A multi-functional field-assisted chemical mechanical polishing device and wafer polishing method

Abstract

The application provides a multi-energy field assisted chemical mechanical polishing device and a wafer polishing method. The device comprises a polishing disc, a polishing pad arranged on the polishing disc, and a polishing head for pressing a workpiece against the polishing pad for polishing. The device further comprises at least two processing stations, each of which is provided with a polishing disc and a polishing pad, and an energy field assisted assembly for assisting in removing the surface material of the workpiece. The energy field assisted assembly comprises a combination of one or more of a light field assembly, a sound field assembly, an electric field assembly, a magnetic field assembly, a thermal field assembly, and a plasma field assembly. The energy field assisted assemblies or their combinations arranged in the at least two processing stations are different from each other. A moving assembly is connected to the polishing head and is used to move the polishing head and the workpiece clamped thereby between the at least two processing stations. The application sets the processing stations with multiple different energy fields or energy field combinations, so that the polishing process can be switched as needed, thereby improving process flexibility and material adaptability.

Description

Technical Field

[0001] This application relates to the field of semiconductor processing technology, and in particular to a multi-field assisted chemical mechanical polishing apparatus and a wafer polishing method. Background Technology

[0002] Chemical mechanical polishing (CMP) is currently a key technology for achieving global planarization of wafers. However, when dealing with hard and brittle materials such as silicon carbide (SiC) and sapphire, traditional CMP suffers from problems such as low material removal rate (MRR), long processing time, and easy introduction of surface and subsurface damage.

[0003] To improve polishing efficiency and quality, existing technologies have introduced single-energy-field assistance methods such as electric fields, acoustic fields, and optical fields. However, limited by the mechanism of action of a single energy field, these methods also have some drawbacks. For example, the anodic oxidation rate assisted by an electric field is constrained by reaction kinetics, limiting its potential for improvement; acoustic field assistance easily leads to uneven material removal and may even induce microcracks; optical field assistance suffers from severe recombination of photogenerated electron-hole pairs, resulting in insufficient oxide layer formation rate. To address this, some studies have attempted to apply composite energy fields at the processing location, such as a combination of electric and acoustic fields, in order to compensate for the shortcomings of a single energy field through the synergy of the two fields. Experiments have shown that this can improve removal efficiency or surface quality to a certain extent.

[0004] Currently, whether using a single energy field or a composite energy field, these solutions all employ a fixed application method throughout the entire process. This results in the energy field configuration being unable to be adjusted during the entire processing, making it difficult to flexibly switch the optimal energy field combination according to the differentiated needs of different materials or different processing stages of the same material. Consequently, the improvement of processing flexibility and overall efficiency is constrained.

[0005] Therefore, how to solve the problem of fixed energy field configuration and inflexible switching in existing polishing technology has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] This application provides a multi-energy-field assisted chemical mechanical polishing device and a wafer polishing method. By setting up processing stations with multiple different energy fields or combinations of energy fields, the polishing process can be switched as needed, thereby improving process flexibility and material adaptability.

[0007] The technical solution adopted in this application is as follows: In the first aspect, a multi-energy field assisted chemical mechanical polishing apparatus is provided, the apparatus including a polishing disc, a polishing pad disposed on the polishing disc, and a polishing head for pressing a workpiece against the polishing pad for polishing; The device further includes: At least two processing stations, each processing station is provided with the polishing disc and the polishing pad, and an energy field auxiliary component for assisting in the removal of material from the surface of the workpiece. The energy field auxiliary component includes one or more combinations of light field component, sound field component, electric field component, magnetic field component, thermal field component and plasma field component, and the energy field auxiliary components or combinations thereof provided in at least two processing stations are different from each other. A movable component, connected to the polishing head, is used to move the polishing head and the workpiece clamped thereon between the at least two processing stations.

[0008] Preferably, the moving component includes a rotary drive component, a lifting drive component, and a connector. The rotary drive component includes a central rotating shaft and a first drive component. The lifting drive component includes a telescopic shaft and a second drive component. One end of the telescopic shaft is connected to the central rotating shaft through the connector, and the other end is connected to the polishing head. The telescopic shaft is parallel to the axial direction of the central rotating shaft. The first driving member is used to drive the central rotating shaft to rotate, so as to drive the polishing head to rotate around the central rotating shaft between different processing stations; The second driving member is used to drive the telescopic shaft to extend or retract, so as to move the polishing head in a direction closer to or further away from the polishing pad.

[0009] Preferably, the number of processing stations is three, and the three processing stations are respectively used for rough polishing, fine polishing and final polishing of the workpiece; wherein, the number of types of energy field auxiliary components set in the processing station used for rough polishing is greater than the number of types of energy field auxiliary components set in the processing stations used for fine polishing and final polishing. The first driving member is used to drive the central rotating shaft to rotate, so as to drive the polishing head and the workpiece clamped thereon to pass sequentially through the processing station for rough polishing, the processing station for fine polishing and the processing station for final polishing.

[0010] Preferably, the light field assembly includes at least one set of light sources located above the polishing pad for emitting light that can excite a photocatalytic reaction onto the polishing liquid on the polishing pad.

[0011] Preferably, the sound field assembly includes a sound wave generator and at least one sound wave transducer, the sound wave transducer being integrated inside or at the bottom of the polishing disk, the sound wave generator being electrically connected to the sound wave transducer for driving the sound wave transducer to generate a sound field.

[0012] Preferably, the electric field assembly includes an anode component, a cathode component, and an adjustable power supply. The anode component is integrated inside the polishing head for electrical connection with the workpiece. The cathode component is the polishing disc made of conductive material, or a cathode ring embedded in the polishing disc, or a cathode plate disposed above the polishing pad and in contact with the polishing liquid. The positive terminal of the adjustable power supply is connected to the anode component, and the negative terminal of the adjustable power supply is connected to the cathode component.

[0013] Preferably, the magnetic field assembly includes at least one magnetic field generator, which is located below the polishing disc or around the polishing pad, for generating a static magnetic field or an alternating magnetic field in the polishing area of ​​the polishing pad.

[0014] Preferably, the thermal field assembly includes at least one heat source surrounding a polishing area disposed on the polishing pad for heating the workpiece or the polishing liquid on the polishing pad.

[0015] Preferably, the plasma field assembly includes at least one plasma generator, which is located beside the polishing area of ​​the polishing pad and is used to modify or activate the workpiece.

[0016] Preferably, the polishing pad has multiple gaps, the shape of which includes one or more of the following: circular, square, rhomboid, elongated, and honeycomb. The multiple gaps are arranged in concentric rings, spirals, grids, radial lines, or fan shapes. The upper surface of the polishing disc has grooves, and the gaps cooperate with the grooves to form a reservoir for accumulating polishing fluid.

[0017] In a second aspect, a wafer polishing method is provided, applied in the multi-field assisted chemical mechanical polishing apparatus provided in the first aspect, the method comprising: The wafer is clamped in the polishing head; The polishing head is moved by a moving component, thereby moving the wafer sequentially to multiple processing stations; At each processing station reached, the wafer is pressed against the polishing pad by the polishing head, and the polishing disk is driven to move relative to the polishing head to perform chemical mechanical polishing on the wafer; at the same time, the energy field auxiliary component set at the processing station is activated to provide energy field assistance to the wafer. The energy field auxiliary components include one or more combinations of light field components, sound field components, electric field components, magnetic field components, thermal field components and plasma field components, and the energy field auxiliary components or combinations thereof set at different processing stations are different from each other.

[0018] According to the specific embodiments provided in this application, the following technical effects are disclosed: The technical solution of this application provides a multi-energy field assisted chemical mechanical polishing apparatus and a wafer polishing method. The apparatus includes a polishing disc, a polishing pad disposed on the polishing disc, and a polishing head for pressing a workpiece against the polishing pad for polishing. The apparatus also includes at least two processing stations, each processing station being provided with a polishing disc and a polishing pad, and an energy field auxiliary component for assisting in the removal of material from the workpiece surface. The energy field auxiliary component includes one or more combinations of light field components, sound field components, electric field components, magnetic field components, thermal field components, and plasma field components, and the energy field auxiliary components or combinations thereof provided at the at least two processing stations are different from each other. A moving component is connected to the polishing head for moving the polishing head and the workpiece it clamps between the at least two processing stations. This application sets up at least two processing stations and makes the energy field auxiliary components or combinations of each processing station different from each other. At the same time, it uses a moving component to drive the workpiece to process sequentially between different processing stations. This allows multiple different energy fields or combinations of energy fields to be used successively according to the material properties or process requirements during the entire polishing process. This breaks the limitation of the prior art that only a certain energy field or combination of energy fields can be applied throughout the entire process, and helps to improve the flexibility of the polishing process and its adaptability to different materials. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is one of the overall structural schematic diagrams of the multi-field assisted chemical mechanical polishing device provided in the embodiments of this application; Figure 2 This is the second schematic diagram of the overall structure of the multi-field assisted chemical mechanical polishing device provided in the embodiments of this application; Figure 3 This is a top view schematic diagram of the multi-processing station provided in the embodiments of this application; Figure 4 This is a schematic diagram of the structure of the mobile component provided in an embodiment of this application; Figure 5 This is a connection diagram of the electric field component provided in an embodiment of this application; Figure 6 This is a schematic diagram of the gaps in the polishing pad provided in an embodiment of this application; Figure 7 This is a schematic diagram showing the fit between the gap of the polishing pad and the groove of the polishing disc provided in the embodiments of this application; Figure 8 This is a flowchart of the wafer polishing method provided in the embodiments of this application.

[0021] Figure label: 1. Polishing disc; 100. Groove; 101. Spindle; 2. Polishing pad; 20. Gap; 3. Workpiece; 4. Polishing head; 5. Moving component; 50. Rotary drive component; 51. Lifting drive component; 52. Connector; 500. Central rotating shaft; 501. First drive component; 510. Telescopic shaft; 511. Second drive component; 6. Light source; 7. Acoustic transducer; 70. Power cord; 8. Adjustable power supply; 9. Magnetic field generator; 10. Heat source; 11. Plasma generator; 12. Liquid supply assembly; 120. Polishing fluid. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] As described in the background section, currently, whether using a single energy field or a composite energy field, these solutions all employ a fixed application method throughout the entire process. This results in the energy field configuration being unable to be adjusted during the entire processing, making it difficult to flexibly switch the optimal energy field combination according to the differentiated needs of different materials or different processing stages of the same material. Consequently, the improvement of processing flexibility and overall efficiency is constrained.

[0024] Based on this, this application provides a multi-energy-field assisted chemical mechanical polishing device and a wafer polishing method, aiming to solve the problem of fixed energy field configuration and inflexible switching in the prior art.

[0025] The embodiments of this application will be analyzed in detail below with reference to the accompanying drawings.

[0026] Example 1 refer to Figures 1 to 3 The multi-field assisted chemical mechanical polishing device provided in this embodiment includes a polishing disc 1, a polishing pad 2 disposed on the polishing disc 1, and a polishing head 4 for pressing the workpiece 3 against the polishing pad 2 for polishing.

[0027] The polishing disc 1 is driven to rotate by a spindle motor below it (the spindle 101 shown in the figure is the drive shaft of the spindle motor, and the spindle 101 is connected to the bottom of the polishing disc 1), and the polishing pad 2 rotates synchronously with the polishing disc 1; the polishing head 4 is rotatably disposed above the polishing disc 1, and the polishing head 4 can clamp and drive the workpiece 3 to rotate, while applying pressure to the workpiece 3 towards the polishing pad 2. Through the relative rotational motion of the polishing disc 1 and the polishing head 4, and the chemical action of the polishing fluid 120, the material on the surface of the workpiece 3 is removed. In this embodiment, the workpiece 3 can be a silicon carbide wafer, a sapphire wafer, or a single-crystal silicon wafer.

[0028] Continue to refer to Figures 1 to 3 The device also includes: at least two processing stations, each processing station being provided with a polishing disc 1 and a polishing pad 2, and an energy field auxiliary component for assisting in the removal of surface material from the workpiece 3. The energy field auxiliary component includes one or more combinations of light field component, sound field component, electric field component, magnetic field component, thermal field component and plasma field component, and the energy field auxiliary components or combinations thereof provided at the at least two processing stations are different from each other; and a moving component 5, connected to the polishing head 4, for driving the polishing head 4 and the workpiece 3 clamped thereon to move between the at least two processing stations.

[0029] The energy field auxiliary components are used to introduce additional physical or chemical effects during chemical mechanical polishing to improve material removal efficiency, surface quality, or reduce processing damage. Specifically, light fields, acoustic fields, electric fields, magnetic fields, thermal fields, and plasma fields are all types of energy fields. The light field component can provide light to the polishing slurry to excite photocatalytic reactions and promote oxidation of the workpiece surface. The acoustic field component generates cavitation and micro-stirring effects through high-frequency vibration, enhancing the mechanical removal of the workpiece surface by abrasive particles. The electric field component generates a soft oxide layer on the workpiece surface through electrochemical reactions, facilitating subsequent mechanical removal. The magnetic field component couples with magnetic abrasive particles or magnetically sensitive media in the polishing slurry 120 to enhance the mechanical action of abrasive particles on the workpiece surface. The thermal field component reduces material hardness by heating the workpiece surface or the polishing slurry 120, utilizing a thermal softening effect. The plasma field component improves chemical reactivity by dry modification or activation of the workpiece surface. It should be noted that this embodiment does not limit the specific implementation of the above-mentioned energy field components, and those skilled in the art can select the appropriate energy field auxiliary components and their supporting structures according to actual needs.

[0030] Furthermore, the requirement that the energy field auxiliary components or their combinations configured at at least two processing stations are different means that the energy field auxiliary components configured at any two processing stations are not completely identical in type or in combination. For example, if one processing station is equipped with only a light field component and the other with only an electric field component, then they are different. Similarly, if one processing station is equipped with a combination of a light field component and a sound field component, and the other with a combination of an electric field component and a thermal field component, then they are also different. Through this differentiated configuration, combined with the moving component 5 driving the workpiece 3 to be polished sequentially between different processing stations, multiple different energy fields or combinations of energy fields can be used successively during the polishing process according to material properties or process requirements. This breaks the limitation of existing technologies where only a fixed type of energy field or combination of energy fields can be applied throughout the entire process.

[0031] As an example, workpiece 3 is a silicon carbide wafer. The processing station includes a first processing station and a second processing station. The first processing station is equipped with a combination of an electric field component and an optical field component, while the second processing station is equipped with an acoustic field component. During processing, the moving component 5 first moves the silicon carbide wafer to the first processing station. The polishing head 4 presses the wafer against the polishing pad 2 and drives the polishing disk 1 and polishing head 4 to rotate relative to each other. At the same time, the electric field component and the optical field component are turned on. Through the synergistic effect of electrochemical oxidation and photocatalytic oxidation, a soft oxide layer is quickly generated on the wafer surface, which is then partially removed by mechanical polishing. Subsequently, the moving component 5 moves the wafer to the second processing station. Similarly, the polishing head 4 presses the wafer against the wafer and drives it to rotate relative to each other. At the same time, the acoustic field component is turned on. Utilizing the cavitation effect and micro-stirring effect generated by ultrasonic vibration, the residual oxide layer is effectively removed and a fresh surface is exposed. Through the sequential processing of the above two stations, efficient and low-damage polishing of silicon carbide wafers is flexibly achieved.

[0032] As another example, workpiece 3 is a single-crystal silicon wafer. The processing stations include a third processing station and a fourth processing station. The third processing station is equipped with an optical field component, and the fourth processing station is equipped with an electric field component. During processing, the moving component 5 first moves the silicon wafer to the third processing station, where the polishing head 4 presses the wafer against the polishing pad 2 and drives the polishing disk 1 and polishing head 4 to rotate relative to each other. At the same time, the optical field component is activated, using photocatalytic reaction to generate a thin and uniform oxide layer on the wafer surface. Subsequently, the moving component 5 moves the wafer to the fourth processing station, where it is again pressed against the wafer by the polishing head 4 and driven to rotate relative to it. At the same time, the electric field component is activated, using electrochemical action to planarize the wafer, removing minor undulations and reducing surface roughness. Through the sequential processing at these two stations, low-damage, high-precision polishing of the silicon wafer is achieved.

[0033] It should be noted that workers only need to pre-configure different energy field auxiliary components or combinations thereof for each processing station based on the differences in physicochemical properties between different materials, such as silicon carbide wafers and single-crystal silicon wafers, or the differentiated requirements of different processing stages for the same material, such as the need for high material removal rate in the rough polishing stage and low surface damage in the fine polishing stage. This allows for on-demand switching. Specifically, the energy field auxiliary components described in this embodiment include six types: optical field components, acoustic field components, electric field components, magnetic field components, thermal field components, and plasma field components. For a processing station, the configuration of its energy field auxiliary components can be any one or more of the above six types in combination. Specifically, there are 6 schemes for setting one type of energy field auxiliary component; 15 schemes for setting two types; 20 schemes for setting three types; 15 schemes for setting four types; 6 schemes for setting five types; and 1 scheme for setting six types. Therefore, each processing station has 63 different configuration options. Workers can freely select and combine different stations according to the different workpiece materials or processing stages, thereby achieving flexible switching between multiple energy fields or combinations of energy fields.

[0034] In summary, this embodiment 1 sets up at least two processing stations and makes the energy field auxiliary components or combinations of each processing station different from each other. At the same time, it uses a moving component to drive the workpiece to process sequentially between different processing stations. This allows multiple different energy fields or combinations of energy fields to be used successively according to material characteristics or process requirements during the entire polishing process. This breaks the limitation of the prior art that only a certain energy field or combination of energy fields can be applied throughout the entire process, which helps to improve the flexibility of the polishing process and its adaptability to different materials.

[0035] As a preferred embodiment, refer to Figure 3 and Figure 4 The moving component 5 includes a rotary drive component 50, a lifting drive component 51, and a connecting member 52. The rotary drive component 50 includes a central rotating shaft 500 and a first drive member 501. The lifting drive component 51 includes a telescopic shaft 510 and a second drive member 511. One end of the telescopic shaft 510 is connected to the central rotating shaft 500 through the connecting member 52, and the other end is connected to the polishing head 4. The telescopic shaft 510 is parallel to the axis of the central rotating shaft 500. The first drive member 501 is used to drive the central rotating shaft 500 to rotate, so as to drive the polishing head 4 to rotate around the central rotating shaft 500 between different processing positions. The second drive member 511 is used to drive the telescopic shaft 510 to extend or retract, so as to drive the polishing head 4 to move in the direction of approaching or moving away from the polishing pad 2.

[0036] In a preferred embodiment, there are three processing stations, which are used for rough polishing, fine polishing and final polishing of workpiece 3, respectively. The number of types of energy field auxiliary components set in the processing station for rough polishing is greater than the number of types of energy field auxiliary components set in the processing stations for fine polishing and final polishing. The first driving member 501 is used to drive the central rotating shaft 500 to rotate, so as to drive the polishing head 4 and the workpiece 3 clamped thereon to pass through the processing station for rough polishing, the processing station for fine polishing and the processing station for final polishing in sequence.

[0037] It should be noted that the primary goal of the rough polishing stage is rapid material removal, and setting up a combination of various energy field auxiliary components helps to improve the efficiency of rough polishing; the fine polishing stage focuses on smoothing, and the final polishing stage focuses on improving surface quality. Both have lower requirements for material removal rate, but higher requirements for surface quality and damage control. Setting up fewer energy field auxiliary components can meet the requirements, while also helping to reduce process complexity and reduce interaction interference between energy fields.

[0038] As an example, see reference Figure 3 There are three processing stations: station B, station C, and station D, used for rough polishing, fine polishing, and final polishing, respectively. There is one loading station, station A, used to place the workpiece 3 to be polished and to fix the polishing head 4 to the workpiece 3. Specifically, the moving component 5 is located at the center, with loading station A, station B, station C, and station D arranged around it. Loading station A does not have a polishing disc 1 or polishing pad 2; it is only used for loading and unloading workpiece 3. Each processing station also has a liquid supply component 12. Figure 1 and Figure 2 The liquid supply assembly 12 is located above the polishing pad 2 and is used to supply polishing fluid 120 to the surface of the polishing pad 2. Different processing stations each have their own independent liquid supply assembly 12 to provide specific polishing fluids. For example, the first processing station B can be configured with a polishing fluid targeting the synergistic effects of acoustic, electric, and optical fields, such as containing TiO2 nanoparticles and an appropriate amount of electrolyte, and selecting a viscosity suitable for the acoustic cavitation effect. The second processing station C can be configured with a polishing fluid that facilitates electrochemical reactions, such as containing an appropriate amount of electrolyte. The third processing station D can be configured with a polishing fluid for final planarization or surface treatment. Thus, each processing station not only has different field-aiding components, but the polishing fluid can also be independently optimized, further enhancing the flexibility and specificity of the process.

[0039] refer to Figure 3 When the moving component 5 is in operation, it can rotate counterclockwise. After clamping the workpiece 3 at the loading station A, it sequentially passes through processing stations B, C, and D to perform the polishing operation. (Refer to...) Figure 4The central rotating shaft 500 is vertically arranged. The first driving member 501 is connected to the bottom of the central rotating shaft 500 and is used to drive the central rotating shaft 500 to rotate. The connecting member 52 is vertically connected to the central rotating shaft 500. The telescopic shaft 510 is vertically connected to the bottom surface of the connecting member 52 and is parallel to the central rotating shaft 500. The second driving member 511 is located on the top surface of the connecting member 52 and its output end passes through the connecting member 52 and is connected to the telescopic shaft 510 to drive the telescopic shaft 510 to extend or retract.

[0040] Taking processing station B as an example, which is equipped with a combination of light field, sound field, and electric field components (three-field composite rough polishing), processing station C as an example, which is equipped with an electric field component (electric field-assisted fine polishing), and processing station D as an example, which is equipped with a light field component (light field-assisted final polishing), the specific working process is as follows: First, the moving component 5 drives the polishing head 4 to rotate to the loading station A. The second driving component 511 drives the telescopic shaft 510 to extend, so that the polishing head 4 descends and clamps the wafer workpiece 3 to be processed. Then the telescopic shaft 510 retracts to lift the workpiece 3.

[0041] Next, the first driving component 501 drives the central rotating shaft 500 to rotate counterclockwise, and the connecting component 52 drives the telescopic shaft 510 and the polishing head 4 to rotate together to directly above the processing station B. The second driving component 511 drives the telescopic shaft 510 to extend, so that the polishing head 4 presses the workpiece 3 against the polishing pad 2. At the same time, the polishing disk 1 and the polishing head 4 rotate relative to each other, and the light field component, sound field component, and electric field component are activated. Under the synergistic effect of the electric field and the light field, an oxide layer is rapidly generated on the surface of the workpiece. The cavitation effect of the sound field and mechanical grinding work together to remove the oxide layer, achieving efficient rough polishing. After rough polishing is completed, the telescopic shaft 510 retracts and lifts the workpiece 3.

[0042] Then, the first driving component 501 continues to drive the central rotating shaft 500 to rotate, transferring the workpiece 3 to the processing station C. The polishing head 4 descends again, pressing the workpiece 3 against the polishing pad 2, and the electric field component is activated. Through electrochemical action, the workpiece surface is locally flattened, removing the minute undulations left by rough polishing and achieving fine polishing. After completion, the telescopic shaft 510 retracts.

[0043] Finally, the first driving component 501 drives the central rotating shaft 500 to rotate, moving the workpiece 3 to the processing station D. The polishing head 4 descends to press down, activates the light field component, and uses photocatalytic reaction to perform gentle oxidation and smoothing treatment on the workpiece surface, removing the thin layer damage generated by fine polishing, obtaining an ultra-smooth surface, and completing the final polishing.

[0044] Through the sequential processing of the above three processing stations, combined with the rotation and lifting action of the moving component 5, a complete polishing process for the wafer is realized, from rough polishing to fine polishing and then to final polishing.

[0045] Continue to refer to Figure 3In some examples, the moving component 5 includes four connectors 52, each connected to a different type of polishing head 4. The operator can select a suitable polishing head 4 based on the material, size, or process requirements of the workpiece 3, install the workpiece 3, and move the polishing head 4 between different processing stations via the moving component 5 to perform the polishing operation. The remaining unused polishing heads 4 can be kept idle or used as spares for quick switching between different types of workpieces.

[0046] As a preferred embodiment, refer to Figure 1 and Figure 2 The light field assembly includes at least one set of light sources 6, which are located above the polishing pad 2 and are used to emit light that can excite a photocatalytic reaction onto the polishing liquid on the polishing pad 2.

[0047] By setting up light source 6, photocatalysts in the polishing slurry, such as TiO2 nanoparticles, can be excited during the polishing process to generate highly oxidizing active species, accelerating the oxidation of the workpiece 3 surface and thus improving material removal efficiency. Simultaneously, photocatalytic oxidation is a mild chemical process that helps reduce surface damage.

[0048] As an example, the light source 6 can be an ultraviolet LED lamp assembly, which is positioned towards the polishing slurry on the polishing pad 2, emitting ultraviolet light with a wavelength of 365nm. TiO2 nanoparticles are added to the polishing slurry 120. When the workpiece 3 is a silicon carbide wafer, the ultraviolet light is turned on to irradiate the polishing area. The TiO2 is excited to generate hydroxyl radicals, which oxidize the SiC surface into a softer SiO2 layer, facilitating subsequent mechanical removal.

[0049] As a preferred embodiment, refer to Figure 1 and Figure 2 The sound field assembly includes a sound wave generator and at least one sound wave transducer 7. The sound wave transducer 7 is integrated inside or at the bottom of the polishing disk 1. The sound wave generator is electrically connected to the sound wave transducer 7 and is used to drive the sound wave transducer 7 to generate a sound field.

[0050] In this system, the ultrasonic vibrations generated by the acoustic transducer 7 are transmitted to the polishing fluid and polishing pad 2 through the polishing disc 1, creating a cavitation effect and micro-stirring in the polishing area. This enhances the impact and cutting effect of the abrasive particles on the surface of the workpiece 3, while also promoting the transport of reactants and the removal of byproducts, thereby improving the material removal rate. Furthermore, in the energy field combination, the acoustic field can also accelerate the electrochemical reaction of the electric field or the photocatalytic reaction of the optical field.

[0051] It should be noted that the power line 70 of the acoustic transducer 7 is led out from inside the spindle 101 and connected to an external acoustic generator to avoid the wire harness getting tangled when the polishing disc 1 rotates.

[0052] As an example, the driving frequency of the acoustic transducer 7 is 28kHz, the power of a single transducer oscillator is 60W, and 3 to 6 transducers are evenly arranged on the bottom of the polishing disk 1. When the workpiece 3 is a sapphire wafer, the acoustic field assembly is turned on, and the ultrasonic cavitation effect can reduce the friction during the polishing process and reduce the generation of surface microcracks.

[0053] As a preferred embodiment, refer to Figure 1 , Figure 2 and Figure 5 The electric field assembly includes an anode component, a cathode component, and an adjustable power supply 8. The anode component is integrated inside the polishing head 4 and is used for electrical connection with the workpiece 3. The cathode component is a polishing disc 1 made of conductive material, or a cathode ring embedded in the polishing disc 1, or a cathode plate located above the polishing pad 2 and in contact with the polishing liquid. The positive terminal of the adjustable power supply 8 is connected to the anode component, and the negative terminal of the adjustable power supply 8 is connected to the cathode component.

[0054] In this process, workpiece 3 and the anode component share the same electric potential and act as the anode. Under the influence of an electric field, an electrochemical reaction occurs, forming a soft oxide layer or passivation film on the surface. This oxide layer has a lower hardness than the base material and can be easily removed by mechanical polishing, thereby improving the material removal rate and reducing processing damage. The adjustable power supply 8 can provide DC or pulse signals to adapt to the electrochemical characteristics of different materials.

[0055] It should be noted that, since the polishing head 4 needs to rotate during operation, the electrical connection between the adjustable power supply 8 and the polishing head 4 is achieved through an electric slip ring to avoid wire entanglement. Specifically, the electric slip ring is located at the central rotating shaft 500 or the rotating connection of the polishing head 4. Its stator part is connected to the external power supply line, and its rotor part rotates together with the polishing head 4, thereby maintaining stable electrical contact during rotation. Similarly, if the cathode component is a polishing disc 1 made of conductive material, its electrical connection with the adjustable power supply 8 can also be achieved through an electric slip ring or an electric brush. In addition, among the three forms of the cathode component, one is a polishing disc 1 made of conductive material, which has a simple structure; the second is a cathode ring embedded in the polishing disc 1, which rotates with the polishing disc 1 in a concentric ring shape and is suitable for situations where the polishing disc 1 is non-conductive; the third is a cathode plate independently set above the polishing pad 2 and in contact with the polishing liquid 120, which is fixed and facilitates isolation from other energy field components. Operators can choose any one of these according to actual needs.

[0056] As an example, workpiece 3 is a silicon carbide wafer, polishing liquid 120 is a water-based polishing liquid containing an appropriate amount of potassium chloride electrolyte, and adjustable power supply 8 is an electrochemical workstation that can apply a DC voltage of 50V. The surface of workpiece 3 undergoes anodic oxidation to generate a soft SiO2 layer, which is then removed by mechanical polishing.

[0057] As a preferred embodiment, refer to Figure 1 and Figure 2The magnetic field assembly includes at least one magnetic field generator 9, which is located below the polishing disk 1 or around the polishing pad 2, and is used to generate a static magnetic field or an alternating magnetic field in the polishing area of ​​the polishing pad.

[0058] The magnetic field generated by the magnetic field generator 9 couples with the magnetic abrasive particles or magnetically sensitive medium in the polishing fluid 120, which can enhance the mechanical action of the abrasive particles on the workpiece surface. The alternating magnetic field can also generate a magnetohydrodynamic effect, improve the hydrodynamic characteristics of the polishing area, make the abrasive particle distribution more uniform, and thus improve the polishing uniformity.

[0059] As an example, the magnetic field generator 9 uses an electromagnet and is positioned below the polishing disc 1. Magnetic abrasive particles, such as diamond particles coated with carbonyl iron powder, are added to the polishing fluid. After the magnetic field is activated, the magnetic abrasive particles are attracted to the surface of the workpiece 3 under the action of the magnetic field force, increasing the effective abrasive particle concentration and cutting edge, and improving the material removal rate.

[0060] As a preferred embodiment, refer to Figure 1 and Figure 2 The thermal field assembly includes at least one heat source 10 surrounding a polishing area disposed on the polishing pad 2, for heating the workpiece 3 or the polishing liquid on the polishing pad 2.

[0061] Heating with a thermal field can soften the surface material of a workpiece, reducing its hardness and brittleness, thereby decreasing the cutting force required for mechanical polishing and increasing the rate of chemical reactions. The thermal field can also combine with optical and electric fields to create a synergistic thermo-optical-electric effect, further optimizing the polishing result.

[0062] As an example, heat source 10 uses infrared lamps arranged around the polishing area of ​​polishing pad 2. When the workpiece 3 is a sapphire wafer, heating the polishing area to a preset temperature significantly reduces the surface hardness of the sapphire. Combined with other energy field assistance, this can greatly improve removal efficiency and reduce subsurface damage.

[0063] As a preferred embodiment, refer to Figure 1 and Figure 2 The plasma field assembly includes at least one plasma generator 11, which is located beside the polishing area of ​​the polishing pad 2 and is used to modify or activate the workpiece 3.

[0064] The plasma generator 11 produces low-temperature plasma, which acts on the workpiece surface, altering its chemical state and thus enhancing the chemical reactivity during subsequent chemical mechanical polishing. Plasma treatment is a dry modification method that does not introduce additional liquid contamination.

[0065] As an example, the plasma generator 11 uses a dielectric barrier discharge electrode, and the working gas is oxygen or a mixture of argon and oxygen. When the workpiece 3 is a single-crystal silicon wafer, the plasma is turned on before or during polishing to oxidize and activate the surface, making it easier for the oxidant in the subsequent polishing slurry to react with the silicon surface and improve the removal rate.

[0066] As a preferred embodiment, refer to Figure 6 and Figure 7 The polishing pad 2 has multiple gaps 20. The shape of the gaps 20 includes one or more of the following: circular, square, rhomboid, strip, and honeycomb. The multiple gaps 20 are arranged in concentric rings, spirals, grids, radials, or fan shapes. The upper surface of the polishing disk 1 has a groove 100. The gaps 20 and the groove 100 cooperate to form a liquid storage cavity for accumulating polishing liquid.

[0067] As an example, see reference Figure 6 (a) The polishing pad 2 has circular gaps 20, and multiple gaps 20 are arranged in a concentric ring; Reference Figure 6 (b) The polishing pad 2 has circular gaps 20, and the gaps 20 are arranged radially. (Reference) Figure 6 (c) The polishing pad 2 has square-shaped gaps 20, and the gaps 20 are arranged in a grid pattern; Reference Figure 6 (d) The polishing pad 2 has diamond-shaped, square and circular gaps 20, and the multiple gaps 20 are distributed in a grid pattern.

[0068] in, Figure 1 The polishing pad 2 has no gaps 20, and the polishing liquid 120 accumulates on the surface of the polishing pad 2. Figure 2 The polishing pad 2 has openings 20 into which polishing slurry 120 can flow. The liquid storage cavity formed by the openings 20 and the grooves 100 can accumulate and guide the polishing slurry, promoting reactant transport and by-product discharge. For electric field assistance, it can maintain stable contact between the electrolyte and the surface of the workpiece 3, improving the uniformity of electrochemical oxidation; for optical field assistance, it can increase the residence time and reaction probability of the photocatalyst in the polishing area; for acoustic field assistance, it can provide more nucleation space for ultrasonic cavitation bubbles, enhancing the cavitation effect. This structure optimizes the working environment of various energy fields, further improving the efficiency and quality of multi-energy field synergistic polishing.

[0069] It should be noted that the polishing area of ​​the polishing pad 2 mentioned above refers to the annular or circular area in which the workpiece 3 is in direct contact with the polishing pad 2. This area is covered with polishing liquid 120 and is within the effective range of each energy field auxiliary component.

[0070] The device in this embodiment also includes a controller, which is electrically connected to the moving component 5, the spindle motor of the polishing disc 1, the liquid supply component 12, and each energy field auxiliary component. The controller is used to automatically control the movement of the workpiece 3 between processing stations, the lifting and rotation of the polishing head 4, the supply of polishing liquid 120, and the start / stop and process parameter adjustment of each energy field auxiliary component according to a preset process formula. Through the unified scheduling of the controller, on-demand switching for different materials or different processing stages can be achieved, ensuring the stable and orderly execution of the multi-station, multi-energy field combined collaborative polishing process.

[0071] Example 2 This second embodiment provides a wafer polishing method, applied to the multi-field assisted chemical mechanical polishing apparatus provided in the first embodiment, referencing... Figure 8 The methods include: S1: Clamp the wafer in the polishing head 4; S2: The polishing head 4 is moved by the moving component 5, so that the wafer is moved to multiple processing stations in sequence; S3: At each processing station reached, the wafer is pressed against the polishing pad 2 by the polishing head 4, and the polishing disk 1 is driven to move relative to the polishing head 4 to perform chemical mechanical polishing on the wafer; at the same time, the energy field auxiliary components set at the processing station are activated to provide energy field assistance to the wafer; wherein, the energy field auxiliary components include one or more combinations of light field components, sound field components, electric field components, magnetic field components, thermal field components and plasma field components, and the energy field auxiliary components or their combinations set at different processing stations are different.

[0072] The aforementioned wafers include, but are not limited to, silicon carbide wafers, sapphire wafers, or single-crystal silicon wafers. The technical effects of the method in Embodiment 2 are the same as those of the apparatus in Embodiment 1, and will not be repeated here.

[0073] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0074] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0075] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A multi-field assisted chemical mechanical polishing apparatus, the apparatus comprising a polishing disc (1), a polishing pad (2) disposed on the polishing disc (1), and a polishing head (4) for pressing a workpiece (3) against the polishing pad (2) for polishing, characterized in that, The device further includes: At least two processing stations, each processing station is provided with the polishing disc (1) and the polishing pad (2), and an energy field auxiliary component for assisting in removing surface material from the workpiece (3). The energy field auxiliary component includes one or more combinations of light field component, sound field component, electric field component, magnetic field component, thermal field component and plasma field component, and the energy field auxiliary components or combinations thereof provided in at least two processing stations are different from each other. A moving component (5), connected to the polishing head (4), is used to move the polishing head (4) and the workpiece (3) it clamps between the at least two processing stations.

2. The multi-field assisted chemical mechanical polishing device according to claim 1, characterized in that, The moving component (5) includes a rotary drive component (50), a lifting drive component (51), and a connector (52). The rotary drive component (50) includes a central rotating shaft (500) and a first drive component (501). The lifting drive component (51) includes a telescopic shaft (510) and a second drive component (511). One end of the telescopic shaft (510) is connected to the central rotating shaft (500) through the connector (52), and the other end is connected to the polishing head (4). The telescopic shaft (510) is parallel to the axis of the central rotating shaft (500). The first driving member (501) is used to drive the central rotating shaft (500) to rotate, so as to drive the polishing head (4) to rotate around the central rotating shaft (500) between different processing stations; The second drive member (511) is used to drive the telescopic shaft (510) to extend or retract, so as to move the polishing head (4) in a direction closer to or further away from the polishing pad (2).

3. The multi-field assisted chemical mechanical polishing device according to claim 2, characterized in that, The number of processing stations is three, and the three processing stations are respectively used to perform rough polishing, fine polishing and final polishing on the workpiece (3); wherein, the number of types of energy field auxiliary components set in the processing station used for rough polishing is greater than the number of types of energy field auxiliary components set in the processing stations used for fine polishing and final polishing. The first driving member (501) is used to drive the central rotating shaft (500) to rotate, so as to drive the polishing head (4) and the workpiece (3) it clamps to pass through the processing station for rough polishing, the processing station for fine polishing and the processing station for final polishing in sequence.

4. The multi-field assisted chemical mechanical polishing apparatus according to claim 1, characterized in that, The light field assembly includes at least one set of light sources (6), which are located above the polishing pad (2) and are used to emit light that can excite a photocatalytic reaction onto the polishing liquid on the polishing pad (2).

5. The multi-field assisted chemical mechanical polishing apparatus according to claim 1, characterized in that, The sound field assembly includes a sound wave generator and at least one sound wave transducer (7), the sound wave transducer (7) being integrated inside or at the bottom of the polishing disk (1), the sound wave generator being electrically connected to the sound wave transducer (7) for driving the sound wave transducer (7) to generate a sound field.

6. The multi-field assisted chemical mechanical polishing apparatus according to claim 1, characterized in that, The electric field assembly includes an anode component, a cathode component, and an adjustable power supply (8). The anode component is integrated inside the polishing head (4) for electrical connection with the workpiece (3). The cathode component is the polishing disc (1) made of conductive material, or a cathode ring embedded in the polishing disc (1), or a cathode plate located above the polishing pad (2) and in contact with the polishing liquid. The positive terminal of the adjustable power supply (8) is connected to the anode component, and the negative terminal of the adjustable power supply (8) is connected to the cathode component.

7. The multi-field assisted chemical mechanical polishing apparatus according to claim 1, characterized in that, The magnetic field assembly includes at least one magnetic field generator (9), which is located below the polishing disk (1) or on the periphery of the polishing pad (2) and is used to generate a static magnetic field or an alternating magnetic field in the polishing area of ​​the polishing pad.

8. The multi-field assisted chemical mechanical polishing apparatus according to claim 1, characterized in that, The thermal field assembly includes at least one heat source (10) surrounding a polishing area disposed on the polishing pad (2) for heating the workpiece (3) or the polishing liquid on the polishing pad (2).

9. The multi-field assisted chemical mechanical polishing apparatus according to claim 1, characterized in that, The plasma field assembly includes at least one plasma generator (11), which is located beside the polishing area of ​​the polishing pad (2) and is used to modify or activate the workpiece (3).

10. A wafer polishing method, applied in the multi-field assisted chemical mechanical polishing apparatus according to any one of claims 1 to 9, characterized in that, The method includes: The wafer is clamped in the polishing head (4); The polishing head (4) is moved by the moving component (5) so that the wafer is moved sequentially to multiple processing stations; At each processing station reached, the wafer is pressed against the polishing pad (2) by the polishing head (4), and the polishing disk (1) is driven to move relative to the polishing head (4) to perform chemical mechanical polishing on the wafer; at the same time, the energy field auxiliary component set at the processing station is turned on to provide energy field assistance to the wafer. The energy field auxiliary components include one or more combinations of light field components, sound field components, electric field components, magnetic field components, thermal field components and plasma field components, and the energy field auxiliary components or combinations thereof set at different processing stations are different from each other.

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