retaining rings and grinding equipment

Abstract

This disclosure provides a retaining ring and a polishing apparatus. The retaining ring includes an annular body having an inner peripheral wall, an outer peripheral wall, and a polishing surface connecting the top ends of the inner and outer peripheral walls. The annular body also has a plurality of spaced grooves recessed from the polishing surface, extending from the inner peripheral wall to the outer peripheral wall and communicating through it. The width between the two sidewalls of each groove is not entirely the same in a direction perpendicular to the bottom wall of the groove, and the sum of the widths between the bottom ends of the two sidewalls of all grooves is greater than or equal to the sum of the widths between the top ends of the two sidewalls of all grooves. The retaining ring of this disclosure can reduce polishing defects on the surface of semiconductor structures and improve the polishing rate.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor processing technology, and more particularly to a retaining ring and a grinding apparatus. Background Technology

[0002] Chemical mechanical polishing (CMP) is a process that combines chemical reactions with mechanical polishing, and is frequently used for planarization of semiconductor structures. During the polishing process, the polishing head of the polishing equipment grips the semiconductor structure to be polished, such as a wafer, and applies pressure to the back of the wafer, ensuring that the front of the wafer is in close contact with the polishing pad. Typically, a retaining ring is located below the polishing head to hold the wafer and prevent it from slipping.

[0003] To increase production capacity and meet process requirements, the diameter and integration density of semiconductor structures (such as wafers) are constantly increasing. During the grinding process of a 150mm radius wafer, as the retaining ring is continuously worn down, the grinding fluid and by-products between the wafer and the grinding pad cannot be discharged in time, leading to the accumulation of by-products. Furthermore, new grinding fluid cannot be replenished in time, and as the retaining ring is further ground, the flow rate of the grinding fluid becomes unstable, resulting in grinding defects on the wafer surface and a reduction in the grinding rate.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute related technology known to those skilled in the art. Summary of the Invention

[0005] This disclosure provides a retaining ring and a polishing apparatus that can reduce polishing defects on the surface of semiconductor structures and improve the polishing rate.

[0006] This disclosure provides a retaining ring, including an annular body having an inner peripheral wall, an outer peripheral wall, and a grinding surface connecting the top ends of the inner peripheral wall and the outer peripheral wall; the annular body further has a plurality of spaced grooves recessed from the grinding surface, the grooves extending from the inner peripheral wall to the outer peripheral wall and communicating therethrough; wherein the width between the two sidewalls of the groove is not exactly the same in a direction perpendicular to the bottom wall of the groove, and the sum of the widths between the bottom ends of the two sidewalls of all the grooves is greater than or equal to the sum of the widths between the top ends of the two sidewalls of all the grooves.

[0007] In some embodiments of this disclosure, the plurality of grooves include: a first trapezoidal groove having opposing first bottom walls and a first opening, wherein the width of the first trapezoidal groove gradually increases from the first bottom wall toward the first opening in a direction perpendicular to the first bottom wall; and a second trapezoidal groove having opposing second bottom walls and a second opening, wherein the width of the second trapezoidal groove gradually decreases from the second bottom wall toward the second opening in a direction perpendicular to the second bottom wall.

[0008] In some embodiments of this disclosure, the sum of the width of the first opening of the first trapezoidal groove and the width of the second opening of the second trapezoidal groove is equal to the sum of the width of the first bottom wall of the first trapezoidal groove and the width of the second bottom wall of the second trapezoidal groove.

[0009] In some embodiments of this disclosure, the first trapezoidal groove has a first shape in a cross-section perpendicular to the first bottom wall, and the second trapezoidal groove has a second shape in a cross-section perpendicular to the second bottom wall, wherein the first shape coincides with the second shape after being rotated 180°.

[0010] In some embodiments of this disclosure, the number of the first trapezoidal slot and the number of the second trapezoidal slot are the same.

[0011] In some embodiments of this disclosure, the first trapezoidal groove and the second trapezoidal groove are adjacent and equally spaced.

[0012] In some embodiments of this disclosure, the plurality of grooves include expansion grooves, the surfaces of the two sidewalls of the expansion grooves being recessed in a direction away from each other, and the width of the opening of the expansion groove is equal to the width of the bottom wall of the expansion groove.

[0013] In some embodiments of this disclosure, the surfaces of the two sidewalls of the expansion groove are arc-shaped or bent surfaces.

[0014] In some embodiments of this disclosure, the plurality of grooves further include an expansion groove, wherein the surfaces of the two sidewalls of the expansion groove are arcuate surfaces recessed in a direction away from each other, and the width of the opening of the expansion groove is equal to the width of the bottom wall of the expansion groove; the expansion groove is disposed between the first trapezoidal groove and the second trapezoidal groove.

[0015] In some embodiments of this disclosure, the surface of the bottom wall of the trench is parallel to the grinding surface.

[0016] In some embodiments of this disclosure, the top of the inner peripheral wall of the annular body is provided with a circumferentially extending annular groove, which communicates with a plurality of the grooves.

[0017] In some embodiments of this disclosure, the size of the opening of the annular groove is smaller than the depth of the groove in a direction perpendicular to the grinding surface.

[0018] In some embodiments of this disclosure, the retaining ring further includes a buffer pad disposed on the inner peripheral wall of the annular body.

[0019] In some embodiments of this disclosure, the thickness of the cushioning pad is 0.03 mm to 0.08 mm.

[0020] This disclosure also provides a polishing apparatus for polishing a substrate, including a polishing pad, a polishing head, a retaining ring as described in any of the above embodiments, and a polishing slurry supply device. The polishing head is configured to grip the substrate during polishing and press it against the polishing pad for polishing; the retaining ring is mounted on the polishing head and configured to fix the substrate during polishing, with the polishing surface of the retaining ring facing the polishing pad; the polishing slurry supply device is configured to provide polishing slurry during polishing, the polishing slurry flowing into and out between the polishing pad and the substrate through grooves in the retaining ring.

[0021] As can be seen from the above technical solutions, the semiconductor structure preparation method and semiconductor structure of this disclosure have at least one of the following advantages and positive effects:

[0022] In this embodiment, the retaining ring has multiple spaced grooves on its annular body. The width between the two sidewalls of the grooves is not exactly the same in the direction perpendicular to the bottom wall of the groove. The sum of the widths between the bottoms of the two sidewalls of all grooves is greater than or equal to the sum of the widths between the tops of the two sidewalls of all grooves. This not only increases the cross-sectional area for the polishing slurry to flow into the polishing surface of the semiconductor structure, but also ensures that the flow rate of the polishing slurry does not change significantly as the polishing surface of the retaining ring is continuously worn down during the polishing process. This still ensures that the polishing slurry flows in sufficiently and stably and that byproducts are discharged sufficiently and stably, thereby reducing polishing defects on the surface of the semiconductor structure and improving the polishing rate. Attached Figure Description

[0023] The above and other features and advantages of this disclosure will become more apparent from a detailed description of exemplary embodiments thereof with reference to the accompanying drawings.

[0024] Figure 1 This is a three-dimensional structural schematic diagram of a retaining ring shown in some embodiments of this disclosure;

[0025] Figure 2 This is a top view of a retaining ring shown in some embodiments of this disclosure;

[0026] Figure 3 for Figure 2The cross-sectional view along the middle AA shows the cross-sectional view of the first trapezoidal groove;

[0027] Figure 4 for Figure 2 The cross-sectional view along the middle BB shows the cross-sectional view of the second trapezoidal groove;

[0028] Figure 5 This is a cross-sectional view of the first trapezoidal groove in another embodiment of some embodiments of this disclosure;

[0029] Figure 6 This is a cross-sectional view of the expansion groove shown in some embodiments of this disclosure;

[0030] Figure 7 Cross-sectional view of the expansion groove shown in other embodiments of this disclosure;

[0031] Figure 8 Cross-sectional view of the expansion groove shown in other embodiments of this disclosure;

[0032] Figure 9 for Figure 2 The cross-sectional view along the CC axis shows the cross-sectional view of the annular groove;

[0033] Figure 10 This is a schematic diagram of the structure of the grinding apparatus in some embodiments of this disclosure.

[0034] Explanation of reference numerals in the attached figures:

[0035] 100. Retaining ring; 1. Annular body; 11. Inner peripheral wall; 12. Outer peripheral wall; 13. Grinding surface; 14. Assembly surface; 15. Groove; 151. First trapezoidal groove; 1511. First side wall; 1512. First bottom wall; 1513. First opening; 152. Second trapezoidal groove; 1521. Second side wall; 1522. Second bottom wall; 1523. Second opening; 153. Expansion groove; 16. Annular groove; 2. Buffer pad; w11. Width of the first opening; w12. Width of the first bottom wall; w21. Width of the second opening; w22. Width of the second bottom wall; w31. Width of the opening of the expansion groove; w32. Width of the bottom wall of the expansion groove; d1. Size of the opening of the annular groove; d2. Depth of the groove; t1. Thickness of the buffer pad; O. Center of the annular body; α. First included angle; β. Second included angle;

[0036] 200, polishing pad; 300, polishing head; 400, substrate; 500, polishing slurry supply device; 600, polishing table; 700, first rotating shaft; 800, second rotating shaft; 900, flexible film. Detailed Implementation

[0037] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore their detailed description will be omitted.

[0038] In the following description of different exemplary embodiments of the present disclosure, reference is made to the accompanying drawings, which form part of the present disclosure and illustrate, by way of example, different exemplary structures that can implement various aspects of the present disclosure. It should be understood that other specific embodiments of components, structures, exemplary devices, systems, and steps may be used, and structural and functional modifications may be made without departing from the scope of the present disclosure. Furthermore, while the terms “above,” “between,” “within,” etc., may be used in this specification to describe different exemplary features and elements of the present disclosure, these terms are used herein only for convenience, such as according to the orientation of the examples in the drawings. Nothing in this specification should be construed as requiring a specific three-dimensional orientation of the structure to fall within the scope of the present disclosure. Moreover, the terms “first,” “second,” etc., in the claims are used only as illustrative marks and not as numerical limitations on the object.

[0039] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0040] In addition, in the description of this disclosure, "multiple" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

[0041] Chemical mechanical polishing (CMP) is a process that combines chemical reactions with mechanical polishing. It is frequently used for planarization of semiconductor structures. During polishing, the polishing head of the polishing equipment grips the semiconductor structure to be polished, such as a wafer, and applies pressure to the back of the wafer, ensuring the front of the wafer is in close contact with the polishing pad. A retaining ring is typically located below the polishing head to hold the wafer and prevent it from slipping.

[0042] During the polishing process, the polishing pad rotates, while the polishing head drives the wafer to rotate in the same direction as the polishing pad, causing mechanical friction between the wafer's front side and the polishing pad surface. Through a series of complex mechanical and chemical processes, a certain thickness of film layer is removed from the wafer surface during polishing, thereby achieving wafer planarization.

[0043] With the development of semiconductor technology, the integration of semiconductor structures is becoming increasingly higher, and the requirements for polishing quality are becoming increasingly stringent. During the polishing process, the retaining ring is in contact with the polishing pad. As polishing progresses, the retaining ring is continuously worn down, and the channels on the retaining ring for the flow of polishing slurry become shallower and shallower. This prevents the polishing slurry and by-products between the wafer and the polishing pad from being discharged in a timely manner, leading to the accumulation of by-products. Furthermore, the inability to replenish the polishing slurry in a timely manner results in polishing defects on the wafer surface and reduces the polishing efficiency.

[0044] Based on this, the present disclosure provides a retaining ring 100, such as Figure 1 and Figure 10 As shown, the retaining ring 100 of this embodiment includes an annular body 1. Specifically, the annular body 1 is as follows: Figure 1 and Figure 2 The annular ring shown is described. The annular body 1 has an inner peripheral wall 11 and an outer peripheral wall 12. The annular body 1 has two opposing surfaces. One surface is connected to the top ends of the inner peripheral wall 11 and the outer peripheral wall 12. During grinding, this surface faces and contacts the grinding pad 200; it is called the grinding surface 13, which is planar. The other surface is connected to the bottom ends of the inner peripheral wall 11 and the outer peripheral wall 12. During grinding, this other surface moves away from the grinding pad 200 and connects to the bottom end of the grinding head 300, thus assembling the retaining ring 100 with the grinding head 300. This other surface is called the assembly surface 14, which can be planar or curved; no special limitation is made here.

[0045] In some embodiments, such as Figure 1 and Figure 2 As shown, the annular body 1 also has a plurality of spaced grooves 15, which are recessed from the grinding surface 13 toward the mounting surface 14. Each groove 15 has two sidewalls and a bottom wall, with the bottom wall connected between the two sidewalls as the bottom of the groove 15.

[0046] The groove 15 extends and penetrates from the inner peripheral wall 11 to the outer peripheral wall 12 of the annular body 1, serving as a channel for the flow of grinding fluid and grinding byproducts. Figure 1 and Figure 2 as well as Figure 10 As shown, in some embodiments, the trenches 15 extend radially from the inner peripheral wall 11 to the outer peripheral wall 12, meaning that the extension direction of the trenches 15 does not pass through the center O of the annular body 1. During the polishing process, polishing fluid flows through these trenches 15 between the substrate 400 to be polished and the polishing pad 200, so that the substrate 400 is polished. The substrate 400 is the semiconductor structure mentioned above; it can be a wafer or a chip, or other semiconductor structure requiring planarization, and is not specifically limited here.

[0047] refer to Figure 10 During grinding, the grinding head 300 rotates, and the retaining ring 100 rotates together with the grinding head 300. Therefore, the groove 15 extending radially from the inner peripheral wall 11 to the outer wall is more conducive to the flow of grinding fluid into the retaining ring 100 and the discharge of grinding by-products, avoiding the accumulation of by-products. In some embodiments, the groove 15 may also extend radially along the annular body 1, that is, the extension direction of the groove 15 can pass through the center O of the annular body 1. The extension direction of the groove 15 is not specifically limited here.

[0048] In some embodiments, such as Figures 3 to 8 As shown, the width between the two sidewalls of the groove 15 is not exactly the same in the direction perpendicular to the bottom wall of the groove 15; that is, the two sidewalls of the groove 15 are not parallel to each other. The width between the two sidewalls of the groove 15 can be understood as the distance between the two sidewalls. In this embodiment, setting the width between the two sidewalls of the groove 15 to be not exactly the same allows the cross-sectional area of ​​the groove 15 to be designed into different shapes. This cross-section refers to the surface cut along the extension direction perpendicular to the groove 15, which can increase the flow rate of the grinding fluid into the retaining ring 100, reduce the accumulation of particles during the grinding process, and reduce grinding defects.

[0049] In some embodiments, the sum of the widths between the bottoms of the two sidewalls of all grooves 15 on the annular body 1 is greater than or equal to the sum of the widths between the tops of the two sidewalls of all grooves. That is, the sum of the widths of the bottom walls of all grooves 15 is greater than or equal to the sum of the widths of the openings of all grooves 15. Therefore, during the grinding process, as the retaining ring 100 wears down, even if the depth of the grooves 15 decreases, the width of the grooves 15 will not decrease. This avoids the defects caused by the reduction in the width of the grooves 15, such as the inability to discharge mask byproducts in a timely manner and the inability to supply grinding fluid in a timely manner. At the same time, it also avoids grinding defects caused by unstable factors such as the excessively fast flow rate of the grinding fluid due to the reduction in the width of the grooves 15.

[0050] It should be noted that the bottom of the sidewall of the groove 15 can be understood as part of the bottom wall of the groove 15, and the top of the sidewall of the groove 15 can be understood as the part of the sidewall near the opening.

[0051] In some embodiments, the surface of the bottom wall of the groove 15 is parallel to the grinding surface 13 of the annular body 1, that is, the direction perpendicular to the bottom wall of the groove 15 is also perpendicular to the grinding surface 13. In other embodiments, the surface of the bottom wall of the groove 15 may also have a certain angle with the grinding surface 13 of the annular body 1, which is not particularly limited here.

[0052] In some embodiments, such as Figures 3 to 5As shown, the plurality of grooves 15 include a first trapezoidal groove 151. The first trapezoidal groove 151 has a first bottom wall 1512 and a first opening 1513, and the width of the first trapezoidal groove 151 gradually increases from the first bottom wall 1512 toward the first opening 1513 in a direction perpendicular to the first bottom wall 1512.

[0053] like Figure 3 As shown, the cross-section of the first trapezoidal groove 151 can be an inverted trapezoid, that is, the first opening 1513 of the first trapezoidal groove 151 gradually expands from the first bottom wall 1512. The shape of the cross-section of the first trapezoidal groove 151 can be an isosceles trapezoid, so that the grinding fluid and by-products can pass smoothly through the first trapezoidal groove 151, and at the same time facilitate processing. In some embodiments, the width w11 of the first opening 1513 of the first trapezoidal groove 151 can be 2 to 3.5 mm. For example, in addition to the two end values ​​mentioned above, it can also be 2.5 mm, 2.6 mm, 2.75 mm, 2.8 mm, 2.84 mm, 2.9 mm, 3.15 mm, 3.3 mm, or 3.4 mm. The width w12 of the first bottom wall 1512 can be 1.5 to 2 mm. For example, in addition to the two end values ​​mentioned above, it can also be 1.6 mm, 1.7 mm, 1.75 mm, 1.8 mm, 1.84 mm, 1.9 mm, or 1.95 mm. The depth of the first trapezoidal groove 151 (i.e., the distance from the first bottom wall 1512 to the first opening 1513) can be 1.5 to 2 mm. For example, in addition to the two end values ​​mentioned above, it can also be 1.6 mm, 1.7 mm, 1.75 mm, 1.8 mm, 1.84 mm, 1.9 mm, or 1.95 mm. The first included angle α between the first sidewall 1511 and the first bottom wall 1512 of the first trapezoidal groove 151 can be 91° to 110°. For example, in addition to the two values ​​mentioned above, the first included angle α can also be 92.5°, 93.32°, 94°, 96.5°, 98°, 100°, 102°, 105°, 107°, or 108°. Those skilled in the art can choose according to the actual situation, and no special limitation is made here. Since the width of the first trapezoidal groove 151 gradually increases from the first bottom wall 1512 towards the first opening 1513, the flow rate of the grinding fluid can be increased, so that the grinding by-products can be discharged in time and sufficient grinding fluid can be replenished in time.

[0054] In some embodiments, the plurality of grooves 15 further include a second trapezoidal groove 152, the second trapezoidal groove 152 having opposing second bottom walls 1522 and second openings 1523, and the width of the second trapezoidal groove 152 gradually decreases from the second bottom wall 1522 toward the second opening 1523 in a direction perpendicular to the second bottom wall 1522.

[0055] In some embodiments, the cross-section of the second trapezoidal groove 152 can be trapezoidal, that is, the opening of the second trapezoidal groove 152 gradually converges from the first bottom wall 1512. The shape of the cross-section of the second trapezoidal groove 152 can be an isosceles trapezoid. The width w21 of the second opening 1523 of the second trapezoidal groove 152 can be 1.5 to 2 mm. For example, in addition to the two end values ​​mentioned above, it can also be 1.6 mm, 1.7 mm, 1.75 mm, 1.8 mm, 1.84 mm, 1.9 mm, or 1.95 mm. The width w22 of the second bottom wall 1522 can be 2 to 3.5 mm. For example, in addition to the two end values ​​mentioned above, it can also be 2.5 mm, 2.6 mm, 2.75 mm, 2.8 mm, 2.84 mm, 2.9 mm, 3.15 mm, 3.3 mm, or 3.4 mm. The depth of the second trapezoidal groove 152 (i.e., the distance from the second bottom wall 1522 to the second opening 1523) can be 1.5 to 2 mm. For example, in addition to the two end values ​​mentioned above, it can also be 1.6 mm, 1.7 mm, 1.75 mm, 1.8 mm, 1.84 mm, 1.9 mm, or 1.95 mm. The second included angle β between the side wall of the second trapezoidal groove 152 and the second bottom wall 1522 can be 70° to 89°. For example, in addition to the two values ​​mentioned above, the second included angle β can also be 72°, 73°, 75°, 78°, 80°, 82°, 83.5°, 86°, 86.5°, 86.68°, or 87.5°. Those skilled in the art can choose according to the actual situation, and no special limitation is made here.

[0056] In some embodiments, the cross-sections of the first trapezoidal groove 151 and the second trapezoidal groove 152 may be non-strictly trapezoidal. That is, the first sidewall 1511 of the first trapezoidal groove 151 and the second sidewall 1521 of the second trapezoidal groove 152 may not be planar. In some embodiments, the surfaces of the two first sidewalls 1511 of the first trapezoidal groove 151 and the two second sidewalls 1521 of the second trapezoidal groove 152 may both be concave surfaces in a direction that moves away from each other, and these surfaces may be arc-shaped surfaces (e.g., Figure 5 The first sidewall 1511 and the second sidewall 1521 are curved surfaces formed by connecting multiple planes (not shown in the figure). By setting the surfaces of the first sidewall 1511 and the second sidewall 1521 to be concave in a direction that moves away from each other, the cross-sectional area of ​​the first trapezoidal groove 151 and the second trapezoidal groove 152 can be further increased, thereby increasing the flow rate of the grinding fluid and enabling smooth delivery of the grinding fluid and discharge of grinding by-products. Setting the surfaces to arc-shaped surfaces can reduce the flow resistance of the grinding fluid and prevent grinding residue from accumulating in the groove 15, ensuring the smooth flow of the grinding fluid and grinding by-products.

[0057] like Figure 3 and Figure 4As shown, in some embodiments, the sum of the width w11 of the first opening 1513 of the first trapezoidal groove 151 and the width w21 of the second opening 1523 of the second trapezoidal groove 152 is equal to the sum of the width w12 of the first bottom wall 1512 of the first trapezoidal groove 151 and the width w22 of the second bottom wall 1522 of the second trapezoidal groove 152. Specifically, in some embodiments, the width w11 of the first opening 1513 of the first trapezoidal groove 151 is the same as the width w22 of the second bottom wall 1522 of the second trapezoidal groove 152, and the width w12 of the first bottom wall 1512 of the first trapezoidal groove 151 is the same as the width w21 of the second opening 1523 of the second trapezoidal groove 152. Therefore, the first trapezoidal groove 151 and the second trapezoidal groove 152 can be considered as a combination, and the flow rate of the polishing fluid flowing through each combination is the same. Furthermore, since the widths between the two sidewalls of the first trapezoidal groove 151 and the second trapezoidal groove 152 are different, the flow rate of the polishing fluid can be increased.

[0058] In some embodiments, the first trapezoidal groove 151 has a cross-section perpendicular to its extending direction (i.e., as shown in the figure). Figure 2 The cross section along AA has a first shape, and the second trapezoidal groove 152 has a cross section perpendicular to its extension direction (i.e., as shown in the figure). Figure 2 The cross section along BB has a second shape, and the first shape coincides with the second shape after being rotated 180°.

[0059] Specifically, such as Figure 3 and Figure 4 As shown, the cross-sectional shape of the first trapezoidal groove 151 and the second trapezoidal groove 152 is an isosceles trapezoid. After rotating the cross-section of the first trapezoidal groove 151 by 180°, the cross-sections of the first trapezoidal groove 151 and the second trapezoidal groove 152 can coincide. That is to say, the shape and side length of the cross-sections of the first trapezoidal groove 151 and the second trapezoidal groove 152 are exactly the same. Therefore, the cross-sectional areas of the first trapezoidal groove 151 and the second trapezoidal groove 152 are also the same. Therefore, as grinding wear occurs during the grinding process of the retaining ring 100, such as... Figure 2 As shown, from a top view, the sum of the cross-sectional areas of the first trapezoidal groove 151 and the second trapezoidal groove 152 along the flow direction of the polishing slurry does not change. This can also be understood as the sum of the widths of the first trapezoidal groove 151 and the second trapezoidal groove 152 remaining constant despite wear of the retaining ring 100. In other words, the width of the polishing slurry flow path remains constant, ensuring the stability of the polishing slurry flow and preventing a sudden narrowing of the flow path that could cause the polishing slurry to suddenly accelerate and impact the substrate 400 during polishing, thus avoiding defects on the substrate 400. Simultaneously, since the cross-sectional areas of the first trapezoidal groove 151 and the second trapezoidal groove 152 are the same, the flow rate of polishing slurry flowing into each trapezoidal groove is the same, ensuring the uniformity of the polishing slurry supplied to the retaining ring 1 from all directions, resulting in more uniform polishing.

[0060] In some embodiments, the number of first trapezoidal grooves 151 and second trapezoidal grooves 152 is the same. That is, the annular body 1 has an even number of grooves 15. Since the first trapezoidal grooves 151 and second trapezoidal grooves 152 are combined, the sum of the widths of the first trapezoidal grooves 151 and the second trapezoidal grooves 152 does not change with the grinding wear of the retaining ring 100. Therefore, the flow rate of the grinding fluid flowing through the first trapezoidal grooves 151 and the second trapezoidal grooves 152 remains constant, so that the grinding fluid flows stably into the retaining ring 100, ensuring the stability of grinding and timely discharge of grinding by-products, reducing the generation of grinding defects.

[0061] Of course, in some embodiments, the number of the first trapezoidal slot 151 and the number of the second trapezoidal slot 152 may also be different. The difference between the two numbers may be 1, 2 or 3, and no special limitation is made here.

[0062] In some embodiments, such as Figure 2 As shown, the first trapezoidal groove 151 and the second trapezoidal groove 152 are adjacent and equally spaced. That is, the first trapezoidal groove 151 and the second trapezoidal groove 152 are interleaved, with each pair of adjacent grooves 15 containing one first trapezoidal groove 151 and one second trapezoidal groove 152. Therefore, when grinding wear occurs at a certain part of the grinding surface 13 of the retaining ring 100, causing the groove 15 depth to decrease, the grinding wear is made to occur simultaneously in the first trapezoidal groove 151 and the second trapezoidal groove 152 as much as possible, ensuring that the flow rate of the grinding fluid remains constant and guaranteeing the stability of the grinding process.

[0063] Of course, in some embodiments, the first trapezoidal slot 151 and the second trapezoidal slot 152 may not be arranged adjacently. For example, the two first trapezoidal slots 151 may be adjacent and the two second trapezoidal slots 152 may be adjacent. They may also be arranged randomly. No special limitation is made here.

[0064] In other embodiments, such as Figures 6 to 8 As shown, the plurality of grooves 15 in this embodiment of the present disclosure include a plurality of expansion grooves 153. The surfaces of the two sidewalls of the expansion groove 153 are recessed in a direction away from each other, and the width w31 of the opening of the expansion groove 153 is equal to the width w32 of the bottom wall of the expansion groove 153.

[0065] In some embodiments, such as Figure 6As shown, the surfaces of the two sidewalls of the expansion tank 153 are concave arc-shaped surfaces extending outwards in a direction away from each other. This outward expansion of the two sidewalls increases the cross-sectional area of ​​the expansion tank 153, thereby increasing the flow rate of the grinding fluid. Simultaneously, designing the sidewalls of the expansion tank 153 as arc-shaped surfaces reduces fluid resistance, ensuring smooth inflow and outflow of the grinding fluid and the discharge of grinding byproducts. Furthermore, the width w31 of the opening of the expansion tank 153 is equal to the width w32 of its bottom wall. When the retaining ring 1 is worn down by grinding, the width of the expansion tank 153 will not decrease, thus preventing a sudden increase in the flow rate of the grinding fluid, ensuring the stability of the grinding fluid flow, and reducing the generation of grinding defects.

[0066] In some embodiments, such as Figure 7 and Figure 8 As shown, the surfaces of the two sidewalls of the expansion groove 153 are concave curved surfaces, i.e., multiple curved planes. These multiple planes make the shape of the cross-section of the expansion groove 153 perpendicular to its extension direction hexagonal, octagonal, decagonal, dodecagonal, or other numbers of polygons, etc., without special limitation here. The fact that both sidewalls of the expansion groove 153 are concave in a direction away from each other can increase the cross-sectional area of ​​the expansion groove 153 and increase the flow rate of the grinding fluid.

[0067] like Figures 6 to 8 As shown, in some embodiments, the surfaces of the two sidewalls of the expansion groove 153 are mirror-symmetrical. That is, the cross-section of the expansion groove 153 is an axisymmetric figure. The axis of symmetry is perpendicular to the bottom wall of the expansion groove 153 and passes through the center of the bottom wall of the cross-section. In this way, the degree of concavity (such as the curvature when the sidewall is an arc surface) and the size of the two sidewalls are exactly the same, so that when the polishing slurry flows through the expansion groove 153, it is subjected to the same pressure on the two sidewalls, ensuring the stability of the polishing slurry flow and avoiding impact on the substrate being polished, thus preventing polishing defects.

[0068] In some embodiments, the annular body 1 has a plurality of expansion grooves 153 as described in the above embodiments. In other embodiments, the annular body 1 has a first trapezoidal groove 151 and an expansion groove 153, which can be interlaced and equally spaced, without particular limitation. In other embodiments, the annular body has a first trapezoidal groove 151, a second trapezoidal groove 152, and also an expansion groove 153, which can be disposed between the first trapezoidal groove 151 and the second trapezoidal groove 152. The expansion groove 153 can also be disposed between a combination of a first trapezoidal groove 151 and a second trapezoidal groove 152, or between multiple combinations of the first trapezoidal groove 151 and the second trapezoidal groove 152, while still ensuring stable flow of the grinding fluid. Of course, in other embodiments, the expansion groove 153 may also be disposed between the two first trapezoidal grooves 151 or between the two second trapezoidal grooves 152. No special limitation is made here. Adding the expansion groove 153 between the first trapezoidal grooves 151 and the second trapezoidal grooves 152 can further ensure the stability of the polishing fluid flow and avoid impacting the substrate being polished, thus preventing polishing defects.

[0069] In some embodiments, such as Figure 2 and Figure 9 As shown, the top of the inner peripheral wall 11 of the annular body 1 is provided with an annular groove 16 extending in a circumferential direction, and the annular groove 16 is connected to a plurality of grooves 15.

[0070] Continue to refer to Figure 2 , Figure 9 as well as Figure 10 During the grinding process, the grinding head 300 grips the substrate 400 and uses the retaining ring 100 to fix the substrate 400 and prevent it from slipping during grinding. As grinding progresses, grinding byproducts increase and need to be discharged through the groove 15 of the retaining ring 100 in a timely manner. However, during the grinding process, since the edge of the substrate 400 comes into contact with the inner peripheral wall 11 of the retaining ring 100, grinding byproducts tend to accumulate in the edge area of ​​the substrate 400. For example, grinding debris and particles from the used grinding fluid will accumulate in the edge area of ​​the substrate 400 and cannot be discharged in time, causing defects in the grinding area of ​​the substrate 400 due to over-grinding.

[0071] To overcome the aforementioned drawbacks, in this embodiment, a circumferentially extending annular groove 16 is formed at the top of the inner peripheral wall 11 of the annular body 1. Specifically, an annular groove 16 is formed on the inner peripheral wall 11 of the annular body 1, near the top of the grinding surface 13, and extends circumferentially along the inner peripheral wall 11. The width of the annular groove 16 is the distance between the opposite sidewalls of the annular groove 16, i.e., the size of the annular groove 16 in the direction perpendicular to the grinding surface 13.

[0072] During the polishing process, the retaining ring 100 rotates together with the polishing head 200. The substrate 400, located inside the inner peripheral wall 11 of the retaining ring 100, also rotates with the retaining ring 100. In some embodiments, the width of the annular groove 16 can be less than or equal to the thickness of the substrate. Thus, during polishing, the annular groove 16 does not affect the gripping force of the retaining ring 100 on the substrate. When polishing residue is generated, as the substrate 400 and the polishing pad 200 rotate, the polishing residue is transported to the edge of the substrate 400 by the flow of polishing fluid due to centrifugal force and enters the annular groove 16. Since the annular groove 16 is connected to the trench 15, the polishing residue will be further discharged through the trench 15, preventing the polishing residue from accumulating in the edge area of ​​the substrate and causing damage to the edge of the substrate, thereby improving the yield of the substrate. The specific width of the annular groove 16 can be set by those skilled in the art according to the thickness of the substrate, and is not specifically limited here.

[0073] In some embodiments, in a direction perpendicular to the grinding surface 13, the size d1 of the opening of the annular groove 16 is smaller than the depth d2 of the groove 15.

[0074] Specifically, the size d1 of the opening of the annular groove 16 is the width of the opening of the annular groove 16 in the direction perpendicular to the grinding surface 13, and the depth of the groove 15 is the distance between the opening of the groove 15 and the bottom wall of the groove 15 in the direction perpendicular to the grinding surface 13. Since the groove 15 is mainly used for the inflow of grinding slurry and the discharge of grinding by-products, the depth d2 of the groove 15 is greater than the size d1 of the opening of the annular groove 16 to facilitate the timely discharge of grinding slurry and grinding by-products. Of course, the size d1 of the opening of the annular groove 16 and the depth d2 of the groove 15 can be set according to the actual situation, such as according to the size of the substrate 400 to be ground and the thickness of the annular body 1 of the retaining ring 100, and no special limitation is made here.

[0075] In some embodiments, the retaining ring 100 may further include a buffer pad 2 disposed on the inner peripheral wall 11 of the annular body 1.

[0076] During the grinding process, the retaining ring 100 rotates together with the grinding head 300, and the substrate 400 to be ground is gripped by the retaining ring 100, allowing the substrate 400 and the retaining ring 100 to rotate together. However, during the grinding process, due to unstable gripping, the substrate 400 is prone to slipping, or due to unstable pressure applied to the substrate 400 during rotation, the substrate 400 is prone to breakage. By providing a buffer pad 2 on the inner peripheral wall 11 of the annular body 1, the friction between the inner peripheral wall 11 of the retaining ring 100 and the edge of the substrate 400 can be increased, thereby increasing the stability of gripping, preventing the substrate 400 from slipping during the grinding process, ensuring the stability of the substrate 400 during the grinding process, improving the uniformity of the pressure on the substrate 400, and thus preventing the substrate 400 from breaking.

[0077] In some embodiments, the material of the cushioning pad 2 may be reinforced polytetrafluoroethylene (PTFE / PEEK, where PTFE is polytetrafluoroethylene and PEEK is polyetheretherketone), or carbon fiber reinforced polyetheretherketone (CF / PEEK, where CF is carbon fiber and PEEK is polyetheretherketone). The material of the cushioning pad 2 has a certain degree of flexibility, and its material differs from that of the retaining ring 100; the material of the cushioning pad 2 is more flexible than that of the retaining ring 100. Those skilled in the art may also choose other materials, which are not specifically limited here.

[0078] In some embodiments, the thickness t1 of the buffer pad 2 can be 0.03mm to 0.08mm. Specifically, in addition to the two values ​​mentioned above, the thickness t1 of the buffer pad 2 can also be 0.04mm, 0.05mm, 0.055mm, 0.06mm, or 0.07mm. Those skilled in the art can select the thickness based on the size of the retaining ring 100, and no special limitation is made here.

[0079] In some embodiments, such as Figure 9As shown, the buffer pad 2 is disposed on the entire inner peripheral wall 11 of the annular body 1, that is, from the top end to the bottom end of the inner peripheral wall 11, including the wall surface of the annular groove 16. For example, the buffer pad 2 is disposed on both side walls and the bottom wall of the annular groove 16. In this way, the entire buffer pad 2 can be a single piece. Compared with a buffer pad with notches, the single buffer pad 2 can avoid damage to the buffer pad 2 caused by the impact of polishing fluid on the notches and the rotational collision of the substrate 400, thus extending the service life of the buffer pad 2. Of course, if the wall surface of the annular groove 16 is provided with the buffer pad 2, the space of the annular groove 16 can be understood as the space of the annular groove 16 after the buffer pad 2 is provided. The size of the annular groove 16 described in the above embodiment is the size of the annular groove 16 after the buffer pad 2 is provided.

[0080] In other embodiments, the buffer pad 2 may also be disposed on the inner peripheral wall 11 of the annular body 1, but excluding the wall surface of the annular groove 16. That is, the buffer pad 2 is disposed on one side from the top of the inner peripheral wall 11 to the opening of the annular groove 16, extending beyond the opening of the annular groove 16, and from the other side of the opening to the bottom of the inner peripheral wall 11. This can save raw materials for the buffer pad 2 and simplify the process. Those skilled in the art can choose the placement position of the buffer pad 2 according to the actual situation, and no special limitation is made here.

[0081] In some embodiments, the buffer pad 2 can be attached to the inner peripheral wall 11 of the annular body 1 by means of pasting or pressing. Gaps should be avoided between the buffer pad 2 and the inner peripheral wall 11 to prevent the grinding fluid from flowing into the gaps and scouring the buffer pad 2, which could cause the buffer pad 2 to separate from the inner peripheral wall 11 in a short time or the buffer pad 2 to be damaged.

[0082] In summary, in this embodiment of the present disclosure, a plurality of spaced grooves 15 are provided on the annular body 1 of the retaining ring 100, and the width between the two sidewalls of the grooves 15 is not exactly the same in the direction perpendicular to the bottom wall of the grooves 15. The sum of the widths between the bottoms of the two sidewalls of all the grooves 15 is greater than or equal to the sum of the widths between the tops of the two sidewalls of all the grooves 15. This not only increases the cross-sectional area for the flow of the polishing slurry, allowing the polishing slurry to flow fully into the polishing surface of the substrate to be polished, but also ensures that the flow rate of the polishing slurry does not change significantly as the polishing surface 13 of the retaining ring 100 is continuously worn down during the polishing process. This still ensures that the polishing slurry flows in fully and stably and that the polishing byproducts are discharged fully and stably, thereby reducing polishing defects on the surface of the substrate 400 and improving the polishing rate.

[0083] This disclosure also provides a polishing apparatus for polishing a substrate 400. For example... Figure 10As shown, the polishing apparatus includes a polishing pad 200, a polishing head 300, a retaining ring 100 as described in any of the above embodiments, and a polishing slurry supply device 500. The polishing head 200 is configured to grip the substrate 400 during polishing, simultaneously applying pressure to the substrate 400 and pressing it against the polishing pad 200 for polishing. The retaining ring 100 is mounted on the polishing head 300 and configured to fix the substrate 400 during polishing, with its polishing surface 13 facing the polishing pad 200 during polishing. The polishing slurry supply device 500 is configured to supply polishing slurry during polishing, the slurry flowing in and out between the polishing pad 200 and the substrate 400 through the grooves 15 of the retaining ring 100.

[0084] Specifically, such as Figure 10 As shown, the polishing equipment also includes a polishing table 600, a polishing pad 200 disposed on the polishing table 600, and a substrate 400 to be polished placed on the polishing pad 200, where friction occurs between the substrate 400 and the polishing pad 200, thus achieving polishing of the substrate 400. (Continue to refer to...) Figure 10 A first rotating shaft 700 is connected below the grinding table 600. During the grinding process, the grinding pad 200 is laid on the grinding table 600. The first rotating shaft 700 is driven to rotate by a motor, thereby driving the grinding table 600 and the grinding pad 200 to rotate together.

[0085] like Figure 10 As shown in the embodiment of this disclosure, the retaining ring 100 is disposed at the bottom end of the grinding head 300. Specifically, the retaining ring 100 includes opposing mounting surfaces 14 and grinding surfaces 13. The mounting surface 14 is connected to the bottom end of the grinding head 300 to achieve assembly between the retaining ring 100 and the grinding head 300. The connection between the retaining ring 100 and the grinding head 300 can be a threaded connection, adhesive bonding, etc., which are not specifically limited here. The inner diameter of the retaining ring 100 should be slightly larger than or equal to the diameter of the substrate 400 to be ground, so that after the substrate 400 is gripped, the substrate 400 is ground within the retaining ring 100, preventing the substrate 400 from slipping. The specific structure of the retaining ring 100 has been described in detail in the above embodiments of the retaining ring 100, and will not be repeated here.

[0086] Continue to refer to Figure 10The grinding head 300 also includes a flexible membrane 900. During the grinding process, the grinding head 300 provides pressure, which can be gas supplied by a pneumatic device. This pressure acts on the flexible membrane 900, causing it to press against the substrate 400 to be ground. The pressure is adjusted until the pressure applied by the flexible membrane 900 to the substrate 400 reaches a preset value, and grinding begins. A second rotating shaft 800 is connected above the grinding head 300. During grinding, the second rotating shaft 800 is driven to rotate by a motor, thereby causing the grinding head 300, the retaining ring 100, and the substrate 400 within the retaining ring 100 to rotate together, so that the substrate 400 is ground on the surface of the grinding pad 200.

[0087] Continue to refer to Figure 10 The polishing slurry supply device 500 is used to provide polishing slurry containing abrasive particles to facilitate polishing of the substrate 400. After the polishing slurry is provided to the polishing pad 200, it flows into the space between the substrate 400 to be polished and the polishing pad 200 through the groove 15 of the retaining ring 100.

[0088] In some embodiments, the substrate 400 may be a semiconductor structure such as a wafer or a chip, and no special limitation is made here.

[0089] In summary, the polishing apparatus of this embodiment employs the retaining ring 100 described in the above embodiment. The retaining ring 100 has a plurality of spaced grooves 15. The width between the two sidewalls of the grooves 15 is not exactly the same in the direction perpendicular to the bottom wall of the groove 15. The sum of the widths between the bottoms of the two sidewalls of all grooves 15 is greater than or equal to the sum of the widths between the tops of the two sidewalls of all grooves 15. This not only increases the flow cross-sectional area of ​​the polishing slurry, allowing the polishing slurry to flow fully into the polishing surface of the semiconductor structure, but also ensures that the flow rate of the polishing slurry does not change significantly as the polishing surface 13 of the retaining ring 100 is continuously worn down during the polishing process. This still ensures that the polishing slurry flows in fully and stably and that byproducts are discharged fully and stably, reducing polishing defects on the surface of the substrate 400 after polishing and improving the polishing rate.

[0090] It should be understood that this disclosure is not limited to the detailed structure and arrangement of the components presented in this specification. This disclosure is capable of other embodiments and can be implemented and performed in various ways. The foregoing variations and modifications fall within the scope of this disclosure. It should be understood that this disclosure, as disclosed and defined in this specification, extends to all alternative combinations of two or more individual features mentioned or apparent in the text and / or drawings. All these different combinations constitute multiple alternative aspects of this disclosure. The embodiments described in this specification illustrate the best known mode for implementing this disclosure and will enable those skilled in the art to adopt this disclosure.

Claims

1. A retaining ring, characterized in that, include: The annular body has an inner peripheral wall, an outer peripheral wall, and a grinding surface connecting the top ends of the inner peripheral wall and the outer peripheral wall; The annular body also has a plurality of spaced grooves recessed from the grinding surface, the grooves extending from the inner peripheral wall to the outer peripheral wall and communicating with each other; The width between the two sidewalls of the trench is not exactly the same in the direction perpendicular to the bottom wall of the trench, and the sum of the widths between the bottoms of the two sidewalls of all the trenches is greater than or equal to the sum of the widths between the tops of the two sidewalls of all the trenches. The plurality of said trenches include: The first trapezoidal groove has a first bottom wall and a first opening, and the width of the first trapezoidal groove gradually increases from the first bottom wall toward the first opening in a direction perpendicular to the first bottom wall. The second trapezoidal groove has a second bottom wall and a second opening, and in a direction perpendicular to the second bottom wall, the width of the second trapezoidal groove gradually decreases from the second bottom wall toward the second opening; Wherein, the sum of the width of the first opening of the first trapezoidal groove and the width of the second opening of the second trapezoidal groove is equal to the sum of the width of the first bottom wall of the first trapezoidal groove and the width of the second bottom wall of the second trapezoidal groove; The first trapezoidal groove has a first shape in a cross section perpendicular to its extension direction, and the second trapezoidal groove has a second shape in a cross section perpendicular to its extension direction. The first shape coincides with the second shape after being rotated 180°. The number of the first trapezoidal slots and the second trapezoidal slots are the same, and the first trapezoidal slots and the second trapezoidal slots are adjacent and equally spaced.

2. The retaining ring according to claim 1, characterized in that, The plurality of grooves further include: an expansion groove, wherein the surfaces of the two sidewalls of the expansion groove are arc-shaped surfaces that are concave in a direction away from each other, and the width of the opening of the expansion groove is equal to the width of the bottom wall of the expansion groove; The expansion slot is located between the first trapezoidal slot and the second trapezoidal slot.

3. The retaining ring according to claim 1, characterized in that, The bottom wall of the groove is parallel to the grinding surface.

4. The retaining ring according to any one of claims 1 to 3, characterized in that, The top of the inner peripheral wall of the annular body is provided with a circumferentially extending annular groove, which communicates with a plurality of grooves.

5. The retaining ring according to claim 4, characterized in that, In a direction perpendicular to the grinding surface, the size of the opening of the annular groove is smaller than the depth of the groove.

6. The retaining ring according to claim 1, characterized in that, Also includes: A buffer pad is provided on the inner peripheral wall of the annular body; The thickness of the buffer pad is 0.03mm to 0.08mm.

7. A grinding apparatus for grinding a substrate, characterized in that, include: Abrasive pad; A grinding head is configured to grip the substrate during grinding and press the substrate against the grinding pad for grinding. The retaining ring as described in any one of claims 1 to 6 is mounted on the grinding head and configured to fix the substrate during grinding, wherein the grinding surface of the retaining ring faces the grinding pad; as well as A polishing slurry supply device is configured to provide polishing slurry during polishing, the polishing slurry flowing in and out between the polishing pad and the substrate through the grooves of the retaining ring.

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