Wafer regeneration chemical mechanical polishing system and process

Abstract

The invention provides a wafer regeneration chemical mechanical polishing system and process, and belongs to the technical field of semiconductor manufacturing, and the wafer regeneration chemical mechanical polishing system comprises a buffer unit, a conveying unit, a polishing unit, a cleaning unit and a control unit, the conveying unit, the polishing unit and the cleaning unit are located on the same side of the buffering unit and are sequentially arranged along the first linear path, and the conveying unit is located between the polishing unit and the cleaning unit; the buffer unit comprises a plurality of wafer cassettes, an optical detection station located on one side of the plurality of wafer cassettes, and a transmission mechanism located on one side, close to the conveying unit, of the wafer cassettes; the conveying unit comprises a transfer disc moving along the second linear path; the polishing unit comprises a first polishing assembly and a second polishing assembly which are arranged along the second linear path. Each polishing assembly comprises at least two polishing discs and polishing heads corresponding to the polishing discs.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing technology, specifically relating to a wafer regeneration chemical mechanical polishing system and process. Background Technology

[0002] The semiconductor manufacturing industry continues to research and mass-produce more refined process nodes, gradually moving from the relatively mature 28nm and 22nm processes to 19nm and even more advanced processes, resulting in high demand for wafers as the core substrate. However, control wafers and test wafers used for equipment debugging and process monitoring face scrap after a single use due to residual film layers, scratches, and particulate defects. This not only causes a serious waste of silicon resources but also increases overall manufacturing costs. Especially in the context of advanced process modular applications, regenerated wafers must simultaneously meet the multiple demands of high-precision surfaces and efficient, low-cost regeneration.

[0003] Chemical mechanical polishing (CMP) can achieve global planarization of the wafer surface through the synergistic effect of chemical etching and mechanical grinding. Treating the surface of control wafers and test wafers with CMP facilitates recycling and reduces costs.

[0004] The matching degree between the equipment structure and process parameters in chemical mechanical polishing (CMP) directly determines the wafer regeneration effect. Currently, it has the following drawbacks: (1) Chemical mechanical polishing devices are mainly divided into two categories: "single-disc single-head" and "multi-disc single-head". "Single-disc single-head" can only achieve single-machine polishing and has low efficiency; "multi-disc single-head" supports multi-step polishing, but most of them are series fixed structures, which cannot operate independently and cannot meet the flexible switching requirements of the number of stages.

[0005] (2) Existing multi-stage polishing processes are mostly designed based on fixed equipment parameters, without taking into account the differences in wafer damage. This results in redundant processes for low-damage wafers and incomplete processing of high-damage wafers, leading to poor process adaptability. If parameter adjustment is required, it is necessary to rely on manual experience to judge wafer damage and manually match process parameters, which is not only inefficient but also prone to affecting regeneration quality due to parameter mismatch.

[0006] (3) Insufficient coordination between processes and equipment, lack of independent control over the pressure of polishing head, difficulty in adapting to different film layers (oxide film and metal film) and different damage areas, easily leading to uneven polishing and film residue.

[0007] (4) The risk of cross-process transfer is high. When wafers are transferred between different polishing units or polishing-cleaning equipment, there is a lack of anti-contamination and high-precision positioning structure, which can easily introduce environmental particles and edge damage, resulting in insufficient yield stability and difficulty in meeting the high efficiency and stability requirements of large-scale wafer regeneration. Summary of the Invention

[0008] This invention provides a wafer regeneration chemical mechanical polishing system and process, aiming to solve the technical problems of existing chemical mechanical polishing systems, such as inflexible parameter adjustment, poor process adaptability, difficulty in adapting to different film layers, and high risk of cross-process transfer of contamination.

[0009] In a first aspect, embodiments of the present invention provide a wafer regeneration chemical mechanical polishing system, including a buffer unit, a transfer unit, a polishing unit, a cleaning unit, and a control unit. The buffer unit extends along a first straight path, and the transfer unit, polishing unit, and cleaning unit are located on the same side of the buffer unit and arranged sequentially along the first straight path. The transfer unit is located between the polishing unit and the cleaning unit and extends along a second straight path, which is perpendicular to the first straight path. The buffer unit includes multiple wafer cassettes arranged along the first straight path, an optical inspection station located on one side of the multiple wafer cassettes, and a transmission mechanism located on the side of the wafer cassettes closer to the transmission unit. The conveying unit includes a transfer tray that moves along the second straight path; The polishing unit includes a first polishing component and a second polishing component arranged along the second straight path. The polishing component includes at least two polishing discs and polishing heads corresponding to the polishing discs. The multiple polishing discs are used to perform pre-polishing, rough polishing, fine polishing and buffer cleaning processes respectively. The cleaning unit is used to clean the polished wafers; The control unit is configured to receive the wafer damage level obtained by the optical inspection station, and set the polishing process and cleaning parameters according to the damage level.

[0010] The solution shown in this application embodiment, compared with the prior art, includes multiple polishing disks in both the first and second polishing components. These disks can be used individually or in conjunction with each other to meet different polishing steps in different polishing programs. This allows for adaptation to wafers with different damage levels, distinguishing it from existing fixed series structures. By classifying wafer damage processes through an optical inspection station, differentiated polishing treatments can be performed on wafers with different damage levels, overcoming the limitations of the identical traditional wafer polishing process and improving polishing efficiency and wafer reuse rate. Wafer damage identification, polishing, and cleaning are integrated into a single device, unlike the traditional wafer regeneration process where polishing and cleaning are separate devices. This achieves equipment autonomy and process integration, reduces the probability of contamination, and improves the yield of regenerated wafers. The control unit links with other units to achieve automatic adaptation of polishing parameters, polishing fluid, and sorting logic.

[0011] In conjunction with the first aspect, in one possible implementation, the buffer unit further includes: A guide rail extends along the first straight path and is located on the side of the plurality of wafer cassettes near the transfer unit; The transmission mechanism is slidably connected to the guide rail and is used to transfer the wafers in the wafer cassette to the optical inspection station, and to move the wafers in the optical inspection station to the transfer unit.

[0012] In conjunction with the first aspect, in one possible implementation, the transmission unit further includes: The first storage area includes multiple workstations, and the first storage area corresponds to the first polishing component; The second storage area includes multiple workstations, and the second storage area corresponds to the second polishing component; A clamping mechanism is used to clamp the transfer tray and place it on the workstation.

[0013] In conjunction with the first aspect, in one possible implementation, the transfer unit further includes a conversion mechanism located between the first storage area and the second storage area, for transferring the transfer tray from the first storage area to the second storage area.

[0014] In conjunction with the first aspect, in one possible implementation, both the first polishing component and the second polishing component include: A rotating mechanism is located at the center of the plurality of polishing discs; The polishing arm is fixed to the rotating mechanism; Each polishing head is fixedly connected to the polishing arm in a one-to-one correspondence.

[0015] In conjunction with the first aspect, in one possible implementation, both the first polishing component and the second polishing component include: A polishing pad dresser having a swingable dressing head having a first state of contacting a polishing pad on the polishing disk and a second state of being located on the outer periphery of the polishing disk; The liquid supply line has an outlet located above the polishing disc.

[0016] In conjunction with the first aspect, in one possible implementation, the cleaning unit includes a cleaning brush cleaning mechanism, a pen-type spray cleaning mechanism, and a single-piece cleaning mechanism arranged at intervals along the second straight path, with a transfer mechanism provided between two adjacent cleaning mechanisms.

[0017] Secondly, embodiments of the present invention also provide a wafer regeneration chemical mechanical polishing process, employing the aforementioned wafer regeneration chemical mechanical polishing system, comprising: S10: The polishing program is pre-set in the control unit according to the degree of damage; S20: The wafers in the wafer cassette are moved to the optical inspection station for damage assessment via a transfer mechanism. S30: The control unit sorts the wafers according to their degree of damage and processes them in descending order of damage. S40: The transfer mechanism places the wafer on the transfer tray, and the transfer tray delivers the wafer to the corresponding polishing unit according to the polishing program corresponding to the wafer. S50: The polishing unit polishes the wafer according to the polishing program corresponding to the wafer, and then the wafer enters the cleaning unit to clean it.

[0018] The solution described in this application, compared with the prior art, classifies wafer damage levels by integrating infrared optical detection into the buffer unit; it can also distinguish the film layers of highly damaged wafers based on the intensity of reflected light, avoiding the problem of incomplete film removal due to incorrect polishing slurry selection. The differentiated graded polishing process system design, through precise adaptation of parameters such as pressure, rotation speed, and polishing time, balances wafer defect removal efficiency and surface quality, preventing under-polishing or over-polishing. Dynamic sorting optimization of the buffer unit based on wafer damage level prioritizes highly damaged wafers entering the polishing unit, staggering the allocation of different polishing processes to avoid equipment capacity backlog, balancing production efficiency and polishing quality. Detection, program, and equipment linkage control achieve automatic adaptation of polishing parameters, polishing slurry, and sorting logic.

[0019] In conjunction with the second aspect, in one possible implementation, step S20 includes: Infrared light irradiation was used to collect the intensity fluctuation value of reflected light from the wafer; If the fluctuation value is ≤5%, the wafer is judged to be of low damage. If the fluctuation value is 5% to 10%, the wafer is judged to be of medium damage. If the fluctuation value is ≥10%, the wafer is determined to be highly damaged, and the film type determination process is triggered. If the reflectivity of infrared light is ≥80% and the reflected light waveform is uniform without impurities, it is considered to be a wafer containing a metal layer. If the reflectivity of infrared light is 10% to 80% and there are impurities in the waveform of the reflected light, it is considered to be a non-metallic film wafer.

[0020] In conjunction with the second aspect, in one possible implementation, the polishing degree corresponding to the low-damage wafer is rough polishing and fine polishing; The polishing process for moderately damaged wafers is rough polishing, fine polishing, and buffer cleaning. The polishing levels corresponding to high-damage wafers are pre-polishing, rough polishing, fine polishing, and buffer cleaning. Attached Figure Description

[0021] Figure 1A simplified structural schematic diagram of the wafer regeneration chemical mechanical polishing system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the main structure of the first polishing component used in an embodiment of the present invention; Figure 3 A schematic diagram of the wafer regeneration chemical mechanical polishing process provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the wafer processing used in an embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures: 10-Buffer unit; 11-Wafer box; 12-Optical inspection station; 13-Transmission mechanism; 14-Guide rail; 20-Transfer unit; 21-First storage area; 22-Second storage area; 23-Workstation; 24-Clamping mechanism; 25-Transfer tray; 26-Conversion mechanism; 30-Polishing unit; 31-First polishing assembly; 32-Second polishing assembly; 33-Polishing disc; 34-Polishing head; 35-Rotation mechanism; 36-Polishing arm; 37-Polishing pad dresser; 38-Liquid supply line; 40-Cleaning unit; 41-Cleaning brush cleaning mechanism; 42-Pen-type spray cleaning mechanism; 43-Single-piece cleaning mechanism; 44-Transfer mechanism.

[0023] 50 - Control Unit.

[0024] 60-film layer. Detailed Implementation

[0025] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0026] Please refer to the following: Figures 1 to 2 The wafer regeneration chemical mechanical polishing system provided by this invention will now be described. The wafer regeneration chemical mechanical polishing system includes a buffer unit 10, a transfer unit 20, a polishing unit 30, a cleaning unit 40, and a control unit 50. The buffer unit 10 extends along a first straight path; the transfer unit 20, polishing unit 30, and cleaning unit 40 are located on the same side of the buffer unit 10 and arranged sequentially along the first straight path. The transfer unit 20 is located between the polishing unit 30 and the cleaning unit 40 and extends along a second straight path, which is perpendicular to the first straight path.

[0027] The buffer unit 10 includes a plurality of wafer cassettes 11 arranged along a first straight path, an optical inspection station 12 located on one side of the plurality of wafer cassettes 11, and a transmission mechanism 13 located on the side of the wafer cassettes 11 near the transmission unit 20.

[0028] The conveying unit 20 includes a transfer tray 25 that moves along a second straight path.

[0029] The polishing unit 30 includes a first polishing component 31 and a second polishing component 32 arranged along a second straight path. Each polishing component includes at least two polishing discs 33 and polishing heads 34 corresponding to the polishing discs 33. The multiple polishing discs 33 are used to perform pre-polishing, rough polishing, fine polishing, and buffer cleaning processes, respectively.

[0030] The cleaning unit 40 is used to clean the polished wafer.

[0031] The control unit 50 is configured to receive the wafer damage level obtained by the optical inspection station 12 and set the polishing process and cleaning parameters according to the damage level.

[0032] It should be noted that the wafer has undergone pre-cleaning and rough grinding before being placed into the wafer cassette 11. Pre-cleaning is to remove contaminants from the wafer surface, and rough grinding is to remove the thick film layer 60 and deep damage.

[0033] In this embodiment, the multiple polishing discs 33 can respectively perform pre-polishing, rough polishing, fine polishing, and buffer cleaning. When the total number of polishing discs 33 in the polishing unit 30 is exactly four, the four polishing discs 33 perform different processes; when the total number of polishing discs 33 in the polishing unit 30 is greater than four, some polishing discs 33 may perform the same process. For example, there are five polishing discs 33, one for pre-polishing, one for rough polishing, two for fine polishing, and one for buffer cleaning.

[0034] By classifying wafer damage, three polishing processes can be defined: low-damage wafers undergo simplified two-step polishing; medium-damage wafers undergo standard three-step polishing; and high-damage wafers undergo enhanced four-step polishing.

[0035] The following describes the wafer movement trajectory using a four-step polishing process as an example: After the wafer is removed from the wafer cassette 11 by the transport mechanism 13, it is placed in the optical inspection station 12 for wafer damage type classification. After optical inspection, the control unit 50 automatically selects the polishing level, and the transport mechanism 13 removes the wafer and transports it to the transfer tray 25 on the transport unit 20. The position of the transfer tray 25 corresponds to the first polishing assembly 31. The polishing head 34 on the first polishing assembly 31 picks up the wafer from the transfer tray 25 and moves it to the polishing tray 33 for polishing. After polishing is completed on the first polishing component 31, the wafer is placed back onto the transfer tray 25 on the transfer unit 20. The transfer tray 25 moves the wafer to the corresponding position on the second polishing component 32. The polishing head 34 on the second polishing component 32 picks up the wafer from the transfer tray 25 and moves it to the polishing tray 33 for polishing. After contact, the polishing head 34 sends the wafer back onto the transfer tray 25. Then the wafer enters the cleaning unit 40. After the cleaning process is completed, the transfer unit 20 docks with the transfer mechanism 13 and sends the wafer back to the buffer unit 10.

[0036] It can be seen that the wafer box 11 is used not only to store unprocessed wafers, but also to store processed wafers. Different wafer boxes 11 store different types of wafers.

[0037] As an optional implementation, the control unit 50 may include a machine tool controller, a pressure controller, a computing module, a power supply module, a storage module, a damage identification module, and a transmission control module.

[0038] The wafer regeneration chemical mechanical polishing system provided in this embodiment, compared with the prior art, includes multiple polishing disks 33 in both the first polishing component 31 and the second polishing component 32. These disks can be used individually or in conjunction with each other to meet different polishing steps in different polishing programs. This system is adaptable to wafers with different damage levels, unlike existing fixed series structures. The optical inspection station 12 divides the wafer damage process, allowing for differentiated polishing treatment for wafers with different damage levels. This overcomes the limitations of the traditional wafer polishing process, improving polishing efficiency and wafer reuse rate. Wafer damage identification, polishing, and cleaning are integrated into a single device, unlike the traditional wafer regeneration process where polishing and cleaning are separate devices. This achieves equipment autonomy and process integration, reduces the probability of contamination, and improves the yield of regenerated wafers. The control unit 50 is linked with other units to achieve automatic adaptation of polishing parameters, polishing fluid, and sorting logic.

[0039] Specifically, an online wafer thickness detection device can be added to the polishing unit 30 to monitor and adjust the surface flatness of the wafer in real time.

[0040] In some embodiments, an improved implementation of the buffer unit 10 may employ, as follows: Figure 1 The structure shown. See also Figure 1The buffer unit 10 also includes a guide rail 14, which extends along a first straight path and is located on the side of the plurality of wafer cassettes 11 near the transfer unit 20.

[0041] The transfer mechanism 13 is slidably connected to the guide rail 14 and is used to transfer the wafers in the wafer cassette 11 to the optical inspection station 12 and to move the wafers in the optical inspection station 12 to the transfer unit 20.

[0042] According to the instructions of the control unit 50, the guide rail 14 and the transmission mechanism 13 take out the corresponding wafer to be regenerated from the wafer box 11, place it on the optical inspection station 12 for damage judgment, and then clamp and transport it to the transfer tray 25.

[0043] In this embodiment, the guide rail 14 provides a fixed motion trajectory for the transfer mechanism 13, preventing deviation in direction during transfer and ensuring accurate transfer of the wafer to the optical inspection station 12 and the transfer unit 20, thus reducing positioning errors. The transfer mechanism 13 slides in conjunction with the guide rail 14, making it more responsive to commands from the control unit 50. This allows for efficient and continuous operation of wafer cassette 11 picking, inspection station 23 feeding, and transfer unit 20 moving, shortening process intervals. By positioning the guide rail 14 on the side of the wafer cassette 11 closest to the transfer unit 20, the wafer transfer path is shortened, improving the response speed of the transfer mechanism 13 between the buffer unit 10 and the transfer unit 20, and reducing the risk of collisions during transfer.

[0044] In some embodiments, an improved implementation of the above-described transmission unit 20 may employ, as follows: Figure 1 The structure shown. See also Figure 1 The conveying unit 20 also includes a first storage area 21, a second storage area 22, and a clamping mechanism 24. The first storage area 21 includes multiple workstations 23 and corresponds to the first polishing component 31. The second storage area 22 includes multiple workstations 23 and corresponds to the second polishing component 32. The clamping mechanism 24 is used to clamp the transfer tray 25 and place it on the workstation 23.

[0045] The transfer tray 25 is held by the clamping mechanism 24 and can move along the first straight path or the second straight path with the clamping mechanism 24, as well as rotate within a preset angle range.

[0046] The first storage area 21 and the second storage area 22 correspond to the first polishing component 31 and the second polishing component 32, respectively. The partitioning and positioning of the transfer tray 25 are clearly defined to avoid confusion of wafers in different polishing steps, ensure that the wafers can be accurately docked with the corresponding polishing components, and reduce the positioning time of process switching.

[0047] The design of multiple workstations 23 supports the parallel flow of multiple wafers. Combined with the layout of multiple polishing disks 33 in the polishing unit 30, wafers with different damage levels and different polishing stages can be processed at the same time, breaking the capacity limitation of a single production line and improving the overall processing efficiency.

[0048] The clamping mechanism 24 stably clamps the transfer tray 25 to prevent the wafer from shifting, bumping or contaminating during transfer and storage, thus ensuring the surface quality of the wafer. At the same time, it provides a stable foundation for the subsequent polishing head 34 to accurately pick up the wafer and reduce polishing defects caused by wafer positioning deviation.

[0049] Optionally, the clamping mechanism 24 can be a robotic arm, which uses the coordinated action of cylinders and springs to grip the wafer. The clamping force can be controlled by adjusting the cylinder pressure to prevent wafer damage. The spring mechanism can accelerate the closing speed of the grippers in the robotic arm, improving work efficiency.

[0050] In some embodiments, an improved implementation of the above-described transmission unit 20 may employ, as follows: Figure 1 The structure shown. See also Figure 1 The transfer unit 20 also includes a conversion mechanism 26, which is located between the first storage area 21 and the second storage area 22, and is used to transfer the transfer tray 25 of the first storage area 21 to the second storage area 22.

[0051] The conversion mechanism 26 connects the first storage area 21 and the second storage area 22, and can automatically transfer the wafers that have completed the first polishing assembly 31 process to the corresponding station 23 of the second polishing assembly 32 without the need for the transfer tray 25. The transfer tray 25 is only used for transporting between the first storage area 21 and the buffer unit 10. The conversion mechanism 26 and the transfer tray 25 are each responsible for their respective areas, do not interfere with each other, and have shorter transport routes, resulting in higher transmission efficiency.

[0052] The synergistic effect of the conversion mechanism 26 and the transfer disk 25 can adapt to the polishing requirements of various damaged wafers, ensuring that the wafers flow between the polishing disks 33 corresponding to each process; realizing the smooth switching of multiple polishing programs and ensuring the orderly execution of complex polishing programs.

[0053] Optionally, the conversion mechanism 26 may adopt the same structure as the clamping mechanism 24.

[0054] In some embodiments, a specific implementation of the polishing assembly described above may employ, as follows: Figure 2 The structure shown. See also Figure 2 The first polishing assembly 31 and the second polishing assembly 32 both include a rotating mechanism 35 and a polishing arm 36. The rotating mechanism 35 is located at the center of the plurality of polishing discs 33; the polishing arm 36 is fixedly mounted on the rotating mechanism 35; and the polishing head 34 is fixedly connected to the polishing arm 36 in a corresponding manner.

[0055] The rotating mechanism 35 includes a rotary motor, a bearing spindle, a rotary joint, and a sweeping mechanism. Each polishing head 34 can be controlled independently. Taking a polishing assembly containing two polishing disks 33 as an example, two wafers can be processed on each side at a time, improving the processing efficiency of regenerated wafers.

[0056] The rotating mechanism 35 in this embodiment enables the polishing head 34 to quickly switch between multiple polishing discs 33, shortening the process changeover time. The polishing head 34 and polishing arm 36 correspond one-to-one, and combined with the precise transmission of the rotating mechanism 35, ensures consistency in the pressure angle and position of the polishing head 34 on the wafer, avoiding polishing problems caused by loose installation or transmission deviation.

[0057] Specifically, the polishing head 34 uses its own elastic membrane assembly to precisely control the regional pressure of the wafer in different areas, and works with the polishing pad and polishing fluid to complete the wafer polishing process.

[0058] To facilitate the inspection of wafer polishing, a detection device can also be installed at the end of each polishing assembly.

[0059] Currently, 300nm wafer polishing commonly uses polishing heads with 6 or 8 independent zones for precise pressure control, achieving a control accuracy of ±0.05psi, which can adapt to both conventional and advanced wafer manufacturing processes.

[0060] In some embodiments, an improved implementation of the polishing assembly described above may employ, as follows: Figures 1 to 2 The structure shown. See also Figures 1 to 2 Both the first polishing assembly 31 and the second polishing assembly 32 include a polishing pad dresser 37 and a liquid supply line 38. The polishing pad dresser 37 has a swingable dressing head, which has a first state of contact with the polishing pad on the polishing disk 33 and a second state of being located on the outer periphery of the polishing disk 33. The liquid supply line 38 has a liquid outlet located above the polishing disk 33.

[0061] The liquid supply line 38 can supply up to four types of polishing slurries. For example, the liquid supply line 38 includes a polishing slurry supply and a pure water rinse supply. The on / off state of the line is controlled by a pneumatically controlled solenoid valve, and the flow rate is precisely controlled by a closed-loop flow controller (CLC). The purpose of pure water rinsing is to clean the polishing interface in real time, avoid contamination accumulation, and ensure polishing accuracy and wafer surface quality.

[0062] The polishing pad dresser 37 is mainly used to polish and dress the polishing pad on the polishing disk 33 before, during, or after the polishing process. By precisely transmitting the set rotation speed and pressure, the polishing slurry on the polishing pad is distributed more evenly; it can also scrape away by-products in the grooves of the polishing pad in time, and achieve uniform removal of wafer surface material in combination with the chemical action of the polishing slurry and the mechanical abrasive force.

[0063] It should be noted that each polishing disc 33 corresponds to one polishing pad dresser 37 and one liquid supply line 38. As a variation, two polishing discs 33 may share one polishing pad dresser 37.

[0064] In some embodiments, a specific implementation of the cleaning unit 40 described above may employ, as follows: Figure 1 The structure shown. See also Figure 1 The cleaning unit 40 includes a cleaning brush cleaning mechanism 41, a pen spray cleaning mechanism 42, and a single-piece cleaning mechanism 43 arranged at intervals along the second straight path, and a transfer mechanism 44 is provided between two adjacent cleaning mechanisms.

[0065] The cleaning brush mechanism 41 consists of two cleaning brushes, one upper and one lower. The cleaning brushes are made of polyvinyl alcohol (PVA) and their lifting and lowering can be controlled by a servo motor. The pressure of the cleaning brushes on the upper and lower surfaces of the wafer can also be adjusted. It is surrounded by cleaning fluid and pure water rinsing pipelines, and particles are removed through physical and chemical action via rotational friction.

[0066] The pen-type spray cleaning mechanism 42 primarily uses a brush shaft to drive a rotating sponge brush head, which cleans the wafer surface. A pressure sensor is installed nearby to control the downward pressure of the sponge brush head on the wafer surface. The sponge brush head has internal liquid outflow channels that allow chemical solutions to flow out. The removal of particulate matter from the wafer surface is achieved through the rotation and radial movement of the sponge brush head.

[0067] The single-wafer cleaning mechanism 43 incorporates a two-fluid nozzle and an isopropyl alcohol (IPA) drying module. It removes minute residues through gas-liquid mixing and impact, and rapidly dries the wafer with nitrogen, achieving comprehensive and efficient cleaning and drying of the wafer.

[0068] With multiple cleaning mechanisms, the operating parameters of each cleaning mechanism can be flexibly adjusted according to the surface condition of the polished wafer, adapting to the cleaning needs of 60 wafers with different damage levels and different film layers, further ensuring that the surface roughness and cleanliness of the regenerated wafers meet the standards.

[0069] The transfer mechanism 44 between adjacent cleaning units enables rapid connection of wafers at different cleaning stations 23. The transfer mechanism 44 can be controlled by the control unit 50 to achieve rapid response, shorten the cleaning cycle, and meet the high-efficiency requirements of large-scale mass production.

[0070] Based on the same inventive concept, see [link to inventive concept] Figure 3 This application also provides a wafer regeneration chemical mechanical polishing process, employing the above-mentioned wafer regeneration chemical mechanical polishing system, including: (1) The polishing program is pre-set in the control unit 50 according to the degree of damage. Four pre-set fixed polishing programs are provided, corresponding to three types of damage: Program 1 is for Class I low damage - simplified two-step polishing; Program 2 is for Class II medium damage - standard three-step polishing; Program 3 is for Class III high damage - enhanced four-step polishing (metal layer); and Program 4 is for Class III high damage - enhanced four-step polishing (non-metal layer). These four programs are pre-entered into the control unit 50, and the optical inspection station 12 communicates with the control unit 50.

[0071] (2) The wafer in the wafer box 11 is moved to the optical inspection station 12 by the transfer mechanism 13 for damage assessment. First, the pre-cleaned and coarsely ground wafers are loaded into wafer cassette 11. The transfer mechanism 13 removes the wafers to be inspected from wafer cassette 11 and delivers them to the optical inspection station 12 for sorting. The optical inspection station 12 irradiates the wafers with an infrared light source, and a reflective light sensor collects the fluctuation values ​​of the reflected light intensity. If the fluctuation value is ≤5%, the wafer is classified as Class I low-damage-simplified two-step polishing. If the fluctuation value is between 5% and 10%, the wafer is classified as Class II medium-damage standard three-step polishing. If the fluctuation value is ≥10%, the wafer is identified as a Class III high-damage-strengthening four-step polishing process, and the film layer 60 type judgment process is triggered. If the infrared light reflectivity is ≥80% and the reflected light waveform is uniform without impurities, it is considered a wafer with a metal layer. If the infrared light reflectivity is 10% to 80% and the reflected light waveform has impurities, it is considered a non-metallic film layer 60 wafer.

[0072] Next, the control unit 50 receives the detection signal and automatically calls the corresponding polishing program. Once the program is in place, it sends a signal to the buffer unit 10. After receiving the signal, the buffer unit 10 uses the transfer mechanism 13 to transfer the wafer from the detection station 23 to the polishing unit 30 for subsequent polishing operations.

[0073] (3) The control unit 50 sorts the wafers according to the degree of damage and processes them in descending order of damage degree. After wafer inspection and grading, the control unit 50 can automatically link with the buffer unit 10 to optimize the polishing sorting of wafers. According to the priority scheduling of high damage → medium damage → low damage, high-damage wafers are sent to the polishing unit 30 first. By staggering the allocation of polishing programs with different time consumption, the backlog of production capacity is avoided and the overall production efficiency is improved.

[0074] In practice, when a custom program is required, the automatic allocation can be paused by the control unit 50 after wafer inspection, and the custom program can be manually selected before the buffer unit 10 is triggered to load the wafer.

[0075] (4) The transfer mechanism 13 places the wafer on the transfer tray 25, and the transfer tray 25 delivers the wafer to the corresponding polishing unit 30 according to the polishing program of the wafer. The movement from buffer unit 10 to polishing unit 30, from buffer unit 10 to cleaning unit 40, from polishing unit 30 to cleaning unit 40, from first polishing component 31 to second polishing component 32, and from cleaning unit 40 to buffer unit 10 is all achieved by the robotic arm of transfer unit 20. Transfer disk 25 can be used for transfer along the first straight path, the second straight path, and the preset angle rotation direction.

[0076] (5) Polishing unit 30 polishes the wafer according to the polishing program corresponding to the wafer, and then the wafer enters cleaning unit 40 to clean it. This section describes each polishing assembly as having 2 polishing discs 33 and 3 polishing heads 34, from right to left: PX1 polishing disc 33, PX2 polishing disc 33, PY1 polishing disc 33, and PY2 polishing disc 33.

[0077] For low-damage wafers, after pre-cleaning and rough grinding, only fine surface particles and a thin oxide layer remain, with no deep scratches or thick film residue. A two-step polishing process is then employed to achieve efficient removal and rapid finishing. Rough polishing uses moderate pressure to quickly remove surface impurities, while fine polishing directly optimizes surface micro-smoothness. No additional pre-polishing is needed to break the stress layer, nor is buffer cleaning required, resulting in minimal residual impurities. Both polishing steps are accompanied by online water rinsing, which directly removes small amounts of residue. This removes a 0.5–0.7 μm damage layer from the wafer surface, reducing the roughness to approximately Ra 0.1 nm. This process is the fastest and achieves the desired results, avoiding unnecessary steps that consume equipment capacity.

[0078] The two-step polishing procedure is as follows: Step 1 (PX2, coarse polishing): PX2 rotation speed 90-100 rpm, polishing head 34 rotation speed 80-90 rpm, polishing head 34 pressure 1.5-2.5 psi; polishing pad is a grooveless polyurethane pad with Shore hardness D40-50; polishing fluid is coarse polishing fluid (online dilution ratio 1:20-1:30), the main component is silica nano-abrasive particles, the flow rate is 200-300 ml / min, and the polishing time is 1-2 min; the polishing pad dresser 37 operates by polishing and dressing simultaneously, and the dresser pressure is 3-5 blf.

[0079] Step 2 (PY1, Fine Polishing): PY1 rotation speed 90-100 rpm, polishing head 34 rotation speed 80-90 rpm, polishing head 34 pressure 0.5-1.5 psi; polishing pad is a grooveless soft polyurethane pad with Shore hardness D30-40; polishing fluid is fine polishing fluid (online dilution ratio 1:30-1:50), the main component is silica nano-abrasive particles, the flow rate is 200-300 ml / min, and the polishing time is 0.5-2 min; the polishing pad dresser 37 works by polishing and dressing simultaneously, and the dresser pressure is 3-5 blf.

[0080] For moderately damaged wafers, there are hidden surface scratches and medium-thickness dielectric film residues. The three-step polishing process is essentially a combination of defect removal and hydrophilic cleaning enhancement: coarse polishing removes the dielectric film and visible defects; fine polishing eliminates hidden scratches and improves flatness; and buffer cleaning removes residual abrasive particles and polishing fluid accumulated from the previous two polishing steps. Through the wetting effect of the cleaning fluid, the hydrophilicity of the wafer surface is significantly improved, facilitating the subsequent cleaning process in cleaning unit 40. After three-step polishing, a 0.7–1.0 μm damage layer is removed from the wafer surface, reducing the roughness to approximately Ra 0.1 nm.

[0081] The three-step polishing procedure is as follows: Step 1 (PX2, coarse polishing): PX2 rotation speed 90-100 rpm, polishing head 34 rotation speed 80-90 rpm, polishing head 34 pressure 2.0-3.0 psi, using high pressure to quickly remove the damaged layer on the wafer surface; the polishing pad is a grooveless polyurethane pad with Shore hardness D40-50; the polishing fluid is a coarse polishing fluid (online dilution ratio 1:20-1:30), the main component of which is silica nano-abrasive particles, the flow rate is 200-300 ml / min, and the polishing time is 1-2 min; the polishing pad dresser 37 operates by polishing and dressing simultaneously, and the dresser pressure is 3-5 blf.

[0082] Step 2 (PY1, Fine Polishing): PY1 rotation speed 90-100 rpm, polishing head 34 rotation speed 80-90 rpm, polishing head 34 pressure 0.5-1.5 psi; polishing pad is a grooveless soft polyurethane pad with Shore hardness D30-40; polishing fluid is fine polishing fluid (online dilution ratio 1:30-1:50), the main component is silica nano-abrasive particles, the flow rate is 200-300 ml / min, and the polishing time is 0.5-2 min; the polishing pad dresser 37 works by polishing and dressing simultaneously, and the dresser pressure is 3-5 blf.

[0083] Step 3 (PY2, buffer cleaning): PY2 rotation speed 50-60 rpm, polishing head 34 rotation speed 40-50 rpm, polishing head 34 pressure 0.5-1.5 psi; polishing pad is a grooveless soft polyurethane pad with Shore hardness D30-40; the chemical solution used is a cleaning solution containing fluorine and surfactant (online dilution ratio 1:5-1:10), flow rate 200-300 ml / min, polishing time 0.5-1.5 min; polishing pad dresser 37 works offline, first dressing and then polishing, dresser pressure 3-5 blf.

[0084] The cleaning solution in this step serves the following purposes: It removes most of the polishing slurry from the wafer surface, preventing residual slurry from causing secondary contamination. Through the action of surfactants, it changes the wafer surface from hydrophobic to hydrophilic, improving its wettability and facilitating particle removal during subsequent cleaning processes. It removes most particles from the wafer surface, reducing the number of particles on the wafer surface. Finally, it repairs the roughness of the wafer surface, making it smoother and more even.

[0085] For highly damaged wafers, which contain deep scratches, subsurface damage, and thick film residue, pre-polishing is required to remove the stress layer before progressively removing defects. The four-step polishing process is essentially a combination of stress removal, main body removal, finishing optimization, and cleaning enhancement: pre-polishing removes the thick film layer and deep scratch stress layer on the wafer surface; coarse polishing removes the defective layer of the main silicon layer; fine polishing repairs the flatness; and buffer cleaning removes residual abrasive particles and polishing fluid accumulated from multiple polishing steps. This prevents secondary contamination, and the wetting effect of the cleaning fluid significantly improves the hydrophilicity of the wafer surface, facilitating subsequent cleaning processes. After four steps of polishing, a 1.5–2.0 μm damage layer is removed from the wafer surface, reducing the roughness to approximately Ra 0.1 nm.

[0086] The four-step polishing procedure is as follows: Step 1 (PX1, pre-polishing): PX1 rotation speed 90-100 rpm, polishing head 34 rotation speed 80-90 rpm, polishing head 34 pressure 2.5-3.0 psi; polishing pad is a grooved polyurethane pad with Shore hardness D50-70, concentric grooves are preferred; polishing slurry flow rate is 200-300 ml / min, polishing time 1-3 min; polishing pad dresser 37 operates by polishing and dressing simultaneously, dresser pressure is 5-7 blf. The polishing slurry used with a metallic film layer 60 mainly consists of alumina abrasive particles, while the polishing slurry used with a non-metallic film layer 60 mainly consists of silica abrasive particles, which can avoid the fluctuation in removal volume caused by the hardness difference between the film layer 60 and the silica layer during coarse polishing.

[0087] Step 2 (PX2, coarse polishing): PX2 rotation speed 90-100 rpm, polishing head 34 rotation speed 80-90 rpm, polishing head 34 pressure 2.0-3.0 psi, using high pressure to quickly remove the damaged layer on the wafer surface; the polishing pad is a grooveless polyurethane pad with Shore hardness D40-50; the polishing fluid is a coarse polishing fluid (online dilution ratio 1:20-1:30), the main component of which is silicon dioxide nano-abrasive particles, the flow rate is 200-300 ml / min, and the polishing time is 1-2 min; the polishing pad dresser 37 operates by polishing and dressing simultaneously, and the dresser pressure is 3-5 blf.

[0088] Step 3 (PY1, Fine Polishing): PY1 rotation speed 90-100 rpm, polishing head 34 rotation speed 80-90 rpm, polishing head 34 pressure 0.5-1.5 psi; polishing pad is a grooveless soft polyurethane pad with Shore hardness D30-40; polishing fluid is fine polishing fluid (online dilution ratio 1:30-1:50), the main component is silica nano-abrasive particles, the flow rate is 200-300 ml / min, and the polishing time is 0.5-2 min; the polishing pad dresser 37 works by polishing and dressing simultaneously, and the dresser pressure is 3-5 blf.

[0089] Step 4 (PY2, Buffer Cleaning): PY2 rotation speed 50-60 rpm, polishing head 34 rotation speed 40-50 rpm, polishing head 34 pressure 0.5-1.5 psi; polishing pad is a grooveless soft polyurethane pad with Shore hardness D30-40; the chemical solution used is a cleaning solution containing fluorine and surfactant (online dilution ratio 1:5-1:10), flow rate 200-300 ml / min, polishing time 1-2 min; polishing pad dresser 37 operates offline, first dressing and then polishing, dresser pressure 3-5 blf.

[0090] In this polishing process, the polishing pad and wafer must be rinsed after each polishing step. The rinsing time for the polishing pad is 6-10 seconds, and the rinsing time for the wafer is 8-12 seconds. This is beneficial for the wafer roughness and final surface grain size to meet the standards.

[0091] The wafer regeneration chemical mechanical polishing (CMP) process provided in this embodiment, compared with existing technologies, classifies wafer damage levels by integrating infrared optical detection in the buffer unit 10; it can also distinguish the film layer 60 of highly damaged wafers based on reflected light intensity, avoiding the problem of incomplete removal of film layer 60 residue caused by incorrect polishing slurry selection. The differentiated graded polishing process system design, through precise adaptation of parameters such as pressure, rotation speed, and polishing time, balances wafer defect removal efficiency and surface quality, preventing under-polishing or over-polishing. Dynamic sorting optimization of the buffer unit 10 based on wafer damage level prioritizes highly damaged wafers entering the polishing unit 30, staggering the allocation of different polishing processes by time, avoiding equipment capacity backlog, and balancing production efficiency and polishing quality. Detection, program, and equipment linkage control achieve automatic adaptation of polishing parameters, polishing slurry, and sorting logic. This process is applicable to the chemical mechanical polishing of poly wafers (not limited to) with different film layers 60. It is also applicable to the regeneration CMP process of 6-inch, 8-inch, and 12-inch wafers (not limited to).

[0092] In the wafer regeneration chemical mechanical polishing process of this application, see [link to relevant documentation]. Figure 4 The removal amount for pre-polishing is a, the removal amount for rough polishing is b, and the removal amount for fine polishing is c.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wafer regeneration chemical mechanical polishing system, characterized in that, It includes a buffer unit, a conveying unit, a polishing unit, a cleaning unit, and a control unit. The buffer unit extends along a first straight path. The conveying unit, polishing unit, and cleaning unit are located on the same side of the buffer unit and arranged sequentially along the first straight path. The conveying unit is located between the polishing unit and the cleaning unit and extends along a second straight path. The second straight path is perpendicular to the first straight path. The buffer unit includes multiple wafer cassettes arranged along the first straight path, an optical inspection station located on one side of the multiple wafer cassettes, and a transmission mechanism located on the side of the wafer cassettes closer to the transmission unit. The conveying unit includes a transfer tray that moves along the second straight path; The polishing unit includes a first polishing component and a second polishing component arranged along the second straight path. The polishing component includes at least two polishing discs and polishing heads corresponding to the polishing discs. The multiple polishing discs are used to perform pre-polishing, rough polishing, fine polishing and buffer cleaning processes respectively. The cleaning unit is used to clean the polished wafers; The control unit is configured to receive the wafer damage level obtained by the optical inspection station, and set the polishing process and cleaning parameters according to the damage level.

2. The wafer regeneration chemical mechanical polishing system as described in claim 1, characterized in that, The buffer unit further includes: A guide rail extends along the first straight path and is located on the side of the plurality of wafer cassettes near the transfer unit; The transmission mechanism is slidably connected to the guide rail and is used to transfer the wafers in the wafer cassette to the optical inspection station, and to move the wafers in the optical inspection station to the transfer unit.

3. The wafer regeneration chemical mechanical polishing system as described in claim 1, characterized in that, The transmission unit further includes: The first storage area includes multiple workstations, and the first storage area corresponds to the first polishing component; The second storage area includes multiple workstations, and the second storage area corresponds to the second polishing component; A clamping mechanism is used to clamp the transfer tray and place it on the workstation.

4. The wafer regeneration chemical mechanical polishing system as described in claim 3, characterized in that, The transfer unit further includes a conversion mechanism located between the first storage area and the second storage area, which is used to transfer the transfer tray from the first storage area to the second storage area.

5. The wafer regeneration chemical mechanical polishing system as described in claim 1, characterized in that, Both the first polishing assembly and the second polishing assembly include: A rotating mechanism is located at the center of the plurality of polishing discs; The polishing arm is fixed to the rotating mechanism; Each polishing head is fixedly connected to the polishing arm in a one-to-one correspondence.

6. The wafer regeneration chemical mechanical polishing system as described in claim 1, characterized in that, Both the first polishing assembly and the second polishing assembly include: A polishing pad dresser having a swingable dressing head having a first state of contacting a polishing pad on the polishing disk and a second state of being located on the outer periphery of the polishing disk; The liquid supply line has an outlet located above the polishing disc.

7. The wafer regeneration chemical mechanical polishing system as described in claim 1, characterized in that, The cleaning unit includes a cleaning brush cleaning mechanism, a pen-type spray cleaning mechanism, and a single-piece cleaning mechanism arranged at intervals along the second straight path, and a transfer mechanism is provided between two adjacent cleaning mechanisms.

8. A wafer regeneration chemical mechanical polishing process, employing the wafer regeneration chemical mechanical polishing system as described in any one of claims 1-7, characterized in that, include: S10: The polishing program is pre-set in the control unit according to the degree of damage; S20: The wafers in the wafer cassette are moved to the optical inspection station for damage assessment via a transfer mechanism. S30: The control unit sorts the wafers according to the degree of damage and processes them in descending order of damage. S40: The transfer mechanism places the wafer on the transfer tray, and the transfer tray delivers the wafer to the corresponding polishing unit according to the polishing program corresponding to the wafer. S50: The polishing unit polishes the wafer according to the polishing program corresponding to the wafer, and then the wafer enters the cleaning unit to clean it.

9. The wafer regeneration chemical mechanical polishing process as described in claim 8, characterized in that, Step S20 includes: Infrared light irradiation was used to collect the intensity fluctuation value of reflected light from the wafer; If the fluctuation value is ≤5%, the wafer is judged to be of low damage. If the fluctuation value is 5% to 10%, the wafer is judged to be of medium damage. If the fluctuation value is ≥10%, the wafer is determined to be highly damaged, and the film type determination process is triggered. If the reflectivity of infrared light is ≥80% and the reflected light waveform is uniform without impurities, it is considered to be a wafer containing a metal layer. If the reflectivity of infrared light is 10% to 80% and there are impurities in the waveform of the reflected light, it is considered to be a non-metallic film wafer.

10. The wafer regeneration chemical mechanical polishing process as described in claim 9, characterized in that, Low-damage wafers correspond to rough polishing and fine polishing. The polishing process for moderately damaged wafers is rough polishing, fine polishing, and buffer cleaning. The polishing levels corresponding to high-damage wafers are pre-polishing, rough polishing, fine polishing, and buffer cleaning.

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