Electrochemical mechanical polishing device and wafer processing equipment comprising same

Abstract

The invention provides an electrochemical mechanical polishing device and wafer processing equipment comprising the same. The electrochemical mechanical polishing device comprises a polishing head and a polishing pad, the electrochemical mechanical polishing device further comprises an electrochemical workstation and an electrolyte supply assembly, an anode of the electrochemical workstation is connected with a gas film at the polishing head, a cathode of the electrochemical workstation is connected with a polishing disc, and a reference electrode is connected with a reference electrode measuring head at the polishing disc. According to the invention, the semiconductor surface polishing removal rate can be improved through electrochemical reaction, and the consumption of consumables is reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing; more specifically, the present invention relates to an electrochemical mechanical polishing device and a wafer processing equipment comprising the same. Background Art

[0002] Traditional chemical mechanical polishing (CMP) is a key technology used for surface flattening in the semiconductor manufacturing process. The traditional chemical mechanical polishing removal mechanism is mainly that the wafer material rubs against the polishing pad and the abrasive particles in the polishing liquid under the pressure applied by the polishing head, thereby achieving material removal on the wafer.

[0003] In recent years, with the advancement of semiconductor technology, semiconductor materials represented by silicon carbide, gallium nitride, zinc oxide, and diamond have received widespread attention. During the wafer polishing process, due to the high hardness of these semiconductor materials, the efficiency of chemical mechanical polishing is relatively low, and the surface roughness and total thickness deviation of the wafer are poor.

[0004] In order to solve this problem, the downward pressure during the polishing process needs to be increased, which increases the wear of the consumables and has a certain impact on the wafer surface and the roughness of the wafer surface. High-pressure polishing will also reduce the service life of the consumables and increase the cost of use. Summary of the invention

[0005] In view of this, the present invention provides an electrochemical mechanical polishing device and a wafer processing equipment including the same, so as to solve or at least alleviate one or more of the above-mentioned problems and other problems existing in the prior art.

[0006] To achieve the above-mentioned object, a first aspect of the present invention provides an electrochemical mechanical polishing device, wherein the electrochemical mechanical polishing device comprises:

[0007] A polishing head, the polishing head comprising an air film for vacuum adsorbing the wafer to be polished, the air film being a first conductive material;

[0008] a polishing disc configured with an electrolytic cell opening toward the polishing head, the polishing disc being a second conductive material;

[0009] A polishing pad, which covers the polishing plate, the polishing pad is provided with through holes, the through holes are in fluid communication with the electrolytic cell, and the polishing head can press the wafer adsorbed on the air film onto the polishing pad for polishing;

[0010] an electrochemical workstation, wherein an anode of the electrochemical workstation is connected to the gas film, a cathode of the electrochemical workstation is connected to the polishing disk, and a reference electrode of the electrochemical workstation is connected to the electrolytic cell; and

[0011] An electrolyte supply assembly is used to distribute electrolyte to the polishing pad.

[0012] In the electrochemical mechanical polishing device as described above, optionally, the anode of the electrochemical workstation is connected to the air film via a first working electrode wire, the cathode of the electrochemical workstation is connected to the polishing disk via a second working electrode wire, the reference electrode of the electrochemical workstation is connected to a reference electrode measuring head via a reference electrode wire, the reference electrode measuring head is located in an electrolytic cell formed on the polishing disk, and the reference electrode measuring head is in an open state through the through hole.

[0013] In the electrochemical mechanical polishing device as described above, optionally, a light source is provided on the upper surface of the polishing plate, and the light emitted by the light source can be irradiated to the surface of the wafer through the through hole to promote electron distribution.

[0014] In the electrochemical mechanical polishing device as described above, optionally, the light source is a blue light source or an ultraviolet light source, and the blue light source is a blue light LED.

[0015] In the electrochemical mechanical polishing device as described above, optionally, four grooves are arranged on the upper surface of the polishing disk, and the grooves are in the shape of arcs that are not concentric with the polishing disk or straight lines that are oblique to the diameter of the polishing disk, and the light source is arranged in the grooves.

[0016] In the electrochemical mechanical polishing device as described above, optionally, a light-transmitting end cover is provided in the groove to protect the light source in the groove.

[0017] In the electrochemical mechanical polishing device as described above, optionally, the through holes form a plurality of groups on the polishing pad, each group consists of a plurality of concentrically arranged rows of the through holes, and at least one row of the through holes is aligned with the grooves.

[0018] In the electrochemical mechanical polishing device as described above, optionally, four electrolytic cells are arranged on the polishing disk, and the electrolytic cells are evenly distributed circumferentially around the periphery of the polishing disk. A reference electrode measuring head is arranged in each electrolytic cell, and the four grooves are respectively located between two adjacent electrolytic cells. The electrolytic cells are blind holes, and the upper openings of the electrolytic cells are inclined toward the center of the polishing disk.

[0019] In the electrochemical mechanical polishing device as described above, optionally, the first conductive material is conductive rubber, and / or the second conductive material is an aluminum alloy with a graphene coating sprayed on the surface.

[0020] In the electrochemical mechanical polishing device as described above, optionally, the electrochemical mechanical polishing device includes a polishing turntable structure driven by a driving structure, and the polishing turntable structure includes:

[0021] a body, wherein the body is fixed;

[0022] a turntable rotatably mounted on the body via a bearing; and

[0023] An insulating disk is installed above the turntable, and the polishing disk is installed above the insulating disk. The insulating disk is used to insulate the turntable from the polishing disk.

[0024] In the electrochemical mechanical polishing device as described above, optionally, the driving structure includes a driving motor and a reduction mechanism, the reduction mechanism includes a pulley connected to the turntable, and the driving motor drives the pulley to rotate via a toothed belt.

[0025] In the electrochemical mechanical polishing device as described above, optionally, the insulating disk is made of a marble material that has been surface-sprayed.

[0026] In the electrochemical mechanical polishing device as described above, optionally, a conductive slip ring is provided at the center of the body, the second working electrode wire is electrically connected to the polishing disk through the conductive slip ring, and the reference electrode wire is electrically connected to the reference electrode measuring head through the conductive slip ring.

[0027] In the electrochemical mechanical polishing device as described above, optionally, a detachable retaining ring is provided on the outer periphery of the polishing disk and the polishing pad, and the detachable retaining ring extends upward from the polishing disk and beyond the polishing pad to keep the polishing liquid on the polishing disk.

[0028] In the electrochemical mechanical polishing device as described above, optionally, the end of the polishing disk toward the polishing head is configured as a frustum structure with a gradually decreasing radius, the lower end of the removable retaining ring is configured as a flared structure matching the frustum structure, and a sealing gasket is arranged between the frustum structure and the flared structure.

[0029] In the electrochemical mechanical polishing device as described above, optionally, the removable retaining ring can be raised and lowered. During the polishing process, the removable retaining ring is raised so that the top end of the removable retaining ring is higher than the top surface of the polishing pad to keep the polishing liquid on the polishing disk. When the polishing head adsorbs the wafer to be polished and moves to the outer periphery of the polishing pad, the removable retaining ring is lowered so that the top end of the removable retaining ring is not higher than the top surface of the polishing pad.

[0030] In order to achieve the aforementioned objective, a second aspect of the present invention provides a wafer processing equipment, wherein the wafer processing equipment comprises an electrochemical mechanical polishing device as described in any one of the aforementioned first aspects.

[0031] It can be seen from the above technical solutions that the present invention discloses an electrochemical mechanical polishing device and a wafer processing equipment, which can improve the semiconductor surface removal rate and reduce the amount of consumables by promoting the removal operation through electrolysis.

[0032] In an optional technical solution, the electrochemical mechanical polishing device can be assisted by light to promote electron distribution, further improve the removal rate of semiconductor materials, reduce the polishing liquid required, save costs, and increase the service life of consumables. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The disclosure of the present invention will become more apparent with reference to the accompanying drawings. It should be understood that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In the drawings:

[0034] Figure 1 A schematic cross-sectional view of an embodiment of an electrochemical mechanical polishing device according to the present invention is shown;

[0035] Figure 2 A removable retaining ring and a polishing disk in another embodiment are schematically shown, wherein a sealing gasket is shown;

[0036] Figure 3 Schematically shows Figure 1 A top view of the polishing disc in which the grooves are shown;

[0037] Figure 4 Schematically shows Figure 3 A cross-sectional view at AA of the polishing plate in FIG. 1 , showing the electrolytic cell and the reference electrode measuring head on the polishing plate;

[0038] Figure 5 Schematically shows Figure 3 A cross-sectional view of the polishing plate BB in FIG. 1 , showing a light-transmitting end cap on the polishing plate and a groove for placing a light source; and

[0039] Figure 6 Schematically shows Figure 1 A top view of the polishing pad in FIG. 1 shows how the through holes on the polishing pad correspond to the grooves on the polishing plate.

[0040] Reference numerals:1-polishing head; 2-air film; 3-electrochemical workstation; 4-first working electrode wire; 5-second working electrode wire; 6-reference electrode wire; 7-detachable retaining ring; 8-light source; 9-polishing pad; 10-electrolytic cell; 11-polishing disk; 12-insulating disk; 13-turntable; 14-turntable body; 15-rotating bearing; 16-conductive slip ring; 17-driving structure; 18-electrolyte supply assembly; 19-polishing turntable structure; 20-driving motor; 21-pulley; 22-toothed belt; 23-sealing pad; 24-groove; 25-reference electrode measuring head; 26-transparent end cover; 27-through hole; 28-group. DETAILED DESCRIPTION

[0041] With reference to the accompanying drawings and specific embodiments, the structure, composition, characteristics and advantages of the electrochemical mechanical polishing device of the present invention and the wafer processing equipment including the same will be described below in an exemplary manner. However, all descriptions should not be used to form any limitations on the present invention.

[0042] For any single technical feature described or implied in the embodiments mentioned in this document, or any single technical feature displayed or implied in the accompanying drawings, the present invention still allows any combination or deletion between these technical features (or their equivalents) without any technical obstacles, and thus it should be considered that these more embodiments according to the present invention are also within the scope of the description of this document.

[0043] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features.

[0044] Figure 1 A schematic cross-sectional view showing one embodiment of an electrochemical mechanical polishing apparatus according to the present invention.

[0045] from Figure 1 It can be seen that the electrochemical mechanical polishing device of this embodiment can include the following five parts, namely, a polishing head 1, a polishing disc 11, a polishing pad 9, an electrochemical workstation 3 and an electrolyte supply assembly 18.

[0046] As shown in the figure, the bottom of the polishing head 1 is used to hold the wafer, and can press the surface to be polished of the wafer to contact the polishing pad 9 and move and rub relative to the polishing pad 9 to achieve polishing of the surface to be polished of the wafer.

[0047] In this embodiment, an air film 2 may be installed at the bottom of the polishing head 1, and the air film 2 is used to vacuum absorb the wafer to be polished and hold the wafer on the polishing head 1. In an optional example, a retaining ring may also be arranged at the bottom of the polishing head 1 to accommodate the wafer therein and radially limit the wafer.

[0048] Figure 1 The specific structure of the polishing head is only an example; in optional embodiments, other forms of polishing head 1 structures may also be used, which will still fall within the protection scope of the present invention.

[0049] The polishing pad 9 is arranged on the turntable 13 of the polishing turntable structure 19, specifically covering the polishing disc 11. Specifically, in the illustrated example, the polishing turntable structure 19 may include a driving structure 17, a turntable body 14, a rotating bearing 15, a turntable 13, a polishing disc 11, a polishing pad 9, etc. According to the illustrated polishing turntable structure 19, the turntable body 14 is fixed, and the driving structure 17 drives the turntable 13 to rotate, which can drive the polishing disc 11 and the polishing pad 9 to rotate. When the polishing head 1 presses the wafer to contact the polishing pad 9, the wafer can be polished.

[0050] According to the example in the figure, it can be seen that a rotary bearing 15 can be provided between the fixed turntable body 14 and the movable turntable 13 to achieve relative free rotation between the two. In different embodiments, the rotary bearing 15 can also be located between the fixed turntable body 14 and the driving shaft driving the turntable 13. The fixed turntable body 14 is located at the bottom of the turntable 13, which can keep the turntable 13 in a stable position.

[0051] The polishing pad 9 may be provided with through holes 27, which may, for example, be used to transport polishing liquid, ensure chemical corrosion, and remove waste chips. The polishing pad 9 can achieve a polishing effect through the friction between the abrasive and the polishing pad 9. After the polishing turntable structure 19 is started, the polishing pad 9 can evenly transport the polishing liquid to the surface of the polishing pad 9 in a rotating manner to ensure that the surface to be polished of the wafer can fully contact the polishing liquid during the polishing process. The polishing pad 9 can utilize its own elasticity to maintain stable contact between the abrasive and the surface to be polished of the wafer during the polishing process, and deform in time during the polishing process to adapt to different polishing requirements. The reactants and abrasive chips generated during the polishing process can be carried away by the polishing liquid and discharged through the through holes 27 or the surface structure of the polishing pad 9 to maintain the stability of the polishing environment.

[0052] The polishing pad 9 can be a polymer porous material, which can store electrolyte and polishing liquid, transport electrolyte and polishing liquid and discharge waste liquid, etc. The polishing pad 9 can be made of a material with good hydrophilicity, so that during the polishing process, the polishing pad 9 is in contact with a liquid containing water and other chemical components, and can more effectively absorb and distribute the polishing liquid, ensuring that the entire polishing process is carried out evenly. In addition, the polishing pad 9 with good water affinity can also help dissipate heat through water evaporation, prevent overheating of the polishing surface, and reduce thermal damage. The material of the polishing pad 9 can also have good corrosion resistance and mechanical properties.

[0053] In order to keep the polishing liquid on the polishing disk 11, that is, the polishing liquid is not released from the polishing disk 11 during the polishing process, a removable retaining ring 7 can be provided on the outer periphery of the polishing disk 11 and the polishing pad 9. The removable retaining ring 7 extends upward from the polishing disk 11 until it exceeds the polishing pad 9, so that the removable retaining ring 7 can prevent the polishing liquid from flowing out from between the polishing disk 11 and the polishing pad 9, and from the top of the polishing pad 9. The polishing liquid can accumulate on the polishing disk 11, thereby increasing the current density.

[0054] In an optional embodiment, the detachable retaining ring 7 can be set to be able to rise and fall. The detachable retaining ring 7 has a liftable design. During the polishing process, the detachable retaining ring 7 can be lifted so that the top of the detachable retaining ring 7 is higher than the top surface of the polishing pad 9 so that the polishing liquid is kept on the polishing plate 11. When the polishing head 1 absorbs the wafer to be polished and moves to the outer periphery of the polishing pad 9, the detachable retaining ring 7 can be lowered so that the top of the detachable retaining ring 7 is not higher than the top surface of the polishing pad 9 to prevent the detachable retaining ring 7 from interfering with the polishing head 1.

[0055] In a further optional embodiment, the detachable retaining ring 7 can be configured to have a slope at the bottom, see Figure 2 and combination Figure 2 The end of the polishing disc 11 toward the polishing head 1 is configured as a truncated cone structure with a gradually decreasing radius, the lower end of the detachable retaining ring 7 is configured as a flared structure matching the truncated cone structure, and a sealing gasket is provided between the truncated cone structure and the flared structure to further prevent leakage of the electrolyte and the polishing liquid.

[0056] In order to assist in the polishing process, a polishing liquid supply assembly may be provided above the polishing pad 9 of the polishing turntable structure 19. The polishing liquid supply assembly may provide polishing liquid and the like to the polishing pad 9 during the polishing process, so that the polishing pad 9 undergoes corrosion and dissolution on the surface to be polished of the wafer, and then the polishing surface is processed by the grinding action of the abrasive particles in the polishing liquid. Optionally, the polishing liquid assembly may also provide other fluids such as water to the polishing pad 9 as required, for example, for timely cleaning after polishing. Alternatively, in other embodiments, a component specifically used to provide other fluids such as water may be provided above the polishing pad 9 of the polishing turntable structure 19, which is provided independently of the polishing pad 9 supply assembly, so as to facilitate flexible control and be applicable to more application scenarios.

[0057] As shown in the figure, the driving structure 17 in this example may include a driving motor 20, a toothed belt 22, a pulley 21, etc. During operation, the driving motor 20 drives the toothed belt 22, the toothed belt 22 drives the pulley 21 to rotate, and the pulley 21 drives the turntable 13 to rotate through the input shaft, etc., thereby driving the polishing disc 11, the polishing pad 9, etc. to rotate. In different embodiments, the driving motor 20 can drive the turntable 13 to rotate through various speed change devices, such as but not limited to the belt drive shown in the figure, and can also include gear drive, chain drive, etc.; no further description is given here.

[0058] As shown in the figure, the electrochemical mechanical polishing device also includes an electrochemical workstation 3. The electrochemical workstation 3 is connected to the polishing head 1 and the polishing turntable structure 9 through wires. Specifically, in the illustrated example, the anode of the electrochemical workstation 3 is connected to the gas film 2 through the first working electrode wire 4, the cathode of the electrochemical workstation 3 is connected to the polishing disk 11 through the second working electrode wire 5, and the reference electrode of the electrochemical workstation 3 is connected to the reference electrode measuring head 25 through the reference electrode wire 6. In order to ensure the normal operation of the second working electrode wire 5 and the reference electrode wire 6 during the operation of the polishing turntable structure 19, conductive sliders 16 can be respectively provided at the center of the turntable body 14 and the turntable 13, and the second working electrode wire 5 can be electrically connected to the polishing disk 11 through a conductive slip ring 16, and the reference electrode wire 6 can be electrically connected to the reference electrode measuring head 25 through a conductive slip ring 16. The use of the conductive slip ring 16 ensures that when the turntable 13 and the body 14 rotate, the second working electrode wire 5 and the reference electrode wire 6 will not generate twisting and winding interference signal transmission.

[0059] In an optional embodiment, the electrochemical workstation 3 may have a power supply and a data acquisition and analysis system. The power supply may be a battery or a high-voltage static discharge, which is used to provide the electrical energy required for the electrochemical reaction to the surface of the wafer to be polished. The data acquisition and analysis system may be used for data collection and analysis related to the electrochemical reaction, so as to control the electrochemical reaction and adjust the polishing parameters as needed.

[0060] The air film 2 may be made of a first conductive material. In this example, the air film 2 may be made of a flexible conductive material, such as a conductive rubber material. The conductive rubber material can expand the contact area with the wafer, which is beneficial to increase the current density and improve the removal efficiency.

[0061] The air film 2 absorbs the back side of the wafer, and the polishing head 1 presses the wafer onto the polishing pad 9, which contacts the front side of the wafer for polishing. The air film 2 is connected to the anode of the electrochemical workstation 3. Specifically, the anode of the electrochemical workstation 3 can be connected to the polishing head 1 through a cable, and the internal parts of the polishing head 1 are then connected to the air film 2 to achieve the conductive function.

[0062] The polishing disc 11 may be made of a second conductive material. In this example, the second conductive material may be an aluminum alloy with a graphene coating sprayed on the surface, which is easy to conduct electricity and resistant to acid and alkali corrosion.

[0063] In addition, in order to insulate the polishing disc 11 from the turntable 13, an insulating disc 12 can be arranged between the polishing disc 11 and the turntable 13. In this example, the insulating disc 306 can be made of marble. Since the marble is alkali-resistant but not acid-resistant, the surface of the marble is sprayed, so that the insulating disc 306 can insulate the turntable 307 from the polishing disc 305 and prevent conduction. As shown in the figure, the polishing pad 9 is first placed on the polishing disc 11, and the polishing disc 11 is placed on the insulating disc 12. The insulating disc 12 can also make the current distribution more uniform during the polishing process and prevent the current from leaking to unnecessary areas, thereby protecting the equipment and the wafer from damage. The insulating disc 12 is then placed on a turntable 13. When a polishing operation is required, the drive structure 17 drives the turntable 13 to rotate, and the insulating disc 12, the polishing disc 11 and the polishing pad 9 on the turntable 13 also rotate together.

[0064] The reference electrode measuring head 25 may be located in the electrolytic cell 10 formed on the polishing plate 11, and the reference electrode measuring head 25 may be in an open state through the through hole 27. Figure 1 As can be seen in FIG. 1 , the electrolytic cell 10 can be located at the outer periphery of the polishing plate 11, with its top opening connected to the through hole on the polishing pad 9, and the reference electrode measuring head 25 is located in the electrolytic cell 10. For the specific distribution of the electrolytic cell 10, please refer to Figure 3 and combination Figure 3 For detailed description of the reference electrode measuring head 25, please refer to Figure 4 and combination Figure 4 Detailed description.

[0065] The figure schematically shows an electrolyte supply assembly 18, which can release electrolyte, and the electrolyte can be distributed and filled into the polishing pad 9 and the wafer, so as to realize the connection between the cathode and anode of the electrochemical workstation 3, and an electrochemical reaction occurs at the surface to be polished of the wafer. In some embodiments, the electrolyte supply assembly 18 can be provided by the polishing liquid supply assembly, and the electrolyte or polishing liquid can be released as needed; or a separate electrolyte supply assembly 18 can be provided to specifically release the electrolyte.

[0066] According to the illustrated embodiment, when the electrochemical mechanical polishing device is working, the electrolyte supply assembly 18 releases the electrolyte, and the electrolyte fills the electrolytic cell 10 and the through hole 27 of the polishing pad 9. Figure 1 As shown in the figure, a plurality of through holes 27 are opened in the polishing pad 9, and the size of the through holes 27 can directly affect the current density during the polishing process, and the current density can directly affect the material removal rate. Therefore, a reasonable and effective hole opening method is crucial to ensure that the current conduction is continuous and effective when the polishing disk 11 rotates and the polishing head 1 sweeps over. Figure 6 FIG. 2 shows an example of a reasonable and effective way to open holes in the polishing pad 9. FIG.

[0067] In the illustrated example, during polishing, the electrochemical workstation 3 needs to remain in working condition to ensure the effective conduction of the electrochemical process. Specifically, the anode of the electrochemical workstation 3 is connected to the air film 2 at the polishing head 1 through the first working electrode wire 4. When the wafer is adsorbed and fixed on the polishing head 1 by the air film 2, the air film 2 can conduct the current to the surface to be polished of the wafer. The cathode of the electrochemical workstation 3 is connected to the polishing disk 11 through the second working electrode wire 5, and the electrolyte on the polishing disk 11 conducts the current to the surface to be polished of the wafer. Therefore, the positive and negative electrodes are connected on the surface to be polished of the wafer, and an oxide film that is easily removed by a specific polishing liquid is formed on the surface to be polished of the wafer. The oxide film is removed by polishing, which can beneficially improve the polishing efficiency.

[0068] As shown in the figure, a reference electrode measuring head 25 is installed inside the electrolytic cell 10, and the reference electrode measuring head 25 is connected to the electrochemical workstation 3 through a reference electrode wire 6. The function of the reference electrode measuring head 25 is to provide a stable potential reference, so that the potential change of the working electrode, i.e., the wafer surface relative to the reference can be accurately measured. This is beneficial for controlling the electrochemical process. Under the condition of accurately controlling the potential, it can ensure that the material on the wafer surface is removed in the expected manner.

[0069] As mentioned above, in actual operation, since the turntable 13 needs to be continuously rotated during the polishing process to ensure uniform polishing, all electrical connections must be able to maintain good electrical conductivity in the rotating state. Therefore, the second working electrode wire 5 and the reference electrode wire 6 both realize the electrical conduction function during the rotation process through the conductive slip ring 16 in the polishing turntable structure 19. Specifically, the conductive slip ring 16 can have a rotor part and a stator part, the polishing disk 11 and the reference electrode measuring head 25 of the polishing turntable structure 16 can be connected to the rotor part of the conductive slip ring 16, and the second working electrode wire 5 and the reference electrode wire 6 can be connected to the stator part of the conductive slip ring 16. The design of the conductive slip ring 16 allows the second working electrode wire 5 and the reference electrode wire 6 to be unaffected when the turntable 13 and the body 14 rotate, thereby ensuring continuous current transmission and ensuring continuous electrical connection between the electrochemical workstation 3 and the polishing disk 11.

[0070] It can be understood that the anode of the electrochemical workstation 3 is connected to the air film 2, the cathode is connected to the polishing disk 11, and the reference electrode is connected to the reference electrode measuring head 25. When electrochemical mechanical polishing is performed, the electrolyte supply assembly 18 releases electrolyte to the polishing pad 9, and the electrolyte is filled into the through hole 27 of the electrolytic cell 10 and the polishing pad 9. The electrolyte realizes the conduction between the wafer and the polishing pad 9, thereby realizing the connection between the anode and the cathode of the electrochemical workstation 3. After the electrolyte is electrolyzed, the surface of the wafer in contact with the polishing pad 9 will undergo an oxidation reaction to form an oxide film, which is easily removed by a specific polishing liquid. At the same time, the polishing liquid can contain abrasive particles. The pressure applied by the polishing head 1 to the wafer is combined with the abrasive particles, and the turntable 13 is constantly rotating, so that the wafer will be further easily polished. This technical solution enables the polishing head 1 to polish under a relatively small pressure, increase the service life of consumables, greatly reduce the amount of polishing liquid used during polishing, and save costs.

[0071] It can be understood that the electrochemical mechanical polishing device constitutes a complete electrochemical system under the conductive action of the electrolyte, so that the electrochemical reaction can be carried out on the wafer surface, promoting the electrochemical dissolution and removal of materials, and improving the wafer surface polishing rate. For example, for silicon carbide materials, a material removal rate of about 15μm / h can be achieved, and the amount of consumables can be significantly reduced.

[0072] Further, in the illustrated embodiment, a light source 8 is optionally provided on the upper surface of the polishing disc 11, and the light source 8 is a light source suitable for emitting light that can promote electron distribution. The light emitted by the light source 8 can be irradiated to the surface of the wafer through the through hole 27 of the polishing pad 9 to promote electron transfer, optimize electron distribution and wafer surface roughness, and further promote electrochemical reactions on the surface to be polished of the wafer. In an optional embodiment, the light source 8 can be a blue light source or an ultraviolet light source. Further, the blue light source can be a blue LED (light emitting diode).

[0073] Figure 2 The detachable retaining ring 7 and the polishing disc 11 in another embodiment are schematically shown, wherein the sealing gasket 23 is shown. The end of the polishing disc 11 facing the polishing pad 9 is configured as a truncated cone structure with a gradually decreasing radius, the lower end of the detachable retaining ring 7 is configured as a flared structure matching the truncated cone structure, and the sealing gasket is arranged between the truncated cone structure and the flared structure. Since the radial dimensions of the polishing disc 11 and the detachable retaining ring 7 are significantly greater than their heights, the radial middle portions of the polishing disc 11 and the detachable retaining ring 7 are omitted here by a break line.

[0074] from Figure 2 It can be seen that in an optional embodiment, the outer peripheral surface of the polishing disc 11 can be designed with a slope, and accordingly, the lower end of the detachable retaining ring 7 can be designed with a slope that matches the outer peripheral surface of the polishing disc 11. When the polishing disc 11 is installed and contacted with the detachable retaining ring 7, the slope design advantageously blocks the leakage of the polishing liquid or the electrolyte, and better achieves the purpose of preventing the liquid from being released.

[0075] In addition, the top of the detachable retaining ring 7 can be higher than the top surface of the polishing pad 9, so that the polishing liquid can be kept on the polishing disk 11 and the current density can be increased.

[0076] In a further embodiment, a sealing gasket 23 may be provided between the outer peripheral surface of the polishing disk 11 and the lower end of the removable retaining ring 7. When the polishing disk 11 and the removable retaining ring 7 are installed together, the slope design may advantageously prevent leakage of the polishing liquid or the electrolyte.

[0077] Figure 3 Schematically shows Figure 1 A top view of the polishing disk in FIG. 1 , showing the grooves.

[0078] Depend on Figure 3 It can be seen that the groove 24 provided on the upper surface of the polishing disk 11 is in the shape of an arc that is not concentric with the polishing disk 11 or in the shape of a straight line that is oblique to the diameter of the polishing disk 11. Without considering the obstruction of the polishing pad 9, due to the design that the arc is not concentric with the polishing disk 11 or the straight line is oblique to the diameter of the polishing disk 11, when the polishing disk 11 rotates and the polishing head 1 performs a sweeping action, the light source can effectively and continuously illuminate the front side of the wafer.

[0079] The figure also shows four electrolytic cells 10 in the polishing disc 11. Specifically, in this example, four electrolytic cells 10 are arranged on the polishing disc 11, and the electrolytic cells 10 are evenly arranged around the polishing disc 11. A reference electrode measuring head 25 can be arranged in each electrolytic cell 10, and the polishing disc 11 is divided into four parts by the diameter of the four electrolytic cells 10, and the four grooves 24 are respectively located in different parts. With such an arrangement, when the polishing disc 11 rotates, the electrolyte can easily reach the electrolytic cell 11, be collected by the electrolytic cell 10, and reach the reference electrode measuring head 25 in the electrolytic cell 10, which is beneficial to the normal progress of electrochemical mechanical polishing.

[0080] Figure 4 Schematically shows Figure 3 sectional view at the polishing plate AA in FIG. 1 , which shows the electrolytic cell 10 and the reference electrode measuring head 25 located on the polishing plate 11 .

[0081] from Figure 4 It can be seen that in this embodiment, the electrolytic cell 10 can be a blind hole, and the upper opening of the electrolytic cell 10 is inclined toward the center of the polishing disk 11. During the electrochemical mechanical polishing process, the electrolyte will be thrown out to the periphery of the polishing pad 9 due to the centrifugal force. Through the arrangement of the electrolytic cell 10, it can collect the thrown electrolyte, and can effectively avoid the situation that the electrolyte in the electrolytic cell 10 is thrown out due to the centrifugal force, resulting in the electrolyte being unable to be completely collected by the electrolytic cell 10, thereby affecting the normal operation of the reference electrode measuring head 25.

[0082] When the turntable 13 rotates, the electrolyte or polishing liquid may be thrown out due to centrifugal force, which may cause leakage of the electrolyte or polishing liquid, resulting in a significant increase in the amount of electrolyte or polishing liquid used, which increases the cost. In this example, the electrolytic cell 10 is designed as an inclined blind hole, and the upper opening of the electrolytic cell 10 is inclined toward the center of the polishing disc 11, so that the thrown electrolyte or polishing liquid can be collected in the electrolytic cell 10.

[0083] like Figure 4 As shown in , a reference electrode measuring head 25 can be installed inside each electrolytic cell 10, and four reference electrode measuring heads 25 can be connected to a reference electrode wire 6, and are connected to the electrochemical workstation 3 through the reference electrode wire 6. In this embodiment, the design of four reference electrode measuring heads 25 can avoid the situation where data is invalid when there is only one reference electrode measuring head. Here, the reference electrode of the electrochemical workstation 3 provides a constant potential reference for this electrochemical mechanical polishing device, so that the change of the working electrode relative to the reference can be measured, which is convenient for flexible control of polishing.

[0084] In the illustrated example, the reference electrode measuring head 25 can be arranged at one side of the bottom of the electrolytic cell 10 close to the rotation center of the polishing disk 11. With such an arrangement, when the polishing disk 11 rotates, the bottom of the electrolytic cell 10 can more effectively collect the electrolyte at its bottom, and the reference electrode measuring head 25 can more advantageously contact the electrolyte to facilitate its normal measurement work.

[0085] Figure 5 Schematically shows Figure 3 sectional view at the polishing disc BB in FIG. 1 , which shows the light-transmitting end cap 26 on the polishing disc 11 and the groove 24 for placing the light source.

[0086] like Figure 5 As shown in , the electrochemical mechanical polishing device can use a light source 8 to assist in operation. In this embodiment, the light source 8 can be a blue light LED. In other embodiments, an ultraviolet light source can also be used. The light source 8 can be used to promote electron distribution, optimize electrochemical reactions, and improve wafer surface roughness.

[0087] Combination Figure 1 , Figure 3 and Figure 5 It can be understood that in the illustrated embodiment, four grooves 24 can be designed around the polishing disc 11, each groove 24 is used to place a blue LED, and a plurality of blue LEDs can be installed in each groove 24. When the blue LED irradiates the surface of the wafer to be polished, when the semiconductor material of the wafer absorbs photons of sufficient energy, the electrons will gain energy and transition to a higher energy level, i.e., the conduction band, which promotes the distribution of electrons and is beneficial to improving the roughness of the surface of the wafer to be polished.

[0088] In order to ensure that the blue light LED is not affected by the electrolyte or polishing liquid used in the polishing process and to prevent it from being corroded, a transparent end cap 26 is installed on each groove 24. This transparent end cap 26 not only allows the blue light to pass smoothly to continue its role in the polishing process, but also acts as a physical barrier to protect the LED from chemical corrosion. In addition, a certain height difference can be maintained between the transparent end cap 26 and the polishing disc 11. Specifically, the transparent end cap 26 can be slightly lower than the surface of the polishing disc 11, which can not only ensure the effective transmission of light, but also reduce the interference of waste liquid generated during the polishing process to the system, thereby gradually affecting the polishing process, minimizing adverse factors, and optimizing the overall polishing effect.

[0089] Figure 6 Schematically shows Figure 1 FIG. 1 is a top view of the polishing pad 9 , which shows the correspondence between the through holes 27 on the polishing pad 9 and the grooves 24 on the polishing disk 11 .

[0090] like Figure 1As shown, a polishing pad 9 is laid on the polishing plate 11, and the light emitted by the light source 8 needs to pass through the polishing pad 9 and directly irradiate the surface to be polished of the wafer to promote electron transition and improve the microstructure of the wafer surface. In order to meet this process requirement, Figure 6 As shown in FIG. 8 , a series of through holes 27 are designed and processed on the polishing pad 9 .

[0091] like Figure 6 As shown in , these through holes 27 form a plurality of groups 28, specifically four groups, and the through holes 27 in each group 28 are arranged in a concentric circle manner. Furthermore, the position of at least one row of through holes 27 corresponds to the grooves 24 on the polishing disk 11, so as to ensure that the light emitted by the blue light LED can penetrate the polishing pad 9 and directly reach the wafer surface, thereby playing its role in enhancing electron transition. In addition, these through holes 27 not only provide a channel for blue light, but also allow the electrolyte to pass through, thereby forming a current loop on the wafer surface, promoting the electrochemical reaction during the electrochemical mechanical polishing process. This design not only improves the uniformity and controllability of polishing, but also enhances the effect of the entire polishing process, so that the surface quality of the wafer is significantly improved.

[0092] The present invention introduces electrochemical action to significantly improve the material removal rate during the polishing process, reduce the dependence on polishing pads and abrasive particles, thereby reducing polishing costs and improving the flatness and quality of the wafer surface. Furthermore, the technology is also conducive to reducing the amount of polishing liquid used and reducing the impact on the environment, thereby providing a more efficient, economical and environmentally friendly solution for wafer semiconductor manufacturing.

[0093] The technical solution provided by the present invention is introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An electrochemical mechanical polishing device, characterized in that: The electrochemical mechanical polishing device comprises: A polishing head (1), the polishing head (1) comprising an air film (2) for vacuum adsorbing a wafer to be polished, the air film (2) being a first conductive material; A polishing disc (11) having an electrolytic cell (10) opening toward the polishing head, wherein the polishing disc (11) is made of a second conductive material; A polishing pad (9) is covered on the polishing disc (11), and through holes (27) are distributed on the polishing pad (9), and the through holes (27) are in fluid communication with the electrolytic cell (10), and the polishing head (1) can press the wafer adsorbed on the air film (2) onto the polishing pad (9) for polishing; an electrochemical workstation (3), wherein the anode of the electrochemical workstation (3) is connected to the gas film (2), the cathode of the electrochemical workstation (3) is connected to the polishing disk (11), and the reference electrode of the electrochemical workstation (3) is connected to the reference electrode measuring head (25) in the electrolytic cell (10); and An electrolyte supply assembly (18), wherein the electrolyte supply assembly (18) is used to distribute electrolyte to the polishing pad (9).

2. The electrochemical mechanical polishing device according to claim 1, characterized in that: The anode of the electrochemical workstation (3) is connected to the gas membrane (2) via a first working electrode wire (4), the cathode of the electrochemical workstation (3) is connected to the polishing disk (11) via a second working electrode wire (5), the reference electrode of the electrochemical workstation (3) is connected to the reference electrode measuring head (25) via a reference electrode wire (6), the reference electrode measuring head (25) is located in the electrolytic cell (10) on the polishing disk (11), and the reference electrode measuring head (25) is in an open state through the through hole (27).

3. The electrochemical mechanical polishing device according to claim 1, characterized in that: A light source (8) is arranged on the upper surface of the polishing disc (11), and the light emitted by the light source (8) can be irradiated onto the surface of the wafer through the through hole (27) to promote electron distribution.

4. The electrochemical mechanical polishing device according to claim 3, characterized in that: The light source (8) is a blue light source or an ultraviolet light source, and the blue light source is a blue light LED.

5. The electrochemical mechanical polishing device according to claim 3, characterized in that: Four grooves (24) are arranged on the upper surface of the polishing disc (11), the grooves (24) are in the shape of an arc not concentric with the polishing disc (11) or in the shape of a straight line obliquely intersecting the diameter of the polishing disc (11), and the light source (8) is arranged in the grooves (24).

6. The electrochemical mechanical polishing device according to claim 5, characterized in that: A light-transmitting end cover (26) is arranged in the groove (24) and is used to protect the light source (8) in the groove (24).

7. The electrochemical mechanical polishing device according to claim 5, characterized in that: The through holes (27) form a plurality of groups (28) on the polishing pad (9), each group (28) is composed of a plurality of concentrically arranged rows of through holes (27), and at least one row of through holes (27) is aligned with the groove (24).

8. The electrochemical mechanical polishing device according to claim 5, characterized in that: Four electrolytic cells (10) are arranged on the polishing disc (11). The electrolytic cells (10) are evenly distributed around the periphery of the polishing disc (11). A reference electrode measuring head (25) is arranged in each electrolytic cell (10). The four grooves (24) are respectively located between two adjacent electrolytic cells (10). The electrolytic cells (10) are blind holes, and the upper openings of the electrolytic cells (10) are inclined toward the center of the polishing disc (11).

9. The electrochemical mechanical polishing device according to any one of claims 1 to 8, characterized in that: The first conductive material is conductive rubber, and / or the second conductive material is an aluminum alloy with a graphene coating sprayed on the surface.

10. The electrochemical mechanical polishing device according to claim 1, characterized in that: The electrochemical mechanical polishing device comprises a polishing turntable structure (19) driven by a driving structure (17), and the polishing turntable structure (19) comprises: A body (14), wherein the body (14) is fixed; a turntable (13), the turntable (13) being rotatably mounted on the body (14) via a bearing (15); and An insulating disk (12), wherein the insulating disk (12) is installed above the turntable (13), and the polishing disk (11) is installed above the insulating disk (12), and the insulating disk (12) is used to insulate the turntable (13) from the polishing disk (11).

11. The electrochemical mechanical polishing device according to claim 10, characterized in that: The driving structure (17) comprises a driving motor (20) and a reduction mechanism, wherein the reduction mechanism comprises a pulley (21) connected to the turntable (13), and the driving motor (20) drives the pulley (21) to rotate via a toothed belt (22).

12. The electrochemical mechanical polishing device according to claim 10, characterized in that: The insulating disk (12) is made of a marble material that has been subjected to surface spraying treatment.

13. The electrochemical mechanical polishing device according to claim 10, characterized in that: A conductive slip ring (16) is provided at the center of the body (14) and the turntable (13); the second working electrode wire (5) is electrically connected to the polishing disk (11) through the conductive slip ring (16); and the reference electrode wire (6) is electrically connected to the reference electrode measuring head (25) through the conductive slip ring (16).

14. The electrochemical mechanical polishing device according to claim 1, characterized in that: A detachable retaining ring (7) is arranged on the outer periphery of the polishing disc (11), and the detachable retaining ring (7) extends upward from the polishing disc (11) and exceeds the polishing pad (9) so as to keep the polishing liquid on the polishing disc (11).

15. The electrochemical mechanical polishing device according to claim 14, characterized in that: The end of the polishing disc (11) facing the polishing head is configured as a truncated cone structure with a gradually decreasing radius, the lower end of the detachable retaining ring (7) is configured as a flared structure matching the truncated cone structure, and a sealing gasket (23) is provided between the truncated cone structure and the flared structure.

16. The electrochemical mechanical polishing device according to claim 14, characterized in that: The detachable retaining ring (7) can be raised and lowered. During the polishing process, the detachable retaining ring (7) is raised so that the top of the detachable retaining ring (7) is higher than the top surface of the polishing pad (9) so that the polishing liquid is kept on the polishing disk (11). When the polishing head (1) absorbs the wafer to be polished and moves to the outer periphery of the polishing pad (9), the detachable retaining ring (7) is lowered so that the top of the detachable retaining ring (7) is not higher than the top surface of the polishing pad (9).

17. A wafer processing equipment, characterized in that: The wafer processing equipment includes the electrochemical mechanical polishing device according to any one of claims 1 to 16.

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