Bearing head for wafer processing and chemical mechanical polishing equipment

Abstract

The invention relates to a retaining ring for chemical mechanical polishing, a bearing head for wafer processing and chemical mechanical polishing equipment. The retaining ring is provided with an annular base body, the annular base body is provided with a top face and a bottom face opposite to the top face, the top face is suitable for being installed on the bearing head, a plurality of bases partially protruding from the retaining ring are distributed on the bottom face, and the plurality of bases correspondingly retain a plurality of universal first balls. The first balls can freely roll in all directions and are suitable for being in rolling contact with the polishing pad; the multiple bases are arranged into a plurality of concentric rings, a plurality of polishing solution channels extending from the inner side of the retaining ring to the outer side of the retaining ring are formed along gaps among the multiple bases, and pressure difference is formed between the two ends of each polishing solution channel when the retaining ring works so that polishing solution can flow into or be discharged out of the inner space of the retaining ring along the polishing solution channels. According to the technical scheme, the friction force between the retaining ring and the polishing pad is reduced, polishing liquid can flow into or be discharged out of the retaining ring, and the polishing efficiency is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of chemical mechanical polishing, and specifically relates to a retaining ring, a carrier head and a chemical mechanical polishing device for chemical mechanical polishing. Background Art

[0002] The chemical mechanical polishing (CMP) process is an important process for polishing and flattening the surface of semiconductor wafers. In this process, the retaining ring is used to prevent the wafer from slipping from under the carrier head, and at the same time, the pressure on the edge of the wafer is adjusted by contact with the polishing pad to improve the polishing effect. However, with the widespread application of high-hardness materials such as gallium nitride (GaN) and silicon carbide (SiC) and other difficult-to-process materials, the CMP process faces increasing challenges. The polishing pressure required for these materials is relatively large, resulting in a significant increase in the friction between the retaining ring and the polishing pad, resulting in increased wear of the retaining ring and the need for frequent replacement. This reduces processing efficiency and increases the cost of use.

[0003] In addition, the retaining ring that forms surface contact with the polishing pad wears quickly, and the groove on the retaining ring for passing the polishing liquid becomes shallower, which reduces the injection amount of the polishing liquid and causes abnormal wafer removal rate. In addition, due to the large friction between the retaining ring and the polishing pad, the carrier head and the retaining ring will tilt, resulting in a difference in the radial wear rate of the retaining ring, which in turn causes over- or under-polishing of the wafer edge. Summary of the invention

[0004] In view of this, the present application provides a retaining ring for chemical mechanical polishing, a carrier head and a chemical mechanical polishing device, thereby solving or at least alleviating one or more of the above-mentioned problems and other problems existing in the prior art.

[0005] In order to achieve the aforementioned objectives, the first aspect of the present application provides a retaining ring for chemical mechanical polishing, the retaining ring having an annular base, the annular base having a top surface and a bottom surface opposite to the top surface, the top surface being suitable for being mounted on a carrier head, and a plurality of bases partially protruding from the retaining ring are distributed on the bottom surface, the plurality of bases correspondingly retaining a plurality of universal first balls, the first balls being able to roll freely in all directions and being suitable for rolling contact with the polishing pad; the plurality of bases are arranged into a plurality of concentric circles, and a plurality of polishing liquid channels extending from the inner side of the retaining ring to the outer side of the retaining ring are formed along the gaps between the plurality of bases, and a pressure difference is formed at both ends of the polishing liquid channel when the retaining ring is working, so as to cause the polishing liquid to flow into or out of the internal space of the retaining ring along the polishing liquid channel.

[0006] Optionally or alternatively, the circumferential gap between circumferentially adjacent bases is larger than the radial gap between radially adjacent bases, and the polishing liquid channel is formed by connecting a plurality of the circumferential gaps in series.

[0007] Optionally or alternatively, the radial gap is configured to allow the polishing liquid to flow circumferentially to adjust the flow rate and flow velocity of the polishing liquid in the polishing liquid channel.

[0008] Optionally or alternatively, each circle contains the same number of the first balls, the corresponding first balls in each circle are radially aligned so as to be radially distributed on the bottom surface, and the polishing liquid channel is formed as a straight channel extending radially.

[0009] Optionally or alternatively, all the first balls are divided into a plurality of ball groups distributed circumferentially along the bottom surface, each ball group has the same number of the first balls, the circumferential gap between the first balls in each ball group is smaller than the circumferential gap between the individual ball groups, and the polishing liquid channel is formed between adjacent ball groups.

[0010] Optionally or alternatively, the first balls corresponding to each circle are radially offset to be distributed in a staggered manner on the bottom surface, and the polishing liquid channel is formed as a radially extending wavy channel.

[0011] Optionally or alternatively, the first balls corresponding to each circle are sequentially offset clockwise or counterclockwise in radial direction, and the polishing liquid channel is formed as a channel inclined along the clockwise offset direction or along the counterclockwise offset direction.

[0012] Optionally or alternatively, all the first balls are divided into a plurality of ball groups distributed circumferentially along the bottom surface, each ball group has the same number of the first balls, the circumferential gap between the first balls in each ball group is smaller than the circumferential gap between the individual ball groups, the corresponding first balls in each ball group are radially offset clockwise or counterclockwise, and the polishing liquid channel is formed between adjacent ball groups.

[0013] Optionally or alternatively, the polishing liquid channel is inclined at 20 to 60 degrees relative to a radial direction where an inner end thereof is located, and the inclination direction is toward the rotation direction of the retaining ring.

[0014] Optionally or alternatively, the first balls in the outermost circle and the first balls in the innermost circle are denser than the first balls in the middle circles; or the first balls in the outermost circle and the first balls in the innermost circle are sparser than the first balls in the middle circles.

[0015] Optionally or alternatively, the first ball is made of plastic, or the exterior of the first ball is coated with a corrosion-resistant protective layer.

[0016] Optionally or alternatively, each of the first balls is mounted on the bottom surface via a corresponding base, the base having a cavity for accommodating the first ball, the inner wall of the cavity being hemispherical, the cavity having an opening facing the polishing pad, a portion of the first ball being exposed from the opening to the outside of the cavity, and the exposed portions of all the first balls protruding from the bottom surface by the same distance, and the opening being used to limit the first ball from escaping from the base.

[0017] Optionally or alternatively, the opening includes a spherical ring band surrounding the outside of the first ball, the original spherical diameter of the spherical ring band matches the diameter of the first ball, and the opening is used to achieve free rotation of the first ball relative to the base.

[0018] Optionally or alternatively, a plurality of second balls are disposed in each base, and the plurality of second balls are located between the first balls and the inner wall of the cavity, so as to achieve rolling friction between the first balls and the inner wall.

[0019] Optionally or alternatively, the bottom surface is provided with a plurality of mounting holes for mounting the base, the base comprises a mounting column and a boss, and the opening is located at the boss.

[0020] Optionally or alternatively, a neck is provided between the mounting column and the boss, and the neck is configured as an annular groove.

[0021] Optionally or alternatively, the mounting post is configured to be inserted into the mounting hole in an interference fit manner until the boss abuts against the bottom surface for positioning.

[0022] Optionally or alternatively, the mounting column is accommodated in the mounting hole, and the boss is welded or screwed to the bottom surface for positioning and fixing.

[0023] In order to achieve the aforementioned objective, a second aspect of the present application provides a carrier head for wafer processing, wherein the carrier head has a chemical mechanical polishing retaining ring as described in any one of the aforementioned first aspects.

[0024] In order to achieve the aforementioned objective, a third aspect of the present application provides a chemical mechanical polishing device, wherein the polishing device has a carrier head for wafer processing as described in the aforementioned second aspect.

[0025] The present application provides a retaining ring for chemical mechanical polishing, a bearing head and a chemical mechanical polishing device. The retaining ring for chemical mechanical polishing of the present application reduces the friction between the retaining ring and the polishing pad by arranging a first ball on the bottom surface, significantly reduces the wear rate of the retaining ring, thereby extending its service life, effectively solving the technical problems of excessive wear and uneven polishing of traditional retaining rings when processing difficult-to-process materials, reducing the tilt of the bearing head caused by uneven friction between the retaining ring and the polishing pad, improving the radial wear uniformity of the retaining ring, and improving the stability and uniformity of polishing, so that a wafer with a flatter polishing surface can be obtained.

[0026] Furthermore, a polishing liquid channel is formed through the arrangement of the base and the first ball thereon, so that when the retaining ring is working, the polishing liquid can be guided through the polishing liquid channel to flow into the interior of the retaining ring and diffuse inside the retaining ring for wafer polishing under the action of the pressure difference at both ends of the polishing liquid channel, or the polishing liquid can be guided through the polishing liquid channel to carry polishing debris out of the interior of the retaining ring, thereby improving the replacement efficiency of new and old polishing liquids inside the retaining ring, reducing blockage and accumulation of polishing debris, reducing scratches on the wafer surface by debris, and making chemical mechanical polishing efficient, which is conducive to obtaining flatter wafers with higher surface quality.

[0027] In a further embodiment of the present application, a variety of arrangements of the first balls are provided, which can help control the flow rate of the polishing liquid, facilitate the diffusion and uniform distribution of the polishing liquid in the retaining ring, and improve the uniformity of wafer polishing. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0029] The disclosure of the present application 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 application. In the drawings:

[0030] Figure 1 A full cross-sectional view from the main perspective of a retaining ring for chemical mechanical polishing of the present application;

[0031] Figure 2 is a full cross-sectional view of a first ball mounted on a base through an interference fit;

[0032] Figure 3 for Figure 2 A-direction view in the figure;

[0033] Figure 4 is a full cross-sectional view of a first ball mounted via a screw-on base;

[0034] Figure 5 for Figure 4 B view in the figure;

[0035] Figure 6 A bottom view of the radial arrangement of first balls installed through an interference fit base;

[0036] Figure 7 A bottom view of the radial arrangement of first balls installed by screwing the base;

[0037] Figure 8 A bottom view of the radial grouping arrangement of the first balls;

[0038] Fig. 9 A bottom view of the staggered arrangement of the first balls;

[0039] Fig.10 A bottom view of the dense arrangement of the first balls;

[0040] Fig.11 A bottom view of the radial angle arrangement of the first ball;

[0041] Fig.12 A bottom view showing the radial angle grouping arrangement of the first balls;

[0042] Fig.13 A bottom view showing the arrangement of the inner, middle and outer rings of the first ball;

[0043] Fig.14 A bottom view showing another arrangement of the inner, middle and outer rings of the first ball;

[0044] Fig.15 A full cross-sectional view of a carrier head for wafer processing having a retaining ring for chemical mechanical polishing of the present application;

[0045] Fig.16 It is a schematic diagram of the structure of a chemical mechanical polishing device having a carrier head for wafer processing according to the present application.

[0046] Figure markings: 10-carrying head; 15-base; 20-polishing pad; 30-retaining ring; 31-base; 311-top surface; 312-bottom surface; 321-first ball; 322-base; 323-second ball; 324-screw; 325-cavity; 326-opening; 327-mounting column; 328-boss; 33-ball grouping; 34-ball group; 35-inner ring ball; 36-outer ring ball; 37-middle ring ball. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the embodiments of the present application should fall within the scope of protection of the embodiments of the present application.

[0048] In the description of the present application, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0049] In addition, in the description of the present application, unless otherwise specified and limited, it should be noted that the terms "installation" and "connection" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal connection between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0050] 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.

[0051] In the present application, the terms "CMP processing" and "CMP polishing" both mean "chemical mechanical polishing"; the terms "arrangement" and "arrangement" have the same meaning.

[0052] Figure 1 This is a full cross-sectional view from the main perspective of the retaining ring for chemical mechanical polishing of the present application.

[0053] like Figure 1 As shown, the retaining ring 30 includes a retaining ring base 31 and a first ball 321. In this embodiment, the retaining ring 30 mainly includes an annular base 31, and the base 31 has a top surface 311 and a bottom surface 312 (see Figure 2). The bottom surface 312 is a circular ring. The bottom surface 312 and the top surface 311 are located on both sides of the base 31, facing opposite directions. During the CMP process, the carrier head 10 is located above the retaining ring 30, and the top surface 311 of the retaining ring 30 can be firmly installed on the carrier head 10. The base 31 is an annular structure, and a through hole is formed in the center of the base 31. When performing CMP processing, the carrier head presses the wafer and the retaining ring 30 downward onto the polishing pad 20 to apply polishing pressure. The surface of the wafer to be processed faces the polishing pad 20 below. The retaining ring 30 surrounds the outside of the wafer to radially limit its range of movement. A plurality of bases 322 (see FIG. 322 ) partially protruding from the retaining ring are distributed on the bottom surface 312. Figure 2 ), a plurality of bases 322 correspondingly hold a plurality of universal first balls 321. These first balls 321 can roll freely in all directions. During the polishing process, the retaining ring and the polishing pad 20 are in rolling contact through these first balls 321. Each first ball 321 is designed to be able to roll freely in all directions, thereby converting the sliding friction between the retaining ring and the polishing pad 20 into rolling friction. This design greatly reduces the friction resistance, reduces the heat accumulation caused by friction, and reduces the interference of temperature changes on the stability of the polishing process; and the friction resistance is more evenly distributed along the entire circumference of the retaining ring, so that the carrier head can operate more smoothly, and the carrier head can make the retaining ring tightly pressed against the polishing pad at all places in the circumference, avoiding the tilting of the carrier head due to uneven friction resistance, and thus avoiding the gap between the retaining ring and the polishing pad due to the tilt of the carrier head, which causes the wafer to slip out of the retaining ring and break, reducing the risk of wafer breakage and damage to other components; and it can distribute the polishing pressure more evenly, improving the efficiency of the entire polishing process and the quality of the final polished surface.

[0054] Polishing pressure refers to the pressure applied downward by the carrier head during the CMP process. This pressure presses the wafer and the retaining ring 30 onto the polishing pad 20, while driving the carrier head to rotate. The wafer and the retaining ring 30 are fixedly connected to the carrier head and rotate synchronously with the carrier head. The retaining ring of the traditional structure forms a surface contact with the polishing pad. When the retaining ring 30 rotates relative to the polishing pad 20, sliding friction is generated between the two, and the friction coefficient is relatively large. The retaining ring 30 of the present application contacts the polishing pad 20 through the first ball 321, so that the sliding friction between the retaining ring 30 and the polishing pad 20 is converted into rolling friction.

[0055] Rolling friction has a lower friction coefficient than sliding friction. Therefore, during the polishing process, the friction between the retaining ring 30 and the polishing pad 20 in the rolling friction state is much smaller than the friction between the two in the sliding friction state. This feature not only improves the operating efficiency of the chemical mechanical polishing equipment, but also reduces the energy loss during the polishing process. Secondly, due to the reduction of friction, the phenomenon of uneven friction on the retaining ring 30 during the polishing process is also weakened, thereby effectively reducing the tilt of the carrier head, avoiding the problem of wafer slipping due to the tilt of the carrier head, and reducing the damage to the wafer and the equipment. The uniformity of the wafer polishing process is improved, and the possibility of over-polishing and under-polishing is reduced. In addition, since the retaining ring base 31 and the polishing pad 20 are in rolling contact through the first ball 321, the retaining ring base 31 is almost no longer worn. Due to the small rolling friction coefficient, the wear rate of the first ball 321 is much lower than that of the traditional retaining ring. This design not only extends the service life of the retaining ring as a whole, reduces the replacement frequency, but also reduces the maintenance frequency and cost. Finally, the design of the first rolling balls 321 enables the retaining ring 30 to contact the polishing pad 20 more stably during the polishing process. Multiple first rolling balls 321 are distributed on the bottom surface 312 of the retaining ring 30, so that the retaining ring 30 can contact the polishing pad 20 more stably during the polishing process, and the force is more uniform, thereby reducing the uneven polishing phenomenon of the wafer. The design of the first rolling balls 321 improves the surface quality of the final product and reduces the occurrence of polishing defects.

[0056] Figure 2 A full cross-sectional view of a first ball mounted via an interference fit base.

[0057] from Figure 2As can be seen in the figure, each first ball 321 is fixedly mounted on the bottom surface 312 of the retaining ring through a corresponding base 322. A cavity 325 is provided inside the base, and the function of the cavity 325 is to accommodate the first ball 321. The inner wall of the cavity 325 is hemispherical. An opening 326 is provided in the direction of the cavity 325 toward the polishing pad 20. The diameter of the retaining ring opening 326 is smaller than the diameter of the first ball 321. A part of the first ball 321 is exposed outside the cavity 325 from the opening 326, while more than half of the first ball 321 is located in the cavity 325, so that the first ball 321 cannot escape from the base 322 from the opening 326. During the CMP process, the exposed part of the first ball 321 is used to contact the polishing pad 20. The tops of the exposed parts of the multiple first balls 321 are aligned with each other after precise adjustment, that is, the exposed parts of all the first balls 321 protrude from the bottom surface 312 of the retaining ring by the same distance, ensuring that they remain on the same plane. During the polishing process, the contact between the retaining ring and the polishing pad 20 is uniform, and there will be no unevenness, which ensures the polishing surface quality of the wafer. During the CMP process, the carrier head drives the wafer and the retaining ring to rotate and move relative to the polishing pad 20 at the same time, resulting in the rolling direction of the first ball 321 relative to the polishing pad 20 constantly changing. Therefore, the universal first ball 321 makes the movement of the carrier head smoother, making the polishing process more stable and smooth.

[0058] Furthermore, in order to make the first ball 321 roll smoothly in the opening 326, the surface of the opening 326 facing the first ball 321 can be set as a spherical annulus. The "spherical annulus", or "ball zone", means the part of the spherical surface sandwiched between two parallel sections. The spherical annulus surrounds the outside of the first ball 321, and the diameter of its original spherical surface matches the diameter of the first ball 321. The spherical annulus forms a surface contact with the first ball 321 to limit the relative movement of the first ball 321 relative to the base 322, which prevents it from falling out of the opening 326 and limits the movement of the first ball 321 parallel to the bottom surface 312. Due to the surface contact, the first ball 321 can rotate freely and smoothly under the restriction of the opening 326.

[0059] Furthermore, since a gap is formed between the inner wall of the spherical cavity 325 and the first ball 321, in order to further reduce the friction between the first ball 321 and the inner wall of the cavity 325, a plurality of second balls 323 are arranged in the cavity 325 of the base 322. These second balls 323 are located between the first balls 321 and the inner wall of the cavity 325, forming a rolling friction interface. Specifically, when the first ball 321 rotates during the polishing process, the second ball 323 can roll freely between the first ball 321 and the inner wall of the cavity 325, thereby greatly reducing the friction resistance. Through the design of the second ball 323, the first ball 321 can run more smoothly during the polishing process, which improves the durability of the ball and makes the polishing process more stable and efficient.

[0060] exist Figure 2 In the illustrated embodiment, each base 322 is configured to be inserted into the mounting hole in an interference fit manner, thereby being fixedly connected to the bottom surface 312 of the retaining ring. Specifically, the bottom surface 312 is provided with a mounting hole corresponding to each base 322. The base 322 includes a mounting post 327 and a boss 328. The diameter of the mounting hole is slightly smaller than the diameter of the mounting post 327 of the base 322, and the mounting post 327 is installed in the mounting hole by an interference fit. Interference fit is a common mechanical fixing method, which makes the size of the mounting post 327 slightly larger than the mounting hole so that a certain pressing force is generated during the installation process, thereby achieving a firm connection between the base and the base 31. In order to ensure the smooth progress of the installation process, the end of the mounting post 327 is designed with a chamfer, which makes it easier to insert the mounting post 327 into the mounting hole for installation and alignment, while avoiding unnecessary stress concentration during the installation process and avoiding damage to the mounting hole or the mounting post 327. The boss 328 abuts against the bottom surface 312 to form a limit for the base 322. The opening 326 is disposed at the center of the boss 328 and connected to the cavity 325 .

[0061] A neck may be provided between the boss 328 and the mounting column 327, and an annular groove may be formed on the neck. The boss 328 and the groove may be used to accurately axially position the base 322. With the boss 328 closely fitting the bottom surface 312, the base 322 is more firmly installed, and the normal operation of the retaining ring 30 will not be affected due to looseness or displacement.

[0062] In addition to the interference fit connection, the base 322 and the base 31 can also be connected by welding to form a more reliable limiting and fixing structure. The base 322 includes a mounting column 327 and a boss 328. The mounting column 327 of the base 322 is inserted into the mounting hole of the bottom surface 312, and the end of the mounting column 327 is provided with a chamfer. However, unlike the aforementioned interference connection implementation, the mounting column 327 of this embodiment is connected to the mounting hole by a clearance fit, and its diameter is slightly less than or equal to the diameter of the mounting hole. The boss 328 abuts against the bottom surface 312 and is fixedly connected to the bottom surface 312 by welding. The center of the boss 328 is provided with an opening 326, which is connected to the cavity 325. The mounting column 327 is configured to an appropriate size and is clearance-matched with the mounting hole, so that the base 322 will not move along the radial direction of the mounting hole, which plays a limiting role, thereby facilitating the welding operation. By performing a welding operation between the boss 328 and the end face of the mounting hole, the base 322 is more firmly mounted on the base 31. The welded connection ensures that the base will not loosen or shift under high stress conditions, making it suitable for polishing difficult-to-machine materials.

[0063] Figure 3 for Figure 2 A view in the figure.

[0064] from Figure 3 It can be seen that the first ball 321 is located in the center of the top of the base 322, ensuring uniform force and smooth rolling. The diameter of the opening 326 is smaller than the first ball 321, preventing the first ball 321 from detaching from the base 322 during operation. The outer contour of the base 322 is circular, which facilitates installation and alignment, ensuring the symmetry and stability of the components during assembly. In addition, the circular contour simplifies the manufacturing process.

[0065] Furthermore, during the chemical mechanical polishing process, there is a flowing polishing liquid between the retaining ring and the polishing pad 20. The polishing liquid may contain one or more of abrasives, buffers, polishing agents, and additives. The bottom of the retaining ring 30 has a polishing liquid channel, through which the polishing liquid enters the polishing gap between the wafer and the polishing pad 20. The polishing liquid causes a chemical reaction on the surface of the wafer to produce a relatively easy-to-remove surface layer, which is then removed by friction by the polishing pad 20, thereby producing a uniform polishing surface on the end face of the wafer facing the polishing pad 20. Since the first ball 321 is in direct contact with the polishing liquid, the polishing liquid may be brought into the cavity 325 as the first ball 321 rotates, and contacts the second ball 323 and the inner wall of the cavity 325. When the polishing liquid accumulates in the cavity 325, it is likely to corrode the second ball 323 and contaminate the lubricating substance, affecting the normal operation of the second ball 323 and accelerating its wear. Therefore, a micro-discharge channel can be designed in the cavity 325 of the base 322. These channels allow the polishing liquid to flow out through the tiny openings at the bottom or side of the cavity 325, preventing the liquid from accumulating in the cavity 325, while not affecting the normal operation of the second ball 323. In addition, a sealing structure, such as an O-ring or an elastic seal, can be added between the first ball 321 and the opening. The seal can effectively prevent the polishing liquid from entering the cavity 325, maintaining the cleanliness of the second ball 323 and the lubricant in the cavity 325. The design of the seal can prevent the lubricating substance from being contaminated and ensure that the first ball 321 can rotate freely during the polishing process.

[0066] In addition, self-lubricating materials can be used to make the second ball 323 and the inner wall of the cavity 325. Self-lubricating materials such as polytetrafluoroethylene (PTFE) or oil-containing nylon can provide good lubrication performance without traditional lubricants, reducing the impact of the polishing liquid on the lubrication environment after entering the cavity 325. In addition, a special high-chemical resistance lubricant can be used, which can maintain its lubricating effect when in contact with the polishing liquid, thereby preventing wear problems caused by lubricant contamination. The use of such a lubricant can reduce the frequency of maintenance and extend the service life of the second ball 323.

[0067] In order to improve the overall durability of the retaining ring, especially in a corrosive polishing liquid, the base 31 of the retaining ring and the first ball 321 can be made of engineering plastics or ceramic materials. Specifically, high-performance engineering plastics such as polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyethylene terephthalate (PET) or polyamide-imide (PAI) and ceramic materials with similar properties such as alumina (Al2O3) and silicon nitride (Si3N4) can be used. These materials have good corrosion resistance, wear resistance and mechanical properties, and can maintain their structural integrity under corrosive and complex force working conditions.

[0068] In addition, as an alternative embodiment, a protective layer made of the above-mentioned engineering plastic or ceramic material can be coated on the bottom surface 312 of the substrate 31 and the outer side of the first ball 321. At the same time, other parts of the substrate 31 and the first ball 321 can be made of other suitable materials: the substrate 31 can be made of stainless steel, including SUS316, SUS316L, SUS304, and the first ball 321 can be made of plastic, ceramic or metal. It is worth noting that the implementation method of the term "coating" includes: integrally forming the substrate 31 and the first ball 321 with the protective layer through a special process, or installing the protective layer on the bottom of the substrate 31 and the outside of the first ball 321 by bonding, fastener connection or welding. The selection of the above-mentioned materials ensures the durability of the substrate 31 and the first ball 321, so that the substrate 31 and the first ball 321 are not corroded and worn by the polishing liquid, thereby extending the service life of the retaining ring.

[0069] Figure 4 A full cross-sectional view of the first ball mounted via a screw-on base.

[0070] As can be seen from the figure, the base 322 can also be fixed by mechanical fasteners, further improving the maintainability of the installation. The bottom surface 312 is provided with mounting holes corresponding to each base 322. The base 322 includes a boss 328 and a mounting column 327. The mounting column 327 is inserted into the corresponding mounting hole, and a chamfer is provided at the end to ensure the smooth progress and alignment of the installation process. It is worth noting that, unlike the interference fit connection method, the mounting column 327 and the mounting hole can adopt a clearance fit, so that the base 322 can be easily inserted into the mounting hole and radially positioned using the mounting hole. The boss 328 is against the bottom surface 312. The opening 326 is arranged at the boss 328 and is connected to the cavity 325.

[0071] A screw hole is provided at the boss 328 outside the opening 326, and the screw holes can be arranged symmetrically around the center of the opening 326. The screws 324 are passed through the screw holes to firmly fix the base 322 to the base 31. The number of screws can be two or other numbers. The screw connection has the advantage of being easy to install and disassemble, making it more convenient for routine maintenance or component replacement of the retaining ring, reducing downtime and maintenance costs. Another advantage of the screw connection is that the connection part can be regularly inspected and tightened during the operation of the retaining ring to ensure that the base always maintains a stable position, thereby further improving the reliability of the polishing process and the consistency of the product.

[0072] In order to connect the base 322 to the retaining ring base 31 by screws, the boss 328 of the base 322 is additionally provided with screw holes, resulting in corresponding structural and shape changes. The first ball 321, the second ball 323 and other structural features and functions of the base 322 in this embodiment are the same as those in the embodiment of the present invention. Figure 2In addition, the drainage channel and the sealing structure that can be added to the base 322, as well as the materials of the first rolling ball 321, the second rolling ball 323, the inner wall of the cavity 325 and the base 31 have been described above, so they will not be repeated here.

[0073] Figure 5 for Figure 4 B view in the figure.

[0074] from Figure 5 It can be clearly seen that the first ball 321 is located in the center of the base 322 to ensure that it is evenly stressed during rotation and runs smoothly. The screw holes are symmetrically distributed on the boss 328. The screw 324 passes through the screw hole of the base 322 and is fixedly connected to the retaining ring base 31. The base 322 has a diamond-shaped profile and is symmetrical and stable. Under different configuration conditions, the base 322 can be densely or sparsely arranged, and the diamond-shaped base 322 shape is conducive to increasing the installation density of the base 322.

[0075] A plurality of bases 322 and first balls 321 held therein are distributed on the bottom surface 312, and they can be arranged in a variety of ways, and a polishing liquid channel is formed between adjacent bases 322 (or between adjacent first balls 321). During the CMP process, the carrier head 10 drives the retaining ring to rotate and move above the polishing pad 20, and a pressure difference is formed at both ends of the polishing liquid channel, so that the polishing liquid under the wafer and the retaining ring is discharged to the outside, and at the same time, the polishing liquid outside the retaining ring flows along the polishing liquid channel to participate in the polishing process.

[0076] Combination Figure 6-Figure 14 It can be seen that the multiple bases 322 are arranged into multiple concentric circles, and multiple polishing liquid channels extending from the inner side of the retaining ring to the outer side of the retaining ring are formed along the gaps between the multiple bases 322. The two ends of the polishing liquid channel form a pressure difference when the retaining ring is working. For example, when the chemical mechanical polishing equipment is running and the carrier head drives the retaining ring to rotate, the gas or polishing liquid on the inner and outer sides of the retaining ring causes a pressure difference on both sides. The pressure difference at both ends of the polishing liquid channel prompts the polishing liquid to flow into or discharge from the internal space of the retaining ring along the polishing liquid channel to achieve efficient polishing of the wafer and timely discharge of debris. It should be understood that in the illustrated embodiment, since the base 322 corresponds to the first ball 321 one by one, the arrangement of the base 322 is consistent with the arrangement of the first ball 321. Therefore, this article only describes the arrangement of the base 322 or the first ball 321 and omits the repetitive description of the arrangement of the other one.

[0077] In a preferred embodiment, the circumferential gap between circumferentially adjacent bases 322 is larger than the radial gap between radially adjacent bases 322. The polishing liquid channel is formed by connecting (or penetrating) a plurality of circumferential gaps in series, that is, the overall extension direction of the polishing liquid channel is along the radial direction, and the width of the polishing liquid channel can be roughly represented by the above circumferential gap. Since the circumferential gap is larger than the radial gap, the polishing liquid as a whole will flow following the guidance of the polishing liquid channel.

[0078] The radial gap can be set to 0, that is, the base 322 is tightly fitted along the radial direction, so that the polishing liquid can flow better under the guidance of the polishing liquid channel, and it is beneficial for the polishing liquid to have a higher flow rate when passing through the polishing liquid channel. The higher the flow rate, the more conducive it is to the rapid diffusion of the polishing liquid to the center part of the retaining ring, so that the polishing liquid in the retaining ring is quickly and evenly distributed, thereby improving the polishing efficiency and the degree of wafer flatness.

[0079] In addition, the radial gap can be slightly larger than 0 to allow the polishing liquid to flow circumferentially, that is, to flow through the radial gap to adjust the flow rate of the polishing liquid in the polishing liquid channel. This design can be suitable for situations where the polishing liquid flow rate is large in local areas. For example, in the area where the polishing liquid is supplied to the polishing pad, the flow rate of the polishing liquid may be large. At this time, the flow rate of the polishing liquid in the polishing liquid channel of the part of the retaining ring facing this area will be greater than the flow rate of the polishing liquid in the polishing liquid channel of the part away from this area. The polishing liquid can be distributed from the polishing liquid channel with a larger flow rate to the polishing liquid channel with a smaller flow rate through the radial gap, thereby reducing the difference in the polishing liquid flow rate and flow velocity in each polishing liquid channel, and then enabling the polishing liquid to diffuse more evenly from the entire circumference of the retaining ring to the inside, thereby improving the uniformity of the distribution of the polishing liquid in the retaining ring, thereby improving the uniformity of wafer polishing and improving the flatness of the wafer.

[0080] Figure 6 A bottom view of the radial arrangement of first balls installed through an interference fit base.

[0081] like Figure 6 As shown, multiple bases 322 are arranged into multiple concentric circles, correspondingly having multiple circles of first balls 321, and each circle contains the same number of first balls 321. Four first balls 321 are evenly arranged in a straight line along the radial direction of the circular ring of the bottom surface 312 of the retaining ring to form a ball grouping 33. The corresponding first balls 321 in each circle are radially aligned and radially distributed on the bottom surface 312. The number of first balls 321 contained in different ball groups 33 is the same, and the arrangement intervals of the first balls 321 in these ball groups 33 are equal. These ball groups 33 are evenly arranged along the circumferential direction of the circular ring of the bottom surface 312. It can be seen that Figure 6The base 322 of the first ball 321 is installed on the retaining ring base 31 by interference connection, which ensures that the first ball 321 is firmly fixed to the retaining ring 30 and enhances the overall stability of the retaining ring. Figure 6 The polishing liquid channel is formed as a straight channel extending radially between the circumferentially adjacent ball groups 33, which can be roughly regarded as a radial straight groove, and these radial straight grooves are evenly arranged along the circumferential direction of the bottom surface 312 ring, and the directions of these straight grooves all point to the center of the bottom surface 312 ring. Further, the number of balls included in each row of first balls 321 can also be other values, which are adjusted according to the width of the bottom surface 312 ring.

[0082] exist Figure 6 In the embodiment, the first balls 321 included in each row of first balls 321 are arranged in a tight manner, and the adjacent bases 322 are arranged in a manner of installation without gaps and fit each other, that is, the radial gap can be set to 0, so that the bottom surface 312 ring of the same width can accommodate the maximum number of first balls 321, and the polishing liquid channel can better guide the flow direction of the polishing liquid, which is conducive to obtaining a higher flow rate. Furthermore, a certain interval can be set between the bases 322 of the same row of first balls 321, and the radial gap can be slightly greater than 0, so that the arrangement of the corresponding first balls 321 is looser, and the polishing liquid flow rate and flow rate in each polishing liquid channel can be adjusted, the difference in flow rate and flow rate can be reduced, and the uniformity of the distribution of the polishing liquid in the retaining ring can be improved.

[0083] Figure 7 A bottom view of the radial arrangement of the first balls mounted via a screw connection base.

[0084] Figure 7 The embodiments shown and Figure 6 The difference between the two is that the connection method between the base 322 and the bottom surface 312 is different. This also leads to the structural change of the base 322 in the two. The specific structural changes are as follows Figure 2 and Figure 4 The arrangement of the first balls 321 on the bottom surface 312 is similar to Figure 6 Same. As you can see, Figure 7 The bases 322 corresponding to the radially arranged first balls 321 in each column are closely attached to each other, so as to install as many first balls 321 as possible in the column. More first balls 321 can better disperse the polishing pressure, reduce the wear of the first balls 321, and extend the service life. Figure 6 Same, Figure 7The number of radially arranged first balls 321 in each row of the embodiment shown can also be adjusted according to actual conditions. Furthermore, in the first balls 321 in the same row, a certain arrangement interval can be set between the bases 322 of adjacent balls, so that the first balls 321 are arranged more sparsely, thereby improving the passing capacity and replacement efficiency of the polishing liquid.

[0085] like Figure 6 and Figure 7 As shown, each row of radially arranged first balls 321 are arranged in a straight line, and a straight polishing liquid channel is formed between the first balls 321 in adjacent rows. This shape of the polishing liquid channel improves the replacement efficiency of the polishing liquid and makes the polishing effect of the wafer more uniform. During the CMP process, the polishing liquid will change from "new" to "old". The effective components such as particles and chemicals used for polishing contained in the "new" polishing liquid will gradually be consumed and become "old" polishing liquid. If the old polishing liquid is not updated and replaced with a new polishing liquid, the polishing efficiency will decrease, making it difficult to control the polishing effect within the same processing time. In the design of the retaining ring of the present application, the new polishing liquid can flow into the retaining ring along the polishing liquid channel and reach the bottom of the wafer. At the same time, the old polishing liquid can also leave the bottom of the wafer along the polishing liquid channel and flow out of the retaining ring, thereby achieving the effect of replacing the old polishing liquid with the new and updating the polishing effective components in the polishing liquid. The present application uses the term "replacement efficiency" to describe the replacement speed of the polishing liquid.

[0086] Figure 8 This is a bottom view of the radial grouping arrangement of the first balls.

[0087] like Figure 8 As shown, in this embodiment, the bases corresponding to the first balls 321 installed on the retaining ring 30 are installed on the base 31 by interference connection. The first balls 321 are distributed in multiple circles on the bottom surface 312, and each circle of the first balls 321 is arranged radially along the bottom surface 312 to form a ball group 33. Each group 33 has the same number of first balls 321, and the corresponding first balls 321 in these groups 33 are arranged at equal intervals and aligned radially. In this embodiment, four first balls 321 form a ball group 33. Furthermore, Figure 8 The first ball 321 in Figure 6Further developed on the basis of the arrangement shown, four groups of ball groups 33 form a cluster arrangement of a ball group 34. The number of ball groups 33 contained in different ball groups 34 is the same, and the arrangement intervals of the ball groups 33 in these ball groups 34 are equal. The ball groups 34 are evenly arranged along the circumferential direction of the bottom surface 312 ring. In the ball group 34, the interval between adjacent ball groups 33 is smaller than the interval between the ball groups 34. This arrangement allows a wider polishing liquid channel to be formed between the ball groups 34, which is conducive to the passage of a larger flow of polishing liquid, and the smaller gap between adjacent ball groups 33 inside the ball group 34 can be used to adjust the polishing liquid flow or flow rate in the polishing liquid channel.

[0088] Furthermore, the number of first balls 321 included in a ball group 33 may be other values, and the number of ball groups 33 included in a ball group 34 may be other values. Since the passing efficiency of the polishing liquid through a wide channel is high and the passing efficiency of a narrow channel is low, the interval of the first balls 321 in a ball group 33, the arrangement interval of the ball groups 33 in the same ball group 34, and even the number of ball groups 33 included in the ball group 34 can be adjusted to adjust the number of wider polishing liquid channels and narrower polishing liquid channels, thereby accurately adjusting the replacement efficiency of the polishing liquid, so as to achieve the best balance between the polishing liquid cost and the polishing effect.

[0089] By controlling the first ball to adopt a more dense or dispersed arrangement, a more concentrated or dispersed pressure area can be formed during the CMP polishing process, optimizing the flow path of the polishing liquid, thereby saving costs while improving the polishing accuracy and efficiency. This design is suitable for high-precision polishing scenarios of difficult-to-process wafer materials.

[0090] Fig. 9 This is a bottom view of the staggered arrangement of the first balls.

[0091] like Fig. 9As shown, the first balls 321 are distributed in multiple circles on the bottom surface 312 of the retaining ring, and the corresponding first balls 321 in each circle are radially staggered and distributed in a staggered manner on the bottom surface 312, that is, the first balls 321 in one circle are exactly located in the center of the gap between the two first balls 321 in the inner circle or the outer circle. This staggered distribution design makes the spacing between any adjacent first balls 321 almost equal, ensuring the uniform distribution of the first balls 321 on the bottom of the entire retaining ring, and the polishing liquid channels are curved and extended in the radial direction, and are fluidly connected with each other, thereby providing more uniform polishing liquid flow control. In this embodiment, the base 322 is installed on the base 31 through an interference connection, so that the first balls 321 are firmly fixed to the retaining ring, ensuring the structural stability under polishing pressure. Specifically, the first balls 321 are arranged in four circles in the circumferential direction of the bottom surface 312, and the radius of each circle gradually increases. In addition, the first balls 321 of each circle rotate around the center of the circle at a certain angle, thereby achieving the effect of making all the first balls 321 discrete and evenly distributed. The advantage of the arrangement scheme of this embodiment is that the distribution of the first balls 321 and the polishing liquid channel is more uniform, which balances the radial and circumferential flow of the polishing liquid along the retaining ring 30, is conducive to the uniform distribution of the polishing liquid under the wafer, and is more suitable for scenes with high requirements for polishing stability. Furthermore, in Fig. 9 In the illustrated arrangement of the balls, the number of balls arranged in circles can also be adjusted according to the width of the bottom surface 312 of the retaining ring and the intervals between the balls.

[0092] Fig.10 This is a bottom view of the dense arrangement of the first balls.

[0093] like Fig.10 As shown, Fig.10 The arrangement shown is Figure 6 A special case of the arrangement shown in the embodiment. The ball groups 33 are closely arranged, and any adjacent bases 322 are installed in close contact with each other. The dense arrangement design increases the number of first balls 321 and the contact area with the polishing pad 20, thereby improving the durability and load-bearing capacity of the retaining ring 30. This arrangement is suitable for processing conditions with high polishing pressure. The base 322 of this embodiment is installed on the base 31 by interference connection, ensuring the installation stability and structural reliability of the first ball 321 on the retaining ring.

[0094] Fig.11 This is a bottom view of the radial angle arrangement of the first ball.

[0095] like Fig.11 As shown, multiple circles of first rolling balls 321 are distributed on the bottom surface 312, and each circle of first rolling balls 321 is grouped to form a rolling ball group 33. Fig.11As shown, the first balls 321 corresponding to each ball group 33 are sequentially offset clockwise or counterclockwise in the radial direction, and each ball group 33 has the same number of first balls 321, for example, five first balls 321 are evenly arranged in a direction forming a certain angle with the radial direction of the retaining ring to form a ball group 33. The polishing liquid channel is formed as a channel inclined along the clockwise offset direction or the counterclockwise offset direction between the circumferentially adjacent groups 33.

[0096] Similar to the above embodiment, Fig.11 In the embodiment, the first balls 321 in each ball group 33 can be installed closely to each other, leaving no gap between the corresponding bases 322. In this embodiment, the base 322 is installed on the base 31 by interference connection, ensuring the installation stability and structural reliability of the first balls 321.

[0097] The first balls 321 inside the ball grouping 33 are arranged in a straight line, and the angle between the arrangement straight line and the corresponding radial direction of the retaining ring is 20 to 60 degrees. The arrangement direction of the first balls 321 of different ball groups 33 is the same as the angle between the radial direction. The "radial direction" refers to the radial direction of the ring corresponding to the first ball 321 closest to the center of the ring in the ball grouping 33. The acute angle formed by the arrangement straight line of the first balls 321 included in the ball grouping 33 and the radial direction is the angle. In the process of the angle gradually increasing from 20° to 60°, the angle between the polishing liquid channel formed between adjacent ball groups 33 and the radial direction of the ring also gradually increases, which will affect the width of the polishing liquid channel and the flow direction of the polishing liquid, change the replacement efficiency of the polishing liquid, and thus adapt to different process requirements. This design allows more flexible control of the flow and distribution of the polishing liquid to optimize the polishing effect. The advantage of this arrangement is that the flow direction of the polishing liquid is not along the radial direction of the retaining ring, but forms a certain angle. Therefore, different angles can be configured for different polished materials to achieve different polishing effects, and it has high adaptability.

[0098] Preferably, the inclination direction of the polishing liquid channel faces the rotation direction of the retaining ring. For example, when the retaining ring rotates counterclockwise, the polishing liquid channel faces counterclockwise and forms an angle of 20 to 60 degrees with the radial direction of the retaining ring. The inclination direction of the polishing liquid channel and the rotation direction of the retaining ring are designed in the same direction, which can help to smoothly guide the polishing liquid into the interior of the retaining ring during the rotation of the retaining ring, without hindering the inflow of the polishing liquid in the reverse direction.

[0099] Further, in Fig.11In the embodiment, the bases 322 corresponding to the adjacent first balls 321 in the same ball group 33 can be installed at intervals, so as to adjust the number of the first balls 321 in the ball group 33, and then adjust the installation density of the first balls 321, adjust the flow rate and flow velocity of the polishing liquid, change the polishing pressure distribution, and enhance the adaptability of the retaining ring. Fig.11 In the polishing ring shown, the first balls 321 in each ball group 33 can also be arranged in a curve. The arrangement curve can be adjusted according to the actual situation of the polishing process. Different arrangement curves and spacing distances between ball groups 33 can change the replacement efficiency of the polishing liquid.

[0100] Fig.12 This is a bottom view of the radial angle grouping arrangement of the first ball.

[0101] like Fig.12 As shown, the arrangement of the first balls 321 in the ball group 33 is similar to Fig.11 The embodiment shown is the same and will not be described again. The difference is that in this embodiment, four ball groups 33 form a ball group 34, forming a cluster arrangement. Different ball groups 34 contain the same number of ball groups 33, and in the ball groups 34, the ball groups 33 are evenly arranged along the circumferential direction, and the ball groups 34 are evenly arranged along the circumferential direction of the bottom surface 312 ring, and the circumferential spacing between adjacent ball groups 33 is smaller than the circumferential spacing between adjacent ball groups 34. Fig.12 It can be seen that a wider inclined groove, i.e., a polishing liquid channel, is formed between adjacent ball groups 34, and a narrower inclined groove is formed between adjacent ball groups 33 inside the ball group 34, which can be used to adjust the polishing liquid flow or flow rate in the polishing liquid channel. These polishing liquid channels form a certain angle with the radial direction of the ring. Further, the applicable range of the angle is 20 degrees to 60 degrees. Preferably, the inclination direction of the polishing liquid channel is toward the rotation direction of the retaining ring. Further, the spacing between adjacent ball groups 34, the number and spacing of ball groups 33 in the ball group 34 can be adjusted, thereby changing the distribution of CMP polishing pressure. By adjusting the angle between the inclined groove and the radial direction, the angle and cross-sectional area of ​​the polishing liquid channel are adjusted, and then the flow direction and flow rate of the polishing liquid in the CMP process are adjusted to meet the process requirements of different polishing objects.

[0102] Fig.13 This is a bottom view of the arrangement of the inner, middle and outer rings of the first ball.

[0103] like Fig.13As shown, the bottom surface 312 is annular and has multiple circles of first balls 321, and the first balls 321 include inner ring balls 35, outer ring balls 36, and middle ring balls 37. The inner ring balls 35 include first balls 321 distributed in the innermost circle of the annular bottom surface 312, the outer ring balls 36 are distributed in the innermost circle of the annular bottom surface 312, and the middle ring balls 37 are distributed between the inner and outer ring balls 35 and 36. The inner ring balls 35, the outer ring balls 36, and the middle ring balls 37 are evenly arranged along the circumferential direction. In this embodiment, the bases 322 corresponding to the adjacent inner ring balls 35 are closely attached to each other, forming a close arrangement, which improves the stability of the inner ring of the retaining ring. The outer ring balls 36 are aligned with the inner ring balls 35 in the radial direction, and the close arrangement effect is also achieved, which enhances the support capacity and stability of the outer ring of the retaining ring. The middle ring balls 37 are arranged in the area between the inner ring balls 35 and the outer ring balls 36. The arrangement of the inner ring balls 35 and the outer ring balls 36 is denser than that of the first balls 321 of each circle of the middle ring balls 37. Fig.13 In the arrangement mode, the middle circle balls 37 are arranged in two circles, and the balls in each circle are aligned along the radial direction of the ring. Further, the middle circle balls 37 can be arranged in one circle or multiple circles, depending on the width of the retaining ring bottom surface 312 and the actual processing conditions. Furthermore, the arrangement density, number of ball circles and alignment angle of the inner circle balls 35, the outer circle balls 36 and the middle circle balls 37 can also be adjusted to achieve the best polishing effect.

[0104] The inner ring balls 35 and the outer ring balls 36 are closely arranged, which not only improves the support capacity of the retaining ring, but also makes the force of the retaining ring 30 more uniform. The middle ring balls 37 are arranged more sparsely, which improves the exchange efficiency of the polishing liquid. Fig.13 The arrangement design of the inner ring, outer ring and middle ring balls in the illustrated embodiment balances the load-bearing capacity of the retaining ring 30 and the exchange efficiency of the polishing liquid, thereby improving the CMP polishing effect on difficult-to-process materials.

[0105] Furthermore, the inner ring balls 35 and the outer ring balls 36 may also be arranged at a certain distance, but their arrangement must be denser than the middle ring balls 37. The arrangement distance of the middle ring balls 37 may also be adjusted according to the actual needs of the CMP process to achieve the best polishing effect.

[0106] Fig.14 This is a bottom view of another arrangement of the inner, middle and outer rings of the first ball.

[0107] like Fig.14As shown, the bottom surface 312 is annular and has multiple circles of first balls 321, and the first balls 321 include inner ring balls 35, outer ring balls 36, and middle ring balls 37. The inner ring balls 35 include first balls 321 distributed in the innermost circle of the annular bottom surface 312, the outer ring balls 36 are distributed in the innermost circle of the annular bottom surface 312, and the middle ring balls 37 are distributed between the inner ring balls 35 and the outer ring balls 36. The inner ring balls 35, the outer ring balls 36, and the middle ring balls 37 are evenly arranged along the circumferential direction. The middle ring balls 37 are arranged in the area between the inner ring balls 35 and the outer ring balls 36. In this embodiment, the bases 322 corresponding to the adjacent middle ring balls 35 are closely attached to each other, forming a close arrangement, which improves the stability of the middle ring of the retaining ring. The middle ring balls 37 are arranged in double circles, and the balls of each circle are aligned along the radial direction of the ring. The arrangement of the inner ring balls 35 and the outer ring balls 36 is sparser than the first balls 321 of each circle of the middle ring balls 37. Further, the middle ring balls 37 can be arranged in one circle or multiple circles, depending on the width of the retaining ring bottom surface 312 and the actual processing conditions. Further, the arrangement density, the number of ball circles and the alignment angle of the inner ring balls 35, the outer ring balls 36 and the middle ring balls 37 can also be adjusted to achieve the best polishing effect.

[0108] The close arrangement of the middle ring balls 37 not only improves the support capacity of the retaining ring, but also makes the force of the retaining ring 30 more uniform. The sparse arrangement of the inner ring balls 35 and the outer ring balls 36 improves the exchange efficiency of the polishing liquid. Fig.14 The arrangement design of the inner ring, outer ring and middle ring balls in the illustrated embodiment balances the load-bearing capacity of the retaining ring 30 and the exchange efficiency of the polishing liquid, thereby improving the CMP polishing effect on difficult-to-process materials.

[0109] Fig.13 , 14 The unique arrangement of the first ball 321 in the illustrated embodiment, the inner ring ball 35, the outer ring ball 36 and the middle ring ball 37 provide different load-bearing characteristics and polishing liquid passability during the polishing process, making the design of the retaining ring first ball 321 highly flexible. The large spacing arrangement provides sufficient polishing liquid flow, improving the polishing liquid replacement efficiency of the polishing ring, and the small spacing arrangement improves the bearing capacity and durability of the corresponding area. This retaining ring design makes the edge pressure distribution of the wafer more uniform, while allowing sufficient polishing liquid to flow into the bottom of the wafer, thereby obtaining a higher polishing removal rate.

[0110] Furthermore, the first balls 321 in the above-described embodiments are all fixedly mounted on the retaining ring 30 through the base 322, and cannot be displaced in any direction relative to the retaining ring 30, but the first balls 321 can also be slidably mounted on the retaining ring 30. Specifically, a slide groove is provided on the bottom surface 312. A portion of the first ball 321 is exposed from the slide groove mouth for contacting the polishing pad 20. When the carrier head 10 drives the retaining ring 30 and the wafer to rotate and translate relative to the polishing pad 20, the first ball 321 can rotate freely relative to the retaining ring 30, and can also slide along the slide groove. This embodiment is used to reduce the rolling resistance and the number of the first balls 321 used, thereby reducing the difficulty of the assembly process.

[0111] Fig.15 It is a full cross-sectional view of a carrier head for wafer processing having a retaining ring for chemical mechanical polishing of the present application.

[0112] The retaining ring is fixedly connected to the base 15 of the carrier head 10 through a specific structure. The carrier head 10 uses the retaining ring 30 disclosed in the present application, which can effectively improve the stability of the polishing process. The design of the first ball 321 reduces the friction between the retaining ring 30 and the polishing pad 20, extending the service life of the retaining ring 30. At the same time, adjacent first balls 321 form a polishing liquid channel, so that the polishing liquid can flow more evenly, improving the polishing efficiency and surface finish. By adopting a special arrangement of the first balls 321, it is ensured that the carrier head 10 achieves high-precision CMP polishing to meet the fine polishing requirements of different processed materials.

[0113] Fig.16 It is a schematic diagram of the structure of a chemical mechanical polishing device having a carrier head for wafer processing according to the present application.

[0114] The polishing equipment is equipped with Fig.15 The carrier head 10 of the structure shown can improve the polishing accuracy during the CMP polishing process and ensure the uniformity and flatness of the polished material. In addition, the polishing equipment can effectively control the movement and stability of the retaining ring during the polishing process to avoid uneven polishing, especially excessive wear on the edge of the wafer. The design of the first ball 321 ensures the free flow of the polishing liquid, making the polishing process more efficient and smooth. In addition, during use, the polishing equipment has the characteristics of high precision and high durability, which can greatly improve the polishing effect and is suitable for precision processing of various semiconductor materials.

[0115] The above implementation methods are only used to illustrate the embodiments of the present application, and are not limitations on the embodiments of the present application. Ordinary technicians in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the embodiments of the present application. Therefore, all equivalent technical solutions also belong to the scope of the embodiments of the present application. The scope of patent protection of the embodiments of the present application should be limited by the claims.

Claims

1. A retaining ring for chemical mechanical polishing, characterized in that: The retaining ring has an annular base, the annular base has a top surface and a bottom surface opposite to the top surface, the top surface is suitable for being mounted on the carrier head, and a plurality of bases partially protruding from the retaining ring are distributed on the bottom surface, the plurality of bases correspondingly hold a plurality of universal first balls, the first balls can roll freely in all directions and are suitable for rolling contact with the polishing pad; The multiple bases are arranged into multiple concentric circles, and multiple polishing liquid channels extending from the inner side of the retaining ring to the outer side of the retaining ring are formed along the gaps between the multiple bases. When the retaining ring is working, a pressure difference is formed at both ends of the polishing liquid channel to promote the polishing liquid to flow into or discharge from the internal space of the retaining ring along the polishing liquid channel.

2. The retaining ring according to claim 1, characterized in that The circumferential gap between the circumferentially adjacent bases is larger than the radial gap between the radially adjacent bases, and the polishing liquid channel is formed by connecting a plurality of the circumferential gaps in series.

3. The retaining ring according to claim 2, characterized in that The radial gap is configured to allow the polishing liquid to flow circumferentially to adjust the flow rate and flow velocity of the polishing liquid in the polishing liquid channel.

4. The retaining ring according to claim 2, characterized in that Each circle contains the same number of the first balls, and the corresponding first balls in each circle are radially aligned so as to be radially distributed on the bottom surface, and the polishing liquid channel is formed as a straight channel extending radially.

5. The retaining ring according to claim 4, characterized in that All first balls are divided into a plurality of ball groups distributed circumferentially along the bottom surface, each ball group has the same number of the first balls, the circumferential gap between the first balls in each ball group is smaller than the circumferential gap between each ball group, and the polishing liquid channel is formed between adjacent ball groups.

6. The retaining ring according to claim 2, characterized in that: The first balls corresponding to each circle are radially staggered to be distributed in a staggered manner on the bottom surface, and the polishing liquid channel is formed as a radially extending wavy channel.

7. The retaining ring according to claim 2, characterized in that The first balls corresponding to each circle are sequentially displaced clockwise or counterclockwise in radial direction, and the polishing liquid channel is formed as a channel inclined along the clockwise dislocation direction or the counterclockwise dislocation direction.

8. The retaining ring according to claim 7, characterized in that All first balls are divided into a plurality of ball groups distributed circumferentially along the bottom surface, each ball group has the same number of the first balls, the circumferential gap between the first balls in each ball group is smaller than the circumferential gap between the individual ball groups, the corresponding first balls in each ball group are radially offset clockwise or counterclockwise, and the polishing liquid channel is formed between adjacent ball groups.

9. The retaining ring according to claim 7 or 8, characterized in that: The polishing liquid channel is inclined at 20 to 60 degrees relative to the radial direction where the inner end thereof is located, and the inclination direction is toward the rotation direction of the retaining ring.

10. The retaining ring according to claim 1 or 2, characterized in that: The first balls in the outermost circle and the first balls in the innermost circle are denser than the first balls in the middle circles; or The first balls in the outermost circle and the first balls in the innermost circle are more sparsely distributed than the first balls in the intermediate circles.

11. The retaining ring according to any one of claims 1 to 8, characterized in that: The first rolling ball is made of plastic, or the first rolling ball is coated with a corrosion-resistant protective layer.

12. The retaining ring according to any one of claims 1 to 8, characterized in that: Each of the first balls is mounted on the bottom surface through a corresponding base, the base has a cavity for accommodating the first ball, the inner wall of the cavity is hemispherical, the cavity has an opening facing the polishing pad, a portion of the first ball is exposed from the opening to the outside of the cavity, and the exposed portions of all the first balls protrude from the bottom surface by the same distance, and the opening is used to limit the first ball from escaping from the base.

13. The retaining ring according to claim 12, characterized in that The opening comprises a spherical ring band surrounding the outside of the first rolling ball (321), the original spherical diameter of the spherical ring band matches the diameter of the first rolling ball, and the opening is used to realize the free rotation of the first rolling ball relative to the base.

14. The retaining ring according to claim 12, wherein: A plurality of second balls are arranged in each base, and the plurality of second balls are located between the first balls and the inner wall of the cavity, so as to realize rolling friction between the first balls and the inner wall.

15. The retaining ring according to claim 12, wherein: The bottom surface is provided with a plurality of mounting holes for mounting the base, the base comprises a mounting column and a boss, and the opening is located at the boss.

16. The retaining ring according to claim 15, characterized in that A neck is provided between the mounting column and the boss, and the neck is configured as an annular groove.

17. The retaining ring according to claim 15, characterized in that The mounting post is configured to be inserted into the mounting hole in an interference fit manner until the boss abuts against the bottom surface for position limiting.

18. The retaining ring according to claim 15, wherein: The mounting column is accommodated in the mounting hole, and the boss is welded or screwed to the bottom surface for limiting and fixing.

19. A carrier head for wafer processing, characterized in that: The carrier head has a chemical mechanical polishing retaining ring as claimed in any one of claims 1 to 18 .

20. A chemical mechanical polishing device, characterized in that: The polishing apparatus has a carrier head for wafer processing as claimed in claim 19 .

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