Polishing head assembly, chemical mechanical polishing system and wafer preparation method

Abstract

The embodiment of the invention provides a polishing head assembly, a chemical mechanical polishing system and a preparation method of a wafer. The polishing head assembly includes: a rigid base; the elastic bearing part is arranged on one side of the rigid base, and the elastic bearing part is provided with a bearing surface which is deviated from the rigid base and is used for bearing a wafer; the thickness detection assembly is arranged on the rigid base and located on the side, away from the bearing face, of the elastic bearing part, and the thickness detection assembly is configured to be used for obtaining thickness distribution data of the elastic bearing part; and the pressure sensing assembly is arranged on the elastic bearing part, and the pressure sensing assembly is configured to detect the pressure distribution state between the bearing surface and the wafer when the polishing head assembly executes the polishing operation. The polishing head assembly can solve the problem that the aging state and the actual interface pressure of wafer carrier consumables cannot be observed in real time in the semiconductor chemical mechanical polishing (CMP) process.

Description

Technical Field

[0001] This application relates to the field of semiconductor materials technology, and in particular to polishing head assemblies, chemical mechanical polishing systems, and methods for preparing wafers. Background Technology

[0002] As integrated circuit manufacturing processes evolve, the number of layers in multilayer interconnect structures continues to increase, placing extremely high precision demands on the global planarization of the wafer surface. Chemical mechanical polishing (CMP) is currently a key process technology capable of achieving global planarization.

[0003] In CMP (Chemical Mechanical Polishing), the polishing head assembly carries the wafer and presses it against a rotating polishing pad, removing excess material through the synergistic effect of chemical slurry and mechanical friction. The stability and uniformity of the polishing process directly determine the yield and electrical performance of the final product. With the increase in wafer size (e.g., 300mm wafers) and the narrowing of the process window, the manufacturing system places higher demands on its ability to monitor the process.

[0004] However, in actual production, ensuring the performance consistency of polishing head assemblies under long-term, high-intensity operation and reducing unplanned downtime and wafer scrap caused by equipment status fluctuations remains a common challenge that urgently needs to be addressed in the semiconductor manufacturing industry. Related technologies often have monitoring blind spots when dealing with the aforementioned extremely high-precision planarization requirements, making it difficult to meet the stringent standards of advanced processes in terms of process stability, thereby affecting production efficiency and manufacturing costs. Summary of the Invention

[0005] In view of this, embodiments of this application provide a polishing head assembly, a chemical mechanical polishing system, and a wafer fabrication method, aiming to eliminate the problem that the aging state of the wafer carrier consumables and the actual interface pressure cannot be observed in real time during semiconductor chemical mechanical polishing (CMP).

[0006] The technical solution of this application is implemented as follows: In a first aspect, embodiments of this application provide a polishing head assembly, the polishing head assembly comprising: Rigid base; An elastic support element is disposed on one side of a rigid base. The elastic support element has a support surface that is away from the rigid base and is used to support the wafer. A thickness detection component, mounted on a rigid base and located on the side of the elastic support member opposite to the bearing surface, is configured to acquire thickness distribution data of the elastic support member; and A pressure sensing component is disposed on the elastic support member and is configured to detect the pressure distribution between the support surface and the wafer when the polishing head assembly performs a polishing operation.

[0007] In some embodiments, the thickness detection assembly includes a laser emitter and a photodetector, wherein the optical path of the laser emitter is arranged to point toward the surface of the elastic support.

[0008] In some embodiments, the thickness detection component is configured to acquire thickness values ​​of multiple sampling points of the elastic support when the polishing head assembly is in a non-working state, and to calculate the total thickness change of the elastic support based on the thickness values ​​of the multiple sampling points.

[0009] In some embodiments, the pressure sensing component includes a flexible thin film substrate and a plurality of pressure sensing units disposed on the flexible thin film substrate, wherein the flexible thin film substrate is disposed on an elastic support member.

[0010] In some embodiments, the plurality of pressure sensing units are distributed on a flexible thin film substrate, and the plurality of pressure sensing units cover the effective area in the bearing surface corresponding to the wafer.

[0011] In some embodiments, the elastic support member includes a rubber pad, which is fixedly connected to the rigid base by a retaining ring.

[0012] In some embodiments, the polishing head assembly further includes a data transmission module electrically connected to the thickness detection component and the pressure sensing component, and the data transmission module is configured to send thickness distribution data and pressure distribution status to an external control terminal.

[0013] In some embodiments, the data transmission module includes a wireless communication unit disposed within a rigid base.

[0014] Secondly, embodiments of this application provide a chemical mechanical polishing system, comprising: According to the polishing head assembly of the first aspect; A polishing table is provided with a polishing pad, and a polishing head assembly is configured to press the wafer against the polishing pad; and The control terminal is connected in communication with the polishing head assembly. The control terminal is configured to receive thickness distribution data and compare the thickness distribution data with preset reference thickness data; The control terminal is also configured to allow the polishing head assembly to perform polishing operations when the thickness distribution data meets preset conditions, and to receive and record the pressure distribution status.

[0015] In some embodiments, the control terminal is also configured to generate a real-time pressure distribution cloud map when receiving the pressure distribution status.

[0016] Thirdly, embodiments of this application provide a method for fabricating a wafer, which is performed using a polishing head assembly according to the first aspect, and the method includes: When the polishing head assembly is not in operation, the thickness detection assembly is controlled to scan the elastic support to obtain thickness distribution data. Determine whether the thickness distribution data is within the preset acceptable range; When the thickness distribution data is within the preset acceptable range, the polishing head assembly is controlled to pick up the wafer and perform the polishing operation; and During the polishing process, the pressure distribution between the elastic support and the wafer is collected in real time through pressure sensing components.

[0017] In some embodiments, the preparation method further includes: After installing the new elastic support component, control the thickness detection component to scan and obtain initial thickness data; Store the initial thickness data as reference thickness data; The process of determining whether the thickness distribution data is within a preset acceptable range includes: calculating the difference between the thickness distribution data and the reference thickness data, and determining whether the difference is less than a preset threshold.

[0018] In some embodiments, the preparation method further includes: locking the polishing head assembly and issuing an alarm signal when the thickness distribution data exceeds a preset qualified range.

[0019] This application provides a polishing head assembly, a chemical mechanical polishing system, and a wafer fabrication method to eliminate the "black box" problem in the semiconductor chemical mechanical polishing (CMP) process, namely, the inability to observe the aging state of the wafer carrier consumables and the actual interface pressure in real time. The polishing head assembly integrates a thickness detection component and a pressure sensing component within a rigid base and elastic support structure. This structural combination enables, on the one hand, predictive screening and lifetime management of consumables through static thickness scanning, preventing operations before defective wafers are generated and avoiding costly yield losses; on the other hand, it provides real-time visualization of wafer stress through dynamic pressure monitoring and lays the hardware foundation for dynamic closed-loop compensation control of the control system, thereby significantly improving the uniformity, stability, and controllability of the CMP process. Attached Figure Description

[0020] Figure 1 A schematic structural diagram of a chemical mechanical polishing system provided for an embodiment of this application.

[0021] Figure 2 A schematic cross-sectional view of the polishing head assembly provided in an embodiment of this application.

[0022] Figure 3 A schematic cross-sectional view of the polishing head assembly provided in the embodiments of this application when carrying a wafer.

[0023] Figure 4 A schematic cross-sectional view of the polishing head assembly provided in the embodiments of this application when carrying a wafer.

[0024] Figure 5 A flowchart illustrating a wafer fabrication method provided in an embodiment of this application.

[0025] Figure 6 A comparison curve of wafer removal amount profiles under different elastic support thicknesses. Detailed Implementation

[0026] The technical solutions in this application will now be clearly and completely described with reference to the accompanying drawings.

[0027] In chemical mechanical polishing (CMP), the material removal rate typically follows the principle that "removal rate is proportional to the applied pressure and relative speed." In actual wafer fabrication processes, the speed variable is usually precisely controlled by a high-precision motor driver, making it relatively easy to quantify. However, research has revealed that the "pressure" variable exhibits extremely high uncertainty at the microscopic interface, posing a core risk factor for process deviations.

[0028] Specifically, the wafer is not directly and rigidly connected to the drive shaft. Instead, it is held in place and pressurized by an elastic support element in the polishing head assembly, typically a flexible diaphragm made of rubber. This design aims to compensate for the microstructure differences on the back side of the wafer by utilizing the deformation of the elastomer. However, this mechanism of force transmission relying on the elastomer introduces a subtle variable: the physical degradation of the consumable material.

[0029] Analysis of a large number of failure modes reveals the following phenomena.

[0030] First, there is static morphology drift. After thousands of compression and release cycles, the thickness distribution of the elastic support component undergoes nonlinear changes due to the hysteresis effect of the polymer material and the wear of the grinding environment. In particular, the edge regions fixed to the rigid base (such as those near the fixing ring) tend to wear faster than the central regions. Although this thickness variation may be on the micrometer scale and difficult to detect macroscopically, at the 7nm process node, it is sufficient to cause a significant deviation in the removal rate at the wafer edge.

[0031] To visually demonstrate the critical impact of variations in the thickness of the elastic support component on the uniformity of CMP polishing, see [link to relevant documentation]. Figure 6 The diagram shows a comparison of wafer removal profiles under different elastic support thicknesses. Curve ① represents the wafer removal profile obtained using an elastic support with a thickness of 23.03 mm, and curve ② represents the wafer removal profile obtained using an elastic support with a thickness of 23.19 mm. Figure 6As shown, even a small thickness difference (approximately 0.16 mm) in the elastic support component of the polishing head assembly can significantly alter the wafer removal profile, resulting in an overall shift in the removal profile. This experimental verification strongly demonstrates that microscopic thickness variations in the elastic support component can directly change the actual force distribution at various points on the wafer during polishing, leading to significant inconsistencies in the removal rate (RR).

[0032] In addition, there is dynamic pressure distortion. Existing control logic typically assumes that the thickness of the elastic support is uniform and constant. When the elastic support exhibits the aforementioned thickness variation, the actual face pressure transmitted to the back of the wafer will be distorted, even if the pneumatic control system applies a standard set pressure (e.g., 2.5 psi). Thinner areas may transmit greater forces or experience poor contact due to excessive deformation.

[0033] Furthermore, the wafer itself may exhibit warpage of up to tens of micrometers after thin film deposition. In a high-speed rotating wet process environment, this wafer warpage, combined with the aging of the elastic support, results in an extremely complex and invisible distribution of contact stress between the wafer and the polishing pad.

[0034] However, monitoring methods in related technologies are usually limited to monitoring external equipment parameters (such as motor current and total downforce) or rely on offline measurements after polishing. This "black box" operating mode cannot perceive changes in the microscopic state of consumables inside the polishing head assembly in real time. Often, only when multiple wafers show abnormal edge removal rates, such as over-polishing or under-polishing, can it be deduced that the elastic support component has failed, resulting in costly yield losses and waste of consumables.

[0035] In view of this, embodiments of this application provide a polishing head assembly, a chemical mechanical polishing system, and a wafer fabrication method capable of breaking the above-mentioned state, thereby achieving closed-loop control of process stability by constructing dual-modal sensing capabilities in situ.

[0036] See Figure 1 This application provides a chemical mechanical polishing system 1, which is designed to provide nanoscale global planarization for semiconductor wafers of 300 mm, i.e. 12 inches, or larger.

[0037] like Figure 1 As shown, the chemical mechanical polishing system 1 mainly includes a polishing table 200, a polishing pad 201 disposed on the polishing table, a polishing head assembly 100, and a control terminal 300.

[0038] The polishing table 200 can be made of metal, for example, with a surface that has been precision ground to a flatness controlled within extremely small tolerances. In operation, the polishing table 200 can be rotated by a servo motor.

[0039] Polishing pad 201 is attached to the polishing table and is a consumable that comes into direct contact with the wafer. In this embodiment, the polishing pad can be a rigid polyurethane pad with concentric grooves or grid grooves. A chemical slurry is continuously supplied to the surface of the polishing pad during the polishing process. The slurry typically contains nanoscale abrasive particles and chemical components such as oxidants and corrosion inhibitors. The flow rate of the slurry is controlled to ensure sufficient lubrication and reaction medium at the polishing interface.

[0040] The polishing head assembly 100 is the core execution unit of this system. It is configured to pick up the wafer 400 and press it against the rotating polishing pad 201. The polishing head assembly 100 is also driven by a motor to rotate, and its rotation direction is usually the same as that of the polishing table. The rotation speed is usually set to maintain a small speed difference with the polishing table to optimize the uniformity of the removal rate. At the same time, the polishing head assembly 100 can also reciprocate in the radial direction of the polishing table 200 to improve the utilization rate of the polishing pad.

[0041] The control terminal 300, acting as the "brain" of the system, communicates with the polishing head assembly 100. The control terminal 300 can be an advanced process control (APC) system based on an industrial PC. The control terminal 300 is not only responsible for issuing process recipes, such as setting parameters like pressure, speed, and time, but more importantly, it is configured to receive real-time data from sensors inside the polishing head assembly 100.

[0042] Please see Figure 2 , Figure 2 This is a schematic cross-sectional view of a polishing head assembly provided in an embodiment of this application. The polishing head assembly 100 aims to address the problem in the prior art of not being able to detect consumable aging and interface stress in situ.

[0043] like Figure 2 As shown, the polishing head assembly 100 may include: a rigid base 10, an elastic support 20, a thickness detection assembly 30, and a pressure sensing assembly 40.

[0044] The rigid base 10 forms the skeleton of the entire assembly and has an inverted cup or disc-shaped structure. To resist the enormous shear forces and chemical corrosion generated during polishing, the rigid base 10 is typically made of stainless steel or hard anodized aluminum alloy.

[0045] The upper end of the rigid base 10 is connected to the drive shaft of the CMP device and can rotate at high speed with the drive shaft. The rigid base 10 has one or more accommodating chambers for mounting electronic components and pneumatic systems. Importantly, the rigid base 10 provides an absolutely stationary physical reference for the internal precision optical components relative to the polishing head's own coordinate system.

[0046] The elastic support member 20 is disposed on one side of the rigid base 10, i.e., the side facing the polishing pad. The elastic support member 20 may be in the form of a rubber diaphragm or a rubber pad. The elastic support member 20 has a support surface 20A that is opposite to the rigid base 10 and is used to support the wafer 400.

[0047] In this embodiment, the elastic support member 20 can be made of, for example, high-performance ethylene propylene diene monomer (EPDM) rubber or high-purity silicone rubber, to have excellent acid and alkali corrosion resistance and resilience.

[0048] The hardness of the elastic support 20 can be selected according to application requirements. For example, in a fine polishing process, a softer elastic support 20 can be used to obtain better local flatness; while in a rough polishing process, a harder elastic support 20 can be used. The thickness of the elastic support 20 can also be selected according to the thickness of the wafer and the corresponding dimensions of the rigid base 10.

[0049] The edge of the elastic support member 20 is secured to the lower edge of the rigid base 10 by a retaining ring 21. The retaining ring 21 is typically made of a wear-resistant, rigid material. See also Figure 3 The function of the retaining ring 21 is not only to fix the elastic bearing 20, but also to restrict the wafer like a "fence" during the polishing process and prevent the wafer from flying out under the action of centrifugal force.

[0050] It should be noted that the edge area of ​​the elastic bearing member 20 connected to the fixed ring 21 is the part with the most concentrated stress due to repeated inflation and mechanical compression, and is also the high-risk area most prone to wear and thinning.

[0051] To address the issue of "invisible aging of consumables," this application integrates a thickness detection component 30 within the rigid base 10. The thickness detection component 30 is disposed on the rigid base 10 and located on the side of the elastic support member 20 away from the support surface 20A, i.e., the inner side or dry side of the elastic support member.

[0052] The thickness detection component 30 is configured to acquire thickness distribution data of the elastic support member 20. Specifically, the thickness detection component 30 includes a laser emitter and a photodetector, or integrates them into a laser displacement sensor probe.

[0053] Considering that EPDM rubber may be black and has strong light absorption, spectral confocal or laser triangulation techniques can be used. The wavelength of the laser emitter is, for example, red visible light (650-670nm) or near-infrared light to ensure a stable reflection signal on the black rubber surface.

[0054] The optical path of the laser emitter is arranged to point towards the inner surface 20B of the elastic support member 20, that is, the surface of the elastic support member 20 facing away from the support surface 2. In order to achieve full-field scanning, the thickness detection component 30 can be mounted on a miniature linear module inside the rigid base 10, or the polishing head assembly 100 can be rotated by itself in conjunction with a radial movement mechanism to form a spiral or concentric circular scanning trajectory.

[0055] See Figure 3 The sensor emits a laser beam that illuminates the inner surface of the elastic support member 20 and receives the reflected light, thereby accurately measuring the distance d from the rigid base 10 to the inner surface 20B of the elastic support member 20. See also Figure 2 Given the reference distance D from the rigid base 10 to the bearing surface 20A of the elastic bearing member 20 (in the unloaded state), the local thickness T of the elastic bearing member can be derived geometrically. When the elastic bearing member thins due to wear, the distance d increases. The sensor's measurement accuracy can be set as needed, for example, to 0.1 μm to 1.0 μm, to capture minute wear changes.

[0056] The thickness detection component 30 is configured to operate when the polishing head assembly 100 is not in operation, such as during the cleaning stage before polishing or during wafer replacement, to acquire thickness values ​​at multiple sampling points of the elastic support component 20, and construct a thickness distribution map based on these points, thereby calculating the total thickness variation (TTV). If the TTV exceeds a preset threshold (e.g., >30μm), the system will determine that the consumable has reached the end of its lifespan, thereby preventing the use of defective elastic support components in production.

[0057] The polishing head assembly 100 may also be provided with a pressure sensing assembly 40 to solve the problem of unknown interface stress distribution.

[0058] A pressure sensing component 40 is disposed on the elastic support member 20. The pressure sensing component 40 is configured to monitor the pressure distribution between the support surface 20A and the wafer 400 in real time when the polishing head assembly 100 performs a polishing operation.

[0059] like Figure 4 As shown, the pressure sensing component 40 includes a flexible thin film substrate 41 and a plurality of pressure sensing units 42 disposed thereon.

[0060] The flexible film substrate 41 is thin and flexible to avoid affecting the uniformity of polishing. For example, the flexible film substrate 41 can be made of polyimide material, with the thickness adjusted according to the other components of the polishing head assembly 100. This material has excellent high-temperature resistance to withstand the frictional heat generated during polishing and excellent mechanical strength.

[0061] Pressure sensing units 42 can be distributed on a flexible thin film substrate 41 to form an array. The sensing mechanism can be piezoresistive or capacitive. In some embodiments of this application, piezoresistive nanocomposite ink is used for printing, and its resistance decreases logarithmically with increasing pressure. The sensitivity of the pressure sensing units 42 is set according to the accuracy range of the target product to accurately distinguish minute pressure fluctuations, such as 0.1 psi, fully covering the ultra-low pressure window required for advanced polishing processes.

[0062] Multiple pressure sensing units 42 cover the effective area of ​​the bearing surface 20A corresponding to the wafer. For example, for a 300mm wafer, the multiple pressure sensing units 42 can be distributed in a concentric circle, corresponding to the central area, middle area and edge area of ​​the wafer respectively. In particular, the sensor density in the edge area can be higher to monitor the most critical edge repulsion effect.

[0063] To prevent corrosion from chemical slurries, the entire surface of the pressure sensing component 40 is covered with an extremely thin encapsulation layer, which is made of, for example, Teflon (PTFE). In terms of manufacturing process, the component can be attached to the outer surface of the elastic support 20 by adhesive, or directly embedded or vulcanized into the rubber matrix of the elastic support 20, thereby forming an integrated smart elastic support.

[0064] Because the polishing head assembly 100 rotates at high speed during operation, the wired connection is extremely prone to tangling and breakage. Therefore, see Figure 2 In this embodiment, the polishing head assembly 100 also includes a data transmission module 50. The data transmission module 50 is disposed in a sealed cavity inside the rigid base 10 and is electrically connected to the thickness detection assembly 30 and the pressure sensing assembly 40. The data transmission module 50 is configured to send the collected thickness distribution data and pressure distribution status to an external control terminal 300.

[0065] The data transmission module 50 may include a wireless communication unit. To address the shielding issue of the metal base on wireless signals, the rigid base 10 may be designed with a radio frequency (RF) transparent window, such as a cover plate made of PEEK material, or the antenna may be led out to the vicinity of a slip ring at the top of the base. Furthermore, the wireless module can be powered using inductively coupled wireless power supply technology, with the primary coil fixed to the equipment rack and the secondary coil mounted on a rotating shaft, thereby achieving continuous power supply without batteries or maintenance.

[0066] Some embodiments of this application also provide a method for fabricating a wafer using the above-described components. This fabrication method transforms traditional experience-driven maintenance into data-driven process control.

[0067] See Figure 5 , Figure 5This is a flowchart illustrating a wafer fabrication method provided in an embodiment of this application. The fabrication method may include steps S101 to S104.

[0068] In step S101, when the polishing head assembly is in a non-working state, the thickness detection assembly is controlled to scan the elastic support to obtain thickness distribution data.

[0069] In step S102, it is determined whether the thickness distribution data is within the preset acceptable range.

[0070] In step S103, if the thickness distribution data is within a preset acceptable range, the polishing head assembly is controlled to adsorb the wafer and perform the polishing operation.

[0071] In step S104, during the polishing process, the pressure distribution between the elastic support and the wafer is collected in real time by the pressure sensing component.

[0072] Before each polishing operation begins, the control terminal 300 instructs the thickness detection component 30 to scan the elastic carrier when the polishing head assembly 100 is in a non-working state, such as during wafer loading or cleaning, in order to perform static fingerprint collection and consumable life prediction.

[0073] Of particular note is that after installing the new elastic support component, the chemical mechanical polishing system 1 performs an initial calibration. The chemical mechanical polishing system 1 controls the thickness detection component 30 to perform a full-field scan of the new elastic support component, acquiring initial thickness data and storing it as reference thickness data. This serves as a zero-point reference for subsequent wear calculations, thereby eliminating errors caused by manufacturing tolerances between different batches of elastic support components. In subsequent pre-inspection, the polishing head assembly rotates at a low speed, and the thickness detection component scans again to acquire the current thickness distribution data.

[0074] Subsequently, the chemical mechanical polishing system 1 enters the acceptance judgment stage. For example, it can calculate the difference between the current thickness distribution data and the reference thickness data, and calculate the total thickness variation (TTV). If the difference or TTV is within a preset acceptance range, such as less than a preset threshold, the chemical mechanical polishing system 1 determines that the consumable is in good condition and allows subsequent operations to proceed; conversely, if the data exceeds the preset acceptance range, the system will trigger process lock, forcibly stop the machine and issue an alarm signal, thereby preventing operations before defective products are generated and preventing wafer scrap due to consumable failure.

[0075] Only after the static thickness test is passed can the chemical mechanical polishing system 1 control the polishing head assembly to adsorb the wafer and perform the polishing operation. During the polishing operation, the system switches to dynamic monitoring mode, and the pressure sensing component 40 works continuously to collect the interfacial pressure distribution between the elastic support and the wafer in real time.

[0076] In the dynamic pressure imaging and in-situ compensation stage, a flexible sensor array acquires discrete interface pressure data at high frequencies (e.g., 100Hz). The control terminal 300 uses, for example, interpolation to spatially interpolate the discrete data, generating a continuous, high-resolution real-time pressure distribution cloud map, thereby accurately reconstructing the stress morphology of the wafer surface. The chemical mechanical polishing system 1 then compares the measured pressure distribution with the ideal target pressure distribution. If insufficient pressure is detected in areas such as the wafer edge, the control system will increase the back pressure of the corresponding independent gas chamber in real time until the measured pressure returns to the target range, thus achieving millisecond-level process monitoring and compensation.

[0077] Finally, all collected thickness data and pressure cloud maps are bound to the current wafer identification information and stored in the database to enable data traceability and correlation analysis, providing physical-level black box data for subsequent yield analysis.

[0078] It should be noted that the technical solutions described in this application can be combined arbitrarily without conflict.

[0079] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A polishing head assembly, comprising: The polishing head assembly comprises: a rigid base; an elastic carrier arranged on one side of the rigid base, the elastic carrier having a carrier surface facing away from the rigid base and used for carrying a wafer; a thickness detection assembly arranged on the rigid base and located on a side of the elastic carrier facing away from the carrier surface, the thickness detection assembly being configured to obtain thickness distribution data of the elastic carrier; and a pressure sensing assembly arranged on the elastic carrier, the pressure sensing assembly being configured to detect a pressure distribution state between the carrier surface and the wafer when the polishing head assembly performs a polishing operation.

2. The polishing head assembly of claim 1, wherein, The thickness detection assembly comprises a laser emitter and a photoelectric receiver, and an optical path of the laser emitter is arranged to point to a surface of the elastic carrier.

3. The polishing head assembly of claim 1, wherein, The thickness detection assembly is configured to obtain thickness values of a plurality of sampling points of the elastic carrier when the polishing head assembly is in a non-working state, and to calculate a total thickness variation of the elastic carrier based on the thickness values of the plurality of sampling points.

4. The polishing head assembly of claim 1, wherein, The pressure sensing assembly comprises a flexible film substrate and a plurality of pressure sensing units arranged on the flexible film substrate, wherein the flexible film substrate is arranged on the elastic carrier.

5. The polishing head assembly of claim 4, wherein, The plurality of pressure sensing units are distributed on the flexible film substrate, and the plurality of pressure sensing units cover an effective area corresponding to the wafer in the carrier surface.

6. The polishing head assembly of claim 1, wherein, The elastic carrier comprises a rubber pad fixedly connected to the rigid base by a fixing ring.

7. The polishing head assembly of claim 1, wherein, The polishing head assembly further comprises a data transmission module electrically connected with the thickness detection assembly and the pressure sensing assembly, and the data transmission module is configured to send the thickness distribution data and the pressure distribution state to an external control terminal.

8. The polishing head assembly of claim 7, wherein, The data transmission module comprises a wireless communication unit arranged in the rigid base.

9. A chemical mechanical polishing system characterized by comprising: The polishing head assembly according to any one of claims 1 to 8; a polishing table provided with a polishing pad, the polishing head assembly being configured to press a wafer against the polishing pad; and a control terminal in communication connection with the polishing head assembly; The control terminal is configured to receive the thickness distribution data and compare the thickness distribution data with preset reference thickness data; The control terminal is further configured to allow the polishing head assembly to perform a polishing operation when the thickness distribution data meets a preset condition, and to receive and record the pressure distribution state. The control terminal is further configured to generate a real-time pressure distribution cloud chart when receiving the pressure distribution state. The preparation method is performed by using the polishing head assembly according to any one of claims 1 to 8, and the preparation method comprises:

10. The chemical mechanical polishing system of claim 9, wherein, controlling the thickness detection assembly to scan the elastic carrier to obtain thickness distribution data when the polishing head assembly is in a non-working state; 11. A method of manufacturing a wafer, characterized by, determining whether the thickness distribution data is within a preset qualified range; controlling the polishing head assembly to adsorb a wafer and perform a polishing operation when the thickness distribution data is within the preset qualified range; and ​ ​ During the polishing operation, the pressure distribution state between the elastic carrier and the wafer is collected in real time by the pressure sensing assembly.

12. The method of claim 11, wherein the wafer is prepared by a method comprising: The preparation method further comprises: After a brand new elastic carrier is installed, the thickness detection assembly is controlled to perform scanning to obtain initial thickness data; The initial thickness data is stored as reference thickness data; The method further comprises: in the case where the thickness distribution data is out of the preset qualified range, the polishing head assembly is controlled to be locked, and an alarm signal is sent out.

13. The method of claim 11, wherein the wafer is prepared by a method comprising: ​

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