishing operations is reached, the polishing operation on the wafer surface ends and an alarm message is issued.

10. A chemical mechanical polishing apparatus, characterized in that, include: A polishing pad covered with a polishing pad for polishing a wafer surface, wherein the polishing fluid used in the polishing operation contains an inhibitor; A support head for holding the wafer and pressing the wafer onto the polishing pad; The detection module is used to detect the metal film layer on the surface of the wafer to obtain an endpoint detection result, which is used to characterize the thickness of the metal film layer. A cleaning module is used to perform a cleaning operation on the polishing pad and the wafer surface, at least removing residual inhibitors on the wafer surface; The control module is configured to: control the polishing pad to perform a polishing operation on the wafer surface; acquire the endpoint detection result output by the endpoint detector; and, if the endpoint detection result is outside a preset range, control the cleaning module to perform a cleaning operation on the polishing pad and the wafer surface; and control the polishing pad and the cleaning module to alternately perform the polishing operation and the cleaning operation until the endpoint detection result is within the preset range or the number of polishing operations reaches a preset number.

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