A polishing pad with grooves for reducing flow resistance of polishing liquid and a wafer polishing apparatus

Abstract

The present application relates to the technical field of chemical mechanical polishing, and discloses a polishing pad with flow resistance reduction grooves and a wafer polishing device, wherein a polishing layer of the polishing pad is provided with a plurality of first grooves and second grooves on side walls of the first grooves; the first grooves are used for containing polishing liquid; and the second grooves on the side walls of the first grooves are used for reducing flow resistance of the polishing liquid and reducing vortex flow generated in the flow process of the polishing liquid. The polishing pad with flow resistance reduction grooves can solve or improve vortex flow generated in the flow process of the polishing liquid, thereby increasing polishing uniformity, reducing defects such as scratches generated in the local polishing process, and improving utilization of the polishing liquid and a polishing rate.

Description

Technical Field

[0001] This invention relates to the field of chemical mechanical polishing technology, specifically to a polishing pad and wafer polishing apparatus with grooves that reduce the flow resistance of polishing fluid. Background Technology

[0002] Chemical mechanical planarization (CMP) is a process in which semiconductor wafers are polished on a rotating polishing pad under specific temperature, pressure and polishing medium conditions. The polishing process removes defects on the wafer surface, such as rough surfaces, scratches and contaminated layers.

[0003] To optimize polishing pad design, the interactions between the polishing layer, polishing medium, and polishing pad surface during chemical mechanical polishing (CMP) have been an increasingly important subject of research, analysis, and advanced numerical modeling. For many years, the development of most polishing pads has been essentially empirical, involving experimentation with numerous different porous and non-porous polymer materials and their mechanical properties. Many polishing pad designs have focused on providing various void patterns and groove arrangements for the polishing layer, which are claimed to improve slurry utilization and polishing uniformity. Over the years, many different groove and void patterns and arrangements have been implemented. Existing groove patterns include radial, concentric circles, Cartesian grids, and spirals, among others.

[0004] The grooves of the chemical mechanical polishing (CMP) pad and the flow of the slurry between the pad and the wafer significantly affect the polishing rate and flatness. The slurry encounters considerable resistance as it flows through the grooves due to constant impacts from the groove sidewalls. High flow rates also create eddies, leading to uneven shear stress distribution across the wafer surface. High-speed eddies result in excessive shear stress, causing over-polishing and creating depressions, while low-speed eddies lead to under-polishing and creating protrusions. Strong eddies in low-pressure areas can generate cavitation, which, upon collapse, releases microjets that impact the wafer surface, creating micro-pits or damaging the thin film layer. The centrifugal effect of eddies also causes large abrasive particles to migrate towards the periphery of the eddy core, while small particles aggregate towards the center, resulting in abnormal local abrasive concentrations and fluctuations in material removal rates. The concentration of large particles in high-pressure areas increases the risk of defects such as scratches.

[0005] Current polishing pad patents have limited research on the flow resistance of polishing fluid in the grooves. Most groove optimization designs focus on how to make the polishing fluid evenly distributed, aiming to improve polishing uniformity and increase the utilization rate of polishing fluid. There are few studies on improving the flow resistance of polishing fluid by reducing eddies, thereby reducing polishing defects and improving the utilization rate of polishing fluid. However, improving the flow resistance of polishing fluid in the grooves and reducing eddies during the flow of polishing fluid have an important impact on improving polishing quality. Summary of the Invention

[0006] In view of this, one objective of the present invention is to provide a polishing pad with grooves that reduce the flow resistance of polishing slurry, so as to solve or improve the resistance and eddy current phenomenon of polishing slurry during the flow process, thereby improving the problem of damage to the surface of semiconductor wafers and improving the utilization rate of polishing slurry.

[0007] Another object of the present invention is to provide the application of such chemical mechanical polishing pads in wafer polishing apparatus.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0009] A polishing pad with grooves to reduce the flow resistance of polishing fluid is disclosed. The polishing pad includes a polishing layer with a plurality of first grooves and second grooves. The first grooves are used to contain polishing fluid, and the second grooves are disposed on the sidewalls of the first grooves to reduce the resistance and eddy currents of the polishing fluid flow in the first grooves.

[0010] In one specific implementation, the first groove is selected from any one of concentric circular grooves, radial grooves, and spiral grooves, preferably a concentric circular groove.

[0011] In one specific implementation, the second groove is distributed on both sides or one side of the first groove, preferably on both sides of each first groove.

[0012] In one specific implementation, the second groove is uniformly or non-uniformly distributed on the sidewall of the first groove; preferably, the second groove is parallel or staggered on the sidewall of the first groove; preferably, the second groove intersects or does not intersect with the top or bottom of the sidewall of the first groove.

[0013] In one specific implementation, the depth of the first groove is 0.5~2mm, such as 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, etc., and the width of the first groove is 0.5~5mm, such as 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, 1.8mm, 2.0mm, 2.3mm, 2.5mm, 2.7mm, 3.0mm, 3.3mm, 3.5mm, 3.75mm, 4.0mm, 4.5mm, 4.8mm, 5mm, etc., and the spacing between the first grooves is 3~10mm, such as 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, etc.

[0014] In one specific implementation, the width of the second groove is 0.05~0.3mm, for example, 0.05mm, 0.06mm, 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.23mm, 0.25mm, 0.28mm, 0.3mm, etc., and the depth of the second groove is 0.05~1mm, for example, 0.05mm, 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0. The second groove spacing is 0.1~0.6mm, for example, 0.1mm, 0.15mm, 0.18mm, 0.2mm, 0.23mm, 0.25mm, 0.28mm, 0.3mm, 0.35mm, 0.38mm, 0.4mm, 0.45mm, 0.5mm, 0.56mm, 0.6mm, etc., with diameters of 2mm, 0.25mm, 0.3mm, 0.4mm, 0.45mm, 0.5mm, 0.56mm, 0.6mm, etc.

[0015] In one specific implementation, the second groove is selected from any one of linear grooves, sinusoidal grooves, and polygonal grooves.

[0016] In one specific implementation, the second groove is a continuous or discontinuous trench.

[0017] In one specific implementation, the cross-section of the second groove is any one of rectangular, V-shaped, or U-shaped.

[0018] In another aspect of the present invention, a wafer polishing apparatus includes the aforementioned polishing pad;

[0019] The worktable is equipped with a rotating mechanism, and the polishing pad is mounted on the rotating mechanism.

[0020] The wafer mounting mechanism is provided with a rotating end, on which the wafer is vacuum-adsorbed. The rotating end is arranged correspondingly to the polishing pad, and the wafer mounting mechanism is used to press the wafer onto the polishing pad.

[0021] Compared with the prior art, the chemical mechanical polishing pad of the present invention has the following beneficial effects:

[0022] The chemical mechanical polishing pad of the present invention has a second groove on the sidewall of the first groove, and a raised structure is formed in the area outside the second groove. The presence of the second groove can constrain the fluid in the near-wall region and suppress the generation of transverse vortices. The second groove guides the polishing fluid to flow directionally along the groove direction, reducing the random momentum exchange between the polishing fluid and the wall surface, thereby reducing the shear stress on the wall surface. This results in only stable low-speed vortices forming in the first groove. These vortices act as "fluid bearings," creating a sliding effect between the mainstream area and the rough wall surface. By controlling the boundary layer turbulence through microstructure, the flow resistance and high-speed vortices of the polishing fluid in the first groove can be reduced, avoiding abnormal local material removal rates and scratches, thereby ensuring the uniformity of polishing. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a top view of a polishing pad according to one embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the cross-sectional structure of the polishing layer according to one embodiment of the present invention;

[0026] Figure 3 This is a partially enlarged schematic diagram of the polishing layer according to one embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of the cross-section of the polished layer after polishing for a period of time, according to one embodiment of the present invention.

[0028] Figure 5 This is a schematic diagram of the cross-sectional structure of the polishing layer of the polishing pad according to another embodiment of the present invention;

[0029] Figure 6 This is a partially enlarged schematic diagram of the polishing layer according to another embodiment of the present invention;

[0030] Figure 7This is a cross-sectional schematic diagram of the polishing layer after polishing for a period of time, according to another embodiment of the present invention.

[0031] Explanation of reference numerals in the attached figures:

[0032] 100. Polishing layer; 101. Center of polishing pad; 102. First groove; 103. Second groove; 104. Raised surface of the first groove; 105. Raised surface of the second groove. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of 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, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "top," and "bottom," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; or they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0036] Chemical mechanical planarization (CMP) is a process in which semiconductor wafers are polished on a rotating polishing pad under specific temperature, pressure and polishing medium conditions. The polishing process removes defects on the wafer surface, such as rough surfaces, scratches and contaminated layers.

[0037] During the polishing process, the polishing slurry encounters significant resistance as it flows through the grooves of the polishing pad. This is because the slurry is constantly impacted by the sidewalls of the grooves, and eddies are generated at high flow rates. These eddies lead to uneven shear stress distribution across different areas of the wafer surface. High-speed eddy zones experience excessive shear force, resulting in over-polishing and creating depressions, while low-speed zones result in under-polishing and creating protrusions. Strong eddy zones with low pressure may generate cavitation bubbles, which, upon collapse, release microjets that impact the wafer surface, creating micro-pits or damaging the thin film layer. The centrifugal effect of the eddies also causes large abrasive particles to migrate towards the periphery of the eddy core, while small particles aggregate towards the center, leading to abnormal local abrasive concentrations and fluctuations in material removal rates. Large particles concentrate in high-pressure zones, increasing the risk of scratches and affecting polishing quality. Therefore, this invention designs a polishing pad with grooves that reduce the flow resistance of the polishing slurry, addressing or improving the resistance and eddy phenomena during the flow process, thereby mitigating the problem of surface damage to semiconductor wafers.

[0038] The following is combined with Figures 1 to 7 The following describes embodiments of the present invention.

[0039] This invention provides a polishing pad according to a first embodiment, such as... Figures 1 to 3 As shown, it includes concentric first grooves 102 evenly distributed on the surface of polishing layer 100 with polishing pad center 101 as the center, and second grooves 103 distributed on the two side walls of the concentric first grooves 102.

[0040] During polishing, polishing slurry is added to the polishing layer. The slurry interacts with the wafer surface through relative friction, thus polishing the wafer surface. For example... Figures 1 to 7 As shown, the polishing layer 100 is provided with a plurality of first grooves 102, each containing polishing fluid. During the wafer polishing process, abrasive grains flow with the polishing fluid within the first grooves 102. Second grooves 103 are respectively provided on the sidewalls at both ends of each first groove 102. The second grooves 103 do not intersect with the top and bottom of the first grooves 102. Here, the top and bottom of the first grooves refer to the surface of the polishing layer and the bottom of the first groove, respectively. "Does not intersect" means that they are not connected, i.e., the second grooves do not extend to the surface of the polishing layer or the bottom of the first groove.

[0041] The concentric first groove 102 is selected from continuous concentric circular grooves, which are divided into discontinuous circles by uniformly spaced isolation protrusions (i.e., the first groove protrusions 105). The width of the concentric first groove is, for example, 1 mm, the depth is, for example, 1 mm, and the interval is, for example, 5 mm. The width, depth, and interval of each ring of the concentric first groove are consistent, but this is limited to this embodiment. The width and depth of the first groove can vary uniformly or non-uniformly in other embodiments. The second groove in this embodiment is selected from continuous linear grooves and is included on both sides of each first groove in the polishing layer. Each side includes three layers of linear second grooves, which are the first layer, the second layer, and the third layer of second grooves from bottom to top. They are separated by the second groove protrusions 105. The width of the second groove is 0.2 mm, the depth is 0.1 mm, and the interval is 0.3 mm. The center of the first layer of second grooves is 0.3 mm from the bottom of the first groove, and the center of the third layer of second grooves is 0.3 mm from the top of the first groove. Polishing liquid gradually fills the first and second grooves.

[0042] During the polishing process, the polishing pad rotates at high speed, and the polishing slurry mainly flows within the first groove. Due to the arc shape of the first groove, the polishing slurry continuously impacts the arc-shaped wall as it flows within it. As a result, some of the polishing slurry is thrown onto the surface of the polishing pad and contacts the wafer for polishing under the action of centrifugal force. This part of the polishing slurry is beneficial. However, the polishing slurry inside the first groove, especially on both sides of the first groove, forms large eddies. These eddies create significant resistance, which hinders the flow of polishing slurry within the groove. Furthermore, excessive eddies reduce the amount of liquid thrown out, lowering the utilization rate of the polishing slurry. Polishing debris is more easily thrown onto the surface of the polishing pad, resulting in less polishing slurry distributed on the surface of the polishing pad and more polishing debris, causing localized uneven polishing and polishing defects.

[0043] In this embodiment, due to the presence of the second groove, during high-speed rotation, the second groove acts as a flow guide, diverting the polishing fluid and preventing the generation of large eddies, thus reducing flow resistance. Furthermore, the presence of the second groove reconstructs the near-wall turbulent structure, transforming destructive random eddies into ordered secondary flows, lifting the main flow region, and forming low-speed eddies within the groove, creating stratified flow. This ensures that the high-speed main flow within the first groove is almost unaffected by the wall, while the low-speed eddies within the second groove act as a "lubricating layer," isolating the main flow from the wall and further reducing flow resistance. On the other hand, the second groove acts as a step for the ejectable polishing fluid, facilitating its continuous upward and ejection, quickly filling the polishing pad surface, ensuring polishing uniformity. The stepped protrusions formed by the second groove also act as a barrier against polishing debris, preventing it from rising to the polishing pad surface and reducing defects such as polishing scratches.

[0044] In this invention, the term "gap or groove spacing" refers to the distance between the same side edges of a groove, that is, the sum of the width of the raised surface (i.e., the isolation boss) between two adjacent grooves and the width of a groove.

[0045] In this invention, the polishing pad is typically circular and is used to polish at least one of magnetic substrates, optical substrates, and semiconductor substrates.

[0046] In some embodiments, the shape of the first groove can be a concentric circle centered on the center of the polishing pad, or it can be a concentric polygon centered on the center of the polishing pad, such as a concentric square, a concentric pentagon, or a spiral groove, but is not limited thereto.

[0047] Specifically, the polishing layer of the polishing pad can be made of materials commonly used in the art without any limitations. For example, the polishing layer material can be selected from at least one of segment block copolymers or polyurethane elastomers, preferably polyurethane elastomers. The preparation method of the polishing layer can refer to existing technologies, which are well known to those skilled in the art. For example, the polishing layer can be a single or multi-layer structure without any limitations.

[0048] In some embodiments, the first groove is circular in shape, and a plurality of first grooves are arranged in concentric circles. The distance between two adjacent first grooves is 3mm to 10mm, preferably 3mm to 8mm. The width of the first groove is 0.5mm to 5mm, preferably 0.5mm to 4mm, and the depth of the first groove is 0.5mm to 2mm, preferably 0.5mm to 1.5mm.

[0049] In one specific implementation, the depth of the first groove is constant, and the bottom shape of the first groove is not limited, for example, it can be a planar shape or a curved shape, preferably a planar shape. This design makes the polishing fluid flow more easily, thereby reducing the accumulation of debris.

[0050] In one specific implementation, the depth of the second groove is constant, and the bottom shape of the second groove is not limited, such as a planar shape or a curved shape, preferably a rectangular, V-shaped or U-shaped shape. This design can reduce the flow resistance of the polishing fluid.

[0051] In one implementation, such as Figure 4As shown, when polishing reaches a certain level, the thickness of the polishing layer gradually decreases, and the second groove is gradually opened, exposing the polishing surface. At this time, the width of the first groove in the polishing layer changes. The width of the first groove is equal to the sum of the width of the first groove and the depth of the second groove. At this time, the amount of polishing fluid flowing into the surface of the polishing pad increases. Since the depth of the second groove is less than 20% of the width of the first groove, it is within the range of groove width variation, so the fluctuation of the polishing rate is within an acceptable range. However, with the increase of the groove width, the path of the polishing fluid flowing from bottom to top will become wider, generating a pressure drop. This allows the polishing fluid to rise like a jet, effectively replenishing the polishing fluid in the first groove to the surface of the polishing pad and contacting the wafer, which can further improve the uniformity of polishing and the utilization rate of polishing fluid.

[0052] In another implementation, such as Figures 5-7 As shown, the first groove 102 of the polishing pad is the same as in the first embodiment. The second groove 103 of the polishing pad is a sinusoidal groove. In this embodiment, the second groove is selected from the sinusoidal groove and is included on both sides of each first groove of the polishing layer. Each side includes two layers of linear second grooves, namely the first layer and the second layer of second grooves. The width of the second groove is 0.2 mm, the depth is 0.1 mm, and the interval is 0.3 mm. The lowest point of the first layer of second groove is 0.15 mm from the bottom of the first groove, and the highest point of the second layer of second groove is 0.15 mm from the top of the first groove. With a sinusoidal wavelength of π and an amplitude of 0.2 mm, this embodiment utilizes the second groove. During high-speed rotation, the second groove acts as a flow channel to guide the polishing fluid. Furthermore, the sinusoidal micro-groove introduces a periodic geometric disturbance into the sidewall of the first groove. When the fluid flows through these grooves, a relatively stable backflow zone forms within the second groove. The vortices generated in the first groove are trapped within the second groove. These trapped vortices act like ball bearings, forming a virtual smooth surface. The mainstream fluid in the first groove no longer directly contacts the wall but slides over these vortices, effectively reducing flow resistance. Additionally, the second groove structure disrupts typical turbulent processes. The vortices trapped within the second groove stabilize the flow near the wall, reducing the intense exchange of momentum near the wall, thereby lowering energy dissipation and wall shear stress. The second groove structure effectively suppresses the intensity of turbulence near the wall, and the sinusoidal second groove allows the fluid to flow more smoothly, further reducing polishing resistance.

[0053] In this embodiment, the sine wave amplitude can be 0.05mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, etc., and the wavelength can be π, 2π, 3π, etc. In this invention, the sine wave amplitude refers to the vertical distance from the crest or trough of the sine wave to the reference line (zero point).

[0054] Specifically, such as Figure 6 As shown, after polishing has been underway for a period of time, the second groove is opened, and the sinusoidal groove gradually changes from a complete state to an interrupted state. First, the first layer is interrupted. As polishing continues, the second groove is opened in each layer. Similar to the first implementation, the width of the first groove is equal to the sum of the width of the first groove and the depth of the second groove. At this time, the amount of polishing fluid flowing into the surface of the polishing pad increases. Since the depth of the second groove is within 20% of the first groove, within the range of groove width variation, the fluctuation of the polishing rate is within an acceptable range. However, with the increase of the width of the first groove, the path of the polishing fluid flowing from bottom to top will become wider, which can make the polishing fluid rise like a jet. This can effectively replenish the polishing fluid in the first groove to the surface of the polishing pad and contact the wafer, which can further improve the uniformity of polishing and the utilization rate of polishing fluid.

[0055] In one embodiment, a plurality of first grooves are arranged in concentric circles.

[0056] Secondly, this application also provides a wafer polishing apparatus, comprising:

[0057] Polishing pad;

[0058] The worktable is equipped with a rotating mechanism, and the polishing pad is mounted on the rotating mechanism.

[0059] The wafer mounting mechanism is equipped with a rotating end, on which the wafer is vacuum-adsorbed. The rotating end is arranged in correspondence with the polishing pad, and the wafer mounting mechanism is used to press the wafer onto the polishing pad.

[0060] The polishing pad and the wafer are rotated, causing them to rotate relative to each other. The polishing fluid is then filled between the polishing pad and the wafer surface and flows through the first groove, completing the chemical mechanical polishing process.

[0061] In this invention, the polishing pad is mainly used after a hard polishing layer and a buffer layer are bonded together. Specifically, the polishing layer material can refer to existing technologies, for example, it can be selected from block copolymers comprising at least one hard segment and at least one soft segment, including polyethylene oxide, poly(ether ester) block copolymers, polyamide, polyvinyl alcohol, polyvinylpyrrolidone, polyvinylpyridine, polyacrylic acid, polymethacrylic acid, polyaspartic acid, styrene polymers, epoxy polymers, maleic anhydride methyl vinyl ether copolymers, and combinations thereof. The polishing layer material can also be selected from polyurethane elastomers, polyether elastomers, polyether polyester elastomers, polyamide-based elastomers, thermoplastic polyurethane, thermoplastic rubber, styrene-butadiene copolymers, silicone rubber, synthetic rubber, styrene-isoprene copolymers, styrene-ethylene-butene copolymers, and combinations thereof.

[0062] In this invention, the preparation method of the polishing layer can also refer to existing technologies. This invention has no particular limitations. For example, the preparation method of the polishing layer can refer to patent CN112318363A, which involves uniformly mixing a curing agent, isocyanate prepolymer, and functional filler with expanded polymer hollow microspheres to obtain a gelling mixture; pouring the gelling mixture into a mold at 60-100℃ and gelling at room temperature for 15-20 minutes, then demolding; and then performing a secondary vulcanization at 100-120℃ for 12-16 hours to obtain a polyurethane polishing layer; wherein, isocyanate... The cyanate prepolymer is a prepolymer with an NCO content of 9wt%-10wt%, obtained by a two-step reaction of raw materials containing diisocyanate and polytetrahydrofuran polyol. Preferably, aromatic diisocyanate and polytetrahydrofuran polyol are first prepolymerized to obtain an isocyanate prepolymer with an NCO content of 6wt%-8wt%; then, alicyclic diisocyanate is added to the prepolymer from the previous step, and the mixture is thoroughly mixed and stirred for 20-30 minutes to obtain a prepolymer with an NCO content of 9wt%-10wt%. During the reaction of the isocyanate prepolymer with the curing agent, the stoichiometric ratio of NH2 to NCO is 90%-125%. More preferably, the method includes: a. first, prepolymerizing 2,4-toluene diisocyanate with low molecular weight polytetrahydrofuran polyol to obtain an isocyanate prepolymer with an NCO content of 6wt%-8wt%; b. adding hydrogenated MDI to the prepolymer from the previous step, mixing and stirring thoroughly for 20-30 minutes, and then vacuum degassing to obtain an isocyanate prepolymer with an NCO content of 9wt%-10wt% and containing a large amount of monomeric hydrogenated MDI; c. uniformly mixing the curing agent, isocyanate prepolymer, and functional filler with expanded polymer hollow microspheres to obtain a gelling mixture; d. pouring the gelling mixture into a mold at 80°C, gelling at room temperature for 15-20 minutes, demolding, and then performing a secondary curing at 120°C for 12-16 hours to obtain a polyurethane polished layer.

[0063] It should be noted that the wafer polishing apparatus includes the polishing pad provided in the embodiments of this application, and therefore includes all the advantages of the polishing pad mentioned above, so it will not be repeated here.

[0064] The following examples illustrate... Figures 1 to 7 A comprehensive explanation of all the above-mentioned plans is provided.

[0065] The present application is further explained and illustrated below through more specific embodiments, which do not constitute any limitation.

[0066] Unless otherwise specified, the polishing pads in the embodiments and comparative examples of the present invention are prepared by the following method:

[0067] The polishing pad is mainly used after the hard polishing layer and the buffer layer are bonded together. Specifically, the preparation method of the polishing layer refers to patent CN112318363A, which is as follows: Isocyanate prepolymer components: Take 34 parts of TDI-100, 53 parts of PolyTHF1000, and 6 parts of DEG, and react them at 75°C for 2 hours to obtain an initial prepolymer with an NCO% of 7.5%. Then add 7 parts of hydrogenated MDI (4,4'-dicyclohexylmethane isocyanate content 92%, 2,4'-dicyclohexylmethane isocyanate content 8%) and stir for 25 minutes. After vacuum degassing, a prepolymer with an NCO% of 9.0% is obtained. Weigh 2.5g of expanded polymer hollow microspheres 551DE40d42 (functional filler) and add them to 100g of isocyanate prepolymer A1. Then add 30g of a mixed curing agent of MOCA and M-CDEA (MOCA:M-CDEA mass ratio of 60:40), with an NH2:NCO stoichiometric ratio of 90%. Mix the mixture thoroughly at high speed and pour it into a mold at 80℃. After gelling at room temperature for 15 minutes, demold the mixture and then perform a secondary curing at 100℃ for 16 hours to obtain the polyurethane polished layer. The buffer layer uses the SUBAIV model buffer layer manufactured by Dow Chemical Company.

[0068] The obtained polishing pad was grooved according to the data of the examples and comparative examples to obtain a polishing pad with a first groove and a second groove on the final surface.

[0069] The test information and main raw materials used in the embodiments and comparative examples of this invention are as follows:

[0070] Equipment: Mirra™ CMP polisher.

[0071] Profile testing method: Using the FX200 measurement tool, the difference in wafer thickness before and after polishing is measured using an 81-point spiral scan, and the surface flatness is determined by dividing by the polishing time.

[0072] Polishing slurry utilization test method: The utilization rate of polishing slurry was analyzed by weighing the slurry before and after polishing using a Mettler Toledo balance (the increase in the mass of polishing slurry after polishing is due to the reaction between the complexing agent in the polishing slurry and the copper material on the wafer, converting the solid copper material into copper ions dissolved in the polishing slurry). The test method was as follows: 100 ml of unused polishing slurry and 100 ml of polishing slurry collected after polishing were weighed separately, and the weight difference between the two was calculated. The molar mass formula was used: M=m / n, to calculate the molar mass of copper ions, and then the molar mass of the complexing agent participating in the reaction could be obtained. The mass of the complexing agent participating in the reaction could be calculated again according to the molar mass formula. The polishing slurry utilization rate was calculated as the ratio of the mass of the complexing agent participating in the reaction to the mass of the complexing agent in the unused polishing slurry.

[0073] Polishing method: Using a Cu target, under a wafer mounting mechanism pressure of 1.5 psi (10.3 kPa), use U3061 polishing slurry mixed with deionized water at a 1:10 ratio. Polish for three minutes, followed by one minute of diamond dressing. During polishing, the rotation speed of the rotary mechanism is 77 rpm, and the rotation speed of the wafer mounting mechanism is 71 rpm.

[0074] During the polishing process, scratches or residues on the target material are represented by the number of particles with a length less than 0.1 μm on the target surface. Additionally, the number of scratches or residues greater than 0.1 μm and less than 0.5 μm are also counted.

[0075] Example 1

[0076] like Figures 1 to 4 The polishing pad structure shown:

[0077] The polished layer is 2mm thick and 740mm in diameter;

[0078] The first groove is in the shape of concentric circles, with a depth of 1mm and a width of 1mm. The distance between two adjacent first grooves is 5mm.

[0079] Three layers of second grooves are provided on both side walls of all the first grooves. The second grooves are continuous straight grooves, evenly distributed on the side walls. The width of the second groove is 0.2 mm, the depth is 0.1 mm, and the interval is 0.3 mm. The center of the first layer of second grooves is 0.2 mm from the bottom of the first groove, and the center of the third layer of second grooves is 0.2 mm from the top of the first groove.

[0080] Example 2

[0081] Another polishing pad structure in this embodiment:

[0082] The polished layer is 2mm thick and 740mm in diameter;

[0083] The first groove is concentric in shape. Unlike embodiment one, it has a depth of 1.2 mm, a width of 1 mm, and a distance of 5 mm between two adjacent first grooves.

[0084] Three layers of second grooves are provided on both sides of the first groove. The second grooves are continuous straight grooves and are evenly distributed on the side walls. The width of the second groove is 0.2 mm, the depth is 0.1 mm, and the interval is 0.3 mm. Unlike embodiment 1, the center of the first layer of second grooves is 0.3 mm away from the bottom of the first groove, and the center of the third layer of second grooves is 0.3 mm away from the top of the first groove.

[0085] Example 3

[0086] like Figures 5 to 7 This embodiment also includes a polishing pad structure:

[0087] The polished layer is 2mm thick and 740mm in diameter;

[0088] The first groove is in the shape of concentric circles, with a depth of 1.2mm and a width of 1mm. The distance between two adjacent first grooves is 5mm.

[0089] Two layers of second grooves are provided on both sides of the first groove. The second grooves are continuous sine curves and are evenly distributed on the side walls. The width of the second groove is 0.2 mm, the depth is 0.1 mm, the interval is 0.3 mm, the amplitude is 0.2 mm, and the wavelength is π. The lowest point of the first layer of second grooves is 0.15 mm from the bottom of the first groove, and the highest point of the second layer of second grooves is 0.15 mm from the top of the first groove.

[0090] Example 4

[0091] This embodiment also features a polishing pad structure:

[0092] Polished layer 1 has a thickness of 2mm and a diameter of 740mm;

[0093] The first groove is in the shape of concentric circles, with a depth of 1.2mm and a width of 1mm. The distance between two adjacent first grooves is 5mm.

[0094] Unlike Embodiment 3, a second groove is provided on both sides of the first groove. The second groove is a continuous sine curve. The second groove is evenly distributed on the side wall. The width of the second groove is 0.2 mm, the depth is 0.1 mm, there is no gap, the amplitude is 0.2 mm, the wavelength is π, the lowest point of the second groove is 0.3 mm from the bottom of the first groove, and the highest point of the second groove is 0.3 mm from the top of the first groove.

[0095] Example 5

[0096] Another polishing pad structure in this embodiment:

[0097] The polished layer is 2mm thick and 740mm in diameter;

[0098] The first groove is in the shape of concentric circles, with a depth of 1.2mm and a width of 1mm. The distance between two adjacent first grooves is 5mm.

[0099] Unlike Embodiment 2, all first grooves have two layers of second grooves on their sidewalls. The second grooves are continuous straight grooves. Except for the two layers of second grooves being evenly distributed on the sidewalls, they are the same as in Embodiment 2.

[0100] Example 6

[0101] Another polishing pad structure in this embodiment:

[0102] The polished layer is 2mm thick and 740mm in diameter;

[0103] The first groove is in the shape of concentric circles, with a depth of 1.2mm and a width of 1mm. The distance between two adjacent first grooves is 5mm.

[0104] Unlike Embodiment 3, all first grooves have two layers of second grooves on a single sidewall near the edge of the polished layer. The second grooves are continuous sinusoidal grooves and are evenly distributed on the sidewall. The rest is the same as in Embodiment 3.

[0105] Example 7

[0106] This embodiment also includes a polishing pad structure:

[0107] The polished layer is 2mm thick and 740mm in diameter;

[0108] The first groove is in the shape of concentric circles, with a depth of 1.2mm and a width of 1mm. The distance between two adjacent first grooves is 5mm.

[0109] Two layers of second grooves are provided on both sides of the first groove. The second grooves are continuous sine curves and are evenly distributed on the side walls. The width of the second groove is 0.2 mm. Unlike embodiment three, the depth of the second groove is 0.5 mm. The rest is the same as embodiment three.

[0110] Comparative Example 1

[0111] A polishing pad structure in this comparative example:

[0112] Polished layer 1 has a thickness of 2mm and a diameter of 740mm;

[0113] The first groove is in the shape of concentric circles, with a depth of 1.2mm and a width of 1mm. The distance between two adjacent first grooves is 5mm.

[0114] Unlike Embodiment 2, there is no second groove.

[0115] The polishing pads in the examples and comparative examples were subjected to polishing experiments, surface flatness tests and defect tests using the methods described above, and the data obtained are shown in Table 1.

[0116] Table 1

[0117] Test Project Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Number of defects less than 0.1µm per particle 26 28 19 39 37 48 23 90 Number of defects within 0.1µm-0.5µm per particle 4 4 2 5 5 7 4 10 NU / % 2.13 2.10 2.16 2.43 2.05 2.72 2.85 1.83 Polishing slurry utilization rate / % 55 54 58 52 52 54 59 50 RR / Å / min 4065 4049 4102 3987 3985 4001 3983 3895

[0118] As shown in Table 1, Example 3 exhibits the lowest polishing defects and the highest polishing utilization rate. This is due to the presence of the second groove. During the flow of the polishing slurry, the turbulence at the edges is significantly reduced after passing through the sinusoidal micro-concavity, resulting in a substantial decrease in vortices. The polishing slurry flows more smoothly through the first groove, thus greatly reducing the area where polishing debris accumulates due to vortices, thereby significantly reducing defects such as scratches. Furthermore, due to the reduction in vortices, the polishing slurry is evenly distributed on the surface of the polishing pad during the flow, achieving more uniform polishing. When polishing reaches a certain level, the second groove gradually opens, and due to the shape of the sinusoidal curve, it is even more conducive to polishing. The rise and fall of the polishing fluid, due to the width of the first groove plus the depth of the second groove, results in a wider overall width of the first groove. Therefore, the pressure at the bottom is higher and the pressure at the top is lower. Under the effect of pressure drop, the unused polishing fluid in the first groove is gradually lifted to the top, so that more of it can circulate to the top polishing pad and contact the wafer. This not only improves the utilization rate of the polishing fluid but also significantly increases the polishing rate. In addition, due to its larger mass, the polishing debris will be mostly deposited at the bottom of the first groove. During the rising process, the polishing debris on both sides of the first groove is difficult to be transported to the top of the polishing pad due to the obstruction of the second groove, which can effectively reduce defects such as scratches.

[0119] Examples 1 and 2 are slightly lower than Example 3 in terms of polishing defects, polishing slurry utilization, and polishing rate, but higher than the comparative example. Compared to Example 2, Example 1 has three continuous linear second grooves on the sidewall of the first groove, except that the depth of the first groove is slightly lower. Similar to Example 3, the presence of the second grooves reduces turbulence and vortices, thereby reducing defects such as scratches. However, since they are linear grooves, the polishing slurry can only flow along the arc of the first groove on the linear groove, without any lifting or lowering function. Therefore, grooves leading to the top are not formed on the sidewalls of the first groove, so the polishing slurry utilization is lower than that of Example 3. However, when the second groove is opened, as in Example 3, the width of the first groove increases, generating a pressure drop, which can squeeze a small portion of the polishing slurry to the top of the polishing pad, thus improving the polishing slurry utilization and polishing rate.

[0120] Example 4 has only one continuous sinusoidal second groove. Compared with the first three examples, the polishing defects are increased, and the polishing fluid utilization and polishing rate are reduced to a certain extent. This is because there are fewer second grooves, and there is still more turbulence and vortex, but it is significantly better than Comparative Example 1.

[0121] In Comparative Example 1, when only the first groove exists on the polishing pad, a large number of vortices exist during the flow of the polishing fluid, and polishing debris has a greater chance of contacting the wafer, which can easily lead to a significant increase in polishing defects. In addition, compared with the embodiment and comparative example that have a second groove, the utilization rate of polishing fluid and the polishing rate are lower when only the first groove exists because there is no pressure drop.

[0122] As can be seen from the NU (Non-Uniformity, which describes the degree of non-uniformity of material removal rate or thickness on the wafer surface during polishing, with a smaller value indicating better uniformity) data in Table 1, the NU after polishing in both the examples and comparative examples is within 3%, which meets the client's polishing requirements.

[0123] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the substantive technical content of the present invention. The substantive technical content of the present invention is broadly defined within the scope of the claims. Any technical entity or method completed by others that is completely identical to or an equivalent modification of the claims is considered to be covered within the scope of the claims.

Claims

1. A polishing pad with grooves that reduce the flow resistance of polishing slurry, characterized in that, The polishing pad includes a polishing layer, on which a plurality of first grooves and second grooves are provided. The first grooves are used to contain polishing liquid, and the second grooves are provided on the sidewalls of the first grooves to reduce the resistance and eddy currents of the polishing liquid flow in the first grooves.

2. The polishing pad according to claim 1, characterized in that, The first groove is selected from any one of concentric circular grooves, radial grooves, and spiral grooves, preferably concentric circular grooves.

3. The polishing pad according to claim 1, characterized in that, The second groove is distributed on both sides or one side of the first groove, preferably on both sides of each first groove.

4. The polishing pad according to claim 3, characterized in that, The second groove is evenly or non-uniformly distributed on the sidewall of the first groove; Preferably, the second grooves are distributed in parallel or staggered arrangement on the sidewalls of the first groove; Preferably, the second groove intersects or does not intersect with the top or bottom of the first groove sidewall on the sidewall of the first groove.

5. The polishing pad according to claim 1, characterized in that, The depth of the first groove is 0.5~2mm, the width of the first groove is 0.5~5mm, and the spacing between the first grooves is 3~10mm.

6. The polishing pad according to claim 1, characterized in that, The width of the second groove is 0.05~0.3mm, the depth of the second groove is 0.05~1mm, and the spacing between the second grooves is 0.1~0.6mm.

7. The polishing pad according to any one of claims 1-6, characterized in that, The second groove is selected from any one of linear grooves, sinusoidal grooves, and polygonal grooves.

8. The polishing pad according to claim 7, characterized in that, The second groove can be a continuous or discontinuous groove.

9. The polishing pad according to claim 7, characterized in that, The cross-section of the second groove is any one of rectangular, V-shaped, or U-shaped.

10. A wafer polishing apparatus, characterized in that, Includes the polishing pad as described in any one of claims 1-9; The worktable is equipped with a rotating mechanism, and the polishing pad is mounted on the rotating mechanism. The wafer mounting mechanism is provided with a rotating end, on which the wafer is vacuum-adsorbed. The rotating end is arranged correspondingly to the polishing pad, and the wafer mounting mechanism is used to press the wafer onto the polishing pad.

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